Wireless October 1985 85p

68000 computer board

Memory expansion Switched -mode power supply Multi-standard digital terminal

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www.americanradiohistory.com Editor ELECTRONICS PHILIP DARRINGTON Deputy Editor GEOFFREY SHORTER, .Sc. 01-661 8639 Technical Editor MARTIN ECCLES over 70 years inindependent electronics publishing01-661 8638 Projects Editor October 1985RICHARD LAMBLEY 01-661 3039 OR 8637 News Editor HURHUOVolume 91 number 1596 DAVID SCOBIE 01-6618632

MN MINIUM Mlift Nair Mb idMME =NI Drawing Office ROGER GOODMAN 01-6618690 Multistandard digital terminal unit Case study in interface design 58 BETTY PALMER by . Walker 21 by A. Ray Implementing a digital filter with a How the Syscon 6 interface was developed Advertisement Manager microprocessor leads to simple hardware for using Commodore peripherals with a BOB NIBBS, A..I.I. for this programmable modem. BBC computer. 01-661 3130 MICHAEL DOWNING 01-661 8640 The tale of the long -tail pair - part 2 Switched -mode power supply ASHLEY WALLIS by .J. Lidgey 27 by .L. Smith 61 01-661 8641 Further applications ranging from analogue Last part of the instructional series on log/exp circuits, multipliers and dividers, power supplies is a practical design for a Northern and Midland Sales to fast logic gates. 13A, 14V switcher. BASIL McGOWAN 021-356 4838 Group Classified Manager BRIAN DURRANT Half -megabyte memory for SC84 35 Call cost calculator 69 01-661 3033 by J.. Adams by S.A. Cameron Assistant Classified Manager 'Silicon disc' with 256k or 512k of dynamic How the software works and how to reprogram the instrument. MIKE RATCLIFFE memory uses novel refresh technique. 01-661 8161 Classified Supervisor i IAN FAUX The future - what it could hold Digital polyphonic keyboard -2 73 01-6613033 by .. Young 45 by .. Greaves Production Where Britain's hidden strengths exist, Digipoly's .t.l. processor circuit and BRIAN BANNISTER where they are being suppressed, and how microcode program. (Make-up and copy) they could brought to the surface. 01-661 8648 Current issue price 85p, back issues (if available) £1.06, at Retail and Trade Counter, Units 1 & 2, Bankside Industrial 68000 evaluation kit 51 Electronic mailbox Centre, Hopton Street, London SE1. by R.F. Coates by . Allard 77 Available on microfilm; please contact The £100 Kaycomp is Bob Coates 68000 Construction tips and line interface circuits editor. board for engineers, students, and complete this description of an electronic By post, current issue £1.30, back issues message system. (if available) £1.40, order and payments to enthusiasts. EEP Sundry Sales Dept. , Quadrant House, The Quadrant, Sutton, Surrey SM2 5AS. Tel.: 01-661 3378. Editorial & Advertising offices: Quadrant House, The Quadrant, Sutton, iMil , 4110 ill. M.M.Ikal, Surrey SM2 5AD. Telephones: Editorial 01-661 3614. News commentary 4 Feedback - - Advertising 01-661 3130. Swings and swings Electromagnetic paradox 18 Telex: 892084 BISPRS G (EEP) Molecular beam epitaxy Energy transfer *vies I Facsimile: 01-661 2071 (Groups II & III) Optical communication a Beeline (300 baud): 01-661 8978 Spark hazards (Type EWVV to start, NNNN to end). Eftpos comes to High Street Valve preamplifier 68000 computer boar d Subscription rates: 1 year £15 UK and News in brief Relatively interesting £19 outside UK. Student rates: 1 year £10 UK and £12.70 Circuit ideas outside UK. Humidity control 40 Distribution: Quadrant House, The Communications 9 Quadrant, Sutton, Surrey SM2 5AS. commentary Add-on current dumping - Telephone 01-661 3248. RS232 to Centronics British research Mummy expansion Subscriptions: Oakfield House, Interference agro Frequency meter Switebod.mode power supply Perrymount Road, Haywards Heath, Preventing reverse charging Multlstandunl digital tomtits! Sussex RH16 3DH. telephone: 04444 Amateur radio Five -decade op -amp oscillator 59188. Please notify a change of address. NSC800 runs Z80 software USA: $49.40 surface mail, $102.60 airmail. Business Press International Phil Brooker's cover shows (USA). Subscriptions Office, 205 E. 42nd Report New products 81 Bob Coates' 68000 board Street, NY 10017. Television at Montreux; 14 934MHz c.b. transceiver which links to hundreds of USA mailing agents: Expediters of the Satellite broadcasting, Multitasking 6809 with STE bus peripheral cards in the outside Printed World Ltd, 527 Madison Avenue, high definition and the future of Automatic i.c. tester world through its G64 Suite 1217, New York, NY 10022, 2nd class terrestrial tv Control expansion for BBC Micro postage paid at New York. interface. © Business Press International Ltd 1985. ISBN 0043 6062. Trio, quality PMR AOR, monitoring equipment. & surveillance.

TK801S ÁR2002 of the ÁR2001 with Now from TRIO. the eagerly awaited range of high quality. purpose designed, VHF and The NEW ÁR2002 from AOR combines the well known performance are an easier to use press bottom key board, UHF mobile radio transceivers improved operating features. Improvements stepping by knob as well as Built with uncompromising quality in mind. these fully synthesisaed transceivers use a the addition of a signal strength meter, up/down frequency remote control on the canpletely diecast backbone chassis for reliability and ease of use. Up to 32 channels are push button, a headphones lack on the front panel and a socket for 1300 MHz has also been included. held in PROM and frequency changes or additions can be carried but without delay to the rear panel. An additional frequency range from 800 to frequency monitoring/measurement Selective customer. General off air monitoring Spot Detection of unwanted transmis- The transceivers will handle all current frequency allocations including UHF community multi frequency analysis Spectrum surveillance

. . morel repeater channels and. plug in CTCSS modules allow 5 minute installation time with no sions (Bug hunting and much and from 800 to 1300 MHz, in wiring necessary- Frequency coverage is continuous Pram 25 to 550 MHz of AM. FM (wide'). 5r FM (narrow). CTCâ6 encoder/decoder units are available with 3; lose DIP swdch programming, or selectable increments of 5, 12 5. or 25 KHz, and modes spacing A further facility is the ability PROM programming when you wish to allocate different tones on different channels. Any mode can be used at any frequency or channel limits with to law or low to high searching Ifyou deal in radiotelephones, the TRIO range is designed for you Remove your installa- to search between two user programmed high keyboard entry and recall Each - tion and service headaches by contacting the sole distributor right now for further details Twenty memory channels are provided. with easy without any restrictions. The memo- You will not disappointed ory channel stores frequency and mode information' ries can be recalled manually. or may be automatically scanned in sequence for unat- tended monitoring AR2002. monitor receiver £326.09 plus vat. LOWE ELECTRONICS LIMITED Chesterfield Road. Matlock, Derbyshire DE4 5LE -Ihlephonet 0629 2817, 2430, 4057, 4995 Thlex: 377482

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www.americanradiohistory.com COUNTERS & OSCILLATORS LEVELL OSCILLOSCOPES for INSTRUMENTS LEVELL COUNTERS MET100/600/1000 £99/126/175 CROTECH SINGLE TRACE 20MHz 3031/36 £195/216 8 digit 0.5" LED display. 5Hz to 100/600/1000MHz. 2mV-10V /div. 4Ons-0.2s/div. Component tester. Resolves 0.1 Hz. Sensitivity 5mV up to 10MHz. Low pass 3031 CRT 1kV 5x7cm. 3036: CRT 2kV 8x10cm. filter. Mains/rechargeable battery powered. CROTECH DUAL TRACE 20MHz 1@2mV) 3132 £312 LEVELL FUNCTION GENERATORS TG302/3 £156/236 2mV 10V'cm. Ch1±Ch2. -Y mode. Cal 0.2V 1kHz sq. 0.02Hz-2MHz in 7 ranges. Sine, square, triangle, pulse and 40ns-0.2s/cm. Auto, normal or TV trig. Component ramp 20mV to 20Vpp from 50X1. DC offset 01±10V. TTL comparator. DC outputs. input. CRT 2kV 8x10cm. output. TG303 also has a CMOS output and 6 digit 10MHz counter with INT/EXT switch. CROTECH DUAL TRACE 30MHz 1@5mV1 3337/39 £425/570 LEVELL RC OSCILLATORS TG152D/DM £95/120 5mV-50V/cm. Chl±Ch2. Signal delay. X -Y mode. 3Hz-300kHz. 5 ranges, acc 2%+0.1Hz up to 100kHz, 40ns-1 s/cm. Auto, normal or single shot trigger. Cal 0.2V 3% at 300kHz. Sine or square <200A,/ to 2.5Vrms. Distn. 1kHz square. Z input. CRT 10kV 8x10cm. <0.2% 50Hz-50kHz. DM has an output meter. 3339: VDU mode. Component tester. DC outputs.

LEVELL RC OSCILLATORS TG200D/DMP £ 130/165 HAMEG DUAL TRACE 20MHz 1@2mV1 HM203-5 £270 1 Hz -1 MHz. 12 ranges, acc 1.5% + 0.01 Hz to 100kHz, 2mV-20V/cm. Ch2± Ch1 . X -Y. Cal 0.2V/2V 1kHz sq. 2% at 1MHz. Sine or square outputs <204V-7Vrms. 20ns-0.2s/cm. Auto, normal or TV trig. Component test. Distortion <0.05% 50Hz-15kHz. Sync output >1V. DMP CRT 2kV 8x10cm. Long decay CRT £25 extra. has output meter and fine frequency control. HAMEG DUAL TRACE 20MHz 1@5mV1 HM204-2 £365

LEVELL DECADE OSCILLATOR 1 TG66A £330 mV -50V cm. Ch2-+ Ch1 . Sig delay. X -Y mode. Y out. 0.2Hz-1.22MHz. 5 ranges. 4 digits, acc 0.3% 10ns-1.25s/cm. Sweep delay 100ns-1s. Cal 0.2V/2V 6Hz-100kHz. Sine output <3q,V-5Vrms. -2dB/+4dB 1kHz/MHz. Z input. Comp. test. CRT 2kV 8x10cm. and scales. Distn.<0.15% 15Hz-150kHz. Mains/battery. HAMEG DUAL TRACE 60MHz 1@5mV) HM605 £515 1mV.50V/cm. Ch2±Ch1. Sig delay. X -Y mode. Y out. ANALOGUE METERS 5ns-2.5sïcm. Sweep delay 100ns-1 s. Cal 0.2V/2V 1 kHz1 MHz. Z input, Comp. test. CRT 14kV 8x10cm. LEVELL AC MICROVOLTMETERS TM3A/EI £150/170 HAMEG DIGITAL STORAGE 20MHz HM208 £1300 16 ranges 15NVfs/500Vfs, accuracy 1% + 1 %fs+ 1NV. 1mV-50V/cm. Ch2±Ch1. Single shot X -Y modes. - 20dB/+ 6dB scale. ±3dB 1Hz-3MHz. 150mVfs output. and 2Ons-0.25s/cm. 20MHz sampling. Two 2K memories. TM3A: 83mm scale. TM3B: 123mm scale and LF filter. Plotter output 0.1V/cm, 10s cm. CRT 14kV 8x10cm. LEVELL BROADBAND VOLTMETERS TM6A/B HITACHI BATTERY DUAL 20MHz f 235/265 (@5mV) V209 £680 1mV-12V.div, Ch1±Ch2. X -Y mode. Cal 0.5V 1kHz. 16 LF ranges as TM3A/B + 8 HF ranges lmVfs/3Vfs, 50ns-0.5scm. Auto, normal or TV trig. Internal accuracy 4% + 1 %fs at 30MHz. ±3dB 300kHz-400MHz. rechargeable batt. or mains. CRT 1.5kV 5x6.3mm. LEVELL DC MICROVOLTMETER TM8 £130 HITACHI DUAL 20MHz V212/22/23 £299/395/450 23 linear ranges±3NV/±300V and±3pA/±300nA plus 2 1mV-12V/cm. 20MHz@a5mV. Ch1±Ch2. X -Y. Chl log ranges for nulling. Output ±300mV at fs. output. 100ns-0.5s/cm. Auto, normal or TV trigger. Cal 0.5V 1kHz Z LEVELL DC MULTIMETERS TM9ABP £199/235 square. input. CRT 2kV 8x10cm. V222N223: DC offset and alternate magnify. 18 voltage ranges 3NV/1 kVfs. Current ranges 3pA to 1 A V223 : Sweep delay 1Ns-100ms. ITM9A 1mAI. Linear R ranges 30 to 1GO. HITACHI DUAL 40MHz LEVELL MULTITESTER TM11 £175 (@5mV) V422/23 £580/650 As V222N223 but 40MHz, 2Ons/cm and 12kV on CRT. 5C4V/500Vfs ac, 50pA/500mAfs ac, 1504V/500Vfs dc, 150pA/500mAfs dc, 0.20 to 100GO, lin/log null. HITACHI QUAD 100MHz 1@5mV) V1050F £ 1095 Diode/LED test. Optional RF, HV and Temperature. Chl(Ch2: 0.5mV-12V/cm. Trigger Ch3/Ch4: 0.2Vicm. Dual time bases 2ns-0.5s/cm and 2ns-50ms/cm. LEVELL TRANSISTOR TESTER TM12 £195 Signal and sweep delay. CRT 20kV 8x10cm. Transistor, diode and zener leakage to 0.5nA at 2V -150V. Breakdown to 100V at 144A, 100NA, 1mA. Gain at HITACHI QUAD 100MHz V1070/1100A £1580/2390 1NA-100mA. Vsat and Vbe at 1 mA-100mA. 'Ch2: 1 mV-12V/cm. CH3/Ch4: 0.1V-0.5V/cm. Dual time bases 2ns-0.5s/cm and 2ns-50ms/cm. LEVELL INSULATION TESTER TM14 £210 Digital display of set values. CRT 18kV 8x10cm. Log scale covers 6 decades 10MO-10 1-0 at 250V, V1100A: Digital display of ACV, DCV, frequency. 500V, 750V, 1kV; 1M -1T0 at 25V -100V; 100k-100GO LOGIC ANALYSERS at 2.5V -10V; 10k -10G0 at 1V. Current 100pA-1044A. HITACHI DIGITAL STORAGE 10MHz VC6015 £1480 5mV-12Vcm, Ch1±Ch2. Single shot and X -Y modes. THURLBY LOGIC ANALYSERS LA160A/B £395/495 100ns-0.5s/cm. 1MHz sampling. Two 1K memories. DIGITAL METERS 16 data channels. Clock DC-10MHz (20MHz for BI. Plotter output 1V/cm, 5-10s/cm. CRT 2kV 8x10cm. Binary, octal, decimal, or hex. formats. 2K word acquisition memory. Non volatile ref. memory. HITACHI DIGITAL STORAGE 40MHz VC6041 £4400 LEVELL THERMOMETER DIGITAL DT1K £44 1 mV-12V/cm. Ch1±Ch2. Single shot and X -Y modes. - 120°C/+ 820°C, acc 0.2%+1 °C. 3 digit 8.5mm LCD. 20ns-0.5s/cm. 40MHz sampling. Two 4K memories. A standard Type K thermocouple socket is fitted. Bead Plotter output 1V/cm, 2-10s/cm. CRT 12kV 8x10cm. couple is supplied. Battery life >3000 hrs. BENCH POWER SUPPLIES THURLBY 8 CHANNEL MULTIPLEXER 0M358 £179 THURLBY DIGITAL CAPACITANCE METER CM200 £89 Increases any oscilloscope to 8 channels. Choice of trigger 1pF to 25044F, acc 0.2%. 4/ digit 9mm LCD. Fast THURLBY SINGLES PL154/310/320 £159/125/155 from any channel. Response DC-35MHz.

settling. 3 readings per second. Mains/battery. LED digital displays with resolution 10mV, 1 mA. <0.01% change for 50% load change. Remote sense. THURLBY DMMs 1503/1503HA/1504 £169/185/199 154: 0-15V 0-4A. 310: 0-30V 0-1A. 320: 0-30V 0-2A 4% digit LCD. Up to 1 .2kVdc, 750Vac, 10A, 32MO LEVELL DECADE BOXES 4MHz. Resoln. 14V, 10nA, 10mO. Mains battery. THURLBY DUALS PL310QMD/320QMD £269/339 1503: dcV 0.05%. 1503HA: 0.03%. 1504: Tx rms ac. Two 0-30V 0-1A (2A on 320) with isolated, series tracking, series or parallel modes of operation. C410 10pF to 1 1 1, 1 10pF, 1 THURLBY INTELLIGENT MULTIMETER 1905a £349 acc %±2pF £45 R401 14101 4 decades. 1110)0 steps, acc 1% £45 51/2 digit LED. Up to 1 .1 kVdc, 750Vac, 5A, 21M0. THURLBY TRIPLES PL310K/320K £275/345 R601 16101 6 decades. 111010 steps, acc 1% £58 Resoln. 1NV, 1nA, 1mO. dcV 0.015%. Computing and 310K: 0-30V at 0-1A, 0-30V at 1/2A & 4V -6V at 31/2A. R601S : 6 decades. 10 steps, acc 0.3% £69 storage functions. RS232/IEEE interface options. 320K: 0-33V at 0-2A, 0-30V at 1A & 4V -6V at -/A. R701 : 7 decades 1:-) steps, acc 1% £66 FREE DELIVERY IN UK, VAT EXTRA. QUANTITY DISCOUNTS AVAILABLE. Moxon Street, Barnet, Herts., EN5 5SD, England LEVELL ELECTRONICS LTD. Telephone:01-440 8686 & 01-449 5028 CIRCLE 14 FOR FURTHER DETAILS. ELECTRONICS & WIRELESS WORLD OCTOBER 1985 3

www.americanradiohistory.com NEWS COMMENTARY

Swings and swings It's ironic that the electronics knowledge about Nature, some kinds of products is strictly All electronics engineers industry, which has contributed of it very new, into industrial limited. know that the answer to so much to advanced control and domestic products at an If all this only resulted in a instability in a closed -loop technology - giving us such extremly fast rate. And because few financiers, shareholders and control system is damping. It things as automatic blind the gently dozing public is company directors getting their slows down the response of an landing of aircraft and multi- inevitably unaware of the new fingers burnt it wouldn't matter over -reactive chain of cause and variable process control using possibilities offered by these very much. But the worst effect effect. Precise control is microprocessor-can do so little products it has to be woken up is social. The flight of capital, achieved by a careful to control its own business. be advertising and promotion. whether in reduction of combination of proportional, Companies in this field have There is nothing wrong with manufacturing capacity or integral and differential (PID) recently experienced the whole advertising as a means of letting complete shut -down of a plant, terms in the control system gamut of instability, from people know what is available brings social havoc in its wake. equation. If one could apply this uncomfortable fluctuation in on the market. But when it According to an American analogy to an economic system profitability to complete over -persuades a public which study, the resulting it would mean making bankcruptcy. And the . necessarily has no criteria to unemployment brings"... adjustments to achieve semiconductor manufacturing judge the usefulness or psychosomatic illness, anxiety, equilibrium rather than growth. sector is notoriously vulnerable otherwise of entirely new kinds worry, tension, impaired We already have enough to fluctuations in trading. of products, it is doing a bad interpersonal relationships and evidence before our eyes to Yet the basic parameters of service to everyone. The an increased sense of show that the drive for business stability are few, hyperbole even goes to the powerlessness... As self- perpetual economic growth is traditional and well understood. heads of the manufacturers esteem decreases problems of potentially disastrous, socially If you can optimize profit, themselves. But hubris is alcoholism, child and spouse and ecologically. It cannot be operating costs and cash flow, followed by nemesis. We saw it abuse, and aggression sustained and is as unrealistic you are a business -man, my with the over -selling of main- increase." Europeans know this as perpetual motion. It will son. Unfortunately, the big frame computers in the 1960s, too. either result in some kind of unpredictable parameter, the the over-selling of pocket Capital mobility is regarded breakdown in civilisation or, highly independent variable in calculators in the late 1970s and as a technical necessity for a perhaps more likely, in an the control system equation, is we see it in the over -production free-market economy. The unrelievedly painful self-limiting the external one of market of home computers now. At the alternative is often stated to be condition. demand. Here, electronics is worst the public feels it has the rigid bureaucracy and lack An economic system is not a perhaps more vulnerable than been conned. At the best it of enterprise of a centrally - `natural' order or God-given. It many industries. Relying as it signals by passive resistance planned economy, as in certain is man-made, like a does on `high' or leading -edge' that the rate at which it can communist countries. But this servomechanism. It is therefore technology, it is converting consume and digest the new is not so. capable of being stabilized.

possible and multilayer devices wavelength semiconductor laser Molecular beam epitaxy can be made. Thickness and used in optical recording and composition of the layer can be playback systems. Philips Gallium arenside semiconductor on the temperature of the cells. closely monitored by observing Research Laboratories at materials are produced, like The beams can be turned on an the diffraction patterns Redhill have produced lasers silicon, by the growth of off by the use of shutters and produced by a high-energy that can operate at wavelengths cylindrical crystals sliced into the whole system can be electron beam directed at a as short as 707nm, using inter - thin wafers. Unlike silicon, automated with computer grazing angle across the surface band layers as thin as 13nm. though, GaAs devices are not control of the cell temperatures of the layer. The chief advantage is that made directly from these and the shutter operation. One of the first practical these lasers give visible light wafers; they are used as a Abrupt changes in the products to be produced this whereas normal GaAs lasers substrate for the growth of very composition of a layer are way has been the short - operate in the infra -red. The thin layers of gallium arsenide advantage of GaAs over silicon or related alloys. The is the higher mobility of orientation of the layers is electrons, enabling the determined by that of the production of much faster substrate, a phenomenon devices. This has been known as epitaxy. increased even further, using Molecular beam epitaxy, just molecular beam techniques, by emerging from the research the growth of a layer of AlGaAs stage, may be used to grow onto the surface of a high -purity layers with the depth of crystal of GaAs. At the one atom. Molecular beams of intersection of the materials, a the constituent elements, two-dimensional cloud of produced from effusion cells, electrons is found in the gallium impinge on the surface of the arsenide. This has even greater heated substrate to produce the mobility than in normally required epitaxial layer. doped GaAs, and could lead to The growth rate and the production of transistor composition of the layer can be An ultra -high vacuum chamber is needed in this machine for structures able to operate at controlled by the intensity of gallium arsenide molecular beam epitaxy. Philips Research extremely high frequencies, up the beam, which is dependant Labs, Redhill. to 100GHz. 4 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com Eftpos comes to the High Street

Credit or charge -card sales printed out by the terminal. can now be processed on-line in Cresta's Teletran terminal just a couple of seconds using makes use of voice -over -data Britain's first Eftpos system. techniques to exchange signals Eftpos stands for `electronic over the merchant's existing funds transfer at the point of telephone line. Ordinary use of sale', and a system is now the line is unrestricted, but it available from Cresta remains available continuously Communications and British for direct communication with Telecom, initially in the London the central computer and so area. avoids the need for time- The shopkeeper keys in brief consuming dialling. The data details of each transaction on a does not reach the local small data terminal and wipes telephone exchange and is Canon's new T80 autofocusing camera brings the `point and the customer's card through a therefore presumably hacker - shoot' photography of compact cameras to single-lens reflex built-in magnetic reader. The proof: a high degree of security (SLR) cameras, with the benefit of being able to use information is immediately is essential where money is interchangeable lenses. Its liquid crystal `picture selector transferred to a British Telecom concerned. system' allows press -button selection if an appropriate computer which checks it Cost to the retailer is £72 per program for exposure, sharpness detection and autofocusing. against data supplied by the month to rent the terminal, plus The camera has over 28,000 active elements in its i.c. card companies and authorizes 2p per transaction. Cresta, who complement, including a c-mos 8 bit microcomputer, and the purchase (or not) on the have licensed the system to BT, costs £395. spot. A receipt is automatically see a potential market of a quarter of a million terminals; a figure which they expext to includes provision for a Decca Navigator system. increase with the growing use In brief... "reasonable public telephone Anyone with an interest in the of plastic money. By next year service", and if necessary he investigation is invited to give the service is due to be Freefone numbers have only could issue an order to enforce their views or information to he available nationally. been available by asking BT to meet its obligations. the Commission, at 48 Carey exchange operators for the Street, London WC2. number. Now, direct dialling is introduced by the use of dialling The Director -General of Spark hazards codes 0800 and 0345. The Telecommunications has also Although the technical papers Dr Peter Excell, whose work on difference between the two is been called in to arbitrate on are an important part of hazards associated with radio that 0800 numbers are free to the proposed switch from Montreux, (our report starts on induced explosions is the caller; 0345 numbers System X (GEC and Plessey) to page 14) the exhibition floor is wellknown, is one of two charge the cost of a local call System Y ( Ericsson) where visitors spend most of academic staff members (the from anywhere in the UK. digital telephone exchanges. their time. other is Dr Alfred Keller) of the BT, who seem to have an Taking into account the possible The emphasis in the University of Bradford who inexhaustible supply of catchy loss of jobs at GEC and exhibition was firmly on the have received a £33,572 grant names have called this service Plessey, and the possible gain production and programme side from SERC to investigate the LinkLine. It is most likely to in employment at Thorn of television. Of the over 200 possibilty that explosions on oil be used by those service Ericsson in Scunthorpe (where exhibitors only about a dozen or rigs and other major chemical companies who gain much of about 70% of the System Y so were showing broadcast installations could be their business from incoming exchanges will be made); and transmitters. accidentally triggered by radio calls, such as catalogue looking at the possible harm to Digital techniques are playing waves. Although safety companies, travel agents, the export prospects of System an ever increasing role in standards already exist they vehicle hirers, hotels, repair X, Carsberg has come to the programme production. The tend to be unduly restrictive and maintenance companies and conclusion that any further French programme company they assume a number of parts suppliers. shifts of orders from X to Y SFP showed a four -minute tv conditions existing should be gradual, over a period clip which was the world's first simultaneously, including a of three years, and give system demonstration of tv material in spark gap in the presence of a Professor Carsberg of Oftel is X manufacturers the chance to which the production and post - concentrated flammable taking seriously the report in meet reasonable cost and production were done entirely mixture. They believe that the Daily Mail that out of 200 delivery requirements in the by digital means. probability factors could safely public telephone kiosks visited, meantime. Although exhibitors and be taken into account to free 120 of them were out of order. visitors regularly complain radio systems from unnecessary He commissioned a survey from about the cramped facilities at restrictions. NOP which found that 50% of The Monopolies and Mergers Montreux, the picturesque The study will extend to call box users had difficulty in Commission has been asked by lakeside location of the TV related hazards, such as the finding one that worked last the Office of Fair Trading to Symposium and Exhibition will likelihood of radio signals from time they tried and is having investigate the possibility of a continue to ensure that one of low power transmitters setting another to see how long specific monopoly in the supply in the the world's most important tv off electro -explosive detonators boxes are out of action. He UK of marine radio navigation events remains where it has or, interfering with aircraft points out that BT's licence receivers compatible with he been for the last 20 years! guidance systems.

ELECTRONICS & WIRELESS WORLD OCTOBER 1985 5

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Farnell Marconi Packard SSG520 AM/FM Signal Generator £1500 2431A 200MHz Counter C295 ewlett 2437A 100MHz Counter/Timer £395 182T Scope Mainframe £1850 Hewlett Packard £650 1332A Display (As new) £950 214A Pulse Generator 100V £750 2438 520MHz Counter/Timer 1741A Storage Scope £3750 612A UHF Generator 450-1230MHz £950 Racal 1809A 4 channel p/in for 180 £1250 8011 A Pulse Generator £625 9514 100MHz IEEE Counter/Timer £750 1821A Timebasep/in for 180 £750 8007B Pulse Generator 100MHz £1650 Tektronix 8015A Pulse Generator Dual 50MHz £1950 £2000 BRIDGES 212 Portable Scope 500KHz £650 80184 Serial Word Generator ackard 465B/DM44 Scope 100MHz £2400 8601A Sweep Generator £1950 Hewlett £950 42718 Digital LCR Meter C3950 475 e £2750 8600A Digital Marker 4342A '0 Meter £2100 485 Scope 350MHz £5950 8616A Signal Generator 1.8-4.5GHz £4000 Monitor (As New) £950 Marconi Marconi 634/1/20 TF1245A '0' Meter £1200 465B Scope 100MHz £1650 TF2002AS AM/FM Signal Generator £950 £650 466 Storage Scope 100MHz £3500 TF2002B AM/FM Signal Generator £950 TF1246 Oscillator TF1247 Oscillator £650 434 25MHz Storage Scope from £1950 7F2016Á+ AM/FM Signal Generator+ £775 Scope Mainframe £3600 TF2173 Synchroniser 120MHz £1350 TF1313A LCR Bridge 5223 TF2700 Bridge £350 5403/041 Scope Mainframe £1950 £1500 TEKTRONIX 7000 SERIES AF SOURCES TF2702 Inductor Analyser cope am rame Hewlett Packard R7603 Scope M/F (Mint) £2650 4204A Decade Oso (New) £595 GENERAL PURPOSE T & M 7623A Storage Scope M/F £3750 Marconi Aso Multimeters model 8's & 9's £80-£85 7633 Storage Scope M/F £7850 TF2000 Signal Source 20Hz-20KHz £450 Fluke 7704A Scope Mainframe £3200 Wavetek 515A Calibrator £1650 7904 Scope M/F 500MHz £6950 185 Sweep Generator £650 887AB Diff. Voltmeter £1500 7A11 FET P/In C1600 184 Sweep/Function Generator 5MHz C750 C750 7A18 D T Amp C800 166 Pulse/Function Generator 50MHz £1950 931B Did Voltmeter £850 7A19 600MHz Amp £1600 Hewlett Packard 7A24 D T P/In £1950 TEKTRONIX GP T & M EQUIPMENT DMM £1750 7A26 TP/In £1650 AM501 Op Amp 300 3465A DMms £350 7850A Timebase £575 005084 Counter 1.3GHz £995 3468A DMMM £495 7E3534 Timebase £585-£985 DC509 Counter/Timer 135MHz £995 3406A Sampling Voltmeter £1500 7B85 Timebase £925 Digital Delay £500 8405A Vector Voltmeter £2000 Timebase £1435 7B87 DFG501 £200 £725 £1400 DM6Ó11/02 467A Amplifer 7D11 Digital Delay 1 MMHz Function Generator £325 116920 Direct Coupler £1500 7D14 525MHz Ditigal Counter £850 £565 £750 FG502 11 MHz Function Generator Marconi 7M11 Delay Line FG503 3MHz Function Generator £395 6460/1 RF Power Meter £1500 In £1850 7S11 Sampling Plug FG504 40MHz Function Generator £1650 TF2603 RF Millivoltmeter £650 7S14 TDR Sampler £4500 MR501 X -Y Display £200 TF2905/8 TV Pulse Generator £750 7T11 Sampling Timebase £4000 PG501 Pulse Generatorp £330 TF2356 + Sampling Head £950 PG502 Pulse Generator £1650 TF2357A S.L.M.S. £3600 S54 Pulse Generator Head £600 PG505 Pulse Generator £450 TF2807A PCM Tester £1350 ANALYSERS PG506 Calibration Generator £1950 TF2904 Colour Gain Test Set £495 PG508 Pulse Generator £1250 TF2950/5 Radio Test Set £1550 Hewlett Packard C250 Distortion Analyser £850 RG501 Ramp Generator TF2809 Data Line Analyser £950 332A SC501 Scope £500 £1250 1615A Logic Analyser £2500 £900 TF2828 Simulator 8559A Spectrum Analyser Plug-in £8250 SC502 Scope TF2829 Digital Analyser £1250 SC504 Scope £995 Data Monitor £1200 Marconi C525 TF2915 TF2300A Modulation Meter £795 SG502 Signal Generator Tektronix SG504 Signal Generator 245-1050MHz £2100 £8500 TF2330A Wave Analyser £1095 C1750 85640/03 Integrating Unit TF2331 Distortion Factor Meter £695 TG101 Time Mark Generator Curve Tracer £9000 TM501 Mainframe £275 Fixture £1500 Tektronix TM504 Mainframe £375 5787/D1 Curve Tracer £2500 308/01 Data Analyser £2500 TM515 Mainframe £400 C250 308 Data Analyser £2250 177 Fixture (577) £1900 1485R TV Waveform Monitor £4250 7001 /DF2 Logic Analyser COUNTERS & TIMERS Monitor £275 TR502 Tracking Generator £3500 A6901 Ground Isolation TR503 Tracking Generator £4250 7220A Communications Counter 1.3GHz 7D02 opt 01 Logic Analyser £3000 (Quantities available) C595 HEWLETT PACKARD COMPUTERS PMI02 Personality Module £500 £850 1900A Counter80MHz C150 26318 ri PM108 Personality Module Hewlett Packard 72218 Plotter £1200 RF SIGNAL GENERATORS 5341A Microwave Counter 10Hz-4.5GHz £1500 9825A Desktop £2950 + 9862A Plotter £750 E H Labs 5300B C950 139B Pulse Generator 50MHz 10V £750 53058 Counter 1.3GHz £650 9885S Disk Drive Electronic Brokers are Europe's largest specialists in quality Electronic Brokers Guarantee second user test equipment. 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SALE DONUT GO DOWN WITH Due to redevelopment and moving to other premises we shall be selling certain electronic equipment. This sale is for callers only and will include Masts, Scopes, Ariels, Transformers, Meters, YOUR SCOPE! If never Plugs, Sockets, Headsets, Speakers, Signal generators, Test equipment, Pye equipment, Valves, 4CX250B etc. 4CX250B was designed to float bases, Waveguide, Racal recievers, Rechargable batteries etc. This SALE will start around the end of September/beginning October. Please Telephone for further details. ac WlarGrMlil 50 my 2 t1Ì6. 20 A.H.THACKER & SONS LTD 10 HIGH STREET, CHESLYN HAY, WALSALL, STAFFS. TELEPHONE: CHESLYN HAY 413300 isolation amplrlier CIRCLE 37 FOR FURTHER DETAILS.

LOW COST UNIVERSAL PROGRAMMER EPROMS EEPROMS MICROS

Completely self contained unit. Eproms: No personality modules required. 2508/16/32/64 Controlled via RS232 serial interface. 2758 The Waugh Instruments Isolation Amplifier enables Supports Intel, Motorola and Ascii 2716/32/32A/64/64A/128/ you to keep scope and make hex data formats. 128A/256/512/513 your earthed still Easily controlled by most computers. 27C16/32/64/128/256/512 measurements up to 1500V from earth, this to- Fast and standard programming modes. 68732/64/66 Low and high byte programming for 16 bit data. gether with over 100dB rejection at 50Hz means Byte, block and chip erase for Eeproms. Eeproms: that you can now observe small signals super- 2816A/64A 52B13/23/33 48Z02 imposed on 350V sine waves so often encountered Micros: in switch mode power supplies, thyristor and triac Price uncased C295 plus VAT. 8748/48H/49/49H firing circuits. For details of this and other oscillo- Micro Concepts scopes accessories contact Peter Waugh at Waugh Tel: 0242 510525 Instruments, Camhelyg Isas, Glyn Ceiriog,

2 St. Stevens Road Cheltenham Glos GL51 5AA Llangollen, Clwyd LL20 7PB. (069172) 597. CIRCLE 35 FOR FURTHER DETAILS. CIRCLE 92 FOR FURTHER DETAILS. ELECTRONICS & WIRELESS WORLD OCTOBER 1985

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Full colour 40/80 column Teletext video display Serial interface RS422-423 Centronics printer interface User definable characters - double height, width Hardware scroll capability Optional Genlock to external video signal Supports - underline, flashing, reverse video Enhanced teletext character set Stroke set - Pixel graphics Full colour - foreground/background and pallet Occupies only 32 Bytes of system memory 8K Video memory expandable to 16K Software drivers written in PL9 Onboard VIA Input/Output Port

, 44a Hobson Street Cambridge Cambridge C131 1NL Microprocessor ffi.9 11I \\.j (0223) 324141 Limited Systems \ ii

CIRCLE 21 FOR FURTHER DETAILS. Instantresults - No messing Time was when oscilloscope trace recording was a science in itself. The new Shackman 7007 with AutoFilm back* removes the mystery and hands you the results. Perfectly and instantly. No messing. The Shackman 7007 cameras are quality recording systems with a high resolution four element glass lens. Available with either manual or electric shutter they allow aperture settings. from f4.5 to f16. Event triggering is standard on all models and there's a range of film options will catch even the fastest transients. that 11111111111 There's also a vast range of instrument adapters to match all types of q1111111!ppl scope. And because all Shackman 7007 cameras have a factory set image - Utl0pp1101uu 0111110 to -object ratio, there's no fiddling around with focusing. r Now all you do to record that trace is swing the 7007 in front of the screen. set the shutter speed and activate the trigger. Hey presto! The Polaroid AutoFilm back ejects the finished print. Perfect. With so many features to read about, you'll need the new colour brochure. Send for your copy now.

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Name Position Organisation Shackman Address 7007 Fits all known scopes. Telephone Shackman Instruments Ltd PO Box 23, Waterside Chesham. Bucks HP5 1 PH Telephone (0494) 784451 Telex: 837265 L CIRCLE 22 FOR FURTHER DETAILS, ELECTRONICS & WIRELESS WORLD OCTOBER 1985 8

www.americanradiohistory.com COMMUNICATIONS COMMENTARY

studying oceanography it is American broadcasters employment offered by the DTI British URSI difficult to dispel the suspicion depended on direct -disc when the service was that the objective could be to recording. transferred from British research topics locate submarines from the There are broadcast Telecom. Even after some fresh The 1985 one -day "National disturbances they create at the engineers still working who recruitment the present staff is Radio Science (URSI) surface. recall using the Marconi -Stille only about 240 compared with Colloquium" held in London The idea of these URSI machines with large spools 340 under BT. under the auspices of The Royal symposia seems excellent, but containing up to 2700 metres of There is little doubt that Society provided an opportunity they do tend to highlight the special Swedish steel tape that domestic interference to catch up with the many tendency of British universities sped by the heads at 1.5m/sec. investigation has been difficult university, Rutherford Appleton and establishments to ignore Lafferty points out: "Editing to justify in terms of cost - Laboratory and British Antarctic work carried on elsewhere in the recorded tapes could be benefit. A high proportion of all Survey studies in the subjects the world - the old "not accomplished through the complaints have been due to covered by nine URSI invented here" syndrome. This tedious and cumberous process ineffective aerials, receiver commissions: electromagnetic is markedly different from the of cutting the tape with tin faults, or so infrequent that the metrology; fields and waves; intense Japanese interest in shears, then soldering or spot- investigation teams have been signals and systems; electronic what is happening in Europe welding the tapes together. unable to observe, let alone and optical devices and and the USA. This has now led Edited tapes could be trace, the interference. The applications; electromagnetic to American industry seeking dangerous, since if a splice introduction of c.b. into the UK noise and interference; remote more engineers versed in the broke during transmission the significantly increased the sensing and wave propagation; Japanese language in order operator risked being slashed number of viewer complaints, ionospheric radio and better to monitor Japanese by the flying steel tape as it though in practice such propagation; waves in plasmas; science and engineering spun." interference, when involving and radio astronomy. publications of which only about The BBC adopted the bulky "legal" c.b. operation, reflected The presentations included a fifth are currently translated Blattnerphone machines at the the poor immunity of many wide-ranging surveys, plus into English. start of the Empire Service in television sets, and could informal talks by young 1932 when "time -shift" became usually be cured by a simple scientists on particular projects, Flying tape essential. Blattner's company filter fitted to the receiver. It including a lively presentation The recent IEE 50th went into liquidation in 1933 could be claimed that the by Dr Lorna Robertson of anniverssary of radar seminar after their failure to interest the existence of the free -services film The later Glasgow University on the so - was only one aspect of the industry. provided by RIS encouraged far unseccussful attempt to increasingly serious interest in Marconi -Stille machines were set -makers to pay little heed to detect gravitational waves the history of electronics smaller, more reliable and immunity. Retailers have which may, if ever detected, technology. The 25th provided better quality. tended to leave it to the finally prove or disprove anniversary (May 15, 1985) of The BBC also adopted the specialist skills of the RIS teams Einstein's theories to the the first demonstration at Philips -Miller film system of or simply to tell customers that chagrin of so many writers of Hughes Research Laboratories, sound recording, mechanically interference problems are the letters to the editor of this Malibu, California by T.H. cutting away an opaque coating fault of the transmitter or journal! Maiman of a working laser did on the film, later using a photo- appliance. British regulations P. Wells (RSRE) described not go unnoticed, although electric cell for high -quality are also very lax in regard to military work on compact, what was once "a solution reproduction. However both spectrum pollution by industrial film recorders transportable satellite terminals awaiting a problem" is now steel tape and equipment, home computers so fof"digital slow -scan tv. Dr P. increasingly regarded aS aC were expensive to operate and the like. Cudd (Sheffield University) solution to military rather than that use was also made of The DTI are, in effect, now described efforts to direct civilian problems. direct -disc recorders, including copying the FCC approach in microwave energy further into A detailed paper by Claud the portable machines used by the provision of a detailed free the body to permit the use of Powell in the IERE Journal the war reporters. German booklet providing good hyperthermia techniques for (June 1985) traces the early work on plastics -backed tape, explanatory advice to viewers/ deeper -seated malignant history, from its conception in leading to the modern tape listeners together with technical tumours with the aifd of phased 1937, of the Decca Navigator recorder, came about to avoid guidance for dealers (it is arrays. system based on the work of having to import the special questionable whether these fit Dr Peter Bradley (RAL) William O'Brien and Harvey Swedish steel. well into a single booklet). reviewed the many research Schwarz. They had great The DTI also intend to projects in the field of difficulties in getting the system Interference incorporate BS905, Part 2 of ionospheric propagation, though adopted in the USA. This led to which provides recommended it is clear that the $64,000 its important but largely aggro minimum immunity standards question of predicting the time unrecorded role (as "QM") in The decision of the Department for television sets, into legally - and shape of future sun -spot the Normandy landings of June of Trade and Industry to binding regulations. This is cycles remains essentially 1944, following secret trials discontinue its free service to good news for amateurs, c.b.- unsolved. between Anglesey and the Isle viewers who complain of radio ers and anyone operating Prof. E.D.R. Shearman and of Man. and television reception transmitters in residential Dr Lucy Watt of Birmingham An SMPTE historical paper problems, and instead to areas. Unfortunately, BS905 University reported on the work by William Lafferty "The use of concentrate its diminished Part 2 currently stipulates on h.f. sea-state radar. This steel tape magnetic recording resources of the Radio immunity tests to be carried out has now abandoned the use of media in broadcasting" similarly Investigation Service on only on signals between 26- pulsed emissions at 1.9MHz in shows that while the "pirate" operation and spectrum 30MHz, though it is to be favour of f.m. - c.. Blattnerphone and Marconi - abuse, it a logical, though in hoped that a set which shows emissions between 6.7 and Stille machines, both stemming some ways regrettable, move. good immunity to such signals 40MHz that do not spread over from the work of Curt Stille, It was made essential because will be reasonably immune to more than about 20kHz of were widely used in Europe of the many members of RIS signals on other frequencies spectrum. Although this project throughout the nineteen -thirties who were unwilling to accept (though not necessarily for is presented as a tool for and early nineteen -forties, the relatively poor terms of 144MHz and above). A real

ELECTRONICS & WIRELESS WORLD OCTOBER 1985 9

www.americanradiohistory.com Electronic Brokers Test & Measurement Instrument Distribution Disvision AUTHORISED DISTRIBUYO For the Leading Brands of Electronic Test & Measurement Equipment Thandar, From Philips, Fluke, Iiameg, ICE, Lyons, Colin, Compact Instruments Thurlby, GP Industrial, Claude OSCILLOSCOPES Fluke 8026B £172 I.C.E. 680G £25 MISCELLANEOUS 3'12 digit, LCD, eight functions include 48 measuring ranges, sensitivity 20Kn/V, DC conductance, audible continuity, true RMS. DC accuracy 2%, 10cm mirror scale, overload PRODUCTS accuracy 0.1%, all 20 series DMMs have 2 year protection. warranty. I.C.E. M80 £19 Fluke 8020B £173 40 measuring ranges, sensitivity 20Kn/V, DC accuracy 2%, wide range of accessories extend 3112 digit, LCD, eight functions include conductance, diode test, audible continuity, DC measuring capabilities. accuracy 0.1%, extensive over -load protection. PULSE, FUNCTION, Fluke 8021B £139 3112 digit, LCD, seven functions include diode test PATTERN GENERATORS Thandar TH 302 £80 and high speed audible continuity, DC accuracy £155 Thandar digital thermometer LCD display of °C Philips PM 5503 and °F, range to 1100°C, resolution 0.25%, safety test leads provided. patterns for mono and -40°C Pattern generator. 5 test 0.1° and 1', for use with type K probes (bead Fluke 8022B £114 colour, video output for CCTV and monitors, RF supplied). 3112 digit, LCD six functions include diode test, output in VHF and UHF range. 1 kHz tone for Philips PM 3206 £286 DC accuracy 0.25%, optional accessories sound checks. 15MHz, compact portable, dual trace, 5mV available to enhance all OMM measuring Thandar TG 101 £110 sensitivity, auto and TV triggering, variable time capabilities. Function generator 0.02Hz to 200kHz, sine, base speed, Z modulation. FlukeJF77 £110 square, triangle, variable DC offset, TTL output, external sweep, 1 OVpp output into variable 3112 digit. LCD with analogue bar graph, auto/manual ranging, DC accuracy 0.3%. touch 600n. and hold facility, supplied with carrying holster. Thandar TG 102 £160 Function generator 0.2Hz to 2MHz, sine, Fluke JF 75 £88 square, triangle. TTL output, variable DC offset, 3112 digit, LCD with analogue bar graph, external sweep, 20Vpp output into variable 50n, auto/manual ranging. DC accuracy 0.5%, seven Thunder TG 105 £105 functions include diode test and audible Pulse generator 5Hz to 5MHz, 10nS, amplitude continuity. 0.1V to 10V into 50n, free -run, gated or Thurlby OM 358 £179 Fluke JF73 £72 triggered modes. TTL output, pulse width Thurlby multiplexer expands any oscilloscope to 3112 digit, LCD with analogue bar graph, auto variable 100nS to 100mS. 8 channels, displays analogue or digital signals, ranging, DC accuracy 0.7%, six functions Thandar TG 501 £295 triggering from any channel, band width 35MHz, include diode test, all 70 series OMMs have 3 Function generator 0.005Hz to 5MHz, sine precision calibrated attenuator. year warranty. square, triangle, ramp, pulse, TTL, variable DC offset, variable start/stop phase, 20Vpp into Fluke JF 25 £193 variable 50n. 3112 digit. LCD with analogue bar graph, sealed ruggedized construction, auto ranging, DC Hameg HM 203-5 £270 accuracy 0.1%. touch -hold facility, extensive COUNTERS & 20MHz, dual trace, add and invert, maximum overload protection. sensitivity 2mV, automatic and normal COUNTER/TIMER triggering, X -Y operation, component tester Thandar SC 110A £175 10MHz, battery powered portable, bright line and economy triggering for battery conservation. TV frame and line triggering. Sensitivity 10mV to 50V. Thurlby CM 200 £89 BENCH & HANDHELD Thurlby digital capacitance meter, 4112 digit LCD, 1 pF to 2500NF range. accuracy 0.2%, fast DMMs battery or mains operation. Thandar TF 200 £175 settling, Counter, 10Hz to 200MHz. 8 digit LCD, battery powered, 10 mV sensitivity, time average period totalize and reset. TP 600 pre -scaler, 40MHz to 600MHz available at £45. Thandar PFM 200A £76 Fluke JF 27 £216 Counter, 20Hz to 200MHz, 8 digit bright LED, 3112 digit, LCD with bar graph, ruggedized battery powered, 10mV sensitivity, resolution construction, auto ranging, DC accuracy 0.1%, 0.1 Hz, selectable gate times, mains adaptor and touch -hold facility, min -max and relative mode TP 600 pre-scaler available. operation. Thandar TM 351 £115 POWER SUPPLIES Philips PM 2519/01 £299 3'12 digit, LCD. 29 ranges of measurement. DC Thurlby PL 154 £159 Tachoprobe £70 4112 digit. LCD with analogue bar accuracy 0.1%, diode test. battery life typically 0 to 15V, 0 to 4A, bench power supply, twin Compact tacho -probe for use with DMMs or graph, auto/manual ranging, 4000 hours, complete with batteries and test LED displays meter voltage and current, high frequency counters, 2 speed ranges from 100 frequency to 1MHz, true RMS, dB, leads. stability and resolution, remote sense facility. to 20,000 RPM, accuracy 1%, non -contact relative reference. range 1m. Thandar TM 451 £195 £7 4'12 digit, LCD display with function legends. EB90 Philips PM 2518X/11 £199 auto/manual ranging, DC accuracy 0.03%, x 1 oscilloscope probe. 4 digit, LCD with electroluminescent sample/hold facility on all ranges, audible EB91 £10 display, auto/manual ranging, true continuity. x 10 oscilloscope probe. RMS, dB, relative reference, current £13 Thandar TM 355 £85 EB95 to 20A. PM 2518X/01 without x 1 and n 10 oscilloscope probe. illumination E145. 3'12 digit, 0.5" bright LED, 29 ranges of £243 measurement. DC accuracy 0.25%, battery or Fluke 8010A diode check, supplied with test LINE CONDITIONERS 10A range, seven mains operation, 3112 digit, LCD, current leads. Claude Lyons LVC 250 £271 functions include conductance, diode test, true 2.5A, 600VA rating. line voltage conditioner. 0.1%. Ni -Cd battery RMS, DC accuracy 8010A fast response (typically 1112 cycles), isolated version £279. input/output, compact and portable for easy Fluke 8060A £ 306 ANALOGUE installation. 4112 digit. LCD, ten functions include Claude Lyons LVC 65 £186 test, continuity, dB. MULTIMETERS conductance. diode Thurlby PL 320 £155 0.65A, 156VA rating, line voltage conditioner, frequency, true RMS. OC accuracy 0.04%. £165 unaffected by frequency variations, transient relative reference mode. Philips PM 2505 0 to 30V, 0 to 2A, bench power supply, constant 62 measuring ranges, 10Mn input impedance, current or constant voltage. precise current limit and noise suppression. All LVC units have 2 year Fluke 8062A £245 ranges, audible continuity. warrantly. functions include diode linear resistance control and monitor system. ripple and noise 4'12 digit. LCD, seven automatic polarity indication, low power test and continuity, relative reference, DC <1mV. test. consumption. Thurlby PL 310 £125 EPROM PROGRAMMERS accuracy 0.05%, true RMS, self diagnosis 141 £88 Fluke 8024B £220 I.C.E. 680R £32 0 to 30V. 0 to 1A. bench power supply, meter GP Electronics UV 0.1%. resolution 0.01 V and 0.001A, EPROM eraser, variable electronic timer. 3'12 digit. LCD, eleven functions include peak hold 80 measuring ranges, sensitivity 20Kn/V. DC accuracy load regulation <0.01% for powerful source, 14 on voltage and current, audible and visual logic accuracy 1%, 12cm mirror scale, overload DC output switch, convenient loading with safetyaevice interlock. rlo level detection, DC accuracy 0.1%. protection. 50% load change. try all products are on Electronic Brokers are leading suppliers of electronic test & measure- Visitors are welcome to our showrooms where wishing to order by phone, we ment equipment. Our Distribution Division handles the major names in the display and demonstration. For customers industry and all products are stocked in depth in our spacious new premises offer a 24 hour answering service. Town, ready for prompt despatch to all parts of the country. All prices are exclusive of VAT and correct at time of going to press. at Camden items unless otherwise stated. Electronic Brokers offer full technical support and expert advice on all Carriage and packing charges extra on all is on request. aspects of electronic test and measuring. A copy of our trading conditions available [I._ Electronic Brokers Ltd 11 i J i_ c- o l L I ,,C=> L n [ _} l 140-146 Camden Street London NW1 9PB Electronic Brokers L_ L) r f 1. I Telephone 01-267 7070 Telex 298694 CIRCLE 43 FOR FURTHER DETAILS. . www.americanradiohistory.com COMMUNICATIONS COMMENTARY

problem, however, will communications network" and planning is too valuable an asset many never reach the stage of continue to exist in the case of for the new "Milstar" network to be lost, yet is an area where coming on air. It is uncertain wideband r.f. amplifiers that are which is intended to be proof manifestly it must be seen to be whether this is due to the cost fitted to devices intended for against neclear electromagnetic fair to all. of equipment, restriction to use in countries with both pulses (NEMP) and on which morse only, or the crowded v.h.f. and u.h.f. television and the US is spending some $400 - state of the novice segments of particularly susceptible to million per year. Even EMP- RAE attacked h.f. bands. American amateurs strong local amateur signals on protection however will not Richard Harris, G3ZWH, head holding higher grades of licence 70, 144 and 430MHz or necessarily prevent disruption of physics at Harrogate College, are being urged to do more to broadcast signals on 95MHz. of communications over an has delivered a strong attack on provide encouragement and The real loss both to extended period in the event of the Radio Amateurs' guidance to the "novices". amateurs and broadcasters is a nuclear attack or the use of Examination run by City & An RSGB "National HF that of the diplomacy of the RIS anti -satellite weaponry. Guilds of London Institute. He Convention" is being held on teams in settling fairly the complains in particular of the Sunday, September 29 at the disputes and social problems refusal of CGL1 to allow actual Belfry Hotel, Milton Common, that arise. While the new examination papers to be Oxford with a crowded booklet does emphasise that it Amateur published or even taken out of programme of lectures, is usually the receiving the examination room and the demonstrations, talk -in installation that is at fault it is Radio unsuitability of many of the stations, "car boot sale" etc. It often virtually impossible for an questions which often will also be possible to take, by amateur or c.b. operator to concentrate on basic theory prior appointment, the official convince an irate neighbour that SSB on 10.1MHz? rather than the principles and morse test... RSGB president this is the case. It could prove practice of amateur radio. He for 1986 is to be W.J. As a morse enthusiast initially, an expensive business for a suggests that the RAE should McClintock, G3VPK... Welsh I welcomed the idea of keeping viewer to call in a dealer to recognize that fewer candidates Amateur Radio Convention is the narrow 10.1 to 10.15MHz trace and cure some of the have prior experience as short- on October 6 at Oakdale band more intractable interference free not only of contest wave listeners and need to ben Community College, operation but also of s.s.b. This problems, and pressure will be encouraged to learn more about Blackwood, Gwent... The form of bandplanning to which put on the amateurs and c.b. the practical aspects of two-way second Yeovil QRP (Low operators to close down. the RSGB became committed at radio communication. He Power) convention is on an early stage, was later objects to the absence of a fixed October 13 at The Preston endorsed by the IARU Region 1 "pass mark" and strongly Centre, Monks Dale, Yeovil.. . C41- Costly CCCI Bureau but depends on believes that "the present A large numer of RAE courses voluntary restraint as, at least situation must not be allowed to began in September at adult The Americans, over the past in Europe, it is not written into continue" - reflecting education centres.. . two decades, have spent the licence regulations. comments that have been made The Radio Amateur Old of on billions dollars strategic There has, however, always over several years in E&WW. Timers Association (RAOTA) command, control, been a valid case for using a and the Dutch Old Timers Club communications and small segment of this band, In are holding activity mornings information (C3I) systems which has interesting "chordal brief (0830 to 1130 GMT) on to provide instant and voice designed hop" propagation along the Good two-way contacts October 6 and 7 on 3.5 and secure access to military twilight "grey -line" paths as a were made from the UK with Dr 7MHz (initial contacts on commanders throughout the result of ionospheric tilts as the Tony England, WOORE on 3600kHz)... The worldwide world. Yet today, it is Fl and F2 layers combine at board the August Challenger Jamboree -on -the -Air takes place that has also increasingly recognized dawn and dusk. The belief that space -shuttle flight. It on October 19 and 20... The many of the projects have c.w./r.t.t.y. operation with its been claimed that the RSGB Royal Navy Amateur Radio turned sour primarily because high average power duty cycle headquarters station at Potters Society celebrates its 25th of the pursuit of ideal rather causes less interference to Bar was the first amateur anniversary and will operate than practical systems. The commercial point-to-point station in Europe to receive GB4KRN throughout October crucial world-wide military communications is hardly a frames of slow -scan television from Tonbridge, Kent... The command and control system tenable theory. The s.s.b. pictures from the shuttle. RSGB Midlands VHF (WWMCS) comprises more than enthusiasts claim that October 27 marks the 50th Convention is at Madeley 60 different communications telephony, with good operating anniversary of the day in 1935 Court, Centre, Telford, on systems linking 27 command Nell G2YL made discipline, enables experimental when Corry, October 12.. . centres under the control of 20 data to be obtained rapidly. It is radio history by working all six In a letter to The Lancet, J. million lines of Cobol software also the case that the absence continents on 28MHz in a single Seager of the Arrowe Park and 35 ageing Honeywell Series of s.s.b. has tended to keep day. Transatlantic contacts on Hospital, Upton, Wirral has 6000 computers. American amateur activity on the band this band had been made in commented on the leukaemia journals suggest that the low. 1928-29 but the declining sun- risks that have been linked with system suffers extensively from There are signs that the spot cycle then resulted in non -ionizing electromagnetic down -time and has failed badly IARU restriction is breaking several years when virtually no radiation in such occupational on several occasions, including down in several countries, long-distance stations were groups as electronic the putting out of a nuclear including the UK - although contacted, until sun -spot assemblers, television attack alert when a war -games the s.s.b. operators are subject activity began to increase again. repairmen and radio amateurs. program got into the main to abuse. Is it not time that this At 9 a.m. she contacted He points to the need for more Colarado neclear warning subject should be reconsidered VU2IJ, Assam; 10.30 a.m. precise analysis of the apparent centre, and a record of dismal with a view to providing an VK4BB Queensland, Australia; risk factors and their relation to failures during real crises in the s.s.b. segment? The alternative 11 a.m. CX1CG Uruguay; the fluuxes and tin/lead alloy 1960s and 1970s. Currently may prove to be a loss of followed by Europe, Africa and used in soldering or the fumes three main up -grading projects confidence in the concept of the USA all before 3.30 p.m. given off during soldering by the are under way for WWMCCS, "voluntary" band plans drawn Less than half of American overheating of synthetic materials. for the slightly less ambitious up by largely self-perpetuating "novice" licence holders renew "minimum essential emergency committees. Voluntary band - or upgrade their licences and PAT HAWKER, G3VA

ELECTRONICS & WIRELESS WORLD OCTOBER 1985 11

www.americanradiohistory.com 01-208 1177 TECHNOMATIC LTD 01-208 1177 DISC DRIVES BBC Micro Computer System TECHNOMATIC drives are fitted with high quality slimline Mitsubishi mechanisms and are available with or without integral mains power supply. The dual drive power supplies are switch BBC Computer & Econet Referral Centre mode type and are generously rated. All drives with integral power supply are fitted with a mains indicator. BBC Computers: All drives are supplied with all the necessary cables, manual and a formatting disc. All drives are capable of operating in single or double density modes. Model B: £299 (a) B+DFS: £346 (a) Single Drives: With integral psu. Model B+Econet: £335 (a) B+Econet+DFS £399 (a) 1 X 100K 40T : TS100 £85(b) PS100 £120(b) 1 x 400K 80/40T - TS400 £125(b) PS400 £145(b) BBC B Plus (available from stock) £409 (a) Dual Drives: (with integral psu) ACORN 2nd Processors: 6502: £175 (a) Z80: £348 (a) Stacked Version: Plinth Versions: TORCH UNICORN: Z80 Card: £299 (a) Z80 Disc Pack: £550 (a) PD200 2 x 100K 40T SS £190(a) PD200P £215(a) PD800 2 x 400K 80/40T DS £265(a) PD800P £289(a) TORCH Graduate G800/2 £869 (a) Note: We can supply drives with Shugart mechanisms at considerably lower prices. Please phone for 20 Mbyte Hard Disc+400K Floppy: £1950 (a) details. 3.5" Drives: TS35 1 x 400K 80T DS £99(b) a We stock the full range of ACORN hardware and firmware and very wide TD35 2 x 400K 80T DS £175(b) range of other peripherals and firmware for the BBC. For detailed specifications and pricing please send for our leaflet. The mechanisms are 80 track double sided and are capable of both single and double density operation. Authorised Distributor PRINTERS Data Recording Products 3M EPSON: RX80T+£210 (a); RX100+£345 (a); 3M FLOPPY DISCS FX80+£315 (a); FX100+£430 (a);JX80 Full Colour Printer £499 (a) Industry Standard floppy discs with a lifetime guarantee Discs in packs of 10 EPSON LX80 £219 (a); Optional Tractor Feed £20 (c) 40 Track SS DD £13 (c) 40 Track DS DD £18 (c) KAGA TAXAN: KP810 £235 (a); KP910 £339 (a) 80 Track SS DD £22 (c) 80 Track DS DD £24 (c) BROTHER: HR15 £310 (a); JUKI 6100 £299 (a). 3z" discs. Pack of ten £38 (c) BUFFALO 32K Buffer for Epson Printers £75 FLOPPICLENE DRIVEHEAD CLEANING KIT FLOPPICLENE Disc Head Cleaning Kit with 28 disposable cleaning discs ensures continued ACCESSORIES optimum performance of the drives. £14.50 (b) EPSON. FX80 plus sheet feeder £129(b) Paper Roll Holer £17(d) FX80 Tractor Attachment £37(c). DRIVE ACCESSORIES Interfaces: 8143 RS232 £28(c); 8148 RS232 + 2K £57(c); 8132 Apple ll £60(c); Single Disc Cable £6 (d) Dual Disc Cable £8.50 (d) 8165 IEEE + Cable £65(c). 10 Disc Library Case £1.80 (d) 30 Disc Storage Box £6 (c) Serial & Parallel Interfaces with larger buffers available. 30/40 Disc Lockable Box £14 (c) 100 Disc Lockable Box £16 (c) Ribbons: RX/FX/MX80 £5.00(d); RX/FX/MX 100 £10(d); LX80 £6(d); FX80 Dustcover £4.50(d); LX80 Tractor Unit £20(c); Spare pens for HI80 £7.50/set(d) MONITORS KAGA TAXAN: RS232 Interface + 2K buffer £78(c);p Ribbon KP810/910 £6(d) MICROVITEC 14in. & 20in RGB JUKI: RS232 Interface £65(c); Spare Daisy Wheel £14(d); Ribbon £2.50(d); Sheet Feeder 1431 Std Res £185 (a); 1431 Ap std Res PAL/Audio £205 (a); £182(a) Tractor Feed Attach £129(a) 1451 Med Res £240 (a); 1451 AP Med Res £280 (a); 1441 Hi Res £389 (a); BROTHER HR15: Feeder Ribbons Carbon or Nylon £4.50(d) Sheet £189(a) Swivel Base for Plastic 14"Microvìtecs £20 (c) Tractor Feed £99(a) 2030CS Std Red £380 (a); 2040CS Hi Res £685 (a) BBC Printer Lead: Parallel (42") £7(d); Serial £7(d) Plinth for 14in. Monitors £8.50. Printer supplied to any other length. Leads can be Microvitec Monitors with TTL/Linear Inputs also available. Plain Fanfold Paper with extra fine perforation (Clean Edge): 2000 sheets 9.5" X 11" £13(b) 2000 sheets 14.5" x 11" £18.50(b) SANYO CD 3125 NB 14in. RGB Std Res £159 (a) KAGA TAXAN 12in. RGB Labels per 1000s: Single Row 3-" X 1 7/16" £5.25(d) Triple Row 2-7/16" X 1 7/16" £5.00(d) Vision II Hi Res £225 (a); New Vision Ill plus £360 (a) BT Approved Modems Green Screens; KAGA 12G £99 (a); SANYO DM811 12CX £95 (a); for (c) MIRACLE WS2000: Swivel Stand Kaga Green £21 SOFTY II BBC Leads: KAGA RGB Microvitec £3.50; Monochrome £3.50 (d) The ultimate world standard BT approved modem covering £5 all common BELL and CCITT standards up to 1200 Baud. This low cost intelligent Allows communication with virtually any computer system in eprom programmer can PRINTER BUFFER UV ERASERS provides a simple way to the world. The optional AUTO DIAL and AUTO ANSWER program 2716, 2516, This printer sharer/buffer UV1 T Eraser with built-in timer and mains indicator. upgrade a multiple computer system by providing boards enhance the considerable facilities already provided 2532, 2732, and with an Built-in safety interlock to avoid accidental exposure greater utilisation of available resources. The buffer on the modem. Mains powered. £129 (c) Auto Dial Board/ adaptor, 2564 and 2764. to the harmful UV rays. offers a storage of 64K. Data from three computers Auto Answer Board £30 (d) each (awaiting BABT approval). Displays 512 byte page on can be loaded into the buffer which will continue It can handle up to 5 eproms at a time with an average Software lead £4.50 TV has a serial and par- accepting data until it is full. The buffer will automati- - erasing time of about 20 mins. £59 + £2 p&p. BUZZBOX: allel I/O routines. Can be cally switch from one computer to next as soon as UV1 as above but without the timer. £47 + £2 p&p. The computer This pocket sized modem complies with V21 300/300 Baud used as an emulator, cas- that computer has dumped all its data. For Industrial Users, we offer UV140 & UV141 era- then is available for other uses. LED bargraph indi- and provides an ideal solution for communications between sette interface. sers with handling capacity of 14 eproms. UV141 has cates memory usage. Simple push button control users, with main frame computers and bulletin boards at a Softy Il £195.00(b) a built in timer. Both offer full built in safety features provides. REPEAT, PAUSE and RESET functions. very economic cost. Battery or mains operated. £62 (c) Adaptor for 2764/ (a). UV140 £61, UV141 £79, p&p £2.50. Integral power supply. £205 Mains Adaptor £8 (d) BBC to Modem data lead £7 2564 £25.00 Cable set £30. ATTENTION CONNECTOR SYSTEMS All prices in this double page advertisment are subject to change without notice. AMPHENOL TELEPHONE ALL PRICES EXCLUDE VAT I.D. CONNECTORS EDGE CONNECTORS CONNECTORS (Speedblock Typet 36 way plug Centronics Please add 50o unless 4 -way 110p carriage No of Header Recep Edge CONNECTORS (solder 500p (IDC) 475p plug indicated as follows: ways Plug adle Conn 36 way skt Centronics 6-way plug ...... 180p 10 Sop 85p 120p 01 0156 (solder) 550p (IDC) 500p 6-way rt ang.skt .. 160p (al £8 (b1 £2.50 ¿cl £1.50 (dl £1.00 195p 20 145p 125p 2- 6.way(commodore) - 300p 24 way plug IEEE (solder) 26 175p 150p 245p Flexible cable 2 c 10-way 150p 475p (IDC) 475p 34 200p 160p 320p 2 x 12.way Iv,c 201 350p 4 -way 50p/m ACORN IEEE INTERFACE way IEEE 40 220p 190p 340p 2 x 18 -way 140p 24 skt (solder) 72p/m A of the IEEE -488 standard, pro- 6-way full implementation 50 235p 200p 390p 2 x 23 -way (2%81) 175p 220p 500p (IDC) 500p viding computer control of compatible scientific & 2 x 25 -way 225p 220p PCB Mtg Skt Ang Pin RIBBON CABLE technical equipment, at a lower price than other sys- 2 x 28 -way (Spectrum) 200p - 24 way 700p 36 way 750p D CONNECTORS 2 x 36 -way 250p - (grey/metre) tems. Typical applications are in experimental work 1 No of Ways x 43way 260p - 10-wáy 40p 34 -way 160p in laboratories. The inter- 2x22way 190p GENDER CHANGERS academic and industrial 15 - 16 -way 60p 40 -way 180p 9 25 37 2 x 43 way 395p 25 way D type a network of up to 14 other compati- 20 -way 85p 50 -way 203p face can support MALE: 1 x 77 way 400p 500p 120p 64 -way would typically link several items of 2 x 50.waylslo0conn, 600p 26 -way 280p ble devices, and Ang Pins 120 180 230 350 Male to Male £10 test equipment allowing them to run with the opti- Solder 60 85 125 170 Male to Female ... £10 ROM is IDC 175 275 325 DIL HEADERS mum of efficiency. The IEEE Filing System - EURO CONNECTORS Female to Female £10 supplied £282. FEMALE: Solder IDC St Pin 100 140 210 380 14 pin 40p í00p Ang Pins 160 210 275 440 DIN 41612 Plug Skt RS 232 JUMPERS 16 pin 50p 110p INDUSTRIAL PROGRAMMER Solder 90 130 195 290 2 X 32 way St Pin 230p 275p (25 way DI 18 pin 60p - IDC 195 325 375 - 2 x 32 way Ang Pin 275p 320p 24' Single end Male £5.00 20 pin 75p EP8000. St Hood 90 95 100 120 3 X 32 way St Pin 260p 300p 24 Single end Female £5.25 24 pin 100p 150p 24" Female Female £10.00 This CPU controlled Emulator Programmer is a pow- 3 x 32 way Ang Pin 375p 400p Screw 130 150 175 - 24" Male Male £9.50 28 pin 160p 200p erful tool for both Eprom programming and develop- Lock IDC Skt A + B 400p 24" Male Female £9.50 40 pin 200p 225p ment work. EP8000 can emulate and program all IDC Skt A + C 400p as stand eproms up to 8Kx8 bytes, can be used TEXTOOL ZIF For 2 x 32 way please specify DIL SWITCHES MISC CONNS alone unit for editing and duplicating EPROMS, as a SOCKETS 24 -pin £7.50 spacing (A + B, A + C). 4 -way 90p 6 -way 105p 21 pin Scart Connector 200p slave programmer or as an eprom emulator £695(a) 1213 -pin £9.00 40 -pin £12.00 8 -way 120p 10 -way 150p 8 pin Video Connector 200p Using 'Prestel' type protoco s. For information TECHNOLINE SYSTEM. TEL: 01-450 9764 and orders - 24 hour service, 7 days a week

12 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com 74 SERIES 74273 2.00 74LS259 1.20 74C SERIES 4076 0.65 74276 1.40 74L5260 0.75 4077 0.25 LINEAR ICs COMPUTER COMPONENTS 7400 74278 1.70 7475261 1.20 74C00 0.70 4078 7401 0.25 AD7581 12.00 LM710 0.48 T84641 - TMS450014,00 KEYBOARD 54279 0.90 74L5266 0.60 74004 EPROMS 75161 3.50 7402 0.50/ 4081 0.24 LM711 1.00 E351 4.00 TMS9901 5.00 74283 1.05 74LS273 1.25 5000808 11.90 75162 4.00 ENCODERs 7403 4069 4081 0.24 AM7S10- LM723 0.60 TBA231 1.20 1802CE 6.50 TMS9902 5.00 74742 3.20 74LS279 0.70 2516.5V 3.50 75172 3.00 7404 74008 0.70 4082 0.25 TBA800 0.80 2650A 10.50 TMS991118.00 4752376 11.50 74290 0.90 7475280 1.90 DC 25.00 LM725CN 3.00 2516.35 5.50 74010 0.70 4085 0.60 6502 4.50 TMS991414.00 75182 0.90 4753600 7.50 7405 74293 7478283 AN -150501.00 LM733 0.65 T85810 0.90 2532 4.50 0.90 0.80 74014 55E62 21.712 00 75188 0.60 74C922 5.00 7406 0.50/ 4086 0.75 AV.3-1350 3.50 7M741 0.22 TBA20 0.80 2532-30 5.50 74298 1.80 7470290 0.80 40106 4584 4089 1.20 65024 6.50 Z80PI0 2.50 75189 0.60 74C923 6.00 7407 74351 AV -3-8910 4.90 LM7747 0.70 TBA820M 0.75 2564 8.00 2.00 74LS292 9.00 74020 0.70 4093 0.35 65028 8.00 Z80APIO 2.75 75365 1.50 7408 743654 AV -3-3912 5.00 7M748 0.30 TBA920 2.00 BAUD RATE 0.80 7470293 0.80 74C32 1.00 4094 0.90 6800 2.50 Z80CTC 2.50 75450 0.80 7409 74366A CA30'9A 1.00 7M1011 4.80 TBA950 2.25 6802 3.00 2708 4.50 GENERATORS 0.80 74L5295 1.40 74C42 1.50 4095 0.90 Z80ACTC 75451 0.50 7409 CA3020 3.50 LM1014 1.50 TC9109 5.00 68032 12.00 2.75 2716.5V 3.50 74367A 0.80 74L5297 9.00 74048 1.50 4096 75452 0.50 MC14411 7.50 7410 0.90 CA3028A 1.10 LM1801 3.00 TCA210 3.50 6809 6.50 280DART 6.50 2716 35 5.50 74368A 0.70 74L5298 1.00 74C73 75453 0.70 COM8116 7411 1.00 4097 2.70 CA3046 LM1830 2.50 TCA220 3.50 6809E 10.00 6.50 74376 1.60 74LS299 2.20 0.70 2732 4.50 75454 0.70 47028 7412 74C74 1.20 4098 0.75 CA3059 3.25 LM1871 3.00 104270 3.50 68809 10.00 7804DART 7 00 77325-2 9.50 7.50 74390 1.10 7470321 3.70 74C76 75480 1.50 7413 1.00 4099 0.90 CA3060 3.50 LM1872 3.00 TCA940 1.75 681309E 12.00 Z8ODMA 7.00 UARTF 74393 1.20 74733224 3.90 74083 2.00 4501 0.36 68000478 36.00 75491 0.65 7414 CA3080E 0.70 LM1886 6.00 TDA1004A 5.00 Z80ADMA 7.50 2732A 30 6.00 74490 1.40 7475323 3.00 74085 8035 3.50 75492 0.65 7416 2.25 4502 0.55 CA3085 1.50 7M1889 4.50 TDA1010 2.25 4731015P 7475324 3.20 80C35 6.00 27324 35 5.50 8T26 1.20 3.00 7417 74C86 0.50 4503 0.36 CA3086 0.60 7M2917 3.00 TDA1022 4.50 Z80ASI07.00 AV51013P 74L5348 2.00 2764.25 2.60 8128 1.20 3.00 7420 74C90 1.90 4504 0.95 CA3089E 2.50 LM3302 0.90 TDA1024 1.10 /0/2/9 COM8017 3.00 7475 74L0352 1.20 8039 4.20 27C64'2510.00 8195 1.20 7421 SERIES 74C93 1.50 4505 3.60 CA309040 3.75 7843900 0.80 TDA1170S 3.00 27128-253.50 4.50 74L5353 1.20 80C39 7 00 Z808PI0 5.00 8196 1.20 1M6402 7422 74C95 1.60 4506 0.90 CA3130E 0.90 LM3909 1.00 TDA2002 3.25 74L5356 2.10 80804 420 Z808CTC 5.00 8197 1.20 7423 747500 0.24 740107 1.00 4507 0.35 CA3130T LM3911 1.80 TDA2003 1.90 MODULATORS 74L5363 1.80 1.30 8085A 3.00 2808DART 9.00 77128-307.50 8198 1.20 7425 747501 0.24 740150 5.00 4508 1.20 CA3140E 0.45 7M3914 3.50 1052004 2.40 7/256 74L5364 1.80 800854 7.50 2520 00 81L595 1.40 6MHZ 7426 74L502 0.24 740151 2.00 4510 0.55 LM3915 3.40 TDA2006 3.20 3.75 74L5365 0.50 CA31401 1.00 21256 30 20.00 81LS96 1.40 7427 747003 0.24 740157 2.50 4511 0.55 TDA2020 3.20 8MHZ 4.50 74L5366 0.50 CA3146 2.25 LM3916 3.40 8086 22.00 27512 P.O.A. 817597 747004 0.24 740160 1.80 4512 0.55 TDA2030 2.50 1.40 7428 74L0367 0.52 CA3160E 1.50 LM13600 1.50 8088 17.50 7M52716 5.00 81L598 1.40 SOUND 8 VISION 747505 0.24 740161 1.80 4513 1.50 M515137 TDA2593 5.00 7430 74L5368 0.50 CA3181E 2.00 2.30 8741 15.00 MEMORIES 88L5120 3.00 7432 747508 0.24 740162 1.80 4514 1.10 CA3162E 6.00 M515167 4.50 TDA2653 7.00 8748 16.00 12MHZ 12.00 74LS373 0.90 CRT 9602' 3.00 7433 747009 0.24 740163 1.80 4515 1.10 CA3189E MB3712 2.00 TDA3560 7.50 TMS1601 12 00 2016-1504.00 74L5374 0.90 2.70 9636A 1.60 1333=113311 7437 747510 0.24 74C173 1.00 4516 0.55 MC1310P 1.50 TDA3810 7.50 2101 4.00 CONTROLLER 74L5375 0.75 CA3240E 1.50 9637AP 1.60 32 768KHZ 1.00 7438 747511 0.24 740174 1.50 4517 2.20 053280G MC1413 0.75 TDA7000 3.50 TMS9980 14.50 2102 2.50 74L5377 1.30 3.00 CRT5027 16.00 100MHz 2.70 7439 747512 0.24 740175 1.50 4518 0.48 MC1458 0.45 1E41002 7.00 TM59995 12.00 5.00 9638 1.90 7470378 0.95 D7002 6.00 2107B CRT5037 12.00 1.8432MHz 2.25 7440 747513 0.34 740192 1.50 4619 0.32 MC1495 3.00 TL061CP 0.40 2111A-35 4.00 7475379 1.30 0AC1408-83.00 Z80 2.50 0916545 9.00 2.00MHz 2.25 7441 74LS14 0.50 740193 1.50 4520 0.60 77062 0.60 21142 3.50 7475381 4.50 DAC0800 3.00 MC1496 0.70 Z80Á 2.90 EF9364 8.00 2.457605Hz0LI 7442A 747015 0.24 740194 1.50 452' 1.15 TL064 0.90 2114 2.50 7470385 3.25 DAC0808 3.00 MC3340P 2.00 EF9365 25.00 2.00 7443A 747020 0.24 740195 1.50 4522 0.80 TL071 0.40 DG308 3.00 MC3401 0.70 ZBOB 5.50 DISC 2 45760Mhz1Sl 74L5390 0.60 740221 2.50 4526 EF9366 25.00 7444 74L521 0.24 0.70 HA1366 1.90 MC3403 0.65 17072 0.70 Z80H 7.50 2147 4.00 CONTROLLER 74LS393 1.00 74C244 EF9367 36.00 2.50 7445 747022 0.20 2.00 4527 0.80 C771136 17074 1.10 IC 7415395A 1.00 6.75 MF100N 4.10 MC6845 6.50 6 2 5MHz 2.50 7446A 741.524 0.50 74C245 2.25 4528 0.65 C77611 TL081 0.35 4116 2.00 7475399 1.40 0.95 MK50240 9.00 MC68455P 6.50 2.662MHz 1.75 7447A 747526 0.24 740373 2.25 4529 1.00 17082 0.55 4116-20 1.50 7654 13.00 74L5445 1.80 C77650 4.00 MK50398 11.00 MC6847 6.50 3.276MHz 1.50 7448 74LS27 0.24 740374 2.25 4531 0.75 17083 0.75 6843 8.00 7475465 1.20 C77660 2.50 ML920 5.00 SFF96364 8.00 3.5795MHz1.00 7450 747528 0.24 740902 1.20 4532 0.65 17084 74L5467 1.20 C780=38 4.00 ML922 4.00 1.00 41256-207.50 TMS9918 15.00 8271 P.O.A 4.00MHz 1.50 7451 74L530 0.24 740911 9.00 4534 3.80 CM7216822.00 17094 2.00 SUPPORT 41256-157.50 8272 13.00 7475490 ISO MM6221A 3.00 TMS9928 10.00 4194MHz 2.00 7453 74L532 0.24 740912 4.50 4536 2.50 TL170 0.50 DEVICES 7475540 1.00 CM7217 7.50 NE529 2.20 TMS992910.00 FD1771 20.00 4.43MHz 1.00 7454 747033 0.24 740922 6.00 4538 0.75 4164.1511 74L5541 1.00 CM7555 090 NE531 1.20 TL430C 1.20 3.00 4 608MHz 2.50 74LS37 0.24 740923 6.50 4539 0.75 2651 12.00 7460 74L5608 7.00 CM7556 1.40 NE544 1.90 UAA1003-39.35 4164 2.00 FD1791 20.00 4 9152MHz2.50 7470 74L538 0.24 740925 6.50 4541 0.90 UA759 3242 8.00 7475610 19.00 LC7120 3.00 NE555 0.22 3.20 4164-20 2.00 INTERFACE F01793 20.00 5.00MHz 1.50 747540 0.24 740926 7.50 4543 0.70 3245 4.50 7472 74LS612 19.00 LC7130 3.00 NE556 0.60 UA2240 1.20 4416-15 3.50 ICs 5.068 1.75 7473 747542 0.50 4551 1.00 LC7131 3.50 NE564 UAA170 1.70 6520 3.00 4532-20 2.50 F01791 22.00 74L5624 3.50 4.00 407581i 15.00 6.00MHz 1.40 7474 74L543 1.50 4553 2.40 LC7137 NE565 1.20 UCN4801A 4.00 6522 3.50 WD1691 15.00 74L5626 2.25 3.50 A00080811.90 6.144MHz 1.40 7475 74L547 0.80 4555 0.36 7E347 1.20 NE566 1.50 ULN2001A 0.75 4816AP/3 2.00 7475628 2.25 74ALS SERIES 6522A 5.50 AD561J 20.00 7 00MHz 1.50 7476 747548 0.90 4556 0.50 7E351 0.60 NE567 ULN2002A 0.75 5101/55014.00 W02143 12.00 7470629 1.25 1.25 6532 4.80 AM25510 3.50 716MHz 1.75 7480 747549 1.60 7447000 0.45 4557 2.40 7E353 0.90 NE570 4.00 ULN2003A 0.75 5514/01144.00 W02793 27.00 7475640 2.00 6551A 6.00 AM25LS2521 3.50 8 00MHz 1.50 7481 74L551 0.24 744L502 0.45 4560 1.40 7E355 0.90 NE571 ULN2004A 0.75 5516 5.00 W02797 27.00 7475640.13.00 3.00 6821 1.50 AM25L52538 3.50 8.867MHz 1.75 74834 747554 0.24 744L504 0.50 4566 1.40 LF356N 1.10 NE592 ULN2068 2.90 5517AP 6.00 7475641 1.50 0.90 68621 2.50 AM26L531 1.20 10 00MHz 1.75 7484A 74L555 0.24 7447008 0.50 4568 2.40 7F357 1.00 NE5532P ULN2802 1.90 74L5642 2.50 1.50 AM26L532 1.20 C*..RAC 10.50MHz 2.50 7485 74LS73A 0.30 74L5642-13.00 7447510 0.45 4569 1.70 LM10CLH 4.50 NE5533P 1.60 ULN2803 1.80 6829 12.50 6116P-3 3.50 TER 66791000 25.00 GENERATORS 1070MHz 1.50 7486 7475744 0.35 74LS643 2.50 7447020 0.45 4572 0.45 7M30 IA 0.30 ULN2804 1.90 6840 3.75 6116LP-3 3.50 NE5534P 1.20 04080- 11.00MHz 3.00 7489 74L575 0.45 74LS643-1 3.00 744L532 0.45 4583 0.90 7M307 0.45 NE5534AP 1.50 UPC575 2.75 68840 6.00 6264-1212.00 081-V 28.00 R032513UC 7.50 12 00MHz 1.50 7490A 7475764 0.36 74L0644 744L074 0.70 4584 0.48 LM3080N 0.75 OP-07EP 3.50 UPC592H 2.00 6850 1.60 62649.15 7.50 3.50 DM8131 6.00 R032513LC 7.00 14 00MHz 1.75 7491 747578 0.42 744L5138 1.50 4585 0.60 LM310 2.25 UPC1156H 3.00 68850 2.50 6264LP-155.00 7475645 2.00 PLL02A 5.00 DP8304 3.50 14.31MHz 1.60 74924 747583,4 0.70 74L545-1 4.00 744L5139 1.50 4724 1.50 LM31 0.60 UPC1185H 5.00 RC4136 0.55 DS3691 3.50 REAL TIME 14 756 74934 747585 0.75 744L5244 4,00 14411 7.50 LM318 1.50 XR210 4.00 6852 2.50 6514-45 4.00 2.50 74L5668 0.90 RC4151 2.00 DS8830 1.40 CLOCK 15 00MHz 7494 747086 0.35 74475245 4.75 14412 7.50 XR2206 4.50 6854 6.50 2.00 74L5669 0.90 LM319 1.80 RC4195 1.50 6810 1.60 058831 1,50 16.00MHz 7495A 747090 0.48 744L5573 2.60 14416 3.00 X92207 3.75 68B54 8.00 745189 1.80 MC6818P 4.00 2.00 74L5670 1.70 LM324 0.45 RC4558 0.55 DS8832 1.50 17.734 1.50 7496 747091 0.90 744L5574 4.50 14419 2.60 XR2211 5.75 6875 5.00 745201 3.50 65817014 9.90 7470682 2.50 LM334Z 1.15 S566B 2.20 058833 2.25 18.00MH2 1.50 7497 74L592 0.35 7475683 744L5580 2.60 14490 4.20 XR2216 6.75 8154 8.50 74S289 2.25 MSM5832R5 3.50 3.00 LM335Z 1.30 550240 9.00 DS8836 1.50 18.432MHz 1.50 74100 74L593 0.54 74LS684 14495 4.50 XR2240 1.20 3.50 4000 SERIES LM336 1.60 SAA1900 16.00 8155 3.80 058838 2.25 TELETEXT 19.969MHz1.50 74107 7475958 0.75 74L5687 3.50 145000 6.50 LM339 0.40 SFF96364 8.00 ZN404 1.00 93415 6.00 07002 i.00 747096 8156 3.80 DECODER 20.000MHz1.50 74109 0.90 7470688 3.50 4000 0.20 14599 2.00 LM3413 0.60 57490 3.00 ZN414 0.80 937422 7.50 MC1488 0.60 7470107 8205 2.25 24.000MHz1.75 74110 0.40 7475783 21.00 4001 0.24 22100 3.50 LM358P ZN419P 1.75 93425 6.00 MC1489 0.60 SA45020 6.00 0.50 SN76013N 3.00 8212 2.00 48.000MHz1.75 74111 7470109 0.40 4002 0.25 22101 7.00 ZN423E 1.30 MC3446 2.50 SAA5030 7.00 LM377 3.00 SN76023N 3.00 8216 1.60 116MHz 2.50 74116 7470112 0.45 74S SERIES 4006 0.70 22102 7.00 LM380N-8 1.50 SN76033N 3.00 ZN424E 1.30 MC3459 4.50 SAA5041 16.00 7470113 0.45 40014 0.48 MCS3470 4.75 PX01000 12.00 74118 4007 0.25 LM380N 1.50 SN76115N 2.15 ZN425E8 3.50 8224 P.O.A SAA5050 9.00 74119 7475114 0.45 74500 0.50 4008 0.60 40085 1.20 MC3480 8.50 LM381AN 1.70 SN76489 4.00 ZN426E8 3.00 8226 4.25 PROMO 74120 7470122 0.70 74S02 0.50 4009 0.45 40097 0.36 MC1496 0.70 SN76495 4.00 ZN427E8 6.00 MC3486 2.25 VOLTAGE 74121 7470123 0.80 74SO4 0.50 4010 0.60 40098 0.40 LM383 3.25 SN76660 1.20 ZN428E8 4.50 8228 5.50 MC3487 2.25 REGULATORS 74122 74L0124 1.40 74005 0.50 4011 0.24 40100 1.50 LM384 2.20 SP0256- ZN429E8 2.25 8243 2.60 28L22 4.00 MC4024 5.60 74123 7470125 0.50 74508 0.50 4012 0.25 40101 1.25 LM386N-1 1.00 AL2 7.00 ZN447E 9.00 8250 9.50 24510 2.50 MC4044 5.50 IA FIXED VOLTAGE PLASTIC 10220 74L5126 0.50 40102 180030 74125 74510 0.50 4013 0.36 1.30 LM387 2.70 SP8515 7.50 ZN449E 3.00 2.00 MC14411 9.00 4VE - 74L0132 0.65 40103 82515 3.25 1854030 2.00 7905 74126 74511 0.75 3014 0.60 2.00 LM389 1.80 TA7120 1.20 ZN450E 7.50 MC14412 7.50 50 7805 0.45 0.50 74128 74L5133 0.50 74520 0.50 40104 8253C-5 3.50 745188 1.80 6V 7806 0.50 7906 0.50 4015 0.70 1.20 LM391 1.80 TA7130 1.40 ZN459CP 3.00 75107 0.90 74132 74L5136 0.45 74522 0.50 40105 1.50 8255AC-5 3.20 745287 2.25 80 7808 050 7908 0.50 4016 0.36 LM392N 1.10 TA7204 1.50 ZN1034E 2.00 75108 0.90 127 7812 0.45 7912 0.50 74L5138 0.55 74530 0.50 40106 8256 18.00 745288 1.80 74136 4017 0.55 0.48 LM393 0.85 TA7205 0.90 ZNA1040 6.60 75109 1.20 15V 7815 050 7915 0.50 74LS139 0.55 74532 0.60 40107 8257C-54.00 740387 2.25 18V 7818 7918 0.50 74141 4018 0.60 0.55 LM394CH 4.00 TA7222 1.50 ZNA134J 23.00 75110 0.90 0.50 74142 74L5145 0.95 74537 0.60 0.60 40108 3.20 82523 1.50 24V 7824 0.50 7924 0.50 4019 LM709 0.35 TA7310 1.50 ZNA234E 9.50 8259C-5 4.00 75112 1.60 74143 74L5147 1.75 74538 0.60 40109 0.80 825123 1.50 1A FIXED VOLTAGE PLASTIC 7092 4020 0.80 8271 P.O.A. 75113 1.20 74144 74L5148 1.40 74S40 0.50 4021 0.60 40110 2.25 825129 1.75 8275 29.00 75114 1.40 5V 78705 0.30 5V 79705 0.45 74145 74L5151 0.65 74S51 0.60 40110 2.25 6V 70706 0.30 12V 79712 0.50 4022 0.70 8279C-5 75115 1.40 74.47 74L5152 2.00 74564 0.45 40147 2.80 4.80 BV 78706 0.30 15V 79715 0.50 4023 0.30 EE PROM 75121 1.40 74148 74L5153 0.65 74S74 0.70 40163 8282 4.00 12V 78712 0.30 4024 0.48 1.00 75122 1.40 15V 78715 0.50 74150 74L5154 1.60 74085 40173 Please note all prices are 3.00 4025 0.24 1.20 8284 4.60 2816-3015.00 75150P 1.20 74151A 747S155 0.65 74586 1.00 40174 1.00 4026 0.90 subject to change without 8287 3.80 2K x8 30.00 75154 1.20 OTHER 74153 74L5156 0.65 745112 1.50 40175 1.00 4027 0.40 8288D 9.50 9306 256 b115 75159 2.20 REGULATORS 74154 74L5157 0.50 745113 1.20 40192 1.00 notice. 4028 0.60 87554 16.00 116x16) 4.50 75160 5.00 74155 74L5158 0.65 745114 1.20 4029 0.75 40193 1.00 F1444 R.9ul.t4r. 74701604 751309K IA 51/ 1.40 74156 0.65 745124 3.00 4030 0.35 40194 1.00 O H 71.182311 3A 51./ 3.50 74157 74751614 0.75 745132 1.00 40244 4031 1.25 1.50 78110514C 5A 511 SAO 74701624 0.75 745133 285777 0.50 74159 0.60 4032 1.00 40245 1.50 0.125" 781112 5A 120 6.40 74160 74751634 0.75 740138 1.80 40257 BPX25 1.80 0.2" 701,05 10A 50 9.00 4033 1.25 1.80 RED TIL209 0.12 74161 74L5164 0.75 745139 1.80 40373 1.80 BPW21 2.90 111.220 015 VARIABLE REGULATORS 4034 2.50 GRN 11L211 0.18 TIL222 LM305A11 250 74162 74751654 1.10 740140 1.00 40374 Only current prime grade 00971 1.80 0.18 4035 0.70 1.80 SEL TIL 212 0.20 71.13177 TO -220 1.50 74751664 1.50 743151 ORP12 1.20 TIL226 0.22 74163 1.50 4036 2.50 80095 0.75 components stocked. Red LEDs 75131711. T03 340 74164 74L5168 1.30 745153 1.50 80097 0.75 ORP60 1.20 LM337T 2.35 4037 1.10 (9/0/Y) 0.30 74165 74LS169 1.00 745157 2.00 80098 0.75 ORP61 1.20 COUNTERS 11.13501 10.4E 0.46 4.00 4038 1.00 COO I31 Colour) LM396K 100a0AR 15.00 74166 7470170 1.40 740158 2.00 SFH205 1.00 4040 0.60 1.00 74C925 11.023N 030 74167 74L0173A 1.00 745163 3.00 T1L32 055 8.50 78111-105KC 5A 50 575 4041 0.55 10 LED 74170 74L0174 0.75 745169 5.50 11778 0.55 74C926 6.50 7811GIC 5A+0AR 6.50 4042 0.50 BarGrapn 78GUIC tAfVAR 74172 74L5175 0.75 745174 3.00 TIL 3113 120 74C928 6.50 4043 0.60 Red 2.2S 7911GICC 5A -VAR 6.75 74L0181 2.00 TIL81 72168 22.00 74173 740175 3.20 1.20 79GUIC IA -VAR 2.50 74L5183 4044 0.60 Grn 225 ZN1040 6.70 74174 1.90 745188 1.80 4045 1.00 TIL 100 0.75 SWITCHING REGULATORS 74L5190 0.75 We also stock ICL7660 2.50 74175 745189 1.80 4046 0.60 MAN6610 2.00 9.13974 74L5191 0.75 D15PLAr5 3.50 $03524 3.00 74176 745194 3.00 4047 0.60 N585881 LM3915 74L5192 0.80 5.70 3.50 T1494 3.00 74178 740195 3.00 4048 0.55 t.00 117311 LM3916 3.50 17497 3.00 74L5193 0.80 a wide range of FND357 6.50 74179 74S196 3.50 4049 0.36 FN0500/ TIL729 1.00 0056118 3.20 78540 2.50 74701944 0.75 RC4195 50 74180 745200 4.50 4050 0.35 TIL730 1.00 117730 1.00 0056184 3.20 74181 74L0195A 0.75 745201 3.20 4051 0.65 FN0507/ MAN8910 1.50 ULN2003 0.90 OPTO -ISOLATORS 74182 74L5196 0.80 74S225 Transistors, Diodes, 5.20 4052 0.60 117729 1.00 ULN2004 0.90 74LS197 0.80 MAN8940 2.50 74184 745240 4.00 0.60 MAN74/ ULN2068 2.90 IL074 130 ulnl 0.70 74L5221 0.90 4053 741854 745241 4.00 4054 0.80 0L704 1.00 DISPLAY ULN2802 1.90 17074 2.20 TIL 112 0.70 74L0240 0.80 745244 Triacs Plastic, 1.10726 1.00 TIL113 74190 4.50 4055 0.80 MAN71/ DRIVERS U' -N2803 1.80 0.70 74L5241 0.80 745251 MC52400 1.90 TIL116 74191 2.50 4056 0.85 DL707 1.00 ULN2804 1.90 0.70 74L5242 0.90 MOC3020 ISO 74192 745257 2.50 MAN3640 1.75 9368 4.50 75491 0.70 6N137 3.60 74L0243 0.90 4059 4.00 Bridge Rectifiers, 74193 74S258 2.50 4060 0.70 MAN4640 2.00 9370 4.50 75492 0.70 614139 1.75 74194 74L5244 0.80 745260 1.00 74LS245 1.10 4063 0.85 74195 745261 3.00 4066 0.40 LOW PROFILE SOCKETS BY TI WIRE WRAP SOCKETS BY TI 74196 7470247 1.10 745283 2.70 Thyristors and Zeners. 74L5248 1.10 4067 2.30 74197 745287 2.25 4068 0.25 8pin 9p 8p1n 16p 24p1 24p 18p in 50p 24pin 70p 74L5249 1.10 8pin 25p 74196 745288 2.00 4069 0.24 14pin 10p Opin 18p 28pi 26p 14pin 35p 20pin 60p 28pin 80p 74199 74L5251 0.75 74S289 2.25 16pin 2pin 7470253 0.75 4070 0.24 II 209 40pi 30p 16pIn 40p 22pin 65p 40pin 100p 7474221 74S299 4.50 4071 0.24 Please phone for details. 74L5256 0.90 74S373 4.00 74251 4072 0.24 TURNED PIN 74259 74LS2457A0.70 745374 4.00 8pin 25p 16pin 35P 20pin 45p 28pin 65p 4073 0.24 LOW PROFILE SKTS 14pin 30p 18pin 40p 24pin 55p dOpin 90p 74265 74752584 0.70 745387 225 4075 0.24

PLEASE ADD 50p p&p & 15% VAT TECH NOM ATIC LTD (Export: no VAT, p&p at Coso MAIL ORDERS TO: 17 BURNLEY ROAD, LONDON NWIO LED Orders from Government Depts. & Colleges etc. welcome. SHOPS AT: 17 BURNLEY ROAD. LONDON NWIO anell2ZIo Detailed Price List on request. 0.1 922800 ITL'\ 208 1177 4 lines) Telex: Stock items are normally by return of post (II 305 EDGWARE ROAD. LONDON W2 Minimum 'telephone Order £5 CIRCLE 51 FOR FURTHER DETAILS.

ELECTRONICS & WIRELESS WORLD OCTOBER 1985 13

www.americanradiohistory.com by Nigel Cawthorne already use PAL, according to . Hsu Chung-ming, there is no significent reason to go for a Television at MAC transmission system through China's d.b.s. satellite. Terrestial rebroadcast stations will take the signal Montreux from the satellite receiver and retransmit it over the local Satellite dishes are now as area. China's d.b.s. satellite much a part of broadcasting will thus be used as a direct as studio cameras and tv feed for a large number of re- transmitters. broadcast transmitters. Tv coverage will be provided for remote mountainous regions which could not be economically serviced by a terrestial transmitter network alone.

Arabsat

In a supporting paper, NIr Shaweesh from Jordan outlined the speed with which developments have taken place in the field of satellite communications during the past 20 years, with particular emphasis on the emergence of

.. regional satellite systems such as the European ECS and Arabsat. The Arabsat project dates back to a meeting of Arab Satellite broadcasting, high -definition and the Ministers of Information in Tunisia in 1967, when it was future of terrestrial television discussed at decided to initiate a study for developing communications in biennial symposium the Arab world including the development and interchange of This year's Montreux TV band (11-14GHz) as opposed to at the same time. tv and radio braodcasting Symposium, the 14th in the C -band (4-6GHz) included the China's current terrestrial tv services. series, brought together over protection of microwave links, transmission network consists Mr Shaweesh explained that 200 exhibitors from 16 the eventual requirement for of 455 main transmitter stations Arabsat offered the only facility countries. There was an provincial beams, and C -band and over 9,000 repeaters with for real-time broadcast coverage international programme of 67 orbit congestion, which, with powers below 1kW. The of major events in the Arab presented and 35 supporting two -degree orbital spacing present network covers just world. Arabsat is seen as an papers covering both tv limits the use of small receiving 64.7% of the 1 billion important broadcast tool both broadcast and c.a.tv topics. On antennas. population. DBS is the key to for use within the Arabsat world the transmission side, d.b.s. East satellite will have "5 -for - providing high -quality radio and as well as for the exchange of and h.d.tv were front-line 2" transposer redundancy. The tv services for the whole material with the non -Arab topics. transposer power will be 230- population of China. world. 250W at the orbital position of A single beam will cover the Shaweesh touched on the 92 degrees East, which is one whole of China, and the problems of d.b.s. and how Chinese DBS of the three (62°E, 80°E and proposed beam -shaping will technological advances since 92°E) WARC-77 positions permit densely populated areas 1977 had outdated the China Broadcast Satellite allocated to China. The earliest to use 1.5m dishes for 'grade 4' provisions of WARC-77. In Corporation president, Mr Hsu eclipse time at this position is community reception, or about particular, improvements in Chung-ming, outlined the at 01.09 Beijing Time: tv 1.0m dishes for 'grade 3.5' satellite receiver front end necessity for establishing d.b.s. transmissions will not take individual reception. Under performance have meant that as the key to the realization of place because of the power clear sky conditions, a 0.75m d.b.s. can be achieved with national tv and radio coverage requirements of the dish is expected to provide lower transmitted power from for the whole of China. He transponders. 'grade 3.5' performance in the satellite for a given antenna announced that some important One satellite will act as a these areas. In the sparsely size or alternatively that smaller technical decisions for China's spare, but it will operate on a populated areas of northwestern receive antenna dishes become new satellite tv services had different pair of channels to the China, 2m dishes will be used practical for a given radiated been taken. main, so that in -orbit -testing of for community reception. power. Mr Shaweesh concluded China plans to have two co - the spare can be made without PAL will be used for that "we are in a period of located satellites in orbit interfering with the main transmission. Since studio extraordinary change in a field operating in Ku -band. Reasons satellite. If necessary, all four equipment and rebroadcast that was considered settled in given for the selection of Ku - channels could be switched on transmitter equipment in China 1977".

14 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com Terrestrial tv lives on Robson advocated that the opportunity for a true Even though there is much worldwide standard would come heated discussion around ,- with the next generation of satellites and how they are ;.,.- . systems and not the present. going to revolutionise tv ?PAL E3'.6 The next generation of tv transmission, terrestrial tv 110 standards would be digital and transmitters are likely to remain free from the present the major carriers for much of constraints of 50/60Hz the world well into the next a ` - .. compatibility. Such a standard century. could then be the standard for Rudi Gressmann, EBU, in a the next fifty years or so. PAL I _-:-SECAM lecture on the history of the -- - _ _-- _--- Robson said that today's talkk development of terrestial tv _- ---- of a standard was not a real transmission in Europe, told world standard. Robson's SÉCAML ==TT . opening remarks were later to delegates that within the EBU __ :X__ A. ter area there are currently some be fiercely contested by several 9,000 transmitters and © speakers. o p b. repeaters in v.h.f. Bands I and Joe Flaherty, CBS, said that III and over 20,000 in u.h.f. m the weakness on Robson's Bands N/V. SECAM B+G 1 argument was his belief that Gressmann questioned lif broadcasters have the power to whether the present plan, as ,4Ó I .~ control the living rooms of the based on the Stockholm future. "But, this is not true!" conferences of 1952 (v.h.f.) Cable, v.t.rs and video discs ( and 1961 (u.h.f.), provided the may have more effect than optimum use of the frequency broadcasters in doing this! spectrum. exception to this is the UK, Gressmann, if it keeps pace In direct reply to Robson's The first problem that the where there are now no longer with modern technology. "This argument that a home display European tv frequency plan programmes at v.h.f. but where is only possible through unit suitable for h.d.tv would comes up against is the one of there are (in most places) four standardization and not be available for 20 years, multiple channel bandwidths. In programme channels at u.h.f. harmonization". Mr Sugimoto, NHK, said that a 1961 there were no less than The programme carrying John Curley, RET, told large flat screen display suitable four separate channel capacity of the terrestrial tv delegates that agreements that for h.d.tv with a target price of bandwidths in operation in the transmitter network in Europe had recently been reached in $2,000 would be on show at the v.h.f. tv bands. The UK's 405 is not likely to increase above some countries between next Montreux in two years line b/w services used 5MHz the present numbers. There are broadcasters and land mobile time. channels, whereas the French already pressures from powerful radio users (e.g. the UK and Prof Messerschmid of the 819 line system used 14MHz mobile radio lobbies to take France) for the sharing of a German radio and tv research channels. There were also the 7 over more frequencies from common frequency band by institute (IRT) strongly and 8MHz channel bandwidths broadcasters. The shared usage different services (l.m.r. and disagreed with Robson's of the 625 line services. Since of Band III between tv tv) precludes any hopt of opening remarks: "Broadcasters then the 5 and 14MHz channel broadcasters and land mobile standardised terrestrial tv cannot just sit back for 20 services have been closed services in France as well as the transmission system across years". down, but even today there is wholescale closure of Band I Europe on v.h.f. Henry Yushkiavitshus, USSR, still disparity between 7 and and III in the UK are indicative threw into the discussion the 8MHz channel bandwidths at of this trend. Gressmann comment that the USSR was v.h.f. Carrier frequencies commented however that looking at a possible system (sound and vision) at v.h.f. are pressure on tv frequencies from High definition using 50Hz in the studio and different all across Europe. other non -broadcast services in 75Hz field rates for At u.h.f., even though there Europe was possibly less now The "Extended/j.d.tv" session transmission. is a uniform channel spacing of than it has been in previous promised to be a lively affair. It There is no disagreement that 8MHz, there are differences in years, but that nevertheless certainly was! George Watson the world does need an h.d.tv the sound -vision carrier spacing broadcaster's must make of RTE, session chairman, studio production standard, but (5.5, 6.0 or 6.5MHz), which optimum use of the spectrum described e.d./h.d.tv as being the question is when. The add to pan-European spectral available. the most important subject at problem with choosing an discord. If terrestrial tv transmission this year's Montreux. h.d.tv production standard too There is little spectral is not to become the "poor Speakers differed by a factor early is that even though harmony of tv transmitters relation" of other media of ten -to -one in their estimates individual parameters (numbers within Europe. Gressmann including d.b.s., cable, of how many years it will take of lines, field rates, interlacing reminded delegates that the videocassettes and videodiscs, for h.d.tv to become reality. and aspect ratios) have been OIRT countries of Eastern then studies should be Tom Robson, IBA, positioned discussed, only one fully Europe still use much of Band II intensified now. Gressmann himself at the far end of the operational standard has been for tv transmissions rather than warned that the mere fact that range with an estimate of 20 proposed. The NHK proposed f.m. as is the case in Western such a large investment had years. According to Robson, it standard being based on 60Hz Europe. been made in the terrestial tv is the realization of a practical presents a conversion problem The average viewing choice transmitter network is in itself h.d.tv home display unit that is for the large number of provided by terrestrial tv no guarantee of the network's crucial to the introduction of countries using 50Hz. broadcasting is approximately survival against the onslaught of h.d.tv, and as he saw it, The Montreux h.d.tv debate one programme per location on new transmission media. suitable flat screen products highlighted the amount of. basic v.h.f. and about two or three Terrestrial tv transmission can would not be available before disagreement that still exists in on u.h.f. Although one major only survive, argued the end of the century. this area.

ELECTRONICS & WIRELESS WORLD OCTOBER 1985 15

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current circuit produces a by Louis Essen, the great ENERGY ELECTROMAG- magnetic field and the reaction English acientist who designed NETIC PARADOX is merely the manifestation of and built the first caesium TRANSFER this field. Local displacement clock. Essen showed that I fear it is not I that have Whereas relativity provides a currents are an embodiment of Einsteinian relativity cannot be misunderstood Ivor Catt (July wealth of paradoxical issues this reaction and so can hardly squared with the facts of Letters), rather the reverse. that have from time to time set up their own magnetic fields nature. Who else would have In my June letter I pointed engaged your readers' interest, as well. In the free space published his critique? I do not out that superposition of forces there is a seldom -discussed situation, with the propagating know of another journal in all could not be expected to paradox of more direct wave, there has to be the world that allows criticism succeed when the forces in significance to anyone something locally in space that of Einstein's paradoxical- question were quadratic concerned about the has an active field -producing indeed, anomalous - beliefs. functions of current or voltage. electromagnetic field. role and something that has a The late Herbert Dingle, I then proceeded to illustrate Maxwell's equations demand reactive and secondary role. professor in the University of this claim by reference to a that, when waves propagate Thus, just as we argue that London, wrote a whole book, simple situation in through the vacuum, magnetic there is a displacement current Science at the Crossroads, on electrostatics, and concluded fields are set up which imply between the plates of an excited his own experience with with a derivation of the that there is an oscillatory capacitor, we must argue that suppression, and attempted magnetic force from Special electric displacement in free in free space there are two suppression, of the debate. Relativity. space. Yet, it is well established 'somethings', only one of which For the editors of WW, a I fear these last two points that electric displacement is the reactive displacement. fervent "Bravo!" detracted from my argument, produced by the motion of an Both must be capable of relative Lee Coe and confused Mr Catt. isolated electron in no way motion with respect to the Berkeley Mr Catt is upset that I choose moderates the primary applicable frame of reference, California to overturn his arguments magnetic action of the electron the inertial frame or USA (concerning forces between in the immediate locality of the electromagnetic reference conductors guiding t. waves) electron. Rosser, for example, frame. Hence, our by discussing static currents writing at p.285 of his 1968 understanding of wave I have followed the articles and and voltages, while he allows book 'Classical propagation is incomplete letters on relativity and the rest himself the privilege of building Electromagnetism via Relativity' unless it caters for the physical of the "modern physics" circus his arguments by reference to published by Butterworths, has existence of two displacements. since the article by L. Essen in these same static forces. endorsed Fitzgerald's opinion This argument lends support October 1978, which so However, I would assert that that displacement currents in to the views expressed in my impressed me that I started there is no difference between the field between the plates of article in Wireless World buying Wireless World instead the static case (with suitably an excited capacitor do not (October 1982, p.37) where I of reading it in the library. chosen values of current and produce a magnetic field. This argued that the ability of the I would like to see more of voltage), and the momentarily is consistent with the vacuum to propagate the subjects which bore quiescent state in the middle of experimental finding by Graham electomagnetic waves without H.Morgan (Letters, July). You a broad pulse. If Mr Catt thinks and Lahoz (Nature, 285, 154 dispersion was direct evidence ask who is competent to decide that there is a difference then (1980)) that, when an of dual or reciprocal who is right. I ask where else he cannot use the static case to externally applied magnetic field displacement characteristic. we can read open debate on prove that the force between acts on the displacement Since writing that article, a these matters if you go back to conductors carrying a pulse is current and a return conductor further advance has shown that being just another electronics zero. current set in parallel, the net the progressive attenuation of magazine, printing inoffensive N.C. Hawkes force acting on the apparatus is one displacement in relation to S -level "physics for electronics Abingdon that applicable to the conductor the other can cause a wave to engineers" - in New Scientist? Oxfordshire current. Since displacement lose frequency slowly in transit If I was a professional current does not produce a and Hubble's constant has been physicist, I think I would be I wonder if some of the magnetic field it cannot respond deduced theoretically (Lett. ashamed to admit it to a lay conceptual difficulties with the in setting up a force when Nuovo Cimento,41, 252 person whose idea of what I did transmission line stems from subject to a magnetic field. (1984)). might well have been formed the assumption - and it is an Surely, it is paradoxical that H. Aspden from television programmes full assumption - that power waves only propagate because Department of Electrical of starry-eyed academics density in an em wave is displacement current in the field Engineering quoting from T.S.Elliot, and a measured by Poynting's vector? sets up magnetic fields but yet The University background of loud, jarring (Do I hear cries of dissent? But we know that in our bench Southampton music. Why do all the worst who remembers what experiments the displacement BBC science programmes have Poynting's theorem actually currents do not set up magnetic this? Is it to drown out the says?) In fact there are any fields. I wonder if your readers RELATIVELY words? I might have claimed to number of vectors that would can provide the answer to this be a psychologist and hoped to be equally valid. problem. INTERESTING be taken for a tough One such is Slepian's vector. Pending a better proposal, In the July 1985 issue, H. behaviourist. Of course, the S=ExH+curl(VH) my suggestion is that the Morgan suggests that Wireles.; truth always comes out paradox can be put in context World "stem the flow of letters eventually. Where are the where V is the electric by noting that for any local and articles on [Einsteinian] reputations of Freud, Cyril Burt potential. Poynting's vector action there has to be a local relativity." and Lysenko now? Remember, tells us that the power flows reaction and this applies But who then would publish all founded powerful, seemingly through the space surrounding whether we look at apparatus the fierce debate between unchallengeable orthodoxies. the wires, i.e. is carried by the on our laboratory bench or at a Einsteinian relativity and Humpty Dumpty and a great em wave. Slepian's vector, on region of remote space. In the Newtonian -Galilean relativity? fall... the other hand, tells us that all bench experiment the primary Several years ago, WW Roderick Saunders the power flows through the motion of electrons in the published an important article Birmingham wires! It seems that either view 18 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com is "true, but not exhaustive" and a cheat. As a letter volume -control slider and the (Churchill's phrase). unanswered might be thought grid of the output stage: this is Choose R so SmA< Is < 30mA under As an engineer I welcome to be unanswerable, Spratt a cathode -follower identical to on load and off load this. It means that I can adopt leaves me with no alternative the first one, with presumably conditions HT 350V either point of view, whichever but to reply. Before I do reply the same input impedance. A on is more convenient for the in some detail to his letter, 1µF capacitance coupled to 500V R load problem in hand. would he please explain his 10M, or even to 1M, looks a Interested readers should evidence in very ordinary words little like overcooking the consult "The Electromagnetic even I can understand as soon bottom end response. And Field in its Engineering as possible. This letter is an surely, (a minor quibble, this) Aspects" by G.W. Carter ultimatum. the polarity of the capacitor, as (Longmans, 1954) Professor I merely quoted drawn, is incorrect. Carter devotes the whole of measurements quoted by Finally, may I suggest a small Chapter 13 to the flow of Eastwood who acknowledged but worthwhile refinement? If energy in an electromagnetic the work of other scientists. the preamplifier, in a warmed - field. Does Spratt realise he has up condition, is suddenly P.L. Taylor libelled Eastwood and other connected to the input of a Marple scientists? He ought to look solid-state main amplifier (as 0V Cheshire before he leaps. when selector switch is the k M.G. Wellard turned from say, `tuner' to i.c Kenley `disc') the output coupling - k Surrey capacitor charging current must OPICAL 0A2 150V B76 flow through the input circuit of 0B2 108V valve base COMMUNI- the main amplifier. In other VALVE DISC words the first transistor base CATIONS would see a positive pulse of range of current flowing through Having read the most PREAMPLIFIER around 150 to 180 volts. It a cold -cathode glow -discharge interesting article in the August Mr Brice's valve disc would not like this. The remedy tube the voltage across it 1985 issue of Electronics and preamplifier (EWW, June 85) is is to include a high resistance, remains nearly constant. The Wireless World entitled "Optical an interesting approach to a say 4M7 or higher, permanently circuit operates like a zener Communications - 1935 familiar design exercise, and I across the preamplifier output, shunt -regulated supply. Its style", your readers may be am with him in sentiment in his and to ensure that the great advantage for h.t. interested to know that there liking for valves for sound preamplifier is fully warmed up regulation is that it is self - are a number of these optical reproduction. However, I would and its voltages at equilibrium protecting, simple and cheap. systems on public display, still take issue with him on two before it is connected to the Just as with zener diodes, the looking as good as the day that points: main amplifier. tubes may be used in series to they were made. Firstly, the RC coupling Despite the foregoing, which provide voltages exceeding Two locations with which I between the cascode stage and some may see as nit-picking, I those of a single tube. The 1M am familiar are the German the next (cathode -follower) say more power to Mr Brice's resistors are added to facilitate Occupation section of the main stage: Mr Brice's footnote on thermionic elbow! striking of each individual tube. museum within Castle Cornet the circuit diagram states that D. Bolton The power supplies were built on the island of Guernsey, and the lOn capacitor and the 1M Victoria on a separate chassis and this the excellent German grid resistor puts the response Australia method of construction is Occupation Museum run by at 20Hz down by 3dB. This recommended on sound -quality Richard Heaume, also on the woul be a fair statement if the I thank Mr. Jones for his grounds. island of Guernsey, at Forest cathode -follower input constructive comments The ECC83 would be suitable near the airport. impedance was in fact the concerning my valve disc as the first -stage cascode valve, If any readers are proposing same, or nearly the same, as preamplifier circuit (Feedback, except that it is less robust than to take their holidays on this the resistor value. However the EWWJuly 1985). Your readers the ECC82 and, consequently, most delightful of islands, a trip conventional wisdom of valve may be interested in two further more microphonic, hence the to these two museums, and in electronics is that the input suggestions regarding this decision to use the latter. I particular the latter, will be well impedance of a cathode follower design. have found there is no worth while, and will afford the is about 10 times the value of I mentioned in the original alternative but to select low - opportunity to study many the grid resistor. (References: article that a smooth supply can noise valves individually for this other examples of contemporary Langford Smith, Radio be obtained with simple RC first stage and that the more German technology. Designer's Handbook; Terman, filtering, but it is better to use a expensive types available are no Alan G. Hobbs, G8GOJ Radio Engineers' Handbook). regulated supply. Not only does better, in this application, than South Croydon The mechanism is akin to that this secure the best hum and the cheap ECC82 s available at Surrey which raises the input noise performance but the about 65 pence each. impedance of a boot -strapped regulator ensures that high off- Richard Brice emitter follower in the world of load voltages are not applied to Teddinton solid state. the anodes of the valves and Middlesex RELATIVITY Assuming, then, that the the power supply decoupling input impedance of the stage capacitors during valve warm- Letters P.H. Spratt uses the word under discussion is 10M, the up time. Several schemes were Letters for publication are 'pretext' in the first sentence of response at 20Hz will be about contemplated and tried. All the always welcome, but the his August letter. This word is -0.03dB. To achieve a -3dB regulator circuits improved the shorter and pithier, the better. I defined in my dictionary as 'a figure at 20Hz a capacitance of sound quality: the final try not to edit original letters, false explanation or motive to about 800p would seem to be arrangement is shown in the but sometimes they are far too disguise the true one.' I assume required. Fig. 1. The OA2 and OB2 are long, and therefore cut, and the Spratt has some experimental Secondly, the coupling two easily available voltage - writers upset. Please keep your evidence to prove I am a liar capacitor (4.t between the stabilizer tubes. Over a certain letters short.

ELECTRONICS & WIRELESS WORLD OCTOBER 1985 19

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20 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com by J.D. Walker B.Sc.(Hons) Multistandard G6FYU terminal unit

Following a period of Implementing a digital filter with a amateur radio interest in digital communications John microprocessor leads to simple hardware for Walker joined the electronics industry in 1979 and this programmable modem. developed a number of microcomputer systems using the Z80, 6502 and Recently I became interested in rate, which in the case of 50 baud and b =cot 1tT(F2-F,) , 6800/6809 microprocessors packet radio and soon realised and Fe is equivalent to a 25Hz for both industrial and hobby that this mode of data communi- modulating frequency on an a.m. a = cos21tFT (3) applications. John, who is cation would require a new tone carrier of 1275Hz. The channel 23, T is the sampling period graduated last year from standard, different to RTTY and filter bandwidth for F, is from the University College of Fo filter centre frequency simple ASCII, and that a new 1250 to 1300Hz and for Fh, 1420 North Wales in electronic terminal unit (or modem) would to 1470Hz, this being the mini- F, lower 3dB point of filter engineering and has been be required. A consideration of mum channel bandwidth for min- Fz upper 3dB point of filter A,B,C,a,b constants based subsequently employed in the various tone standards soon imum signal-to-noise ratio. After are and on Fo,FF2,T the designn development showed that to obtain best per- detection the bandwidth can be of radar display equipment. formance for standard RTTY, usefully reduced to Fm (25Hz) g digital representation of sam- Amtor and packet, both the tone with a post -detection filter. In pled filter output standards and demodulator practice, the filter bandwidths f digital representation of sam- bandwidths must be changed to are normally made slightly wider pled filter input. suit each case. The most com- so that the tuning is not too criti- Equation 1 is the z transform for a References digital bandpass filter and by re- 1. Digital filter design techniques, by mon standards are summarised cal, and to compensate the band- ].T.R.S. Bradly. Wireless World May in Table 1. By using a minimum - width shrinkage between the arranging this an expression in 1983. p.76-8. configuration microcomputer and channel and post -detection fil- terms of previous inputs and out- 2. Radio Communication August 1982. digital filtering implemented in ters. puts may be obtained as given by software, the only alteration to equation 4. cater for a new tone standard is Implementation of filters using digi- = + program addition instead of a tal techniques g fA-f2AZ-2 A wide variety of f.s.k. tone hardware change. Although the +Cgl 1 -Bg2-z (4) standards have become techniques described in this arti- Digital filtering is based on established for modems in cle are quite complicated it sampling a signal at regular inter- The operator z' indicates a delay use on radio circuits. The should be realised that because of vals and then summing previous of one sample period, so Bgzz-z accompanying software its digital implementation this inputs and filter outputs multi- means the filter output at the time supports the established terminal unit is easily built and plied by appropriate constants. In before last multiplied by the con - standards listed here. does not require any setting up. analogue filter design, the appro- Figure 1 shows the block dia- priate transfer function is gram of a conventional analogue obtained by starting with a low- Table 1. Commonly used tone standards for radio data transfer terminal unit which could be used pass prototype and then applying to demodulate RTTY or Amtor a bandpass transform to get a RTTY (45, 50, 75 Baud) signals. The tones from the bandpass transfer function. The Old tones (Hz) Mark (Hz) Space (Hz) 170 1445 1275 receiver are split into two chan- exact details involved in realising shift 425 shift 1700 1275 nels tuned to two frequencies Z the transforms are outside the 850 shift 2125 1275 representing 0 and 1. The out- scope of this article (for a New tones (Hz) puts of the two channel filters are detailed exposition see ref. 1), 170 shift 2125 2295 rectified, low-pass filtered and except to say that by applying a 425 shift 2125 2550 then substracted. The sign of the similar process the transform 850 shift 2125 2975 subtraction indicates which chan- given in equation 1 can be nel contains the largest power at obtained. Amtor that instant and hence the most Tone standards as for RTTY except that the rate is 100 baud and the shift 1-z-2 is always 170Hz. likely correct state of the output. H(Z) = A 1 - CZ -z The filtering operation can there- Ascii (300, 600, 1200, 2400 baud) fore be split into three opera- Kansas computer standard, mark 2400 space 1200Hz. tions, the two channel filters and (1) Other modem tone standards also exist the post detection filter. The T power spectral density for the Packet new tone system (1275, 1445Hz) where AX25 mark 2200Hz space 1200Hz. used for RTTY is shown in Fig. Data rate 300/1200 baud. 2). A 4X25 is the approved packet standard for amateur radio applications of b+1' B C b+1 The channel filter bandwidth is b+l' packet data system. determined by the transmission (2)

ELECTRONICS & WIRELESS WORLD OCTOBER 1985 21

www.americanradiohistory.com TERMINAL UNIT

filters by a small amount, this is 7. A 68B21 parallel interface is of no consequence. The effect of used to input the samples from the actual values can be com- the a -to -d converter and to out- pared with the ideal values either put the demodulated data to the by back -calculation of graphi- computer. Because the microp- cally. By substitution of equation rocessor can only execute one 5 into equation 1, the transfer task at a time the three filtering function in z terms is transformed operations must be executed in into the frequency variable f sequence as shown in Fig. 8. The which upon taking the modulus of need to complete all these opera- the expression reveals and ampli- tions before it is time to take the Fig. 1. Conventional stant B. An alternative method of tude response of the filter, plot- next sample means that careful configuration of a two-tone expressing equation 3 is with a ted in Fig. 5. programming must be used and to cater for some of the higher fre- terminal unit depicted here block diagram, shown in Fig. 4. Z = ej2nFT can be entirely realised by From equation 3 it may be seen quency tone standards the mic- roprocessor must be clocked at mathematical operations that by making the sampling fre- = cos2nFT + j sin 27rFT (5) performed on digital samples quency equal to four times the 2.25MHz, about 12% faster than its rated maximum. However I of the input signal. centre frequency that the con- The other filtering operation is found no problem at a clock rate stant 'a' becomes zero and this the post -detection low-pass filt- of 2.25MHz (using a 9MHz crys- makes C zero, simplifying the fil- tering and this can be expressed tal) using the standard 6809. ter arithmetic. Also in the case of as equation 6 a system with two channels, pro- The filter operations are imple- viding the bandwidths are the n-1 n-1 mented using 16bit arithmetic same, the input (or non -recur- D = E E FhiZ-' (6) because the filtering operations i=n is" sive) part is the same for both involve summing eight -bit num- channels and this yields the confi- bers which inevitably results in where F1 and Fh are the rectified guration in Fig. 4, using a com- greater than 8bit answers. This outputs of the high and low tone mon input section for both filters. means that the terminal unit uses 1275 1445 filters respectively and n is the So that the sampling frequency is the full eightbits of the converter, FREQUENCY (Hz) number of channel filter samples used for one channel and the gen- enabling the unit to operate with during a signal element. In the Fig. 2. Power spectral density eral form for the other channel. input signals from a few millivolts for case of 50 baud and 1445Hz the of the new tones standard This further reduces the arith- to a couple of volts (peak). The 17OHz 50 bits per element time is 20ms and the shift at metic essential if a simple mic- need to use 16bit arithmetic is - sampling period 172µs, so n- second sending speed is to be used to makes the 68B09 an ideal mic- roprocessor 116. accurately matched by the implement the processing. roprocessor for this application digital filter realisations Equation 6 may be expressed The ideal values of A, B, C for because of its low cost compared as a single sum: acheived by the use of an each tone standard may be calcu- to full 16bit microprocessors. inexpensive 8 bit lated using equations 2 and 3, but n-1 The modes of operation (differ- 16 bit microprocessor using in practice close exact fractional D = E (Fr-Fh;}Z (7) ent tone standards and rates) are arithmetic. constants may be used instead. ;a" determined by selecting the Although this tends to widen the appropriate program in the This is also a geometric series eprom. This could have been which can therefore by expressed done with a switch on the front of as the unit, but it was considered that in most cases a computer D = DZ-1+(Fln-Fh) - would be used with the unit and by using an RS232 interface -(Fn-Fnn)z (8) (68B50), the mode could be directly controlled from the key- the final digital output being the board via a set of escape sign of D. By applying equations 5 sequences. This is particularly to 8 the response may be plotted attractive now that most compu- in a similar way to the bandpass ter programs used for RTTY also filters and this is shown in Fig. 6. control the PTT line on the tran- It is interesting to note the rapid sceiver, so resulting in a system cut-off, as expected, and the completely controllable from a sharp null at twice the 3dB fre- keyboard. The digital terminal quency. This means that when unit therefore interfaces with the working in the 50baud mode the transceiver and computer as unit will completely reject shown in Fig. 9. 100baud signals. The ripples in Because the unit is completely the stop -band are not important controlled by a control part, the as these frequencies will have unit also contains a front panel been previously attenuated by status display, shown in Fig. 10, the channel filters. which indicates the tone stand- ard, data rate and output status 11 Practical realisation of the terminal currently in use. Figure shows Fig. 3 & 4 General form of the mark and space filters is a suitable power supply for the given,together with its practical realisation. Note that the The circuit consists of an ana- digital terminal unit. In the case non -recursive part is common to both mark and space logue -to-digital converter and a of f.s.k. signals careful turning of channels which contributes to the economy of mathematical small microcomputer based on the receiver is necessary to dem- operations leading to an elegant solution of the filtering task. the 68B09 microprocessor, Fig. odulate the input signal. This can

22 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com 1275 1450 Because ESC 4 will demodulate any data rate less than 100baud the unit powers up in this mode, but in the case of marginal RTTY signals a further improvement can be obtained by selecting mode 3 (ESC 3). The AX25/Kan- sas mode selected by mode 7 being a high data -rate mode does not lend itself to the two -channel digital filter approach described because of the small number of cycles available per bit time. Although the terminal unit can be programmed to operate as a missing pulse detector, better performance can be obtained at 5 25 50 10 higher rates by using the microp- 150 Baud) (100 Baud) rocessor to measure the time FREQUENCY (Hz) o FREQUENCY (Hz) 1600 between zero crossings. This is Fig. 6. In addition to the achieved by using the a -to -d con- digital realisation of the Fig. 5. Actual response of bandpass filters for 17OHz shift (50 verter as a limiter sampling the channel filters, further post - bits per second) using the new tone standard as predicted by input at 10µs intervals. The time detector filtering tailored to computer modelling. between transitions being used to the bit rate is also provided. decide if the output should be be done either by ear, a Toni only a few of the combinations high or low. Because of the mod- Fig. 7. Circuit of the Tuna (tuning indicator described will be of use. The escape ular programming techniques minimum -configuration in reference 2) or via a tuning vol- sequences given in Table 2 have used a section for 850Hz, 50baud microcomputer used to tage available from the tones -out therefore been allocated in the using digital filtering could easily perform the digital socket during receive. Clearly a prototype although other com- be added by simply adding an processing operations. The vast number of tone combina- binations may be easily imple- extra section to the program with design uses readily available tions and data rates could be mented if required when the the appropriate constants in the low-cost components implemented, but in most cases eprom is programmed. filter algorithm. throughout.

+5V RESET R11to R14 10< 10k IR ESE TI all 3k3 A _ 1 390 82k C1 co 9MHz 8 100n . - disc H IE C7,, 1003, IRQ M.10V 37 2 3 4 33 38 39, 71636 40 6 4 5

10 34 Ais re 11 IC1, 22 2 1y Oj0 Aú. .. v Do 68809 Ao 45138 UAT 2 21 1 15 L8 IC6 RIW Ä10 7 R3 4k7 ZN448E A d7 C3 R5 -ko dRDY 40 3 1-24 J8 110-18 Rx j9 Vcc=16 Gnd=B !'2 6k8 i4 29 AO Al R START 4 4k7 33 26

CalO 8 -1 A 121 23 22.19 36 . 24 20 R 080 A0A10 9 -11 10k 10k 007 13 -17 0 IC4 2 14 2716 319 21 35 12 Tones IC7 out DAC0800 To status SV O d -to -a indicator R/W 18 2 C52 C,o 10n f 8 -1 C4T0n T 16 t 4700n 2322,19 -124 13 12 n 18 23 6 9 -11 IC 13-17 20 tR8 4k7 4k7 pß 6116 1_rA0 68850 24 112 Data raclock ICB QO 22 -15 16 0- IC8 L RS232., 1 07 in 9 All resistors 4W TR4 RS232 MC1488 Vcc=14(.5V) MC1489 Vcc=14 out O 5 Gndn7 Gndn7 1488 R -SV=1 SV Not required for J IRQ ov normal operation

ELECTRONICS & WIRELESS WORLD OCTOBER 1985 23

www.americanradiohistory.com TERMINAL UNIT

Send /receive control Set up Evaluate -B gZÑ2 PTT

Ear __ Data User Add in Transceiver in/out port non -recursive part Mic Input 8 -bit sample --m -K /B & convert iv 16 -bit (1-Z -21f DTV Computer for control & message 2"s complement & take the modulus sending

Control RS232 - Screen in /out port Z 1--- Z-2 Subtract result Zo z-1 from other channel Shift old samples

D=DZ-'+(FLO Fig. 9.How the d.t.u. interfaces with two transceiver and Evaluate /save FHo) (FLn - FHnI computer. (1-Z 2 )f Table 2. Escape sequences used to control the d.t.u. via its RS232 port. Save FLo Old gZL'-gZL` -FHo Sequence Mode Use ESC1 170Hz shift new bones 50B Amateur RTTY ESC2 425Hz Shift new bones 50B Commercial Evaluate Increment RTTY l.p.f. filter pointer ESC3 170Hz Shift old bones 50B FSK position on new rigs CgZ- BgZ- ESC4 170Hz Shift old bones 100 AMTOR & 75B RTTY ESC5 Set normal Resets normal mode to ESC6 1 ESC6 Set invert Output D Caters for invented signals Add in Sign/magnitude ESC7 AX25/Kansas up to 1200 Caters for new ASCII modes. non -recursive part

11 -Z Oil tuning -2)f Fig. 9 must be sent to the DTU and take the modulus. DTU performance Then save via the control port from the com- Wait till time After connecting the unit as in puter. for next sample Fig. 9 and loading a suitable The performance has been Old gZH- gZH RTTY program into the compu- found to be about 10 dB better ter, the digital terminal unit is than the ST -6 TU and the reasons used in a similar way to any other are believed to be twofold: the TU except that to change the channel bandwidths have been mode of operation the appropri- optimized together with the post - Fig. 8. Flowchart of the program used in the digital terminal ate escape sequences as shown in detection filter for the best s/n unit showing how both channel filter response are determined ratio, difficult to achieve with from the same input data samples. The mark and space Fig. 10. Circuit of the status analogue components, and (2) component energies are compared and the resulting indicator board used to the unit does not use a limiter. differences subjected to a final filtering operation. display the tone standard The DTU has also proved to be currently in use. very effective in decoding both Kansas (2400/1200Hz) and Bell . . . +5V 202 (2200/1200Hz) tones at up 850 425 170 506 Low INV ASC 0/P CB2 0 to 1200baud and it therefore ideal // //v/hr//I//ViiV/.iVII to 74504 D D8e Pin 19 11 for use with packet radio. IC12 6881 R15 E 2 1 Although not described or D1 to D6 -Red implemented 2 100 in the eprom the 07- Green circuit given can also generate the 0 R16 Pin 10 DB0 138 - Yellow tones required for transmission 4 / 100 using a suitable sine table and 7 R17 digital -to -analogue converter. 6 5 Finally, at a cost of £80-100 the 100 13 74L5373 unit clearly provides performance 8 R18 9 9 far beyond any other device 14 \ for vV\, /O the price and is easily updated 17 100 to Pin 16 D136 cater for new tone standards 68621 12 11 10 which may become established in the future. Eproms programmed for the 15 13012 Vcc' 20 escape sequences of Table 2 are Gnd -10 available for £ 10 from the author, 13 R 2 21 16 1 at 82A Grosvenor Road, Epsom

100 Downs, Surrey. OV alllhW In a subsequent article John Walker will discuss the basis of R22 0870 >04 r\A/\., the Z transforms used for the 3 Pin 17 100 bandpass and low-pass filters, 68621 IC13 74504 together with the use of the digi- 6 Data out Z tal terminal unit in other data applications. 24 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

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26 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com by John Lidgey The tale of the long - tail pair -part2 Further applications ranging from analogue logarithm and exponential circuits, multipliers and dividers to fast logic gates.

High -precision, wide dynamic - Using the well known exponential in the last article about the strong range, analogue amplifiers rely relation between base -emitter temperature dependence of the on the use of linear resistive com- voltage and collector current we b.j .t. parameter I5, the circuit is ponents to define accurately the can obtain an expredsion for the not particularly good in practice. negative feedback around a high - output voltage V., A modified version based on gain open -loop amplifier. With the long -tail pair structure is this classical feedback -amplifier V = VEß = - VT loge (IC/ISI shown in Fig. 2. The output is configuration, the exact gain and essentially proportional to the linearity of the open -loop ampli- V(, _ - VT loge (VINZ/ I5R) difference in the two transistor fier is of little importance, pro- base to emitter potentials, which vided the open -loop gain is much The b.j.t. yields a better is not dependent upon I5, pro- higher than the closed -loop gain. exponential voltage -to -current vided that the two b.j.ts are very The net gain of the closed -loop relationship than a simple diode, well matched and at the same amplifier is just about equal to the due mainly to that fact that a temperature (i.e. T, = T2). inverse transfer function of the b.j.t. behaves as a very short Though the circuit is rather negative -feedback network. diode, there being essentially no unusual in its topology, both 0A, Clearly, precise, wide dynamic - minority carriers at the edge of and OA, are provided with nega- range, closed -loop, linear gain is the collector-base junction. It is tive feedback, so that both invert- only achieved if the feedback an advantage that the collector - ing inputs are effectively held at network exhibits precise wide to -base potential is held to zero zero potential and hence, dynamic -range linearity. Fortu- by the action of negative feed- nately, resistors are remarkably back, in that no base -width mod- 1 linear and a simple resistive ulation effects occur. However, attenuator, together with a high recalling the problems identified 12 - VREF/R2 open -loop op -amp, are all that is required to achieve a very good Fig. 1. Simple logarithmic linear amplifier. circuit.

Logarithmic and exponential circuits

To produce an exponential (anti - log) or a logarithmic analogue amplifier, the feedback circuit must be formed from a circuit ele- ment that exhibits the inverse relationship. As for the linear amplifier, the quality of the net Fig. 2. High -quality performance is critically depend- logarithmic circuit. ent upon the accuracy of the exponential or logarithmmic cur- rent -to -voltage characteristic used in the feedback path. Logarithmic circuits. First let us consider developing an ana- logue logarithmic converter. Clearly, since the log of zero is minus infinity we can only be talk- ing about positive (unipolar) inputs. The circuit shown in Fig. 1 is a simple log -convertor which uses a bipolar transistor (b.j.t.) in the feedback path. Collector current is equal to V,N/R, and the output of OA, will be negative. ELECTRONICS & WIRELESS WORLD OCTOBER 1985 2-

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Fig. 3. Simple ance in terms of temperature sta- antilog. circuit. bility and non -dependence upon the particular characteristic of the b.j.ts used. However, K, is temperature dependent, as VT is directly pro- portional to absolute tempera- ture. This dependence can be removed if R3 is much larger than R4 and R4 is chosen to have the same temperature coefficient as VT. Since the natural logarithm is related to the base -10 logarithm simply by the multiplier 2.3026, this can easily be catered for in the design choice of K, to produce an output sensibly related to the base -10 log of the input signal. Suppose, for example, the circuit is operated at room temperature, giving VT = 25 mV, and we choose R, = 100 k52 = R2 and VREF = 1 volt; then with (R3 + R4)/R4 = 17.372, the expression for output voltage reduces to

V. = logic, V,N

where V. and VIN are both expressed in volts. The choice of Fig. 4. High -quality Resistors R3 and R4 are chosen so and so combining equations 1 and K, and K2 is determined by the exponential circuit. that the base current into Tr2 2 we get the expression scaling required on the signal and does not load the potential divid- the value against which the input ing action of these resistors on V = K, loge (VIN/K2) 3 is being normalised. the output of OA, and hence the Referring back to equation 3 base to ground potential of Tr2, where K, _ - VT (R3 + R4) /R4 the circuit can be used to obtain VB2, is and K2 = VREF R,/R2. logic, of the ratio of two positive In comparison with the circuit voltages if VREF is replaced by a R4 of Fig. 1 there is no I5 dependence second positive input. This is a Vu = VBE2 VBEI (R3 + R4) - in the output voltage expression, particularly useful in several since this has been cancelled due applications, such as an analogue to the output being directly pro- automatic transfer function plot- As shown in the first article, portional to the difference in ter. since T, = T2 , then base -to -emitter potentials of the So far, R5 has not featured in Fig. 5. High -quality single - two transistors. This represents the analysis. The purpose of R5 is quadrant multiplier/divider. VBE2 - VBE1 = VT loge (I2/I1) 2 a vast improvement of perform- merely to provide some current limit in case excessive current is drawn through Tr1, Tr2 and OA2. If 0A2 is current -limited inter- nally and the transistors can sep- arately handle this peak current, then R5 may be replaced with a direct link. Exponential circuits. To achieve the opposite transfeer function to the circuit of Fig. 1, namely an exponential circuit, the resistor and b.j.t. are swapped over as shown in Fig. 3. A p-n -p transistor is required for positive inputs, the output being given by the equation Vo=-I.R=-I.Rev"w, Again, as was the case for Fig. 1, the circuit has practical limita- tions due to the temperature dependence of Is. Adopting a similar approach, a long -tail pair is employed as shown in Fig. 4 to achieve a superior exponential circuit.

28 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com Following a similar analysis to earlier with the potential dividers

that for a log -circuit of Fig. 2, the R3, R4 and R3, R 4 removed. output expression obtained is Using the analysis developed for the output of the log. circuit, V0 =K4.eKv namely equation 3, the expres- sion for VB2 is where K3=R'4/ VT (R3+R'4) and K, = VREF R2/R 1 VB2 Having employed the well VB2 = matched long -tail pair configura- = - VT loge (VZ/Vy) tion, the IS parameter is absent in for the final expression. As the = VT loge (Vy/VZ) circuit of Fig. 2, the R'4 potential divider is chosen so that the input is simply divided down, the base Since V'B2 is the effective input to Fig. 6. Sign -information Linear differential transconductance circuit. current demand from Tr 2 being a an exponential circuit with Vx amplier negligible load. Resistor R'5 acts replacing the potential, VREF, in the same current limiting role then the output of the entire cir- The transconductance (current as R5 in the previous circuit. The cuit is obtained by modifying output - voltage input) per- only remaining temperature - equation 4 slightly, that is formance of the long -tail pair was dependent parameter VT in K3 investigated in my first article and

may be effectively removed by V =V x ev it was shown that the circuit was compensation with a potential linear over a range of about ±

divider R3, R4 which exhibits the Substituting for V B2 we obtain the 25mV or so (see Fig. 2 of the Sep- same temperature coefficient. final expression tember 1985 article). The sim- plest way of increasing the linear range and increasing the input V = Vx.VY/Vz Multipliers and dividers using log and impedance is to add emitter antilog circuits resistance as shown in Fig. 7. It is important to note that the Two matched long -tail current Multipliers and dividers are clas- temperature of both pairs of sinks are used in preference to of sified in terms of the number b.j.ts should be identical and, as one since such a structure can be quadrants over which they oper- before, the transistor pairs realised on a single chip with two ate. For example, if the circuit should be very well matched. pin -outs provided to allow the will only operate with inputs of These requirements are rela- emitter coupling resistor, R, to the same sign, both positive or tively easily met if the four tran- be inserted by the designer. both negative, the circuit is sistors are all on the same chip. Calling the differential input referred to as single -quadrant. A Also, it should be stressed that voltage VIN and neglecting base multiplier/divider circuit capable the circuit is only single -qua- currents compared with collector of operating with bipolar inputs is drant. In practice should the pro- currents, then we can solve referred to as a four -quadrant duct of two inputs be required, Kirchhoffs voltage law for VIN as multiplier/divider. then Vz should be chosen appro- Single -quadrant multiplier priately as a fixed d.c. reference, divider. Having established rela- providing a useful scaling factor. Vin=V1-V2=VBE1-VBE2 tively simple and accurate log. Alternatively, if the ratio of two +(I,-I/2)R and anti -log. circuits described inputs are required, then either VII, =VT log, earlier, it is quite plausible to Vx or Vy should be a fixed d.c. ref- (II/(I-I))+ assemble a multiplier simply erence, this reference providing a (I1 - I/2) R using two log. circuits of the type scaling factor to the ratio of the shown in Fig. 2, together with a two inputs. Normalizing this equation we conventional summing amplifier, Converting to a four -quadrant obtain the following expressions the output of which is then fed to multiplier. It is possible to use a relating VIN to II and I2. an exponential circuit such as that single -quadrant multiplier shown in Fig. 3. Mathematically, together with some additional VIN/VT = loge ((II/I0)/(1-(I1/I)) we are adopting the following circuitry to create a full four-qua- strategy for obtaining the product drant multiplier. Two precision + ((II/I) - 1/2) IR/VT 5a of two input voltages: input 1 is full -wave rectifiers are needed to Fig. 7. Linearized V, ; input 2 is V2 then V = V,. V, process the two inputs, so that I2/I = 1 -(II /I) 5b long -tail pair. = exp (log0V1 + loge V2). the circuit of Fig. 5 only "sees" Clearly, a divider is created if positive voltages and then the we subtract loge V1 from loge (V2) output is effectively using a differencing circuit. Although quite feasible, such a V. l multiplier is complex, using in = VI I. lV2 1/ VREF total seven op -amps and three well matched transistor pairs. A where the inputs are V1, V2 and V, very elegant solution can be has been replaced by a d.c. refer- achieved more directly using the ence, VREF. In addition, some circuit of Fig. 5. logic is needed to provide the A careful inspection of the cir- sign -bit information. This could cuit reveals that it is the combina- be done simply by testing the tion of the high -quality log. and input signs using the sort of cir- exponential circuits described cuit shown in Fig. 6.

ELECTRONICS & WIRELESS WORLD OCTOBER 1985 ,>ç

www.americanradiohistory.com LONG -TAIL PAIR

I,, = Vy/R,, 6b

Referring to the last section above, the condition needed here is

R. » VT/I1 and R,, » VT/I2 The resistor R, is in the circuit = loge 51A x l y/ (1-y)1+ ly-0 merely to ensure that the base

where A o IoR/VT bias potentials on the Try/Tr6 and x= Tr7/Tr8 are sufficient to keep Mil /VT these transistors in the forward y= It /10 active region. Now potential V, shown in Fig. 9 is V,=VD2-VD,=VTlog,

(I, - IX)/(I, + Ix) 7 This potential now drives the two non-linear (ordinary) long -tail pairs Try/Tr6 and Tr7/Tr8. In the first article in this series the characteristic of the long -tail Fig. 8. Linearized long -tail Equation 5a cannot be turned into rent gain of Tr, and Tr2. pair was established and, in pair transfer characteristic. a straightforward transfer func- The final expressions are really terms of the present circuit, the tion equation, so the best way of quite simple in form, but it is collector currents I5 to I8 can be visualising the equation is to plot necessary to look at the detailed written simply as y = I, /IQ against x = VIN/VT. behaviour in order to assess the Figure 8 shows the plot for differ- maximum differential input vol- I5=I3/(1+e-v,rv,) ent values of A = IoR/VT. Notice tage that may be applied to keep A = 0 corresponds to R = 0 and the maximum non -linearity I6=I3/(1+e+v,iv,) the transfer current of Fig. 8 is within specified bounds. It is left identical to that of Fig. 2 in the to the reader to look closely at I, = I4/ (1 + e+v,w-, first article of this series. As R is equation 5a to establish the limits increased so the total transcon- for a particular application. v,iv I8 = I4/ (1 + ) ductance becomes less but more é linear. This is to be expected, with the substitution from 7 for V, since the effect of increasing R is Monolithic four -quadrant multipliers equations simplifies to to increase the negative feedback to the circuit with the usual result An elegant wide dynamic range I5 = I3 (I, - IX)/2I, of stabilising and hence lineariz- four -quadrant multiplier is shown ing the transconductance at the in Fig. 9. The monolithic circuit I6=I3(I,+IX)/2I, expense of a loss of closed -loop uses four interconnected long - gain. If we are operating the stage tail pairs, two of which operate in I; = I4 (I, + IX)/2I, with a limited input and a high A a non-linear mode. In practice, value then equation 5a reduces to the two diodes would be transis- I8= I4 (I,-IX)/2I, tors connected as diodes with the VIN ( to base = (I/I) - 1/2). RI collector shorted the The differential output voltage is terminal in each. or I,/I = 1/2 + V,N/ (R.I) The circuit is relatively easy to V=R2((I6+I8)-(I5+I7)) and I2/I = 1/2 - V,N/ (R.I) analyse, as each section has already been examined earlier. The differential output con- To simplify the analysis I shall and substituting from equations 7 ductance is now linearly related assume that the ß of each transis- and 8, then to the differential input voltage by tor is high enough for the collec- tor currents to be negligibly dif- V R2 (I3.IX - (I, - I2) /I = 2 VIN/ (R.I) ferent from the emitter currents and also I shall assume that all the Since I3=I2+I and I4 --- I2-Iy and the differential transconduct- b. j .ts, including the diode -con- then V = 2R2 (f,I)/I, and using ance is therefore nected transistors D, and D2, are equations 6 we obtain the final well matched and at the same expression that temperature. g, a = 2/R The emitter resistors R. and R7 V=K,,,V,,.V, and the differential input imped- provide linear converssion to the ance, RIN, is approximately input voltages to the differential where K, is the multiplier's scal- currents IX and I,, shown on the ing factor and is given by K,,, _ RIN = ß.R circuit diagram. 2R2/ (R,,.R,,.I,). Generally K, is chosen to be 0.1 for convenience where ß is the small -signal cur- IX = VX/RX 6a and compatibility with other 30 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com BOOKS

Creative Animation and Graphics on the BBC Micro by Mike James: Collins, 212 pages, soft covers, £7.95, ISBN 0 00 383007 1. Covers animation, sprites, two-dimensional technical graphics (though not graphs and charts), three-dimensional graphics and painting. Examples are in BBC Basic. Many useful tips.

Colour and Mono Television: volume 2, display tubes, timebases, synchronising and power supply circuits, by K.J. Bohlman. Dickson Price Publishers Ltd., 235 pages, soft covers, £8.95, ISBN 0 85380 155 X. Textbook for tv receiver technicians. Many of the circuit examples relate to older sets, perhaps inevitably: there is little enough to see inside the latest ones. For those who collect types of multiplier. Should a ward bias on collector -base junc- Fig. 9. Monolithic four - spellings of 'Schmitt' (as in single -ended output voltage be tion which results in a high quadrant multiplier. trigger), there is a novel one here. required, then the circuit can be minority carrier population inn Schmidtt. Volume 1 deals with the modified by adding a differential the base region. To change state tuner, i.f., video and audio amplifier to the output terminals from "on" to "off" is relatively stages; volume 3, to follow, will describe colour decoders and of Fig. 9. slow as the base region minority digital circuitry. The four -quadrant multiplier carriers must be removed before described here is an excellent the collector current can be specialized, high-speed applica- The Commodore 64 Roms example of the ingenious use of reduced to 'zero'. The e.c.l. gate tions. Revealed by Nick Hampshire the accurate exponential rela- is extremely fast primarily with Richard Franklin and Carl tionship between emitter -base because the "on" state is asso- Graham: Collins, 215 pages, £8.95, ISBN 0 00 383087 X. The voltage and collector current of ciated with current saturation Tail -piece b.j.ts and the close matching and due to the long -tail current sink bulk of the book consists of a reconstructed source -code listing thermal tracking that can be limit on the collector current; The long -tail pair is a very power- of the Commodore roms, with achieved in a single chip circuit. neither b.j.t. ever entering for- ful circuit element with a wide extensive explanatory notes. ward bias VCB type saturation. A range of applications. Some of the Other chapters describe memory typical propagation delay is 2ns applications are dependent upon usage and list main entry points. Emitter-coupled logic for one e.c.l. gate. the precise exponential I -V Essential for the serious The penalty associated with characteristic of the b.j.t. and programmer. So far, the long -tail pair applica- this very rapid performance is a some are dependent on the use of tions discussed have been for high power dissipation per gate a matched differential -pair confi- Commodore 64 Wargaming by analogue signal processing. Even which represents a fundamental guration with a current -sink bias. Owen Bishop and Audrey Bishop: Collins, 252 pages, soft covers, in digital electronics the long -tail limitation on the number of gates I have only discussed b.j.t. long - £8.95, ISBN 0 00 383010 1. pair has some special features. per unit chip area. A further dis- tail pair circuits in these two arti- Programming techniques and The basic emitter -coupled logic advantage of e. c. logic is the poor cles but clearly fets may also be listings for war games in a variety gate is a simple long -tail pair used noise margin, typically 50mV. used in the same configuration of settings from ancient times to with a siingle-ended input, a typi- This is offset somewhat by the though the log/antilog and full the distant future, and how to cal circuit of which is shown in fact that since the power supply four -quadrant multiplier circuits adapt and extend them. Fig. 10. The long -tail is resistive current demand is almost con- will only work with b.j.ts. rather than an active current -sink stant, power supply spike due to CP/M Techniques by Ken to ensure high speed switching. LdI/dt effects on changing state Barbier: Prentice -Hall International, 224 pages, soft A of a with single common -emitter can are much less problem covers, £19.35, ISBN 0 13 be used as a logic switch. Turning e.c.l. than other b.j.t. based 187857 3 (PBK). For the "on" the b.j.t. results in a for- logic. E.c.l. does have a place in Fig. 10. E.c.l. logic gate. programmer with some knowledge of assembly language. Covers programming techniques, i/o, tricks with discs (both floppy and hard) and customizing your Bios. Good clear explanations. Fault Tolerant Hardware Design by Parag K. Lala: Prentice -Hall International, 263 pages, hard covers, £24.95, ISBN 0 13 308248 2. Chapters cover basic concepts of reliability, types of faults in digital circuits and how to model them, test generation, fault -tolerant design of l.s.i. and v.l.s.i. chips, self -checking and fail-safe logic and design for testability. ELECTRONICS & WIRELESS WORLD OCTOBER 1985 31

www.americanradiohistory.com B. BAMBER ELECTRONICS T2xtonix Storage Oscilloscope Type 564.. f250 Airtech UHF Fiter Duplexei 3 RADIOTELEPHONE EQUIPMENT Cavity Type. Model M450-34/14 025 Tektronix Oscilloscope Type 567 c/w 3576 8 3T77 Plug -ins 0450 Hewlett Packard Thermal Printer Type 51504 Pye Base Station Type F30 AM High Band 8 Low Band £220 f65 Tektronix Oscilloscope Type 661 c/w 453 Plug-in L180 Hewlett Packard Power Und 5 volt amp. Type Pye Base Station Type F401 AM High Band C350 48 62005e ... f30 Tektronix Oscilloscope Type 585 c/w Type 86 Plug-in. C120 Hewlett Packard Power Unit 5 volt 4 60 amp. Type Pye Base Station Type F4001 AM High Band £550 62605L C85 Tektronix Oscilloscope Type 454 150MHz £675 Electronic Instruments Twenty Million Megohmmeter Model 29A Pye Reporter Type MF6 AM High Band 8 Low Band f90 f95 Tektronix Oscilloscope Type 515A £100 Multitore Model S Solderability Test Machine Mark Pye Europa Type MFSFM High Band f90 2. £150 S E Labs Oscilloscope Type SM 111 Dual Trace 18 MHz f180 Tektronix Transistor Curve Tracer Type 575. 095 Pye Olympic Type M201 AM High Band £65 Oyanmco Oscilloscope Type 27100. £290 Avo Meters Model 7 C40 Avo Meters Model 8 Pye Motolone Type MF5AM High Band 8 Low Band C45 f80 Telequipment Oscilloscope Type 051 f75 General Radio VHF Oscillator Type 1363 56-500Mhz C50 Pye Westminster Type W 15ÁM High Band 8 Low Band f50 Telequipment Oscilloscope Type S43 f85 Wayne Kerr A.F. Signal Generator 10 Hz -120 Khz. Pye M294 FM High Band f200 £40 Tektronix Time Mark Generator Type 180A C90 General Radio Audio Oscillator Type 1311A 50 Hz-10Khz C50 Pye Base Station Type F9U UHF C90 Marconi Valve Voltmeter Type TF 1041B f40 Airmec Oscillator Type 30Khz-30Mhz Pye Base Station Type F9AM High Band f90 858 C65 Marconi Power Meter Type TF 893A f50 EH Pulse Generator Model 139L8. Pye Base Station Type Fl 7FM High Band f250 f45 Marconi RF Attenuator Type TF 1073A C25 Solartron Pulse Generator Model GO 1101 Pye Base Station Type F412 UHF f200 .. C25 Marconi RF Power Meter Type TF 1020A C65 Anmec Oscillator Type 304A 50 Khz-100Mhz. C85 ITT Base Station Type 30LRU43A UHF f150 Marconi Universal Bridge Type 868B C90 Anmec Modulation Meter Type 409 Pye Pocketfone Type PF2FM High Band 8 Low Band f80 £90

Marconi Universal Bridge Type BEBO f60 Airmec Modulation Meter Type 210A . Pye Pocketfone Type PF2AM High Band 8 Low Band f80 f40 Marconi Delay Generator Type TF 1415. C60 Ad -Vu Precision Phase Meter Type 405H.. £B5 Pye Pocketfone Type PF2UB UHF f80 Marconi Signal Generator Type TF B01 DIES 10mHz to 485 myz C90 Bruel 8 Kjoer Microphone Amplifier Type 2604 050 Pye Pocketfone Type PF5 UHF f40 Marconi Signal Generator Type TF 144H/4 10 kHz to 72mHz f90 Dawe Phase Meter Type 632A Pye Pocketlone Type PF8 UHF f80 040 Marconi AM/FM Signal Generator Type TF 995A/5 1.5 mHz to 220 mHz C120 Dawe Vibration Meter Type 1433A £55 Pye Pocketlone Type PF9 UHF £80 ... Marconi AM/FM Signal Generator Type TF 9956/5 200 kHz to 220 mHz C220 Ferrograph Series 7 Mono Tape Recorders £100 Pye Mains Power Unit Type AC15 C25 ..... Marconi Signal Generator Type TF 10648 68 to 108. 118 to 185 8 450 to 470 60 amp. Alternator 8 Generator Noise Filters.. f1 Pye Mains Power Unit Type AC200 C120 mHz...... £105 Tektronix Oscilloscope Probes. Pye Power Amp Type A200 High Band f50 C10 Marconi UHF Signal Generator Type TF 1060/2 450 /rife to 1200 mHz £60 Mullard Vari -cap Tuners Type ELC2003 Ex Brand New Equip f3.50 Pye Controllers Type PC1 f 8 Marconi FM Signal Generator Type TF 1066B/1 10mHz to 470 mHz . C325 Pye Cambridge/Vanguard 18 Way Control Leads C4 Pye Controllers Type M81 f195 ... Marconi Deviation Meter Type TF 7910. f100 BNC Plugs 75 ohm £SOp Pye Westminster Type W30 AM High Band 8 Low Band f25 Rohde 8 Schwarz Power Signal Generator Type BN 41001 0.1 to 30 mHz. C150 Circulators 590-720 Mhz 'N' sockets C25 Pye Westminster Type LW15 FM High Band C40

Rohde 8 Schwarz Standard Signal Generator Type BN 41409 4 to 300 mHz Transistors Type 2N3055 Brand New . 4 toe Pye Base Station Type F30FM Mid Band f200 C1 AM/FM. £150 Transformers 30 volt 4 1 amp, C1 Pye Europa Type MF5FM Mid Band f60 ..... Rohde 8 Schwarz UHF Signal Generator Type BN 41022 300 to 1000 mHz £150 Transformers 36 volt ea 1.5 amp . C1 PLEASE NOTE all sets are sold less crystals. mikes. speakers power leads 10.7 Mho SSG Xtal Filters 12.4 Khz Bandwidth) Low imp type. Carrier etc. unless otherwise stated. Rohde 8 Schwarz Decade Signal Generator Type BN 41104 0.3 mHz to 500 and mHz £850 unwanted sideband rejection min -400b (needs 10.69835 8 10.70165 xtals CARRIAGE on RT equipment - Mobiles f2.00 each. Base Stations C15 00 Rohde 8 T Type 46453 170 for USB/LSB not supplied) Size approx 2m x 1in 1in 010 each Red Star available at cost. Schwarz V. Demoldulator BN mHz to 220.mHz f150 Marconi RC Oscillator Type TF 1101 20 Hz to 200 kHz f65 Pye F450 UHF Base Station Receiver, Crystaled Controied, Single Channel, Marconi I% Universal Bridge Type TF1313 £220 "OIGITALKER" Mains Operated. Ideal tar Monitoring your local Repeater, UHF Supplied Hewlett Packard DC Power Unit Type 6268B 0 to 40volt 30 amp. £300 Speech Synthesiser Unit Based on The National Semiconductors ' Digitalker' Complete with Circuits etc. £15 plus C5 p.p. plus VAT Hewlett Packard Sweep Oscillator Type 86908 with 2 to 4 gHz Plug -m. 01.200 System Chip Set. The Unit is Mains Powered and Included are a 700 Hz and LOGIC ANALYSERS also available square plug -ms for above 1-2 GHz, 4.8 GHZ 8 8-12 GHz C300 each 200 Hz Filter. Power Amp., Loudspeaker and NASBUS/RS232C Interface

Fluke Model 3010A Programmable PCB Logic Tester £1.500 Hewlett Packard SHF Signal Generator Model 620A 7 to 11 GHz. £220 Circuitry . C20 Plus C2 p.p. Plus VAT. Speech Synthesiser Cards less Fluke Model 3020A Programmable PCB Logic Tester £2,500 EEL 245 Microwave Generator 2 45 GHz 20 to 100 W output 1150 'Oigitaiker Chips £3 Plus f1 p.p Plus VAT BREAKING TEK 545A SCOPES P. & P. or Carriage and V.A.T. at PTE POCKETFONE PF1 RADIOSONDE RS21 15% on total must be added to all FOR SPARES UHF RECEIVER METEOROLOGICAL BALLOON orders. 440-470 MHz, Single Channel, int. CRT type T543 P2 £18 each. Mains Callers very welcome, strictly be- speaker and aerial. Supplied complete Transformers TRANSMITTER T601 £15. with Water Activated Battery, contains tween 9 a.m. and 1 p.m and 2 and with rechargeable battery and service High Voltage Transformer T801 with valves all-weather sensors, fully solid state, £5 5 p.m. Monday to Friday inc. manual, £6 each plus £1 p.p. plus V.A.T. £25. Also Switches, Knobs, Fans, each plus £1 p.p. plus V.A.T. Access taken Capacitors and Metalwork. Barclaycard and Official orders welcome WW2,

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4116 200ns 1 25 1.15 1.10 4164 150ns Not Texas 99 .89 .84 4256 150ns 3.65 3.35 3.10 2114 200ns Low Power 1 75 1.60 1.55 6116 150ns 1 99 1.80 1.65 6264 15Ons Low power 5.00 4.45 4.00 2716 450ns 5 volt 3 85 3.45 3.30 2732 45ons Intel type 4.75 4.25 4.10 2532 45ons Texas type 3.85 3.45 3.30 2764 300ns Suit BBC 2.95 2.65 2.50 27128 300ns Suit BBC 3.95 3.55 3.35 27256 250ns 7 55 6.95 6.50

Low profile IC sockets: Pins 814 16 18 20242840 Pence 12 13 14 16 18 2427 38 Available now - The ROAM BOARD for the BBC Micro. Reads Roms via a Low Insertion Force Socket and saves their contents as files, then reloads a file into its sideways Ram as required. Full details on request.

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8F185 0.30 BZX61 0.17 0495 0.08 0(171 4.40 11X500 0.14 2141307 1.20 2N3710 0.11 AF114 3.50 BC148 0.12 BCY71 0.21 8F194 0.15 Series 06200 0.15 0(200 4.00 6F115 3.50 BCY72 0.21 ZTX501 0.14 2N1308 4.00 2N3711 0.10 BC149 0.13 BFI95 0.15 0ZY88 0.10 06202 0.15 0C201 5.50 ZFX502 0.14 CV Devices AF 116 3.50 BC157 0.12 BCZ11 3.50 2N1309 1.50 2N3771 1.20 BF196 0.15 Series 0A211 1.00 0C202 5.50 ZTX503 0.14 2N1613 0.30 2N3772 1.20 Large stocks AF117 4.00 BC 158 0.13 BD115 0.35 13F197 0.15 CRS1/40 0.60 OAZ200 1.50 0C203 5.50 ZTX504 0.20 214)671 5.00 2N3773 1.60 Priceson AF139 0.55 BC159 0.12 BD123 2.30 13F200 0.33 CR53/40 0.75 04Z201 1.50 0C204 7.00 ZTX531 0.20 2141893 11.30 2N3819 0.50 +pptl0f11Dn AF186 11.75 BC167 0.10 BD124 2.50 BF224 0.12 CR53/60 0.90 04Z206 1.50 0C205 10.00 AF239 0.65 BC170 BD131 0.42 11X550 0.25 2N2147 8.00 2143820 0.611 0.09 8F241 0.12 GEX66 3.00 04Z207 1.50 0C206 8.50 154914 0.05 2N3823 AFZ1I 4.00 BC171 0.11 131)132 0.42 0F244 0.35 2N2148 2.75 0.80 0EX541 6.50 OC16 5.00 0C207 18.00 1N916 0.09 2N3866 1.00 AFZI2 5.00 BC172 0.09 B13135 0.27 8F257 0.30 013M 3.00 6.00 OCP71 2142218 0.32 0C20 2.50 I5441101 0.04 2N2219 6.50 2N39(14 0.10 ASY26 1.40 BC173 0.09 1313136 0.27 13F258 0.30 05403786 1.75 0C22 4.50 ORP12 2.40 EISOL 18.50 EF06 3.0 GXUI 15.35 003 2.50 QY3-65 63.24 11F41 2.14 4-250A 80.54 6CG7 2.50 ' 12AU7 1.75 ' 5545 150.40 VALVES E10(ICC 10.50 EF89 2.54 GXU2 30.00 024 3.50 QY3-125 72.00 UF41 2.10 44006 t7.1111 6CH6 13.80 I:AV6 2.50 55516 120.00 E1801- EF91 2.95 12.05 GXU3 25.40 19206 230 QY4-250 74.00 17190 1.75 4B32 20.00 6CU 1.75 12AV7 330 55526 155.33 61834 9.10 E182CC 13.25 EF92 6.37 GXUI 44.50 PC88 2.50 QY4-400 80.00 11F85 1.75 4C35 120.00 6CW4 1.10 12AX7 1.75 3642 9.54 1.50 62087 13.58 E186F 11.54 E893 GXU50 20.00 PC95 1.75 QY5-500 199.00 131089 2.80 4CX250B 38.00 126Y76 4.10 5654 1.00 EF94 2.50 602 131 62134 1731 E188CC 8.91 GY501 3.00 PC97 1.75 QY5-3000A UL41 5.00 4CX350A 105.00 6DK6 3.01 1284A 3.50 5651 4.45 E280F 22.51 EF95 5.99 A2293 16.00 0232 4.00 PC -900 1.75 472.00 1.75 4X150A 4080 6DQ6B 4.75 12BA6 2.50 5670 4.50 E283CC 12.00 EF98 ULM 62426 27.50 2.00 GZ33 4.75 PCC84 1.54 QZ06.20 32.70 U3180 2.14 4X1500 56.40 6E58 3.80 1113E6 2.50 5675 24.80 E288CC 17.50 EF183 2.00 0234 62521 25.00 4.00 pCC85 1.50 RIO 6.00 1JY41 2.25 58251M 35.0 6E81 2.54 12BH7 2.75 5697 6.10 61900 15.00 R17 3.00 UY85 58155M 35.80 6EW6 2.25 12897 3.40 5696 EA76 121.50 EFF801S 12.00 2.15 1.59 A3343 45.54 KT61 5.00 PCU9 1.75 R18 3.00 VLS63I 5C22 161180 6F6 3.80 12E1 20.00 5718 7.54 EABC80 1.25 EF805S 15.00 15.00 AZ31 2.75 KT66 15.00 PCC189 2.50 R19 9.24 XG1-2500 55.00 51180E 1654.08 6F23 IAN 12E11TT 28.40 5725 5.50 8.211 2.60 EAC9I 3.50 EH90 1.75 KT77 Gold PCC805 1.60 820 2.50 SR4GY 3.50 6E18 134 12E14 65.00 EK90 1.54 XG24/00 5726 11.37 013448 114.90 EAF42 2.50 Lion 12.00 PCC806 1.54 RG3-250 32.68 141.0 5U4G 3.54 6F33 33.34 19E1 174.54 EAF801 2.00 EL32 1.50 5727 7.43 8K484 155.35 KT88 Gold PCE82 2.00 RG3-250A 32.68 XGS-4n0 30.00 5U/GB 2.50 6H1 11.N 19H1 17.51 5749 2.58 BS90 58.00 EE41 4.N EL33 4.N Lon 20.00 PCF80 2.00 RG3-1250 59.50 SVIG 2.50 6H1N 2.75 1985 47.50 E891 1.50 EL34MUl 5751 I.80 00810 4.00XG2640D2.50 PCF02 1.50 RG41250 61.60 163.54 5Y3GT 2.34 6H3N 2.75 1469 67.25 5763 1.50 54.54KT061EBC33 2.54 EL36 2.30 BT5 54.95 KTW61 PCF86 2.50 RG43000 99.45 XR1-1600A 5Z3 1.80 6H6 3.10 30C11 2.80 2.50 2.00 58146 4.80 BT17 151.08 EBC41 2.50 HAI KTW63 2.50 PCF87 2.80 RR3-250 40.00 SZ4G 2.54 6J4 3.54 30CI7 2.10 E1A2 2.50 53.75 5840 1.01 BT19 44.05 EBC01 134 M8079 12.34 PCF200 3.25 883.1250 45.75 x111-32130110.00 SZIGT 2.54 6J6 8.93 10CI0 1.10 5842 EBC90 1.25 EUI 5.25 12.04 BT29 349.15 M8080 8.25 PCF201 .3.25 SIIEI2 65.00 7(R1 -3200A 6.30L2 1.75 637 4.75 30F5 1.60 58766 31.54 BT69 354.80 EBF80 1.50 EU3 6.80 08081 9.82 PCF801 1.50 S130 6.00 XR14400 6634 1.75 61E6 7.50 30FL1/2 138 EBF83 1.75 E1.81 2.25 5479 5.80 0195 129.90 M8082 9.69 PCF802 2.50 5130P 6.00 150.00 6637 3.10 613134 2.54 30FL12 1.84 5886 17.0 CBL31 1.00 EBF89 1.54 EL86 2.75 PCF005 170 STV280-40 YD1120 395.00 66C7 1.14 30FL14 2.00 EBL31 10.00 EL90 3.25 M8083 10.23 610601 2.75 5963 2.54 CL33 4.00 M8091 10.13 PCF8O6 1.74 14.00 YD1240 490.00 6AF4A 4.25 6K) 3.80 30L1 1.54 5965 3.51 EC90 1.25 EL91 7.39 PCF008 STV280-80 CY3I 3.00 M80% 6.10 1.70 "L803U 25.00 6607 3.N 6118 3.M »LIS 2.M 6005 2.25 C1K 20.00 EC91 8.00 EL95 2.14 PCL82 2.N 21.00 15.80 6AH6 5.80 30117 2.10 6021 EC92 1.75 EL156 30.00 M8097 m1_93 6KD6 7.10 4.50 C3A 22.00 M8098 8.158.14Z759 1.005.00SU41 ZM1000 8.N 6A115 5.99 6L6G 3.10 301-6 2.54 6057 12.23 EC137 440.00 EL360 8.54 C31A 22.00 08099 8.0 PCL8/ 1.N SU42 10.54 ZM1001 1.00 46116636063.306 1.S0 6059 12.34 ECC33 4.54 EL500/504 3.00 TD03-10 35.00 DA41 25.00 M81010.30 PCUS 1.50 2911020 f.9.006AL5 6L6GC I.75 3.N 6059 6.80 DA42 18.70 ECC35 4.50 EL509 10.00 PCL86 2.50 TD03-101 35.00 66314 4.1013°30PL1 M8136 11.75 Z61021 9.80 3.00 30PL1/ 1.N 6061 6.80 ECC40 5.0 EU21 13.M TT15 8.00 DAF9I 1.75 M8137 PCI -805/85 2.50 50.006L6GT6AM5 f.N 6L7 1.34 30PLI5 !.N 6063 3.75 DAF96 1.75 ECC81 1.75 EU22 I3.í7 12.25ZM10226.00 21 30.00 66546 6.02 35W1 ELL80 M8140 P0500 ZM1023 9 .N 6N2P 2.50 1.101064 10.20 DET22 35.00 ECU2 1.75 19.00 6.10TTPEPFL2N 45.00 66345 4.75 5005 6.54 ZMI040 ».36 6067 11.75 ECU3 1.75 EM54 M8141 6N3P 2.30 1.54 DET21 49.00 8.00 618142 8.75 00 2.50 TTI0 60.54 ZM1041 16.66 663486 3.51 75131 6.05 6072 4.80 ECC/34 1.75 EMN 2.50 6147 3.00 DF91 9.75 M8144 7.50 P1.36 2.50 TY2-125 65.00 ZM10/2 17.77 6AQ5 3.23 6P25 75C1 4.50 6080 14.00 ECC85 1.75 EMtI TY4-400 4.10 0F% 1.75 M8119 PLO) 1.75 840 3.80 6AS6 0.66 3, 05AI 7.34 6097A 235.80 ECC86 2.54 EM81 2.10 640161 6Q7 DK91 1.75 6.34113GT8.35 PL81A 2.40 TY4-50 110.00 81124 25.00 6AS7G 1.75 6.45 EM85 2.75 195-000 687 3.25 85,52 60978 ä9.80 DK92 1.54 ECM 3.30 M8162 11.75 -82 1.50 225.0 1835A 46.04 6AT6 1.15 6814148 61:08 90AG 20.00 12.00 ECUS 2.14 EM87 2.50.230 TY6-800 220.00 61466 DK% 1.75 268163 025 PL83 2.50 I863 44.80 6AU5GT 5.00 10.40 %AV 20.00 61168 ECC91 8.f3 EN32 25.00 TY6-5000A 12.40 DL92 2.00 6(1190 3.10 PL84 2.54 IRS 1.75 6AU6 2.50 65A7 3.10 90C1 6.14 6159B I9.80 DL91 1.75 ECCIN 2.14 01491 6.50 2.50 13.0 155 1.75 4.50 65 C7 1.75 90CG 14.34 EN92 6.96 548195 I0.45 6189 f. 50 DL% 1.75 ECC007 1.75 5481% 7.54 PL515 5. 0 TY6-50008 ITI 1.75 6GA 1.50 65107 230 90CV 15.45 EY51 2.75 6201 11.40 DLSIO 11.50 ECC808 3.00 082" 1.K PL509 6.110 395.00 2ASI5 11.50 6AXSGT 3.80 65H7 3.10 92AG 20.00 6442 1.50 EY81 156-5000W 28.00 DLSIS 12.50 ECM 2.50 M8112 11.37 PL519 6.00 2C39A 413806137 3.25 6577 3.25 92AV 24.4 6550 8.00 12.50 ECRU 13 EYB3 2.50 548223 6.80 PL801 1.50 446.0 2C13 70.08 658 3.23 6$1(7 3.30 95AI 805 ECF40 2.54 EYM 9.24 TY7-6000A 69838 12.30 DLS19 12.50 548224 6.80 PL801 6.00 221321 3.25 65A6 1.34 6SK7GT 3.80 150131 6.55 6973 ECH35 3.00 EYN 1.75 I. DM70 2.00 PY33 2.50 SS2.08.25 330 150133 8.35 7025 4N8 ECH42 3.54 EY118 1'75 M8244 14.03 PY01 1.30 TY7-6000W 2142 98,90 6BA8A 014 6,SQ7GT 3.44 150C2 3.25 07ÌA ECH81 EY500A DMI60 4.75 3.14 3.0 MD2901 lii.N PY82 1.50 552.00 2355 8245.00 6801 4.10 6587 4.10 ISOCI 6.M 7Si 6_ñ DY87 1.50 ECH83 2.59 EY802 1.75 MUI4 2.54 PY83 1.25 TZ/0 25.00 11706 38154 68E6 1.50 6557 2.75 111 35.80 7586 13.00 ECH84 1.54 E235 1.73 DY802 1.50 11tX119 5531 PY88 2.80 1318-20 3.50 21708 336.0 68346 2.54 6135G 3.50 72363 125.10 7587 23.00 ECUO 1.50 8210 1319 13.75 E551,50.00 2,...,45° 61X123 76.00 PY500A 4.00 23(25 125.00 6816 2.25 6U8A 2.25 803 25.08 7609 56.00 E80CC. 13.00 ECU' 1.75 E241 . MX145 56.70 PY80 1.50 1325 2.50 34001 115.00 68 4 4.50 6V6GT 2.25 805 45.00 7868 6.00 E80CF 11.27 ECU) 130 EZIO 1.S0 31XI51 17.25 1-Y801 1.50 U16 2.50 3500L 100.00 681.6 85.90 6X4 2.15 807 3.75 7895 12.00 ExOF 14.19 ECU3 3.80 E.7.111 1.58 MX152 131.25 QF451 82.59 U37 12.0 3A5 3.N 6BL7GT 4.54 6X5GT 1.75 911A 1833 8005 110.49 E80L 13.73 ECL84 1.51 EZ90 3.0 54X161 152.25 QQ902-6 34.00 UABUO 1.25 3821 11.84 68M6 115.00 787 2.54 8120 31.00 1068 14.08 E81CC 8.00 ECUS 1.54 FW4.500 3.50 54X163 20.25 QQ903-10 25.00 U6F42 1.50 31328 15.35 6BN6 2.0 7C5 4.80 813 valve 65.00 8122 110.00 E811. 13.27 ECill6 1.75 FW4-800 3.50 61X164 QQV03-206 U811 3.00 3829 20.05 6BQ7A 3.54 7C6 2.54 133A 193.16 8136 2.50 25.52 46.38 0810F 35.44 EF37A 510 G1.371K 35.80 03"66 14730 UBC4I 2.25 313240M 17.50 651/7 6.00 7117 4.09 0666 24.45 8417 6.80 E82CC 8.10 EF39 2.75 GSSIK 12.4 64X168 50.0 QQV00-406 UBF89 1.50 38211M 17.50 6BR8A 3.54 787 4.25 872A 24.09 18042 11.53 E83CC 8.44 E1040 5.80 0100.10 17.50 3478 15.10 46.0 UCC84 1.75 3C23 25.0 61357 6.00 757 3.50 922 6.80 18015 10.49 E86C 8.25 FEF41 3.54 0240.20 12.00 0A2 3.25 00V07-50 69.71 UCC85 1.85 3c45 24.54 6BW6 6.10 7y4 2.25 931A 18.54 Tested E88C 8.25 EF42 4.50 G100.1K l'.54 0A3 2.54 QQZ06-906 UCF80 2.14 3CX180A547.80 65W7 1.54 724 2.10 1621 4.10 Ea-Equipment E88CC 10.33 EF50 2.34 GN4 9.80 0A4 6.80 62.20 UCH42 2.50 3E29 4314 6BX7GT 5.80 11E3 55.80 1625 3.54 4CX1505 6.54 E90CC 9.47 EF54 5.00 GNIA 9.00 081 4.35 QU37 12.50 UCH8I 2.50 354 2.54 6BZ6 2.75 116H0 5.10 1010 30 CV Devices UCL82 1.75 E9OF 9.90 EF55 3.54 GS16 16.N 083 2.50 QV03-11 6.14 3V4 1.75 6C4 1.25 11ÁT6 1.51 4212E 39.N ur4estocks E91H 6.25 EF10 1.75 GTIC 25.00 OC2 I QV04-7 3.50 UCL83 2.75 4-6SA 0.10 6CB6A 2.54 12AT7 1.75 4212H 310.10 Pnceson E92CC 8.75 MO 4A0 01350 2040. 0C3 i.""" Q908-100188.00 4-125A 54.01 6CD6GA 5.14 12AU6 1.N 5599 110.00 application E99F 9.10 EF85 17 GU51 20.54 11.75 74150 7486 11.54 741'1 1.75 1665711 1.75 INTEGRATED CIRCUITS 74911 0.72 41'I ISJ ,1711 1211 L\65711 1.75 SADPI 55.00 VCR517B 11.00 74172 11.70 74177 4.1111 1 6A6UIY 1.75 741111 11.35 7417 ILJ% 7442 ì4'11 IIJM1 BASES CRTs 5CP1 10.4 VCR517C N.N 1.25 75173 11.611 74174 11.72 -I007110 3.181 24P1 8.50 5CP1A 44.01 74111 0.36 74311 11.4N 74511 11.311 749_' 11.51 741 + II.611 74174 8.60 11)16480(,) 1.511 2BP1 9.00 5F715A 15.00 7411' 11.36 7422 11.36 7451 11.30 7493 0.54 137G Unskirted 0.40 741-M1 11.55 74175 11111 T065200 1.50 38PI 12.00 7413 11.36 7423 11.36 745i 11.311 7494 11.70 07G Skirted 0.30 5UP7 2í.N 741 98 11.55 74176 1.1111 1A65311 1.511 3DPI 5.40 74114 11.42 7420 11.36 7454 11.311 7445 B94 Unskirted 0.40 007-5 63.32 .(,('.°.5,. 74136 11.711 741811 11.48 1045í11Q 1.75 3EG1 10.00 CRT sockets 74115 11.42 11.36 74611 11.311 7496 09A Skirted 0.50 007-31 58.07 7427 74141 11.16 741411 1.211 104561 /0 1.75 3101-7 6.00 11.4N 7407 1,411 890 035 DG7-32 58.47 Prices on 74116 II.SN 74'° 11.3M1 7,711 7,143 I..b 74101 1. so TOA/r71 1.7$ 0.40 3GP1 6.40 7407 11.55 74311 11.36 7472 11.311 7J11111 O.NJ lot Octal DG7-36 65.00 + liutioo 11,72- 7J19- 1.211 10671X1 1.511 B.N DH3.91 56.83 7408 8.36 7432- 8.36 7473 O.iM1 Lacul 0.55 NE; 1/C sockets 0.40 74107 74147 1.511 741`81 8.60 1067'_0 1.75 08 113.12 74114 11.36 7433 II,.IM1 7471 11.36 741114 ILSJ Nuvistorb+se 2.80 DH7-11 Texas 74148 L41r 74195 1.111 TB/57500 L511 31)1-7 10.80 74111 11.36 7437 11.3M1 7475 11.65 751111 II.JN Valve screening VCR97 741511 1.61 74195 11.72 1068111 I.1N1 :1,,-, low profile 3KPI ISIS w74I,5741 I 1L411 741° 11.4R 74111 11.51 0.36 7476 OnsaBsues VCR138 II.JM1 7,1a6 l'll TBn930 1.75 3RP1 35.4 VCR158A 11.54 8pin 10p 741? 0.42 7439 11.36 74811 11.32 7,II6 1.511 74154 1.411 74197 1.1111 IBA 990 1.511 3WP1 20.4 8.00 14 pm 7413 11.36 74411 11.46 7483 0.441 749)° 1.20 VCR 139A lOp 74)55 0,60 74108 2._211 T('627001.181 7416 11.J8 7441 11.J8 11.72 7J 1 19 1.511 0.447515I16 pin lOp7415n7101 0.40 74100 2.211 l I: 979)96 115 Terms of business CWO. Postage and packing valva and semiconductors 50p per order. CRTs E1.50. Prices excluding VAT, add 15%. Telephone 01-677 2424/7 Price ruling at time of despatch. Telex 946708 correct when going to In some uses prices of Mullord and USA valves will be higher than those advertised. Print vas. E. & O.E. Account facilities available to approved companies with minimum order charge f10. Carriage and packing [1.'i0 on credit orders. Open to callers Monday -Friday 9 a.m.-5 p.m. Over 10,000 types of valves, tubes and semiconductors in stock. Quotations for any types not listed. S.A.E. WW1 f IA!`i F 1 R Fí111 F11ATII1: A P1FTA 33 C ELECTRONICS & WIRELESS WORLD OCTOBER 1985 33

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34 ELECTRONICS 84 WIRELESS WORLD OCTOBER 1983

www.americanradiohistory.com by J.H. Adams, Half -megabyte M.Sc. memory for SC84

`Silicon disc' using 256K dynamic memory chips has novel refresh system.

I use a microcomputer primarily tute itself for an equivalent block An explanation of the design as a means of developing sof- of system memory. SC84, as with philosophy behind multiplexed - tware and of writing long docu- any other good computer design, address dynamic memory was ments, such as this article. My has a mapping facility. The given in my recent series on the SC84 computer gives better per- advantage of mapping is that SC84 computer*. Suffice to say formance than many other com- areas of system memory are not that in addressing dynamic mem- puters but the discs don't go permanently committed to tran- ories, the address of the locations round any faster than anyone sient facilities (the v. d. u. in SC84 to be accessed is latched into the else's. When working back and is a good example of this). One memory in two parts - a row forth between the ends of large must choose the mapping area address and a column address. files with Wordstar or when per- carefully though as it is obviously This saves pins and thus cost on a * SC84 is a 4/6MHz Z80 -based computer forming a major assembly, disc not possible for code executing in 256Kbit device which otherwise running the Scidos operating system for operations take a lot of time. the area of system memory to be would need 18 address pins. It CP/M software, described in the May, June, July, September and October 1984 The reason for this is clear mapped out to access the mapped also allows refreshing of the issues. The three -Eurocard circuit board when one watches the process. In area. For this reason, switches entire memory by regular access - set for this project is still available. both cases the computer is allow the unit to be permanently operating with more than one file. allocated or to be mapped to any In word processing, the compu- 2Kbyte block within an 18bit add- ter memory acts as a 'window' ress range. The silicon disc is into the file. As this window seen as an adjunct to the disc Specification and performance moves up and down a file larger operating system and so, for than the free memory available in SC84, the mapping is over the Memory capacity is 512Kbyte organised as 256 'tracks' of the computer, temporary files are section of memory even more 2Kbyte each and power requirement is +5V at up to 0.5A, created to store the data ahead of fundamental than Scidos itself, depending on the system cycle rate. and behind the window. the resident operating system To test the performance of the 'silicon disc' compared with a In program development, Mcos. conventional system, I used Word star to edit a 120Kbyte assembly means getting data The half-megabyte memory is source file. The procedure was to perform a global alteration from the source file and sending in the form of 16 256Kbit through the file, to save the file using tKS to move to the end data into object and listing files. dynamic memories, although the of the file using tQC and then to move back to the start using Switching between the files takes unit can be built with only half of tQR. time as the drive head has to tra- this capacity. Thought has been Timings for these operations on SC84 with and without the verse the disc surface many given to making the silicon disc as silcon disc and for a DEC Rainbow are shown in the table. As times. There's wear and tear on versatile as possible. As such it shown over extra time taken depends very much on the the drive and the computer oper- relies on only two system signals; distance moved by the drive head during the magnetic disc ator, both of which can be elimi- one indicates that a memory cycle tests, the SC84 and DEC tests were carried out under nated by the use of what has is taking place and the other that a optimum conditions, i.e. with only the source file on the disc. become known as a 'silicon disc'. read operation is occuring. In a The fourth column in the table indicates how long a Silicon disc is a large memory Z80 system these would be computer would take with a typically full disc. During the used either as a buffer into which MREQ and RD; in an 8086 sys- alteration, screen update was suppressed by pressing ESC as the working disc's contents are tem they would be a combination otherwise the test would have reflected the speed of screen loaded or, as in this case, treated of ALE and IO/M and the RD update rather than of disc access -a factor which would have as a pseudo disc. The system signal. considerably increased the DEC timing. described consists of a 512Kbyte Note that no reference is made The final test was to assemble a 20Kbyte Z80 source memory, accessed as one of 256 to external refreshing. The RFSH file to produce an intermediate file which would result in 2Kbyte 'pages'. input shown on the circuit dia- approximately 2Kbyte of object code, and a listing file. The Pages are selected by writing gram is offered as a means of assembler used was M80. an 8bit value into a register on the reducing unnecessary power These tests are reasonably representative of typical uses of silicon disc unit. This is rather consumption in Z80 systems. the silicon disc. Other advantages, particularly noticeable like writing to the track -number Refreshing of the memory is when using Wordstar, are that messages and overlays load register of a floppy disc con- achieved by a combination of and present themselves instantly and noiselessly. troller. Once selected, the page some rather clever facilities pro- may be accessed directly or by vided in the memories specified 'mapping'. In mapping, a block of and the way in which the silicon memory can be made to substi- disc is used.

ELECTRONICS & WIRELESS WORLD OCTOBER 1985 35

www.americanradiohistory.com MEMORY EXPANSION

11a AOtoA10

21a I +5V t 25c' 3,4. 7,8, Use liberal supply line 13,14, I3a DOtoD7 11-18 17,18 decoupling IC1 IC2 2-9 '10a I 5,6, 74LS245 74L5273 9,12, 15,16,19 2,12). 6,10 1 3,10,11 3,5,6,13, 14 10 PL1 Pin numbers suffixed IC3 lc 105 a&c refer to printed 7»LS158 74LS158 7415158 1 IC9 mounted circuit 74LS05 connector to 7, 9,12 4,9 3 12 DIN 41612 64196 1,5-7,9-13 RD 1 2 ...,, .1C10 11cI Two banks of eight HM50256-1S or 74LS14 9 equivalent (see note below) IC10 1012-1027 21c, 10 º- I27a I 12 11- <7. t5,7---` 8 16

'25a I '4 IC6 11.,. C1

I23a I 15 741S85 1 R4 » 1 p47 R IC8 4-I 5 5 3 10 íC11 16 6 6 2 C2 330 7415 153 IC11 330 47p 4 74LS132 1 6 5 16 3 8 C10

28a ! 10 3

26a I 12

'24a ! 14 I07

22a I 15 741 S 85

k2 IC12_27 all pins connected in parallel except for pins 15 which are parallel within each bank and pins 2and 14 which are connected to the 13 1 13 eight data lines, each data line feeding tC 11 MEMDIS 011 R1 3k3 one IC from each bank. 2 19c'

2N 2369 For printed circuit board, add 400 to reference numbers. e.g. ICI becomes 10401 MREQ

9c I RFSH

18cI

Half -megabyte memory ing of all rows. generator, but with 8 bits, into both RAS and CAS high, apply the expansion circuit. Pins 15 of The Z80 has an inbuilt refresh their dynamic memories and pro- row address, switch RAS low, the three LS158 multiplexers generator consisting of a control viding a pin to implement the apply the column address, switch are connected to ground. line and a seven -bit counter refreshing process. This was a CAS low. After this a read, write, which is regularly incremented good idea as it allowed other or read -then -write operation may and output during a period when refreshing techniques such as take place on the addressed bit, the Z80 doesn't need the external standby refreshing to be imple- depending upon the WR control bus. While memories were mented but it took away a much line. Strobe RAS may be taken addressed seven bits by seven needed pin. When 256Kbit i.cs high again a short period after bits (16Kbits) this was accept- were designed, this pin went to CAS has gone low and, as a varia- able. When 64Kbit devices provide the ninth address line but tion, CAS may then be repeatedly appeared, most were made to be in certain devices the internal pulsed to latch in the addresses actually seven bits by nine inter- refreshing mechanism has sur- of, and therefore access, other Kits and p.c.bs nally, although addressed as vived. bits within the same row. Memory board kits excluding eight bits followed by another As mentioned, the address is What never happens in a con- p.c.b. are £92 inclusive from eight. This meant that a Z80 latched into the memory in two ventional addressing situation, could these by of a John Adams at 5 The Close, still refresh devices parts means negative and what is exploited in the Radlett, Hertfordshire WD7 but it did make the i.cs more diffi- transition on one of two control devices under review, is that RAS cult to fabricate. lines, row RAS 8HA. This price is £93 for -address strobe should go low while CAS is low. Some device manufacturers and column -address CAS. readers in other parts of strobe My words are carefully chosen as The standard operating Europe and £94.50 for those attempted to make their 64Kbit sequence the data sheets for most 64Kbit chips more by building for a dynamic memory of this type outside. versatile devices do show a mode called would be as follows. Begin Plated -through -hole p.c.bs an equivalent of the Z80 refresh with `hidden refresh', where after CAS for this project are £16 has gone low and data is being including UK or overseas Test Silicon disc SC84 DEC rainbow SC84 typical accessed (RAS goes high), the postage from Combe Martin Alteration 43 170 179 182 address of a row to be refreshed is Electronics, Kings Street, 2 18 17 22 applied and RAS goes low, forc- Combe Martin, North Devon OR 12 47 62 160 ing a form of refresh. The differ - Assembly 22 110 102 115 EX34 OAD. Continued on page 93 36 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com INFORMATION

INSTRUMENT A NEW SERVICE RENTALS FOR READERS OF ®leiSMU ENTREwusl ELECTRONICS

Instrument Rentals have suhitant tally increased their range of instruments for rental in their new 19X5catalogue-l'est and mea- surement. communication.. microprocessor development. data WIRELESS WORLD products ;nid Ohre opto test egutpmentio detailed in the cata- logue which includes their estremeh' competitive rental rate for pentds of up Ti four years. This information service is a quick and simple method of obtaining the very latest literature.

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ELECTROPi.AN P.S.P.

hoc will almost certainly he awareof Electroplan'sstandingin ¡ he field of electronic measurement. for we are tie UK's leading tech- nical distributor of test and measuring instrumentation In users in lechnology-hased industries. Less well known- perhaps. are our accom alishments in micro- ,mputer-hased instrumentation - a rota-ively new. but now rapidly expanding. arm of our business. 151' Electronics have updated their free short form literature Microcomputers from Hewlett-Packard aid IHM are stocked. which includes photographs and information abruti their com- together wit h a wide range of compatible ha-dware and software. plete range of connectors_ enabling customised measurement systems to he configured to The literature is in full colour. includes stock range additions the needs of specific user application. such as the Souriais 851 series. and can he obtained hycircling the This brochure attempts to describe our capability. and the number on the Free Product Information cond. items below provide listed some indication of our immense PSP is a franchised distributor for ITT Cannon. Thomas & strength -in-depth of standard products that may he applied to lier is. Transradin. ITT Pomona Electronics, Pandutt and Souriau measurement and control problems. and. as always, 151' are able to provide technical advice and ser- Hewlett-Packard Microcomputers 111M ?ersonal Computers vices to meet clients' particular needs. Software for Hewlett-Packard and 113M Computers Scientific Manufacturers' catalogues with full prat et specifications can Computer Interfaces and Accessories Programmable Instru- also he supplied on request. mentation Data Acquisition Computer tided Design. We can supply complete. integrated. measurement systems, together wit h dedicated software. written in house. to provide a complete slut ton for your industrial or scientific application. If you require anyfurt herinformation, please circle the numh, on the Free Product Information cond. CIRCLE 94 CIRCLE 95 FOR FURTHER DETAILS. FOR FURTHER DETAILS.

MOWLEM MICROLEASE The Microl.ease catalogue has been completely restyled, revised MICROSYSTEMS PLC. and updated for 1985/86_ More pages. more equipment, more The Mowlem Technology (in:, has recently launched a new facts. From THE name in electronic equipment rental. Also. 19145 company, .Mowiem Microsystems Limited. In develop and market .sees the introduction of our handy pocket equipment guide - SO a range of data acq«vsition and -nntrol systems hased on the ADI! you can carry all the Micrnl.ease rental infnrmaòon around with

¡Autonomous I tata Acgwsitior l'mti, A part of John .Muwlem& ADU dl. you. CATALOGUE 1985 6 Company PLC. Muwlem Tech ology is dedicated ho supporting Autonomous data The reason for all this actimly is simple - we've concentrated extensive development progranmes wd hin its specialist technol- acquisition tio:t on expanding our equipment range to become the most comprr .1 new woh ro ogy fields and has identified Iht potential of the Al at.' as worthy of +Ppi hensive offered by any U.K.rental company, as well as improv¡ dare acmúsrtier substantial group investment. the basis of this belief Les in the the professional support services that have given Micro easy design cil the product: the Al/ meets the requirements for an (heir unrivalled reputation for speed. efficiency. quality and relic intelligent and highly flexihle device for interfacing between natty. transducers and microcomputers Along with this increase in the range off equipment on offer The design philosophy is suer that the Al is compatible with we've made our rates even more competitive (or 1985/86 - with all readily available microcomputers and accepts signals from a discount plans lv satisfy the most cost-conscious customer. Hut wide range of t rmsd users, as wall as prnv¡di n g both analogue and despite these even more competitive prices. Microl ease still insist digital outputs In its capacity a process controller. nn providing greater levels of service - more reliable delivery. The unit emhodiesall the nee ssary hardwareand software rou- even tighter quality control and complete testing, servicing and tines for data acquisition. test sequencing and adaptive control. calibration by expert technicians.

The AUC'.s internal microcompr tereliminates the need for an in- What's more. we're expanding nurequtpment range all the l ¡m, depth knowledge of interfactngwnd software techniques and the - to keep pace with technological developments. to covera wide, user merely Instructs the At A'o the nature ufthe tests, byinputt- range of Industry applications and to meet the changing require ing simple commands to the h, st mortcomputer. meets of our customers. In fact. even if the particular unit or sys This Hex thinly and simplluc of operation allows the user to THE NAME IN ELECTRONIC rem you need is not shown in these pages. it's more than likeli rapidly set up a testing system talured exactly to his own require- EQUIPMENT RENTAL ;mailable now - simply phone us with your enqutrv. So whatever ments in a substantially shoote red development time. your industry. wherever you are in the l'.K. and whatever vino CIRCLE 96 requirement. Microl ease will deliver - That's why we're TI II: CIRCLE 97 name in elec¡tun, covi pment rental. FOR FURTHER DETAILS. FOR FURTHER DETAILS.

KEMO SPECTRA STRIP

A new 5fi-page Designer's Handbook is now available from Spectra -Strip I.td. and pnivtdes complete engineering details of all the products in the companv'swide range of rihhnn cahlesand 11/C connes tors. Comprehensive electrical and physical specifica - loins are supported by technical graphs tahles This Lipp catalogue from homo (Filters) Ltd. gives full technic cil drawings, and of details of the company's range of variable filtecsfnrsignal-prnrr dimensmns_ together with full ordering information. sign ante allied applications. Filters cowered in the catalogs, Manufactured al the company's modern plant in Romsey. include continuously variable. digitally set, multi -channel. com- llampshire. the ribbon cahles include Twist 'N' Flat. hound 'N' puter -controlled. anti -abasing and noise -measuring types Flat. Croo rid -plane. Colour -ended. Co -ax. Jacketed. Gey Zip. Flat - conductor. Twisted -pair and Iligh-flexing varieties. I tevices are available with cut-off frequencies retwees 0.001 II. The compatible range of WC connectors detailed in the Hand- and 1 MI lx and passhand response down to dc . and among th, hrmk include Sockets. West development features in the catalogue s the companyh Card -edge, Dual in -line plugs. and a variety 0(11 rw System 998 CP113 IEEE serial interface. C`ipies of the cat:i- -subminiature plugs. receptacles and associated accessories. Also detailed is the wide logue are available Gee of charge. range of Headers available from Spectra - The Strip. including Unprotected. 4 -wall Protected, and Low -profile SpectraStrip in all their various forms, such as Straight. Right-angle. etc. Designers Handbook The centre pages of the IlandMuik provide information on Spectra -Strip's very successful 11W Harnessing Service. which is ping fast-growing support fro m manufacturers throughout thee IS.

CIRCLE 98 CIRCLE 99 FOR FURTHER DETA ILS. FOR FURTHER DETAILS.

www.americanradiohistory.com RADICICODE CLOCKS LTD SPECIALISTS IN ATOMIC TIME, FREQUENCY AND SYNCHRONISATION EQUIPMENT NEW PRODUCTS MINIATURE RUBIDIUM OSCILLATOR MODULE Lower power, fast warm up, optional output frequencies, programmable frequency offsets. RUBIDIUM FREQUENCY STANDARD High performance, compact and rugged instrument. 2U rack or'/, ATR case options. INTELLIGENT OFF -AIR FREQUENCY STANDARDS Microcomputer controlled instruments, directly traceable to N.P.L., precision ovened local oscillator, comprehensive monitoring and status information, real time synchronisation. LOW COST MSF FREQUENCY STANDARD Instant operation, directly traceable to N.P.L., self-contained portable unit, no scheduled frequency changes, 24 hr transmission, real time synchronisation

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CIRCLE 143 FOR FURTHER DETAILS. AFFORDABLE ACCURACY HM102 BZ QUALITY MULTIMETERS FROM ARMON £13.00 ANALOGUE DIGITAL 1111.102BZ HC 0010 0 5% Accuracy. Standard Model 1OADC Range, 20KIVVDC, Buzzer, Battery Test £33.50 Scale Lt 3.00 HC -5010T 0. 25% Accuracy. TR Test Facility 19 measuring ranges £35.50 1114102111 All models have full functions and ranges and Low end voltage & current ranges, Jack for feature Audio sip Voltages t11.00 20 measuring ranges. 312 digit 0.5" LED display 1111.1015 Low battery indication Rugged.Pocketsized meter,forgeneral Auto zero & Auto polarity ABS Plastic Casing & Tilt Stand 16 measuring ranges DC AC 10amp Range Battery, Test Leads and Manual included with Overload Protection on all ranges. each model. Battery. Spare Fuse, Test Leads and Manual /0 2E FULL DETAILS ON APPLICATION FROM: - NC 7030 ARMON ELECTRONICS LTD 0.1% accuracy DEPT. A HERON NOUSE, 109 WEMBLEY HILL ROAD, WEMBLEY, IMDDLESEX HAS IMO £39.50 TELEPHONE 01.902 4321 TELEX 923985 PLEASE ADO 15% to your order for VAT. P&P Free of charge. Payment by cheque with order push button Offer epprcable to intend UK anti Trade enqulties Nailed Meese allow 28 days for delivery YVV\I CIRCLE 120 FOR FURTHER DETAILS. RACKMOUNT CASES ELECTRONICS C.A.D. "ANALYSER I & II" PERFORMANCE ANALYSIS of LINEAR CIRCUITS using the BBC MODEL B AND SINCLAIR SPECTRUM 48K MICROS. Simulates Resistors, Capacitors. Inductors, Transformers, Bipolar and Field effect Transistors, and Operational Amplifiers in arty circuit configuration. Performs FREQUENCY RESPONSE ANALYSIS on Circuits with up to 30 Nodes 19"SelfAssembly Rack Mounting Case with lift off Covers. Front Panel 10 gauge, and 100 Components, for Phase and Gain/Loss, Input Impedance and Output Brushed Anodised Aluminium, Case 18 gauge, Plated Steel with Removeable Rear Impedance. & Side Panels. In 1U & 2U Types, a Subplate Chassis isMountedto Bottom Cover. Ideal for the analysis of ACTIVE and PASSIVE FILTERS, AUDIO, WIDEBAND and R.F. In 3U Type the Subplate is located on two Rails Mounted Between The Side Plates, AMPLIFIERS, LINEAR INTEGRATED CIRCUITS etc., etc. ANALYSER" can greatly reduce or even eliminate the need to breadboard new designs. 1U (1%) height, 230m depth £27.00 USED BY INDUSTRIALAND UNIVERSITY R&D DEPARTMENTS WORLD WIDE. 2U (3'/2) height, 308m depth £32.00 VERY EASY TO USE. PRICES FROM £20 ACCESS OR AMERICAN EXPRESS 3U (514) height, 230m depth £39.00 WELCOME... For further details write or phone NUMBER ONE SYSTEMS LIMITED Width Behind Front Panel 437m (All Types). DEPARTMENT \CA.T/ All Prices include Postage & V.A.T. Cheques, Postal Orders Payable to. 9A CROWN STREET, ST IVES HUNTINGDON J. D. R. Sheetmetal, 131 Grenfell Road, Maidenhead, CAMBS. UK. PE17 4EB Berks. SL6 1EX. Maidenhead 29450. TEL 0480 61778 TELEX: 32339 CIRCLE 116 FOR FURTHER DETAILS. CIRCLE89FOR FURTHER DETAILS.

38 ELECTRONICS & WIRELESS WORLD OCTOBER 1985 RAEDEK ELECTRONICS 102 PRIORY ROAD, SCRIBERS LANE, HALL GREEN, BIRMINGHAM, B28 OTB. ENGLAND.

Telex No 312242 MIDTLX G. Tel 021-474 6000 417STOCKIST Mal Ar FOR 1k Apr Richardson .44 Electronics ,414, Electron AMPEREX TubesAMPERITE AirCETRON CTC Du MONT EIMAC ELECTRONS GENERAL ELECTRIC GENALEX ITT LITTON MACHLET T MULLARD NATIONAL OMNI WAVE R C A RAYTHEON STC SIEMENS SYLVANIA TELEFUNKEN THERMOSEN lirVICTOREEN VARIAN TUNGSOL BURROUGHS WESTINGHOUSE R. F. Power Transistors drMOTOROLA GENERAL ELECTRIC R.C.A. JOHNSON AEROTRON QUINTRON REGENCY WILSON T R W MSC ACRIAN TOSHIBA NEC MITSUBISHI PHILIPS AMPEREX R/F CERAMIC CAPACITORS

CIRCLE 139 FOR FURTHER DETAILS. LOOK AHEAD! WITH MONOLITH MAGNETIC TAPE HEADS COMPATIBLES VIDEO HEAD REPLACEMENT KIT DOES YOUR VCR GIVE WASHED OUT NOISY PICTURES - IT'S PROBABLY IN NEED OF A NEW HEAD - FAST FROM OUR EX -STOCK HP Series 200 DELIVERIES. all models SAVE fffs ON REPAIR CHARGES. New 1/2Mbyte nd r OUR UNIVERSAL REPLACEMENT VIDEO HEADS FIT ALL MODELS OF 2Mbyte board as well as VHS OR BETAMAX VCRs. FOLLOWING OUR REPLACEMENT GUIDE usual 256K and 1Mbyte. AND WITH A PRACTICAL ABILITY, YOU CAN DO THE WHOLE JOB IN The 2Mbyte card utilises YOUR OWN HOME WITH OUR HEAD REPLACEMENT KIT. only a single slbt. Compatible Speedup cards, Spoolin and Mass Storageevices Au- A are also availab YOU wide range of software packa NEED including Compilers, Wordproessing and Database management. HP150A/B and II 128K, 256K and 384Kbyte Other compatible productsInc peripheral eery computers, disk eharing ancrVI-TOCLernulatfon: HP9845 B/c., et From 256Kto 2Mbytes on a single card and at less than hairt ost. Other,c6mpatibles include Programmers Toolkit, Command File and n - eMass Storage Roms to give the 9845 enhanced capabilitOts. KIT CONTAINS - NEW VIDEO HEAD, 5 CLEANING TOOLS, HEAD All qiy boards are available from stock and carry a 2 year repl ent CLEANING FLUID, CAN OF AIR BLAST, INSPECTION MIRROR, ANTI- warranty STATIC CLOTH, VHS/BETAMAX MAINTENANCE MANUAL, CROSS As a Hewlett-Packard distrityutorfrotek offers the full range o P personal HEAD SCREWDRIVER, HANDLING GLOVES, MOTOR SPEED DISC, computers, peripherals, interfacesTAttessories and conSum les. SERVICE LABEL. HEAD REPLACEMENT GUIDE. Most items are available VHS KITS £63.25, BETAMAX KIT £75.25. Prices include P&P and VAT from stock. HOW TO ORDER: PLEASE STATE CLEARLY THE MAKE AND MODEL OF YOUR RECORDER. THERE ARE TWO VERSIONS OF THE VHS HEAD AND YOUR ORDER CAN BE PROCESSED FASTER IF YOU LOW COST CHECK THE SIZE OF THE CENTRE HOLE OF THE HEAD WHICH WILL BE EITHER 5mm OR 15mm DIAMETER. CATALOGUE: For our fullCatalogue of Replacement Video and Audio Cassette/Reel to Reel Heads, Motors, Mechanisms, etc. Please forward 50p P&P. THE MONOLITH ELECTRONICS CO. LTD. MEMORY Protek, 10 Grosvenor Place, London SW1X 7HH Tel: 01-245 6844 5-7 Church Street, Crewkerne, Somerset TA18 7HR, England Telephone: Crewkerne (0460) 74321 Telex: 46306 MONLTH G CIRCLE 131 FOR FURTHER DETAILS. ELECTRONICS & WIRELESS WORLD OCTOBER 1985 CIRCUIT IDEAS

Humidity control that the motor is impedance and peak mains voltage. including the sensor, should be overtemperature-protected; The sensor* requires an short and well screened by Normally, the extractor fan in most modern fans include these alternating signal of less than track areas at mains neutral this humidity control circuit is features. Transients produced 1V. An 11V squarewave at the potential. The sensor should be started when the bathroom light by switching are damped by a D1,2 junction is used for this. away from the triac and its is turned on and the motor v.d.r. over the triac but as the Sensor resistance falls as air wiring and it must, of course, stops around 20 minutes after circuit switches at or near zero moisture increases and have access to room air. Bear in the light is turned off. If relative voltage this is not a major eventually the signal passing mind that the whole circuit is humidity exceeds about 80% problem. through the sensor triggers the connected directly to the mains. however, the motor runs for Network R5C1 sets the 20 timer. A potentiometer sets the M.R. Hadley about 20 minutes or until minute delay. A 10V regulated timer trigger level. While the Lyndhurst humidity falls below 80%. supply is derived using C3, R1, light switch is on, the timer i.c. Hampshire Domestic induction -motor D1-3 and a smoothing capacitor; is triggered through C2. *Available from Norbain fans of up to 1.5A can be full Electro -Optics -wave rectification must be Wiring around the high - Ltd, Norbain House, Baulton Road, switched. For safety, check used to stop C3 charging to impedance areas of the circuit, Reading, Berkshire R62 OLT.

C2 103

33n 250Vac class X Live C3 470n 250Vac class X R2 R5 Murata 4M7 47k HOOSS22011

RI 1N 914 `--//\A-+ 14 8 Fun 1 470 .,w\. TRIG SV* 7M5 Lamp R3 I CONTRO_ 3M3 82p 10M 2M2 100k cer 6 THRESHOLD D1nCHARñc R6 TIC206M 4 ONO 680

1

10 On 102 cer 1N914 R4 47k 1N914 220» 10V 1m RS238 615: 0 20 40 60 80 100 T 16V T16V jNeutral RELATIVE HUMIDITY(RH%)

Add-on current negative feedback through Tr2 being the regulating current - dumping derived negative feedback prevents thermal runaway Recently, several `non - without the need for special switching' class -B amplifier thermal feedback. circuits have been published. Take care selecting base Some of these are complex, resistor values RB3B4. Lower some have thermal runaway values of around 20052 are problems and some require preferred to prevent creation of careful matching of devices. an additional pole within the This circuit is so simple that it desired bandwidth. can be implemented in any Drive current ID needs to be class -B amplifier, yet it is set at about twice the value of effective enough to cure all of Tr3/Tr4 maximum collector the problems that traditionally current to allow the drivers to result in crossover distortion. work in class -A throughout the The idea is to make sure that full voltage swing. Quiescent the output device is always current is set by I3 and RB/RE. turned on, by configuring it as a Making Rc equal to RE constant -current source when it simplifies calculations. would normally be turned off. Generating bias voltage with The principle is not new, but diodes allows a simple output the realization is. current limiter to be added in Transistor Tr, is forced into the form of D3.4. constant-current mode by Erik Margan collector current of Tr4. This Ljubljana transistor senses the fall in Tr2 Yugoslavia collector current as IZR, falls, so I4RB4 directly compensates ioRE, 40 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com Easy character - Three stages of division generator timing 2 - 2 - 2 12 MHz B C D A eg.74LS93 adjustment I CCK to 6845 4MHz / Four stages CCK eg 74LS92 Display circuits using 6845 or character clock 1MHz 6MHz Ir / similar controllers usually input < c.r.t. A0 A1 A2 (Low) { have a system of gates and 74LS138 strobe (High) É 7 inverters to extract -1 dct-clock 1 I 1 I 1 1 1_I pulses from the - register Character data 4LD Shift register Latch enable D LD Shift divider. These strobe pulses are -latch enable EN for shift register loading and data latch enabling. B output If this gating is replaced by a

3 -to -8 -line decoder, the outputs C output available cater for most timing requirements in systems with D output 1 up to eight dots/character horizontally and beyond eight A output(CCK) One character time ' if are not required One dots strobes B 0 (Dot clock) -time in the additional space. LS 138, outputs 0 7 - 3 - 4 - 5 - 6 7 -- The advantage of this circuit before qualification is that timing charges are easily made after constriction without the need to rewire or patch. corresponding dot time. A clock in this case. If the 138 is diagram for this application the This permits substitution of switch selects output activity switched to give outputs during 138 outputs are shown without character generator roms and during either the high or low the clock low phase, this should qualification. I would suggest v.d.u. rams of various speeds pulse of the dot clock. be inverted before being used to divider B output for 138 and changes of parameters such Alternative qualifying signals drive the shift register. enabling, E, and a 6MHz dot as dot -clock frequency or may be applied to the enable The special application uses a clock to either E or E. number of dots per character. inputs. 12MHz source to provide a J.B. Bell In the general application, top Fallingdge o= the shift 1MHz CCK signal, a 6MHz dot Grimsby left, each 138 decoder output register LD pulse should clock for six dots per character Humberside goes active low one per coincide with the rising edge of and a 4MHz output for a 6802 character during the the shift clock, which is the dot microprocessor. In the timing

*SV 74LSO4 RS232 -to - t o 11 To centronics plug See table via twisted pair Centronics .1 13 1k5 below A 12 -- NB1Vcc D 11 interface 2N907 N2222 B <21NB2 10 0,--- EPS 3k3 Serial RS232 data is converted Hold off 9 D o-.NP to a form suitable for driving a (RTS) B E ,. TSB printer with a Centronics parallel interface using this 6 circuit. On the AY -3-1015 uart, + 5V R 08 5 D7 for converting the asynchronous 2 13 4k7 AY -3-1015 Busy serial stream to strobed parallel 10k 4k7 2 21 19 busy line is used to Reset DAV Data strobe output, the 18 implement a C: ß handshake. 20 S1 RDAV Acknowledge 15 Data rate and number of stop Received 2N2222 OR 13 330 bits are link or switch data O 1.VV 10p ,\A, (Rxl clock frequency is 4L7 FE 14 330 selectable; RDE 16 times the desired data rate. i 1N914 0V SWE Rx 330 -/ .// Whether one or two stop bits _i3. I4 116 17 T are used depends on the printer - - type. The three leds PE, FE Signal o 19200 4800 1200 300 and OR indicate parity, framing ground 600 and overrun errors respectively. 0V Dat *2400 -1j150 D.J. Virden rate b"' Cheltenham Gloucestershire 112 `5V 15 oA 845611 D 1C 9 8 6 144-1Hz Data,s A B Par i ty C D E 14 bitsSto 7490 74LS398 5 0 0 Odd 0 0 1 0

10n 6 0 1 Even 1 0 2 1

7 1 0 1k :>>1k 2 13 16 17 110 212j7 8 1 1

ELECTRONICS & -WIRELESS WORLD OCTOBER 1985 41

www.americanradiohistory.com CIRCUIT IDEAS

V cc

10k 10k

n n 14 5 6 No offset 1k 4k7 2 3 --10 B CLR CLR set ff 13

a 0V a 74LS123 12 TV: 20 f9 3 CLR CE D7 1'Z VPP 74LS00 To 2716 LATCH counter 8 ÓE & display A10. CKe. T OV

11 13 10 6 5 3 10 11 133 13 12 B C B A B A 1S 15 7 1 9 =10 CI< 15 7 -6-- =10 CK =10 CK =10 CK =10 CK =10 CK 10'

C R C R CLR CLR CLR CLR CLR 14 12 2 14 112 4 2 14 2 2 Yx74HC390 74LS390 71.LS390 74LS390

8 10

100msD°L 74LS00 r --i J

fref fin (r.f * i.f.) From Xtal oscillator first local oscillator & divider

Digital -offset frequency meter Conventionally, the method of displaying receiver input frequency is to take the first local oscillator frequency and mix it with a signal equal to the i.f. Mixer output contains both the sum and difference of the two signals, so filtering must be used to provide a signal suitable for a conventional counter. My circuit uses an all digital method to subtract the two frequencies and is therefore more accurate than the conventional method. Output from the first local oscillator the count to be recognized is possible to program eight feeds a decade counter which which in turn controls a gate different i.f. offsets should be a 74HC or HCT type between the incoming signal simultaneously, and to provide as frequency here can be up to and the frequency counter. For a true frequency indication by 40.7MHz for a receiver input of example, if an offset of disabling the eprom through its 30MHz and an i.f. of 10.7MHz. 10.7MHz is required then all chip -select input. Decade -counter output is locations from 0 to 106 are George Cavarra further divided and used to filled with zeros and remaining Bristol address a 2716, 2Kbyte eprom. locations are left at FF. Data in the eprom determines Using an eight -bit eprom, it

42 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com 8085/NSC800 NiCd battery microprocessor ál5 28 charging A 21 Rod Cooper's articles in the replacement 7 19 } May and June issues showed' 12 the problems of reverse Prompted by the increasing ADO 12 11 charging in sealed NiCd amount of Z80 -oriented CP/M X2 batteries. This circuit is software and Braunschmid's 9 CK designed to reduce these circuit idea on page 51 of the 37 RESOJT 3 problems in a cheap and 33 November 1984 issue, I RCS'N 36 effective manner. 28 1 substituted an NSC800N-4 RAH o 4 SOD 39 Link- processor for original 8085 oo- _5 SID the 29 SO 29 device in an Explorer 27 Si 33 To other similar microcomputer. In doing so I NSt 800 3 PO 32 cell pairs in series noticed some further differences 31 31 to form battery Load current 30 between the two processors. ALE Link 3 34 Comparing the timing cycles, 10 iM 34 3 first obvious difference is WAIT 35 READY the 26 INTA 11 the NSC800 refresh facility. 40 Vcc 40 Although this appears to be 20 GND 20 transparent on the 8085 25 14 6 INIP 3 l3 10 INTR 24 3 17 system, generation of an ALE RST[ 08 I8 9 RST 5.5 2 7 13 address -latching signal may RS TB 06 26 8 RST 6.5 22 12 8 have hardware implications on RSTA I4 7 RST 7.5 21 9 11 NMI 0 I5 6 TRAP some computers. On the 36 16 4 BREO 02 I2 39 HOL D explorer it affected the system 3 15 38 HLDA is to BACK 17 boot cycle. The remedy I1 01 37 gate ALE with refresh signal ONO In a battery, the cells are RFSH using say a 74LS08 in the 74LS240 E grouped in pairs shown. adaptor. va 20 Normally the combined cell A more subtle difference is voltage keeps Tr2 switched on. clock output is that the NSC800 If voltage falls below 1.3V - 180° phase shifted with repect which is equal to two diode to ALE and read strobe RD. 30 ALE voltage drops and one cell Again this may have hardware --. voltage - then Tr2 turns off. implications. On the Explorer, The voltage across one cell which supports an S100 bus, Close link 3 for 74LSOB cannot become negative. ALE and CK signals are gated normal operation 12 Optional diode D, allows other together and so the phase shift 13 cells in the battery to function 7 has to be removed. Using the GND when this cell pair has cut out. original adaptor, the clock Vcc About 0.1 to 0.3V is lost in signal can be passed through a the circuit due to VCEsa, in Tr,. spare inverter on the LS240 i.c. In addition, current passes There is a yet more subtle through R, even when the difference in the length of write Explorer to ensure sufficient these problems, my computer is battery is not in use. Values strobe WR. On the 8085 this time for memory write now satisfactorily running Z80 shown give about 12A leakage lasts for three T states whereas operations. This was simply a software. current and 10QmA load on the NCS800 it only lasts for matter of closing a link, but it T. Sumner current. two. It was necessary to may not be so easy on other Orpington Michael Robertson introduce a wait state on the computers. Having overcome Kent Oxford

current source. Sawtooth output Five +5V -decade at pin 10 of the op -amp is o oscillator uses directed to the internal oscillator input at pin 13 and a 100 T 10p op -amp pulse -train output is taken from one R pin 12. 10k A chopper -stabilized op -amp, Kamil Kraus I 1N914 the ICL7650, replaces two op - Rokycany 2N29074 0-O amps in a previously described Czechoslovakia 11 R3 13 MAf circuit* to provide a simple five - 10k R ICL 7650 Output 2 6 12 decade oscillator, whose lOn 5 frequency is set using only one A o 10k -5V Output 1 potentiometer. Output of the circuit is a squarewave. R4¿20k 10y The i.c's internal oscillator *Siegel, A.M., Single control adjusts t00nx2 R7 squares output of a variable variable oscillator over four decade '\/Vv frequency range ramp generator range, Electronic Design, vol.32 no.24 10k consisting of C1, and a variable Nov. 1984, p281. ELECTRONICS & WIRELESS WORLD OCTOBER 1985 43

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aerospace vehicle by British Aerospace for both unmanned and manned

The preceding articles have beeneffort was put into British radargrammes had much in common.experience and know-how built written with this final one in mind during World War II. Both involved the managementup during World War II, are still in that they have all contained a Although obviously not of thecoordination of the original workbeing used, and are certainly still certain forward -looking element same magnitude, the part playedof a number of teams and theirrelevanttotoday'sthinking. based on the continuation ofby the cluster centred on Bristolinterlinking with other interests.Some of the factors which have existing developments. This may in the evolution of the ConcordeAlso, each of the two groups of Rsupported this `hand -on' process sound far from adventurous in supersonic airliner is of special& D teams were, in effect, enter-are reviewed in the section on relation to innovation but, as has relevance in the context of Theing entirely new technologicalcontinuity. been indicated throughout, such Future'.Concorde was intro-fields where it could be said they Much the same general consid- developmentprogrammes -duced in the first article; andnothing to point the way. How-erations apply to the overall Con- given the right conditions, parti- among those points highlightedever, as has been noted in earliercorde programme. However, in cularly of manning at all levels -was the importance of the back-articles, the ability to adapt and tothis instance it is possible to show can produce a series of inventions up potential of the area, specif-transfertechnologicalknow-how developments achieved with and sub -inventions which are not ically of the suitable skilled labourhow, together with the necessarythis programme, particularly on only of major significance in theirwhich is available. As impliedclimate of confidence existed atthe propulsion side, were fed into own right but also in terms ofalready, 'labour' is used here inall levels in these and in the otheranother aerospace project, but spin-off in other areas. its widest connotation to cover allcases quoted, and were utilizedcomparatively early on - at the The outstanding example hereaspects of the system engineer-to the full. design -study stage. is,of course, afforded by the ing involved, outstandingly in the Inthe presentconnection, The project in question is a re- radar/television interchange andpossession of innovative know-there are several elements of R &usable, unmanned, aircraft -type spin-off which was covered in the how. D activity - fundamental tosatellite launcher with the de- second article of this series, and Taken further in the case ofinventionandinnovation -rived name HOTOL - Horizon- which becomesofparticularConcorde, this extends to supra - which should be identified here, tal Take -Off and Land. From the interest in the present context. management; and inthisin-Foremost among them is thedetails given by British Aero- This did indeed demonstrate thestance, special mention must bequestion of the phasing -in of new space towards the end of 1984, it British capability to work on such made of the " .. managerial anddevelopments within the main can be seen that a number of engi- a scale; and it seems worth re-- evidently - almost inspiredprogramme, and,as indicatedneeringadvanceshavebeen iteratingthatalthoughthe forwardplanning"whichlaypreviously, to determine when tomade with it. From the R & D bringing together of technological behind this bi-national venture.take advantage of earlier, analo-management point of view they, effort on that scale has not really This comment stems from thegous work. These issues areand the way in which they were been seen in the UK since those account given by Sir Stanley Hoo-closely linked with climate of con- evolved, are of the utmost signif- days, the potential for it is even ker of the British section of thefidence,itself linked with theicance, especially with regard to now not far below the surface. venture, notably of the applica-need for continuity to be main-the breadth of the technology that Justification for this statement tion of the Olympus engine to thetained over the whole project.has been covered and the asso- of the hidden strengths of Bri- Concorde. In his autobiography',The penalties of not achievingciated project flow maintained. tain's total engineering power has Sir Stanley gives an inside view ofthis reconciliation and of failing to These statements are been given at several points in the Concorde and how it was con-attain other comparable manage- expanded in the description of this series, with the examples trolled; and it becomes clear thatment targets can be catastrophic. HOTOL which follows. When this usually associated with a `cluster' this represents a classic example It will be appreciated that these information was released, it was as introduced in the first article of of management and direction of Rtwo examples have been chosenin such a form - a concept the series (March, 1985). As & D effort and resources compar-because of the detailed picture(design) study - that it gave a noted in the succeeding article, able with that put into the earlierwhich they give of controlled pro- full account of the course of deve- the United Kingdom itself couldBritish development of radar. ject flow, and how this flow was, lopment which is usually not pro- be regarded as having become a Though not of the same abso-in effect, taken into the future.duced until the project work has clusterwhenunprecedentedlute magnitude, the two pro -Thus,in the radar case,thereached completion. ELECTRONICS & WIRELESS WORLD OCTOBER 1985 45 INVENTION & ELECTRONICS

Comparison of HOTOL with the in a multi -stage European satel- Although not strictly compar- US Space Shuttle is inevitable and lite launcher, Blue Streak "per- able, similar considerations apply major differences in basic tech- formed faultlessly in eleven fir- to the economies effected by the nological philosophy can be seen ings". This project was aban- use of combined air breathing and as a result. doned in the late 1960s. rocket propulsion in conjunction The first of these fundamental In turn, this specific statement with a winged vehicle configura- differences lies in the mode of of experience, extending over tion to permit horizontal take-off take-off of the vehicle itself and some twenty years for launch and - of equal significance - to the propulsion system associated vehicles, leads to the systems make single -stage -to -orbit poss- with it. Taking the HOTOL case, work being undertaken in the ible. These techniques, as dis- with its horizontal take-off (and interlacking fields of remote con- cussed earlier, take full advan- landing) it may be regarded as trol, communication and data tage of existing practice; and, as being a 'conventional' aircraft, handling as required for -- in the case of Concorde', this which in many respects it is. Its unmanned working. The capabil- In 1900 Britain made 60% of applies with particular force to configuration, not least of that of ity of the British Aerospace orga- the world's shipping. Today it the electronically based systems the wings which are used, owes nization, makes 3%. (Engineering with the Rolls Royce Council, see panel) engineering required. much to Concorde; and it is contribution, is best illustrated Thus, with this background it stated that the runways from by a straight quotation from the deployed at this stage in such a is possible to give a two-part which it would operate are of list given by the former in this programme, it can be assumed answer to the first question standard Concorde length. connection: "Automatic and that a more than significant sav- related to the Space Shuttle: remote piloting control systems ing in cost would be achieved. a) On the economic side, the are already capable of handling HOTOL has been called a low- development costs of HOTOL, ascent, in -orbit manoeuvring, cost spacecraft launcher by Brit- eventually fed into the operating payload deployment, re-entry ish Aerospace; and this can be costs, should be much less than and landing." It may be added seen as a key phrase extending for the Shuttle: while with the that HOTOL is shown as being fit- over the entire project. Thus comparative lack of complexity in ted with radar; and it does appear going on from the R & D end of HOTOL both its initial (capital) that the nose cone configuration the studies just quoted, one looks and operating costs should be would be basically the same as for at the engineering economics of Concorde. the whole project, beginning with It will be realised that any com- the advantages exhibited by parison of HOTOL with the Space unmanned, as opposed to Shuttle is bound to finish up with manned, operation. the question, "What advantage First of all, the space occupied After the War Britain was 3rd has largest steel producer. Now it the unmanned vehicle over by the human crew, and particu- is 10th. (Engineering Council, the manned Space Shuttle, with larly by their 'life support' equip- see panel) its inherent capacity to stay in ment, can be devoted to payload, orbit for a period of some days and their individual weight pen- For propulsion, a new depar- and to act as a miniature space alties removed. This gain in pay- ture is being made, with thrust station?" The main substance of load capacity will be offset to a being provided by a combination this question can be put in certain extent by the correspond- of air breathing and rocket another way - "What is the jus- ing demands of the replacement engines to take the vehicle into tification for preceeding with a remote -control equipment; but it Britain once exported motor Low Earth Orbit (LEO). This project which has reached the would appear that these demands bikes to over 100 countries. Now it imports almost every arrangement enables advantage end of its design development would. be much less for the machine. (Engineering Council, to be taken of the free oxygen studies when no immediate appli- unmanned condition. see panel) through which it is flying during cation for it can be seen?." its passage through the earth's Clearly, there are two mutually atmosphere, and correspond- dependent main issues, technical ingly to reduce the amount of and economic, which have to be liquid oxygen which would have examined in the light of the Britain's hidden to be carried for pure rocket unknowns that lie ahead. Even Most critics agree that the Brit- 'bowled -out' cricketer - repro- (liquid hydrogen/liquid oxygen) from the outline descriptions it ish are still a nation of inventors duced in this article - and their propulsion. This forms one ele- becomes evident that by virtue of but that their record for bringing captions carry a story of decline ment in the design considerations this background of experience their new ideas to fruition is in varied UK industries. which make vertical increasingly open to question. These articles counter this take-off and know-how, combined with The range of the criticism is wide with powerful examples, taken unnecessary, an aspect which, the innovative ability shown in and is far from baseless; but this from the build-up of the aero- know-how and background gen- the project studies, these prob- series set out to show that a very space industry, the full range of erally. This will be returned to lems will be found to have been different picture emerges when medical electronics, and - one later; but unique technological strengths of the most telling examples - in in addition to quoting anticipated in great measure as built up over the years are taken computer -based process and Rolls-Royce on propulsion, Brit- an integral part of the essentially into account. If 'built up over the control applications (July arti- ish Aerospace gives three exam- forward -looking project work. years' seems frightening in the cle). With the example of the ples of major rocket projects for Consequently there are good rea- context of invention and amid CEGB's National Grid control the clamour for University -based complex, that article highlights which the Group has had respon- sons for assuming that, with this Science Parks, it is in the 'total the thrust of the series - that sibility, together with two rocket anticipation, the long and damag- engineering' power of the British the British have the power to engines - Spectre and Stantor. ing delays which can take place in that the unique capability to develop their new ideas, and The vehicles ranged from Sky- the early stages of engineering exploit the new ideas exists. more significantly, to set up Opposition to this view is organisations which give com- lark, a small 'sounding' rocket, development would be greatly strongly expressed, in extreme plete flexibility to individual developed originally by RAE, reduced, if not virtually elimi- cases amounting almost to a teams to work on their own pro- Farnborough, through Black nated in many areas of the work. counsel of despair. This is seen, jects. for in Engi- Knight, a 10 tonne -thrust liquid - Thus in view of the extent of the example, the recent Another major aspect dealt neering Council advertisment with is that of continuity which fuelled rocket, to the Blue Streak effort (both in human and mate- where a group of pictures of a brings with it a climate of confid- heavy launcher. As the first stage rial terms) which has to be 46 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com much less. Retention of all elements of the notably for the CEGB in Big -sys- b) Bearing in mind the low-cost basic HOTOL design as described tem automation and telemetry aspect, HOTOL offers a means of for unmanned operation. Provi- (Article 5); and the work of that staying in space in a controlled sion was made for both manned authority enters into the next orbit at an operating height of and unmanned operation right section - on continuity. some 300 km and for a (typical) from the outset as part of the orig- However, there are two duration of 50 hours. While in inal concept. aspects of the aerospace total orbit, satellites with a total mass Forward looking plans for study which have made it up to 7 tonnes can be launched; ultra -high-speed passenger ser- uniquely suitable for this article, and it is inferred that observa- vice with the main section of the both strongly related to the tional data can be acquired for flight consisting of a ballistic tra- future. real-time onward transmission or jectory outside the earth's The first is that, although con- brought back to earth in recorded atmosphere, with a powered ducted as a pure research exer- a max- cise, its content has been pre- form. All this is done without Before the War almost every climb to this path reaching highly trained specialists having car on Britain's roads, was imum of Mach 5, and with a dominantly practical, outstand- to be exposed to the rigorous con- British. Now well over half are corresponding descent path to ingly with regard to 'spin-off'. ditions encountered in space; and foreign. (Engineering Council, landing after re-entry. The pos- Spin-off, in its widest sense, and see panel) without massive ground (rocket - sibilities offered for the future by contributing to a number of major range type) preparation and synchronous launches a reduc- this flight pattern are spectacu- technologies within the aero- operational facilities being tion of 50% is claimed for the larly illustrated by the proposal space context, represents what is required. unmanned operation. In this con- for a one -hour service from Lon- perhaps the greatest strength of Thus, the final conclusion can nection it is also claimed that don to Sydney (overhead to over- this multi -team project. It cer- be reached that, because of all HOTOL would be able to compete head in 45 minutes). tainly justifies the approach these low cost features, "Several realistically for some three quar- With this background, and which has been adopted and HOTOLS could be provided for ters of commercial market reverting to the original compo- which has resulted in the the price of one Shuttle"; and that demands as predicted for the year site question, it can be said that, informed and coordinated built- this means that the number of 2000 onwards. as compared with the Shuttle, up of background of mutual ben- vehicles available for a given pro- This reference to the year 2000 HOTOL would appear to offer a efit to, for example, the aero- gramme expenditure would be serves to introduce the concept of more flexible and a lower cost space and electronics/control greatly increased so that, for HOTOL becoming a manned service for launching satellites example, quick follow-up action aero- and for similar tasks. On the could be taken to gain immediate space plane for the 21st century; other hand, at the present time checks on suspect data. This is in information on these studies hav- the Shuttle stands alone in pro- contrast to the more widely sep- ing been issued at the end of May viding its re -usable Space Station arated 'appearances' of the Shut- 1985. (The comparative figures faclity; and the importance of this tle, with the factors contributing quoted above are taken from this and the pioneering work that to this including a much more source, and are obviously based went into it cannot be over- lengthy turnround time in addi- on up-to-date - confirmed - emphasized. tion to the comparatively large surveys. ) These innovative studies are of cost of setting up a single mis- The salient features of this special interest to all R & D sion. striking project for a 'Transat- engineerss with management of a Comparative figures for the mospheric Skyliner' are: project where more than one two types of operation are a The installation of a capsule - branch of technology and several Britain discovered the wireless. reduction in cost by a factor of five type passenger compartment in separate interests are involved. It now imports 96% of its low payload bay conven- The HOTOL studies, with their portable radios. (Engineering for sending HOTOL into the with Council, see panel) earth orbit; while even for geo- tional airline seating for about 30. comprehensive documentation, and with their interlinking with engineers concerned. This does, Concorde in particular, give an of course, correspond with the inside picture of the way in which interchange and spin-off shown advances are made, and consoli- with radar and television (Article strengths dated, in a large, multi -team, 2) which developed in Great Bri- ence but, for real success, it developed, recognised by acad- high-technology project. A simi- tain even before World War II. depends on rapid adaptation by emics as original and far-reach- lar picture has been built up for For this comparison, it should behaviour under cri- teams to new phases in the work ing: human other comparable UK projects, be pointed out that the spread of and to the changes in approach sis -control stress, immediate which are necessary wham orig- presentation of information for technologies is much greater for inal activity is involved. This unimpeded operational use, and the aerospace concept - both ability to adapt and to transfer hyper -autism, which together radar and television are essen- of mar- technological know-how is fund- with the concept 'data tially electronic in character. amental to the claims of Britain's shalling' have all recently fea- unique capability in invention tured in these pages. Of these, Consequently, spin-off and mut- and innovative development. hyper-autism is particularly ual support extend over a much August's high technology significant in that individuals larger number of fields in the aer- example links automotive engi- have been brought together to ospace case. In turn, this means neering and electronics, where form an R & D organisation simi- innovative development work lar to that described for the priv- 3 that shutting -down an individual undertaken effectively as a priv- ate venture of the August article project of this nature will affect ate venture has brought together but working entirely on a volun- any others which are being sup- small groups operating in the tary basis. September's article plied with information or with field, and has shown that inven- describes their advances. tive ability combined with adapt- This present article, the last in results from it on which they may able know-how are not far below the series, brings together these well be utterly dependent. There the surface; they simply need ideas to show where Britain's is no need to stress the serious- 'bringing out'. hidden strengths exist, where Britain pioneered the world ness of such knock -on conse- In the new discipline of human they are being suppressed, and machine tool industry. Its communications, three areas of how they could be brought to the share is now 3.1%. quences, quite apart from the closely interlocked work have surface again in the future. (Engineering Council, see loss in national terms which panel) comes from the break-up of an ELECTRONICS & WIRELESS WORLD OCTOBER 1985 47

www.americanradiohistory.com INVENTION & ELECTRONICS

established team. concerned with the dual issue of consequent famine which are These considerations are suffi- spin -off and sub -invention. This affecting much of the continent of cient in themselves to justify the obviously cannot be taken into Africa, and have proved of more retention of a project which has the long-term; but clearly it is than passing concern to the rest reached the end of its design/ vital for a reasonable time to be of the world. Expressed in utterly development studies when its seen to be available for the 'side - basic terms, the proposal is that ramifications extend even over a issue' developments to be under- this problem should be tackled at fraction of those as quoted. In taken which produce spin-off. In source with the primary task to other words, on these grounds this connection, it should be provide water on a huge scale, alone one can answer the original pointed out that, in terms of R & first for human consumption and question, with the statement that D management, one cannot jus- then for irrigation. Assuming the losses incurred by shutting tify expenditure of effort and Britain once made all the breeder -reactor power would be textile machinery down a project which has reached resources on 'off -stream' work in the world. available, the water would be the early stages of engineering unless adequate It now makes 8%. (Engineering time is available Council, see panel) obtained by evaporating sea development (as distinct from for it: it must not be scamped. water using nuclear power, and studies), are so great that reten- On the other hand, success sonal qualities required to under- distributed by pipeline, perhaps tion is justified on economic even with a minor, but neverthe- take wide-ranging project work initially by tanker. Each section grounds alone. less new, development, can have and advanced engineering which of this plan would represent a It is, however, in terms of the an effect far beyond the immedi- is demanded for the technological development programme of future that complete justification ate use to which it is put, particu- ventures already described. The unprecendented magnitude; but, may be found; and it is with this larly with regard to the personal acquisition of these qualities is by on the other hand, need not be specific aerospace project under side. That some widening of the no means automatic; although it regarded as insuperable. review that the full extent of the base of the programme has taken has been submitted in this series Power generation would prob- arguments in favour can be seen. place, and that effort has been that, in a sense, they are almost a ably have safety precautions as Quite simply, such projects devoted to the (effectively) sep- national characteristic. How- its biggest project engineering arate work, indicates that the ever, in practical terms, the pro- committment; but there is no project has been made larger with cess of acquisition takes time, reason to believe that this and all a potential for interlinking with whatever the inherent capabilit- the other steps into new design other R & D areas; and this can ies of the individual may be; and and development areas would be offer a wider view of the future. expressed as a period of educa- beyond the capacity of the UK, If successful, there are, of tion (which in many ways it is) bearing in mind the record and course, economicc advantages should be recognized as being achievements of the supply which accrue from such an appro- inseparahble from R & D work. industry and that of the manufac- ach. One of these illustrates the Therefore, there is an implied turing side both at home and principle given in Article (1), that commitment for continuity to be internationally. It is perhaps not methods and techniques deve- maintained for the individual to out of place to refer to a visit to a loped for a specific part of a pro- work effectively and smoothly geothermal station in the North ject do not have to be redis- without worrying about interrup- Island of New Zealand where it Britain made the first practical covered and can be applied in the tions to his specific programme. was clear that a new technological computer. It now has only 5% future, provided continuity of the Information Technology is world had not been found to pres- market. (Engineering Council, maintained over the whole series ent insoluble problems. see panel) of programmes. The macro -project In the same way, pipeline Two main issues covered by 'transmission' of water over long should be carried on because of continuity come in here. The first Throughout this series it has distances can be seen in South the crucial base they provide in is the straightforward use of the been possible to show that there Australia and in the west of the whole areas of technology. word for describing the coordi- is an enormous fund of technolog- island continent where tempera- nating and other processes, and ical knowledge and experience tures can reach values not dissi- the policy behind then, which which can be found in Great Bri- milar to those encountered in Continuity keep even the largest projects tain at the present time and at all Africa. flowing smoothly and success- engineering levels. Moreover it Continued on page 64 The whole question of continuity fully. A number of examples of has been possible to show that has been brought in at relevant such successful UK operations the British retain the power to set points throughout this series; have already been given one of up organizations capable of especially in relation to the clim- the most outstanding in the pres- handling the largest projects ate of confidence which can be ent context being that of the right from initial development to associated with it. Two kinds of CEGB's far-reaching develop- full exploitation of the original climate of confidence, closely ment programme for the control idea or group of ideas on which interlinked, exist here. The first, complex for the National Grid3. the project has been based. technical, has already been given Extending over a considerable However, it is felt that, considerable emphasis, particu- number of years and, if anything, although these examples have larly with regard to the transfer of being accelerated at the present given a representative picture of know-how from one branch of time, this 'total' project has con- the way in which these projects technology to another. tinuity literally as its key feature. are run and of the British exper- The other kind of climate of The second of these issues may tise in such fields, this capability confidence, assurance of the be linked with the continuity should be examined in relation to future, is more than the imposs- which lies behind the proven cap- a project which is very much in ible ideal which it appears to rep- ability of the British to show com- the future. resent, certainly if taken literally. plete flexibility in approach when The 'macro -project' which has However, there are two ele- dealing with the new and untried, been selected for this purpose is ments which do involve the future or of responding quickly to new entirely hypothetical; but the cir- and some degree of assurance. phases in the work. The state- cumstances which surround it are Last year Britain even imported The first of 65% of its sports equipment. these, which comes ment of this capability is in most far from hypothetical. They are How's that! (Engineering under the technical heading, is respects the statement of the per- the conditions of drought and Council, see panel) 48 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

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TS(3660SM 40.300 1030VHF 60dB(1000mel nor -.SdR Ed9 VHF 2545V13VA- 470860 1636UHF - UHF

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CIRCLE 127 FOR FURTHER DETAILS. CIRCLE 17 FOR FURTHER DETAILS. ELECTRONICS & WIRELESS WORLD OCTOBER 1985 49

www.americanradiohistory.com It's a whole new board game with our 7000 Series

Many operations and tasks are now possible through BASIC which could previously ONLY be accomplished in ASSEMBLER. Based on the Intel 8052 (romable version of the industry -standard 8051) single -component Microcontroller, the CPU comes complete with BASIC BASIC CONTROLLER Interpreter, Serial I/O and full support specifically for Industrial Control DISTRIBUTOR ENQUIRIES WELCOME applications. Many unique features are incorporated and the system allows very fast interactive development of user software for super easy deployment in the target system. Static MOS RAM boards Ito 128k). Power down control boards, Decoder boards providing further address line decoding, watchdog, Real-time clock/calendar, plus additional output flags and 1/0. Mass storage devices. Backplanes. PSU and battery packs. Drive boards offering power output, pulse generation, or externally gated outputs. Multi -channel expandable ADC, Remote switch units for power, sound or V.I.S. of vision

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www.americanradiohistory.com 68000 board by R.F. Coates The £ 100 Kaycomp - Bob Coates, 68000 computer board for engineers, students and enthusiasts - is developed using a terminal and takes a G64 bus interface.

Kaycomp is a low cost computer the board has 128Kbyte ram, board of this complexity normally board using a Motorola 68000 64Kbyte eprom, two serial inter- would be. Layout is however for a microprocessor with 16 -bit data faces, a 68230 peripheral i/o plated -through p.c. board which bus. It is designed for use either device and a bus interface which means that some soldering on the as an evaluation/educational tool allows connection to standard top side of the board is necessary. or as the processor board of a peripheral cards. Sockets for i.cs must allow sol- larger system, connecting to a Large systems nowadays can dering on the component side Our front cover shows the wide range of readily available have many processors and direct too. 68000 board in its fullest peripheral cards through its G64 memory access controllers work- In order to keep costs down, form with G64 -bus interface interface bus. ing together on the same bus to some systems use a reduced -bus - this is the basic version. Programs can be entered using multiply processing speed. I con- version of the 68000, the 68008, a terminal to gain access to Kay - sidered that this feature was not which although internally the comp's 23 function monitor pro- essential to learning about and same as the 68000 only has an gram Kaybug. There's also an evaluating the processor and eight -bit data bus and a 20 -bit optional line -by-line assembler leaving it out saved a lot of peri- address bus. I decided against available to speed up program pheral logic. If you are interested using this version. The board development. Alternatively, the in the type of work that requires accepts either the 68000 or an board also links to a host compu- multiprocessing, £1500 won't enhanced version, the 68010, ter with assembler/compiler faci- normally be a problem. running at up to 10MHz. The lities. Communication software is An external bus interface prob- 68010 is a virtual memory ver- included in the monitor program. ably isn't essential for training sion of the 68000. This feature The 68000 microprocessor has and evaluation either, but I cannot be used with Kaycomp, a 32 -bit internal structure. Eight included one to increase the use- but the 68010 also executes some data and seven address general- fulness and versatility of the instructions faster and has some purpose registers are available to board. VME bus is the obvious extra ones too. the programmer, all 32 bits wide. choice for a 68000 processor Memory consists of two eprom Its external address bus is 24 bits board but the cost of implement- and two ram sockets. Two of each Fig.1. The 68000 has a 24 - which gives a linear address ing it is very high. To illustrate, byte -wide memory are required bit external address bus range of 16 megabytes, Fig. 1. one manufacturer produces a to give a 16 -bit data width. Links giving an address range of Motorola evaluation kits for single Eurocard wire -wrap board allow eproms with standard 16Mbyte. the original eight -bit 68000 i.c. for prototyping containing just were available for around £ 150. VME interface chips for £600. There is a similar kit for the 6809 My choice was the European 31 16 15 87 o microprocessor but it was not G64 bus designed for Motorola 00 introduced in the UK. For the eight -bit processors. The inter- of 68000 microprocessor, Motorola face circuit consists just three Eight produce a design module costing t.t.l. devices. G64 is probably the data £1500 -a tenfold increase over best supported eight-bit Euro- registers the price of a 68000 evaluation card bus, with over 200 different kit. cards available from many differ- 07 Of course the 68000 design ent manufacturers, but it is not module is a far more complicated well known in :he UK yet. The 31 16 15 o product than its older equivalents main UK manufacturer is Syntel AO and designed to allow evaluation of Huddersfield which produces a on a wide scale. In many applica- wide range of processor and peri- Seven address tions though this complexity is pheral cards, back planes, rack- registers not necessary and there is cer- ing systems, etc. tainly a need for a low cost evalua- Á tion system. 6 I designed Kaycomp so that it Kaycomp overview User stack pointer 1u.sill Two stack could be built in its basic form for A7 pointers Supervisor stack pointer (s.s.p.) under £100. In this form it has Figure two illustrates the sys- 31 o two RS232 serial interfaces and tem. Kaycomp in kit form is dou- Program general-purpose 1/o lines pro- ble -Eurocard sized, measuring counter 15 8 7 0 vided by a 68681 i.c., a monitor 234 by 160mm, and its p.c.b. is Status System byte User byte 1 register eprom, a small ram and a full 16 - double -sided but to keep costs bit 68000 i.c. When expanded, down, it is not plated through as a ELECTRONICS & WIRELESS WORLD OCTOBER 1985 51

www.americanradiohistory.com 68000 BOARD

On Kaycomp, 664 bus the G64 bus is provided solely for the addition of peripherals. The on -board mem- ory is potentially Optional quite large and 664 bus capable of operating at much interface higher speeds than would be pos- sible with memory operating through the interface bus. On -board bus - 16 data, 16 address

Monitor software

Optional Up to Up to Kaycomp's monitor program MC68230 MC68000 64K byte 128K byte MC68681 dual uart c. p. u. Kaybug allows you to enter and peripheral ram eprom interface/ debug programs and exercise all timer the facilities on the board. Com- LtaLl mands allow Clock you to display/alter generator memory, set break points and run or single-step trace through pro- 24 i/o 10 /o lines ii grams. Registers can also be lines altered. RS232 Kaybug contains all of Alternative Optional the usual interface c.p.u. clock crystal monitor features. At a basic level, Kaybug allows programs to be hand written and Two serial ports typed into memory from a simple terminal using the `memory open' command. There is an optional Fig. 2. Kaycomp a full uses JEDEC pin configurations from Kaycomp can be used to connect line -by-line assembler to simplify 68000 processor and two 2732 to 27512 to be fitted, giving the board to a host development peripheral this job. If a home computer is i.cs from the same a range from 8 to 128Kbyte. Note system or mini/microcomputer. used source family. Using these instead code can be written, that not all larger eproms con- Both RS232 ports come from a edited and stored using the com- of more common 6800 form to the standard pinout, not- 68000 peripheral i.c., the 68681 puter's peripherals facilities. When ready, means higher ably those from Mostek. dual asynchronous receiver/ the source code performance and increases can be sent for Ram sockets currently accept transmitter or duart. The 68681 processing by the Kaycomp line the board's value as an either 2 or 8Kbyte static rams, internal oscillator requires only a assembler. Object code is then evaluation tool. i.e. either 6116 or 6264, to give 3.6864MHz crystal. A cheaper produced and loaded into ram as either 4 or 16Kbytes. The board 3.579545MHz American colour each line is entered. is laid out though to accept 16 and tv crystal will suffice; data rates If you have a development sys- 32Kbyte devices for when mono- will be a little out but still within tem or development facilities on a lithic i.cs become available, the required tolerance. micro or minicomputer, the sec- which will give up to 64Kbytes of For full -speed operation, the ond serial port allows program ram. Hybrid 16 and 32K devices processor requires a separate transfer. Kaycomp is then effect- are available now but they tend to 8MHz crystal clock but if speed is ively connected in the terminal be expensive. Reasonably priced not important, the duart 3.6MHz line from the host computer as hybrid 32Kbyte rams consisting clock may be used. If you need to shown in Fig.3. of four small -outline 6264 i.cs on used the serial ports in an applica- One Kaycomp command a ceramic substrate are produced tion, there's another version of allows the board to become by Digital Memory Systems, the the monitor program available 'transparent', i.e., the terminal DMS8832-15PC, and by Hybrid which allows you to develop pro- communicates directly with the Memory Products, the HMS grams through an external G64 host computer as if the board 62832. did dual serial port card. not exist. Programs can then be To allow programs to be deve- Parallel input/output is pro- written and assembled or com- loped and written on the board, vided by another 68000 -family piled in a high-level there's language a monitor program which i.c., the 68230 peripheral inter- according to the 68000 program fits into two 2732 eproms. This face/timer. This optional i.c. is development software available monitor, Kaybug, requires con- not used by the monitor and all of on the host computer. Another Fig. 3. Kaycomp can be nection used of a separate RS232 its facilities are available for user monitor command allows result- by simply connecting a dumb terminal. a If terminal is not avail- applications and evaluation. ing object code to be loaded into terminal but in able, many this home computers such Finally, there's the optional Kaycomp's memory in Motorola configuration, it is effectively as the BBC microcomputer have G64 bus interface which consists S -format ready for running. The connected in the an RS232 terminal port and can be made to of three t.t.l. bus -interface i.cs. procedure may line from the host computer. vary slightly act as a dumb terminal. With this There are two sections in the G64 depending on the host system In this way, software in mind, the monitor program can bus memory map, one for mem- used but this is a common way of developed using 68000 easily be set to produce either a ory addresses and the other for developing programs. assemblers and compilers on 40 or 80 -column display by a key- peripheral addresses. The peri- Alternatively, a computer with the host can be fed directly board command. pheral area consists of a 1Kbyte 68000 'cross -software' can be into the A board. second RS232 serial port on block somewhere in the memory made to act as both a terminal and map which is decoded on the pro- development system, Fig.4. A Kaycomp cessor board. Valid peripheral monitor command allows object Terminal Host addresses are denoted by asser- Port A Port B code to be loaded through the computer tion of the VPA signal, which is terminal port; the host port is not not to be confused with the 68000 used. signal of the same name. Before you can understand the ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com circuit, you need to know a little system elements are wire-or'd about the 68000 processor, together before entering the pro- Kaycomp Fig. 5. More detailed This each Computer/ descriptions cessor. ensures that Port A Port B are given in the Motorola Data part operates at is highest speed. terminal Manual and the MC68000 Mic- Peripheral i.cs in the 68000 roprocessor User's Manual. family produce the DTACK signal but extra circuits are required for About the circuit this if peripheral devices from 'nterrupt pins. To save on pins Fig.4. A computer can be other families are used. though, the seven interrupt used as both a terminal and Clock drive. The clock input is a Accessing bytes. No A, address levels are turned into three -bit host for developing Kaycomp. t.t.l. compatible signal which is line is available so some means of binary, the eighth value, all pins internally buffered for develop- implementing byte read/write high, indicating no interrupt. ment of the processor internal operations is required. Two sig- Normally, these three pins are clocks. There are 68000 proces- nals handle this, upper data fed directly from the three poss- sor versions with clock speeds strobe UDS for even byte loca- ible interrupt sources. Hence from 4 to 16MHz faster versions tions and lower data strobe LDS only three interrupt levels can be are expected. for odd locations. For a normal used, one, two and four. Address/data buses.These two 16bit word transfer, both signals When servicing an interrupt, buses are fairly straightforward. are asserted. the 68000 fetches an address There are 16 data lines and 23 Figures six and seven summar- from a vector and continues pro- address lines but there is not an ize the various bus transfers. cessing from that address. There external A, address line. Figure six shows a read and then a are two types of interrupt vector- Addresses are considered as write cycle with no wait states ing though, 'auto -vectored' being byte sizes, i.e. eight bits, inserted. After setting up the which is similar to that of the and although A, is used inter- address bus the processor 6800, and vectored, where the Fig. 5. Input/output signals nally, the address bus is only cap- asserts AS, UDS and LDS and interrupting device provides a on the 68000 processor, top, able of generating even -number then waits for DTACK which it vector number on the data bus in and Fig. 6, read -then -write addresses. responds to by releasing the three response to the processor exe- bus transfer with no wait Asynchronous bus control. Bus signals. At that point, the cuting an interrupt acknowledge states. control is a little different to that addressed device must also of previous eight -bit processors release DTACK. If a slow device in that bus transfers between the is addressed, it can be seen that vrr Al -A1 Address bus processor and memory/peripher- wait states are inserted by the GND als are asynchronous. processor after S4 until DTACK is CK On the 68000 for instance bus received. Figure 7 shows the DO-_D15 Dota bus transfers are controlled by a syn- action of UDS and LDS when 68000 chronous timing signal E. This is addressing bytes. microprocessor an equal mark/space ratio signal 68000 peripheral i.c. accesses. AS R/W upon which all bus timings are Asynchronous bus accesses work Asynchronous UDS based. In the case of writing to fine with 68000 peripheral i.cs 0 bus control Processor FC1 LDS memory the processor sets up but not with the wide range of status the address bus and read/write 68000 peripherals which do not FC2 DTACK signal in the first (low) half of the generate DTACK. There are bus cycle and sets up data to be three control pins on the 68000 E BR written in the second half. At the especially for 68000 peripherals. 6800 Bus arbitration peripheral VMA BG end of the cycle, the E signal If the address decoding circuit control control VPA returns low and data is latched asserts valid peripheral address BGI+CK into the memory. signal VPA instead of DTACK, it BERR IPL When reading, the processor indicates to the processor that System RESET IPL1 IInterrupt presents memory with the add- the device or region addressed is control control IPL2 ress and expects it to have data a 68000 family device. The pro- HALT ready on the bus by the time that cessor then executes the rest of the E signal falls to latch the data the bus cycle synchronized to a bus into the processor. This 6800 type E signal as described means that the system designer earlier. It acknowledges this fact must make sure that memory or by asserting low the valid mem- peripherals used are capable of ory address output, VMA, which operating at the speed required is gated with the device's chip - by the processor or, more likely, select signal. that the processor clock speed is The 68000 E signal, with a slow enough to suit the slowest 40:60 mark/space ratio rather device in the system. than 50:50, is at one tenth of the In the 68000, this problem is clock signal so a processor overcome by using asynchronous operating at 10MHz can access bus transfers. The processor sets 1MHz 6800 peripherals. A syn- up the bus in the same way, but it chronous bus access results in a then asserts an address signal somewhat slower cycle than is called AS and holds the bus until it possible with asynchronous receives a data transfer acknowl- transfer. edge signal, DTACK, back from Interrupt control Seven levels of the memory or peripheral. interrupt can be provided for, DTACK signals from the various which ideally would mean seven

ELECTRONICS & WIRELESS WORLD OCTOBER 1985 53

www.americanradiohistory.com 68000 BOARD

Components and Support ISO S7IS0 Individual components Cross -software for various

CK complete kits including double - host computers is available sided p.c.b. and data packs from a number of sources, for A1-A23 are available from Magenta instance, Microtec Research, *A Electronics, 135 Hunter Street, Frances Road, Basingstoke, Burton -on -Trent, Staffordshire supply 68000 cross - ñS DE14 2ST. A kit for the assemblers, Pascal and 'C' UDS minimum system described is crosscompilers for DEC, Data for LDS available £99. General and IBM PC G64 card suppliers include computers. RFW- Syntel Microsystems, Queens Bob Coates will program DTACK Mill Road, Huddersfield, HD1 your pair of eproms (any type) 3PG and Thomson with the Kaybug monitor D8'D15 Semiconducteur whose UK software for £7 sent to 57 DO-D7 111111111111111111111111111 1111111111111111111 1111111111111111111111 distributors include Pronto Dalebrook Road, Burton -on - FCO-F52 Electronic Systems, 466 Trent, DE15 OAB. Machine - Cranbrook Road, Gants Hill, code listings can be obtained 1-Word Oddwritebytes Evenwritebytes write - Ilford, IG2 6LE. G64 bus back- by sending a large s.a.e. +internal signal only planes are available from these marked Kaycomp to our and also from BICC-Vero. editorial offices.

Fig. 7. Action of upper and cycle. This allows different inter- The second use of BERR is in line are reset. lower data strobes UDS and rupting devices on the same conjunction with HALT. If both Taking RESET low externally LDS used when addressing interrupt level to be serviced by are asserted together the proces- will have the same effect on peri- bytes. These strobes are different service routines without sor will attempt to rerun a previ- pherals but it will not affect the needed because the 68000 polling, which saves time. ous, failed, bus cycle in the hope processor. To reset the proces- has no address -line zero. Processor status. When pro- that it will work the second time. sor fully, at power -up for cessing an interrupt the proces- This can be significant in terms of instance, both RESET and HALT sor places a unique code on status reliability if the processor is con- must be taken low together exter- lines FCO/1/2 of all ones, which trolling say a large plant, but nally. If the HALT line is taken is used by Kaycomp to generate omission of this feature on Kay - low on its own, the processor is an interrupt acknowledge signal, comp will probably go unnoticed. held in its current state until the LACK. This signal lets the rest of If you attempt to access a non- line is released. the board know what is happen- existent location, you'll have to Bus arbitration conrol. Three ing. Other states are indicated by press the reset button. pins, bus request, bus grant and the status outputs, Fig.8, but The HALT pin is bidirectional bus grant acknowledge (BR, BG only interrupt acknowledge is and the processor can drive it low and BGACK) make up this sec- used on Kaycomp. to indicate a double bus error. tion. These deal with multi-pro- System control. Three signals Bidirectionality also applies to cessor/d.m. a. functions which constitute the system control the reset pin. A reset instruction are not available on Kaycomp. section, bus error, reset and halt. executed in software causes the Bus error, BERR, is not used on reset pin to be driven low for 124 Bob Coates gives a more Kaycomp. It has two main func- clock periods. All peripheral detailed description of the cir- tions. First, I mentioned earlier devices connected to the RESET cuits in his next article. that bus cycles are terminated with DTACK. If the circuit does not send this signal, if for exam- ple access to non-existent mem- ory location is attempted, the processor stops. A way around this is to have a hardware time- Fig. 8. Function codes out circuit which generates a bus - indicating the state and cycle error signal if DTACK is not type currently executing. asserted within a given period. A These outputs are valid bus -error signal causes exception whenever the address strobe processing to allow an orderly is active (low). recovery - hopefully.

Function code output Cycle type FC2 FC1 FC0

Low Low Low (Undefined, reserved) Low Low High User data Low High Low User program

Low High High I Undefined, reserved 1

High Low Low I Undef ined, reserved 1 High Low High Supervisor data High High Low Supervisor program High High High Interrupt acknowledge The kit p.c.b. is not a plated -through type; this saves money but requires use of turned -pin i.c. sockets.

ELECTRONICS & WIRELESS WORLD OCTOBER 1985

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74-78 Collingdon St. Luton, Beds, LUI 1 RX Tel: (0582) 413174 Telex 825484

CIRCLE 134 FOR FURTHER DETAILS.

IQD- I 1D The world shrinkers IQD Limited North Street, Crewkerne IQD's state-of-the-art DTMF signalling techno ogy now Somerset TA18 7AR England brings you Smartpatch 5700, which allows you to dial Telephone: (0460) 74433 direct into the telephone network while you a -e on the Telex: 46283 move, and to accept incoming calls regardless of your location. Smartpatch 5700 is the only intelligent. tele- communications interconnect system with British Telecom approval. Smartpatch 5700 complements IQD's extensive range of DTMF products, which includes the Codepad, Micropad and Selcall devices. IQD keeps you in touch.

1Q11 COMMUNICATION DEVICES CIRCLE 12 FOR FURTHER DETAILS.

ELECTRONICS & WIRELESS WORLD OCTOBER 1985 55

www.americanradiohistory.com PHONE P. M. COMPONENTS LTD TELEX 0474 60521 SELECTRON HOUSE, SPRINGHEAD ENTERPRISE PARK 966371 4 LINES SPRINGHEAD RO, GRAVESEND, KENT DA11 8HD TOS -PM

STK015 1845300 1.10 TDA2524 1. 5 5.95 TDA2530 CATHODE RAY TUBES Please add £3 additional carriage per tube. INTEGRATED CIRCUITS STK025 3.95 TBA540 1. 1.95 1.35 7042532 1.95 19.00 AN124 2.50 STK043 9.50 1045400 CME822W 55.00 MC1327 1.70 TBA5500 1.95 TDA2540 1.95 25.00 DB7-36 M38-121LA 65.00 AN2140 2.50 STK078 11.95 CME822GH MC13270 0.95 TBA560C 1.45 7042541 2.15 CME1428GH 45.00 DG7.32 45.00 M38-122GW 65.00 AN240P 2.80 STK415 7.95 MC1349P 1.20 T8A560C 1.45 TDA2560 2.15 CME1428W 39.00 DG13.2 45.00 M38-140LA 65.00 AN612 2.15 STK433 5.95 MC1351P 1.50 1.45 TDA2571A 4.50 CME1523W 39.00 DH3-91 55.00 M38-142LA 65.00 AN7140 3.50 STK435 7.95 78A56000 MC1357 2.35 TBA570 1.00 TDA2581 2.95 CME1431GH 39.00 DH7.91 45.00 M38 -341P31 65.00 AN7145 3.50 STK437 7.95 MC1358 1.58 TBA641 A7 2 3.50 TDA2593 2.95 39.00 DP7 5 35.00 M38 -344P39 65.00 AN7150 295 STK439 7.95 ME 1431W MC1495 3.00 TBA651 R 2.50 CME202GH 45.00 DP7.6 35.00 M40 -120W 59.00 BA521 3.35 TDA2600 6.50 MC1496 125 STK461 11.50 TBA720A 2.45 TDA2610 2.50 CME2024W 45.00 ON13.78 35.00 M43-12LG/01 65.00 CA1352E 1.75 MC145106P7,95 TA7061AP 3.95 TBA7500 2.65 TDA2611A 1.95 CME2325W 45.00 F16-101GM 15.00 M44-120LC 65.00 CA3086 0.46 TA7108P M44-120GR MC1723 0.50 1.50 TBA800 0.89 TDA240 3.50 CME3128W 45.00 F16-101LD 75.00 65.00 CA3123E 350 MC3357 2.75 TA7120P 1.65 TBA810AS 1.65 TDA2680A 2.75 CME3132GH 45.00 F21-130GR 75.00 M50-120GH 65.00 2.50 ETT6016 ML231B 1.75 TA7130P 1.50 TBA810P 1.65 TDA2690 2.45 CME31S5W 45.00 F21 130LC 75.00 M50-120GR 65.00 HA1377 3.50 M50 -1200V ML232B 2.50 TA7176AP 2.95 TBA820M 0.75 TDA3310 CRE1400 25.00 F31 .100M 75.00 85.00 HA1156W 150 2.95 M50-120LC MSM5807 6.75 747203 2.95 5048200 1.45 TDA3560 5.50 CV429 89.00 F31 -10GR 75.00 65.00 HA1339A 2.95 PLL02A 5.75 TA7204P 2.15 TBA890 2.50 UPC566H 2.95 CV1450 35.00 F31-10LC 75.00 M61 -120W 75.00 HA1551 2.95 SAA500A 3.50 TA7205AP 1.15 TBA920 1.85 UPC575C2 2.75 CV1526 19.00 F3110LD 75.00 S6AB 45.00 LA1230 1.95 SAA1025 7.25 TA7222AP 1.80 TBA950Y2X2.35 UPC1025H 1.95 CV2185 15.00 F31 -12LC 75.00 SE4/D/P7 45.00 LA4031P 1.95 SAS560S 1.75 TA7227P 4.25 TBA990 1.49 UPC1028H 1.95 CV2191 19.00 F31-12LD 75.00 SE42BP31AL 55.30 LA4102 2.95 SAS570S 1.75 747310P 1.80 TCA270 1.50 UPC1032H 1.50 CV2193 15.00 F31-1300 75.00 SE42BP31 55.00 LA4140 2.95 SAS580 2.85 TA7313AP 2.95 UPC1156H 2.75 CV5119 85.00 F3113LD 75.00 SE5FP31 55.00 LA4400 4.15 TCA270S01.50 SL901B 7.95 747321P 2.25 TCA650 3.50 UPC1158H 0.75 CV5320 85.00 F31-13LG 75.00 1937 65.00 LA4420 1.95 7948N SL917B 6.65 7A7609P 3.95 TCA940 UPC1167C21.95 CVX389 55.00 F41 123LC 185.00 65.00 LA4422 2.50 1.65 SL1310 1.80 TA7611AP 2.95 TDA440 2.20 UPC11B1H 1.25 D9-110GH 39.50 F41 -141 LG 185.00 194811 65.00 LA4430 2.50 SL1327 1.10 TAA310A 2.50 D10-210GH 45.00 F41-142LC 185.00 V4150LC 55.00 LA4461 3.95 TDA1001 1.95 UPC1182H 2.95 SL13270 1.10 TAA320A 1.95 D10-210GH68B 65.00 M7 -120W 19.00 V5004GR 59.00 LC7120 3.25 TDA1004A 5.95 UPC1185H 3.95 SN76003N 3.95 TAA350A 1.95 TDA1006A 2.50 UPC1191V 1.50 D10-230GH 35.00 Mld-1000M 45.00 V5004LD 59.00 LC7130 3.50 SN76013N 3.95 TAA570 1.95 010-230GM 35.00 M14-100LC 45.00 V6001GH 65.00 LC7131 5.50 TOA1010 2.15 UPC1350C 2.95 SN76023N 3.95 TAA661 B 1.95 D10 55.00 M17-151GVR 175.00 V6007DP31 59.00 LC7137 5.50 TOA1035 2.50 UPC1353C 2.45 -2930V/90 SN76033N 3.95 TAA700 1.70 UPC1365C 3.95 D13-30GH 49.50 M17-15100 175.00 V6008GW 59.00 LM324N 0.45 TBA120AS/B/C/ TDA1037 1.95 SN76110N 0.89 TDA1170 1.95 UPC2002H 1.95 D13-47GH/26 55.00 M19-100W 45.00 V6034WA 59.00 LM380N8 1.50 SN76115N 1.25 SA/SB/T/U 1.00 TDA1190 2.15 555 0.35 013-51GL/26 85.00 M19-103W 55.00 V6048CLA 59.00 LM380N14 1.75 SN76131N 1.30 TBA395 1.50 M23-110GH 55.00 V6048J 49.00 LM383T 2.95 TDA12700 3.95 556 0.60 D13-51 GM/26 85.00 SN762260N 2.95 TBA396 0.75 723 0.50 D13-450GH/01 55.00 M23-111LD 55.00 V60648P31 55.00 LM3900N 3.50 TDA1327 1.70 SN76227N 1.05 TBA440N 2.55 TDA2002 1.95 747 0.35 013-471 GH/26 69.00 M23-112GM 55.00 V6064CLA 55.00 M51513L 2.30 SN76533N 1.65 rBA4800 1.25 TDA2020 2.95 747 0.50 013-600GM 59.00 M23-112GV 55.00 V6069GH 55.00 M51515L 2.95 TBA510 55.00 SN76544N 2.65 2.50 TDA2030 2.80 748 0.35 D13-610GH 59.00 M23-112GW V6070P31 49.00 M51521L 1.50 TBA5100 55.00 SN76570N 1.00 2.50 TDA2190 11.95 7805 0.65 D13-611 GH 59.00 M23-112KA V7016A 65.00 MB3712 2.00 TBA520 1.10 SN76650N 1-15 7808 0.60 D GM 59.00 M24 -1200M59.00 V7030 59.00 MC1307P 1.00 7042522 1.95 13-611 SN76660N_ 0.80 TBA5200 1.10 TDA2523 7815 0.85 D13-630GH 59.00 M24-120LC 59.00 V7031GH 59.00 MC1310P 1.50 2.95 S1K014 7.95 TBA530 1.10 D14-150GH 75.00 M24-120WAR 59.00 V7031 /67A 59.00 M24-121GH 55.00 V7035A 49.00 BD223 D14-150GM 75.00 0.59 BFR88 0 30 RCA16335 0.80 M28-12GH 55.00 V7037GH 45.00 SEMICONDUCTORS BD225 0.48 014. 172GH/84 59.00 BFR90 1.50 SKE5F 1.45 014-17200 55.00 M28-13LC 49.00 V8004GR 65.00 AAV 12 0.25 BC178 0.15 BC232 0.35 BFR91 1.75 TIP29 0.40 D14-172GV 55.00 M28-13LG 49.00 V8006GH 65.00 AC125 0.20 BC182 0.10 60233 0.35 6E742 0.35 TIP29C 0.42 D14.173GH 55.00 M28-13GR 49.00 V8010A 65.00 AC126 0.45 BC182LB 0.10 BD234 0.35 8E743 0.35 TIP30C 0.43 D14 -1730M 53.00 M28-131GR 55.00 VCR139A 11.50 AC127 0.20 BC183 0.10 BD236 0.49 BFW92 0.85 TIP31C 0.55 M28-133GH 55.00 2BP1 9.00 80237 D14-173GR 55.00 AC128 0.28 BC183L 0.09 0.40 BFX29 0.30 TIP32C 0.42 M31-101GH 55.00 3BP1 11.50 AC128K 0.32 BD238 0.40 D14-181GH/98 65.00 BC184LB 0.09 BFX84 0.26 TIP33C 0.95 55.00 M31-182GR 55.00 3DPI 11.50 AC141 0.28 BD242 1314-1810J BC204 0.10 0.65 BFX85 0.32 TIP34B 0.95 014-1816M 53.00 M31 .1820v 53.00 3H/OBM 55.00 AC141 K 0.34 BC207B 0.13 BD246 0.75 BFX86 0.30 TIP41A 0.45 D14-181GM50 59.00 M31 -184W 65.00 3W P1 18.50 AC142 K 0.30 BC208B 0.13 BD376 0.32 BFX88 0.25 TIP41C 0.45 M31-184GH 65.00 4EP1 30.00 AC176 BD410 D14-182GH 59.00 0.22 BC212 0 09 0.65 BFY50 0.21 TIP42C 0.47 M31 -184P31 65.00 5BP1 9.00 AC176K 0.31 BD434 0.65 014-2006E 89.00 BC212L 0.09 BFY51 0.21 TIP47 0.65 M31 186W 69.00 58HP1 30.00 AC187 0.25 BC212LA 0.09 BD437 0.75 D14 -2000A/50 85.00 6E452 0.25 TIP120 0.60 M31.190GH 55.00 58HP1 FF 30.00 AC187K 0.28 BC213 0.09 BD438 0.75 1)14.2000M 75.00 BFV90 0.77 TIP125 0.65 75.00 M31-190GR 55.00 5BHP31 30.00 AC188 0.25 BC213L. 0.09 BD520 0.65 D14-210GH 55.00 1311413 1.75 TIP142 1.75 75.00 M31-190LA 5CP1 10.00 AC188K 0.37 BC214 0.09 BD538 0.65 O 14-2706H/50 M31-191GV 55.00 BRY39 0.45 TIP161 2.95 110.00 6EP7/S 39.00 ACY17 1.15 BC214C 0.09 BD597 0.95 D14 -310W M31 -220W 59.00 BR700 0.28 TIP2955 0.80 D14-320GH/82 85.00 13BP1 13.50 AD142 0.79 BC214L 0.09 00701 1.25 TIP3055 M31 -270G1/ 65.00 BR701 0.49 0.55 014-340GH/KM 45.00 13BP4 17.50 AD143 0.82 BC237B 0.09 50702 1.25 BR103 0.55 TIS91 0.20 M31 -271P31 65.00 BD707 D14-340KA 45.00 17DWP4 25.00 AD149 0.70 BC238 0.09 0.90 BRC4443 1.15 TV106/2 1.50 M31-271GW 65.00 BDX32 1.50 D16-100GH 65.00 32J/1085 69.00 AD161 0.39 BC239 0.12 BT100A/02 0.85 2N1308 1.35 M31 -271W 65.00 88Di89B/89Di89L 15.00 AD162 D16- 100GH/65 69.00 0.39 BC251A 0.12 BT106 1.49 2N2219 0.28 M36 -141W 75.00 1273 6E115 0.35 D16 -1000H/67 65.00 39.00 AD161 /2 0.90 BC252A 0.15 B7116 1.20 2N2905 0.40 M36-170LG 75.00 1564 39.00 BF119 0.65 D16-100GH/79 69.00 AF106 0.50 BC258 0.25 1119 315 2N3053 0.40 M38-101GH 65.00 1844 45.00 AF114 BC258A 0.39 6E127 0.39 D16-100GH97 65.00 1.95 BT120 1.65 2143054 0.59 M38-10308 65.00 9442E1 80.00 eC284 6E154 0.20 D 18-160GH 69.00 AF 115 2.95 0.30 BU1O5 1.95 2N3055 0.52 M38 -120W 65.00 954470M 75.00 AF116 2.95 BC300 0.30 BF158 0.22 021-10GH 65.00 BU108 1.69 2143702 0.12 M38-120WA 65.00 954490 75.00 BC301 BF160 0.27 DG7 5 55.00 AF117 2.95 0.30 BU124 1.25 2N3703 0.12 M38-121GHR 65.00 7709631 BC303 0.26 6E167 0.27 DB7 6 35.00 78.50 AF121 0.60 BU125 1.25 2143704 0.12 AF124 0.65 BC307B 0.09 6E173 0.22 8U126 1.60 AF125 0.35 BC327 0.10 6E177 0.38 2613705 0.20 BU204 1.55 2N3706 0.12 AUDIO TAPE HEADS AF126 0.32 BC328 0.10 BF178 0.26 BU205 1.30 2M3708 0.12 AF127 0.65 BC337 0.10 BF179 0.34 BU208 1.39 2N3733 9.50 NEW VIDEO SPARES MONO HEAD 1.50 AF139 0.40 BC338 0.09 13E180 0.29 3.50 BU208A 1.52 2N3773 2.75 AUTO REVERSE AF 150 BC347A 0.13 6E181 0.29 u HEAD 2.95 0.60 BU208D 1.85 2143792 1.35 STEREO AF178 1.95 BC461 0.35 BF182 0.29 BU326 1.20 2144427 1.95 AF239 0.42 BC478 0.20 BF183 0.29 BU407 1.24 2144444 1.15 AFZ12 3.75 BC 527 020 8E184 0.28 BU500 2.25 VIDEO HEADS VIDEO BELT KITS 2N5294 0.42 ELECTRO -OPTICAL ASV27 0.85 BC 547 0.10 BF185 0.28 BU508A 1.95 3HSS £29.50 Akai VS9300/9500/ AU106 4.50 BC548 0.10 6E194 0.11 2145296 0.48 BU526 1.90 2N5298 0.60 Suitable for Ferguson 9800 £3.75 9524H 25.00 AU107 3.50 BC 549A 0.10 BF195 0.11 BU801/ 2.25 2N 54 85 0.45 9677M 22.00 AU 110 3.50 BC 550 0.14 BF196 0.11 BUV698 1.70 3V00, 3V01, 3V06, 3V16, Ferguson 3V16 4.50 2N5496 0.95 P42318AM 19.00 BC107A 0.11 BC557 0.08 6E197 0.11 MJ3000 1.98 3V22, 3V23, 3V24, 3V29, JVCH HR 3330/3600 4.50 BC1078 0.11 BC557B 0.08 8E198 0.16 2SA715 0.80 MJE340 0.40 2SC495 0.80 3V30, 3V31, 8903 and JVC HR 3360/3660 4.50 BC108 0.10 BC558 0.10 BF 199 0.14 MJE520 0.48 2SC496 0.80 many JVC, Akai, Panasonic NV 300 4.00 BC108A 0.11 BCY33A 1.60 13E200 0.40 MPSA13 0.29 2SC1096 0.80 Normende, Telefunken. Panasonic NV 2000B 3.75 WIREWOUND RESISTORS 8C1080 0.12 BD115 030 BF241 0.15 MPSA92 0.30 BC109 010 6E245 0.30 2SC1106 2.50 Panasonic 3000B 3.75 MRF237 4.95 2SC1172V 2.20 BC1098 0.12 BD124P 0.59 6E257 0.28 MRF450A 13.95 4HSS £32.95 Panasonic NV7000 3.50 BC109C 0.12 BD131 0.42 13E258 0.28 2SC1173 1.15 4Wan 204.10K 0.20 MRF453 17.50 2SC1306 1.40 Suitable for National Panasonic NV 8600B/ BC114 0.11 BD132 0.42 8E259 0.28 MRF454 26.50 Panasonic NV333 340, 8610B/VO11 3.75 7 Wan 547-22K 0.20 BC116A 0-15 BD133 0.40 BF271 0.26 2SC1307 1.75 MRF455 17.50 0.50 105 15K 0.25 BC11J 0.19 BD135 0.30 8E273 0.18 2SC1364 2000, 3000, 7000, 7200, Sanyo VTC 5500 3.75 11 Wan MRF475 2.95 2SC1449 0.80 BC119 0.24 BD136 0.30 B F336 0.34 7500, 8170, 8400, 8600, Sanyo VTC 9300 3.75 1R -15K MRF477 10.00 17 Watt 0.30 BC125 0.25 BD137 0.32 BF337 0.29 2SC1678 1.25 8610F, 8620, Sanyo VTC 9300P 3.90 OC16W 2.50 2SC1909 1.45 Blaupunkt BC139 0.20 BD138 0.30 8E338 0.32 RTV 100E, 200, 202, 211, Sharp VC 6300 3.75 BC140 BD139 0.32 BF355 037 0C23 1.50 2SC1945 2.85 031 0C42 0.75 322, RTX100, 200, Sharp VC 7300 3 75 VALVE AND CRT BASES BC141 0.25 BD140 0.30 6E362 0.38 2SC1953 0.95 222, BC142 0.21 BD144 1.10 8E363 0.65 0C44 0.75 2SC1957 0.80 224. Sharp VC 8300 3.75 0C45 0.55 1.95 BC143 0.24 BD150C 0.29 6E371 0.25 2SC1969 Sharp VC 9300 3.75 B5D 8138 OC70 0.45 5.50 0.50 BC )47A 0.12 BD159 0.65 8E394 0.19 2SC2028 1.15 0071 0.55 PS3B £39.50 Sony SL 3000B 3.75 B7G 0.25 B14A 3.00 BC1478 0.12 BD160 1.50 6E422 0.32 2SC2029 1.95 Sony SL 4.50 BF457 0.32 OC72 0.85 2SC2078 1.45 Suitable for Sony C5, C6, 8000/8080 B7G SKID 0.25 12PIN CRT 0.95 BC148A 0.09 BD166 0.55 Sony SL 4.00 BC1483 0.09 BD179 0.72 BF458 0.36 OC81 0.50 2SC2091 0.85 C77, 8000, 8080, Toshiba C7/J7 B8G 1.50 NUVISTOR 2.95 BC149 0.09 BD182 0.70 B F459 036 0C171 3.50 2SC2098 2.95 V5470, V8600, V8700. Toshiba V7540 4.50 B8H 0.70 OCTAL 0.35 2SC2166 1.95 BC157 0.12 0.70 8E467 0.68 R20088 1.45 B9A SK610 35.00 BD183 2SC2314 0.80 0.35 BC158 0.09 BD201 0.83 8E595 0.23 020108 1.45 2SC2371 0.36 (VHS automatic wet/dry 6.50 890 SKT 0.40 UX5 1.75 BC159 B F597 0.25 R2322 0.58 Video Head Cleaning Tape 0.09 BD202 0.65 2SD234 0.50 B9G 0.75 UX7 1.75 BC174 0.09 BD203 0.78 BFR39 0.23 R2323 0.68 Video Head Aerosol Cleane 0.85 3N211 2.95 13106 0.20 CANS 0.30 BC174A 009 60204 0.70 BFR40 0.23 R2540 2.48 Video Copying Lead and Connector Kit 'ZV' 7.95 HCA16334 0.90 3SK88 0.95 BC177 0.15 BD222 0.46 BFR81 0.25 01206 0.14 N23WE 5.00 UNE OUTPUT TRANSFORMERS E H T MULTIPLIERS VARICAP TUNERS PUSH BUTTON UNITS DIODES 81208-800 0.33 N4001 0.04 DECCA 100 7.95 6.35 ELC1043/05 MULLARD 8.65 61210-800 0.33 144003 0.04 ITT CVC20 DECCA, ITT, CVC206WAY 7.95 6.35 ELC1043/06 MULLARD 8.65 4.4119 0.08 61223 0.90 144004 0.05 DECCA 1700 MONO 9.95 ITT CVC30 ITT CVC5 7 WAY 10.19 6.96 U321 BA115 0.13 131298-400 0.22 N4005 0.05 DECCA 1730 8.95 PHILIPS 08 550 8.25 PHILIPS G81550) 6 WAY 14.49 6.91 U322 8A145 0.16 81299-800 0.22 N4007 0.06 DECCA 2230 8.25 RANK T20A 8.25 GEC 8.95 7.57 BA148 0.17 B 1X10 0.20 144148 0.02 2040 THORN 3000/3500 GRUNDIG 1500 15.45 5.80 20MM QUICK BLOW FUSES BA154 0.06 81/X36 -150R 0.20 N4448 0.10 THORN 8500 TNERIIIST9RS GRUNDIG 5010-6010, 2222.5011-601113.45 8.00 BA156 0.15 B VX38-6000 0.60 N5401 0.12 THORN 9000 100MA 8p each TRIPLER 5.45 BA157 0.30 BVX55-600 0.30 N5402 0.14 TiI CVC20 8.20 UNIVERSAL VÁ1040 0.23 200MA-5AMP 5p each BAX13 0.04 BVX71-600 1.10 N5403 0.12 ITT CVC30 8.25 VA1056S 0.23 PHILIPS 08 8.50 BAX16 0.06 BZY95C30 0.35 N5406 0.13 REPLACEMENT VA1104 0.70 BB1058 0.30 CS4B 4.50 N5407 0.18 PHILIPS G9 8.99 VA8650 0.46 20MM ANTI SURGE FUSES BT151 0.79 CS10B 8.45 N5408 0.16 PHILIPS G11 73.39 ELECTROLYTIC CAPACITORS VA1097 0.25 131126 0.10 0447 0.09 TT44 0.04 PYE 725 10.95 100MA - 800MA 15p each 61127 0.11 0490 0.05 1TT923 0.15 ROM T20A 12.40 DECCA 301400-400/350V) 2.85 14 - 5AMP 12p each BY133 0.15 0491 0.06 TT2002 0.10 TANDBERGE 90' 11.15 DECCA 80/100)400/350V) 2.99 81164 0.45 0A95 0.06 TELEFUNKEN711A 11.15 DECCA 1700 SPARES & AIDS 01176 1.20 0A202 0.10 THORN 1590 9.50 (200-200-400-350V) 3.55 131179 0.83 IN21DR 5.00 ZENER DIODES THORN 8000 9.20 GEC 21101600/300V) 2.25 HEAT SINK COMPOUND £1.00 PUSH PULL MAINS SWITCH BT182 0.55 INT3B 5.00 THORN 9000 9.95 ITT CVC20 (200/400V) 1.80 FREEZE IT 0.95 (DECCA, GFC, RANK, THORN BY184 0.35 IN23C 5.00 BZX61 Series 0.15 THORN 9800 22.40 PHILIPS G81600/300V) 2.25 SOLDA MOP 0.64 ETC.) 1.02 PIE IF GAIN MODULE 6.99 B`7199 000 I9123ER 5.00 BZY88 Series 0.10 THORN MAIN TRANSFORMER PHILIPS G9 (2200/63V) 1.19 SWITCH CLEANER 0.85 3000/3500 9.70 PHILIPS G111470/250V1 2.35 W D40 1.75 ANODE CAP (276V) 0.69

56 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com PHONE P. M. COMPONENTS LTD TELEX 0474 60521 SELECTRON HOUSE, SPRINGHEAD ENTERPRISE PARK 966371 4 LINES SPRINGHEAD RD, GRAVESEND, KENT DA11 8HD TOS -PM lI¡ M8225 3.50 QS1202 3.95 UL84 0.85 384 7.00 6BC8 1.00 6.108 2.50 12SJ7 1.50 833A 95.00 A SELECTION FROM OUR ME1401 29.50 QS1203 4.15 UU5 3.50 387 4.50 6504 1.50 6JS6C 4.95 12S07GT 195 866A 4.50 ME1402 28.50 051205 3.95 UU7 8.00 3824 10.00 6806 2.50 6J7G 415 12SR7 2.50 872A 27.50 STOCK OF BRANDED VALVES ME1501 14.00 051206 1.05 UU8 9.00 3826 24.00 68E6 0.72 6K7G 2.00 12S07GT 1.50 873 60.00 MH4 3.60 0S1207 0.90 UY41 3.50 3828 12.00 6K8G 3.00 13D3 3.20 884 5.50 A1714 24.50 EL822 12.56 MHLD6 4.00 UY85 0.70 6BG6G 3.00 13D7 930 9.95 051208 0.90 3626 1.50 6KD6 5.50 3.20 A1834 7.50 EBF80 0.86 EMI 9.00 ML4 4.50 3.15 V235A/1K 68H6 1.95 13D9 3.20 931A 13.95 0S1209 3C4 1.00 6K M8 2.50 A1998 11.50 EBF83 0.85 EM4 9.00 MS48 5.50 QS1210 1.50 250.00 6BH8 1.50 13DE7 2.50 954 1.00 3C23 19.00 6KT8 2.95 A2087 11.50 EBF85 0.16 EM80 0.70 MU14 3.50 0S1211 1.50 V238A/1K 6816 1.20 955 1.00 3C45 24.00 6L1 2.50 13DR7 2.95 A2134 14.95 EBF89 0.70 EM81 0.70 MZI-100 125.00 OS1212 3.20 6BK4 4.00 958A 1.00 295.00 3C86 1.50 6L15 3.15 13E1 145.00 A2293 9.50 EBF93 0.96 EM84 1.85 N37 12.50 0S1213 5.00 68K7Á 1.95 13EM7 3.50 1299A 0.60 V240C/2K 3CN3A 2.50 6L19 3.95 A2426 29.50 EBL1 2.50 EM85 3.95 N78 9.85 OS1215 2.10 6818 115 14S7 1619 2.50 225.00 3CS6 0.95 6L6GC 2.95 1.95 A2599 37.50 EBL21 2.00 EM87 2.50 0A2 0.86 QS1218 5.00 60M8 0.58 17DW4A 2.95 1625 3.00 EC52 0.75 15.00 V241C/1K 3CX3 2.50 6L6GCIGE14.50 A2792 27.50 EN32 0A2WA 2.50 0U37 9.50 6BK4 1.65 17EW8 1626 3.00 EC70 1.75 195.00 3CYS 1.50 6L6GT 1.95 0.95 42900 11.50 EN91 1.50 OA3 2.50 OV03-12 4.95 6BN6 1.65 17.128 4.50 2050W 4.50 EC80 9.50 V2464A/2K 306 4.50 61020 1.15 2050 3.95 A3042 24.00 EN92 4.50 062 0.86 OV05-25 1.75 6BN7 4.50 18D3 6.00 A3283 24.00 EC81 7.95 ESU150 14.95 OB2WA 2.50 OV06-20 29.50 315.00 3D214 29.50 6BN8 3.95 6LF6 7.50 3545 4.00 V339 19.405 3.50 AC/HL/DD 4.00 EC86 1.00 ESU872 25.00 0C2 2.50 0V08-100 3.50 3E22 49.50 6805 0.75 6LJ8 2.50 404A 10.95 V453 12.00 194U4GT 2.50 AC/THI 4.00 EC88 1.00 EY51 0.80 0C3 1.50 145.00 3EH7 1.95 6007A 0.72 6106 4.95 927 15.00 EC90 1.10 VLS631 10.95 19G3 17.00 ACT22 59.75 EY91 2.35 0D3 1.70 0V2-250045.00 3EJ7 1.95 6BL7GTA 3.95 6N7 2.50 1927 EC91 5.50 VP48 4.50 19115 33.50 25.00 AH221 39.00 EY83 1.60 0M4 100 0V3-125 85.00 3W4GT 2.50 6N7GT 2.50 EC92 1.95 VP133 2.00 1.50 1906 9.00 4212E 250.00 AH238 39.00 EY84 5.95 0M58 300 0Y4-250 70.00 485518 115.00 6BR5 0.70 6P15 EC93 1.50 VR75/30 3.00 2042 10.50 43/3C 4.00 AL60 6.00 EY86/87 0.50 0M6 1.75 OV4-400 76.00 4-65A 59.00 6BR7 4.95 6P25 4.00 EC95 7.00 VR101 2.00 20D1 0.70 43280 9.00 AN1 14.00 EYB8 0.56 ORP43 2.50 010 4.00 46874 9.50 6808 2.15 6P26 4.00 EC97 1.10 VR105/30 1.50 201F6 3.50 5642 9.50 ARP12 0.70 EY91 5.50 ORP50 3.96 R16 12.00 4-125A 72.50 68084 2.15 6P28 2.00 EC157 439.50 EY500A 2.50 P61 VR150/30 1.15 68S7 5.50 2011 0.95 5651 2.50 ARP34 1.25 2.50 R17 1.50 4-250A 79.50 607 1.75 EC8010 12.00 EY802 P41 VT52 2.50 60W4 1.50 20P1 0.55 5654 1.95 ARP35 2.00 0.70 2.50 R18 2.50 4.400A 607GT 1.20 ECC32 3.50 EZ35 PABC80 VU29 4.50 87.50 6BW6 5.35 20P3 0.80 5663 1.95 0.75 0.60 R19 2.50 4832 35.00 6R7G 3.15 ECC33 3.60 E240 2.76 PC86 0.76 R20 1.20 VU39 1.50 68W7 1.50 20P4 1.95 5670 3.25 AZ11 4.50 4807A 1?5 6544 ISO ECC35 3.50 EZ41 2.75 PC88 0.75 R1169 55.00 W21 4.50 6BW8 4.00 20P5 1.15 5672 4.50 1.16 482E 1.95 6SA7GT 1.35 5687 4.50 ECC81 EZ80 0.75 PC92 3.50 RG1-125 4.95 W77 5.00 68X6 0.48 21LU8 2.50 B163 2.00 ECC81 Special 4C27 25.00 6SC7 1.50 2401 39.50 5692 3.50 EZ81 0.75 PC97 1.10 RG1140A14.50 W729 1.00 60X707 3.50 1.35 BS450 67.00 Ouality 1.95 1.50 4C28 25.00 6SG7 25L6GT 1.75 5696 3.50 EZ90 PC800 1.10 RG3-250A 3.50 W739 1.50 6826 2.50 6SH7 1.35 BS810 55.00 ECC82 0.65 F6064 PC900 1.25 4C86 1.95 6027 2.95 251306 1.75 5704 3.50 2.95 RG3-1250A X24 4.50 6SJ7GT 1.20 BS814 55.00 ECC82 Philips FW4/800 2.95 PCC84 0.40 4CX2508 49.00 6C4 1.10 29C1 19.50 5718 6.15 35.00 X66/X65 4.95 6SK7 1.35 CIK 19.00 1.95 PCC85 0.64 4CX2508 6C5 1.95 29606 6.50 5725 2.50 RK2K25 62.50 X76M 1.95 6SK7GT 1.35 C3JA 9.50 ECC83 0.85 G55/1K 9.00 PCC88 Ei mac 59.50 30C17 0.40 5726 1.50 0.70 RK -20A 12.00 XC24 1.50 6C6 2.50 6SL7GT 0.85 C6A 9.00 ECC83 Brimer G180/2M 6.95 PCC89 4CX250BM 6C8G 1.50 30C18 1.48 5727 1.95 0.70 A116 1.50 XC25 0.50 6SN7GT 1.35 C1108 65.00 1.35 G240/213 900 PCC189 0.70 75.00 6C71 2.50 30F5 0.95 5749 2.S0 RPL16 12.00 XFW47 1.50 6S07 1.35 C1134 32.00 ECC83 Philips GC108 17.50 PCC805 0.70 4CX250K 30FL1 1.00 5750 1.85 RPY13 2.50 XFW50 1.50 6557 1.95 C1148A 115.00 1.86 GC1OD 17.50 PCC806 0.80 EIMAC 95.00 6C18 2.50 30FL2 1.35 5751 2.95 RPY43 2.50 XG2-6400 6U4GT 1.75 C1149/1 195.00 ECC84 0.50 GC10/48 17.50 PCE82 4CX125C 125.00 6CA4 4.95 30FL12 0.95 5763 4.95 0.80 RPY82 2.50 135.00 608 1.15 C1150/1 135.05 ECC85 0.75 GC10/4E 17.50 PCF80 0.86 EIMAC 6CA7 3.50 30FL13 1.10 5814A 3.25 RR3-250 15.00 XG5-500 22.50 6U8A 1.50 C1534 32.10 ECC86 2.75 GC12/4B 17.50 PCF82 0.60 4CX350A 95.00 6CB5 30FL14 1.25 5829WA 6.50 RR3-1250 35.00 XL1-5V 1.50 3.95 6V6GT 1.50 CCA 2.60 ECC88 0.95 GD86W 6.00 PCF84 0.85 4CX350F 79.50 3011 0.45 RS613 45.00 XL628FT 7.50 6CB6 1.95 6X2N 1.00 5636 5.50 CC3L 0.90 ECC91 2.00 GDT120M 500 PCF86 130 4CX1500B 30115 0.60 RS685 54.95 XNP12 2.50 6CD6GA 4.50 6X4 1.50 5678 7.50 CL33 2.00 ECC180 0.72 GN4 6.00 PCF87 0.40 398.50 30117 0.80 RS688 52.15 XR1-1600A 6CF6 1.50 6X5GT 1.00 5840 3.50 CV Nos Prices ECC189 1.95 GN10 15.00 PCF200 1.85 4GS7 30P4MR 1.00 S6F17 5.95 48.50 2.25 6CG7 2.25 6X5GTV 1.00 5842 11.00 on request ECC801S 3.50 GR10G 4.00 PCF201 1.80 4GV7 30P12 1.00 S6F33 28.95 XR1-3200A 2.25 6CH6 6.95 6X8A 2.25 5847 10.95 D3a 27.50 ECC803S 4.95 GS1OC 16.50 PCF800 0.40 S11E12 38.00 79.50 4.152 75.00 6CL3 3.95 30P18 0.60 D63 1.20 PCF801 746 4.50 5879 8.50 ECC804 0.80 GS1OH 12.00 1.35 530/2K 12.00 XR1-6400A 4.106Á 2.95 6CL6 3.25 30P19 1.00 DA41 22.50 7A7 2.00 ECC2000 12.00 GS12D 12.00 PCF802 0.60 S104/1K 10.00 4X1504 35.00 1.50 3oPL1 2.50 5886 13.95 DA42 17.50 99.50 6CL8A 7AD7 1.75 ECF80 1.15 GT1C 14.00 PCF805 1.25 S109/1K 15.00 Y503 25.00 5A/102D 9.50 6CM5 1.60 30PL13 0.80 5894 39.50 DA90 4.50 PCF806 786 3.50 5899 4.50 0 ECF82 1.15 GT1C S/S 13.00 1.00 S130 5.95 V65 8.95 54152M 9.00 6CM7 2.95 301,114 1.75 DA100 125.00 ECF86 1.70 GTE175M 8.00. PCF808 1.26 7B7 2.50 5963 1.75 S130P 5.95 Y602 12.00 54163K 10.00 6CS6 0.75 31JS6C 5.50 DAF91 0.70 ECF200 1.86 GTR150W 1.00 PCH200 1.50 7C5 3.50 5965 2.25 SC1/800 5.00 VD1100 75.00 54170K 6.25 6CW4 6.50 33A/158M 19.50 DAF96 0.65 ECF202 1.85 GU20 35.00 PCL82 0.86 7C6 2.50 6005 1.85 SC1/1100 6.00 VJ1060 285.00 5A -180M 9.00 6CY5 1.00 35A5 4.50 DC70 1.75 ECF801 0.85 GU60 17.50 PCL83 2.50 7E7 2.50 6012 16.00 SC1/1200 5.00 711020 29.00 5A -206K 10.00 6D6 2.50 3516GT 2.00 DC90 1.20 ECF805 2.50 PCL84 0.75 7117 3.50 6021 3.85 GXU7 13.50 SC1/1300 6.00 YL1070 195.00 SAME 2.15 6DC6 2.35 35W4 0.70 DCX4-1000 ECF806 10.25 PCL85 0.80 7A U7 1.50 6057 2.50 GXU3 24.00 SC1/2000 9.00 711071 195.00 5ÁN8 1.20 6DJ8 0.95 35Z3 1.85 12.00 ECH3 2.50 GXU5OSS PCL86 0.85 5ÁR4 2.00 6058 3.95 SD6000M YL1290 65.00 601(6 1.15 7.17 5.50 38HE7 4.50 DCX4-5000 ECH4 3.00 14.50 PCL800 0.80 5404 1.50 40KD6 6059 3.75 45.00 Z77 1.20 6D05 5.95 7Y4 2.50 5.50 25.00 ECH35 3.50 GY501 1.20 PCL805 0.90 58.110M 10.00 42 6060 2.25 SP41 5.00 Z302C 12.00 6D068 2.50 8138 2.50 6.95 DET16 28.50 ECH42 100 GY802 1.00 PD500 3.50 58-254M 14.50 6062 4.50 SP42 Z359 9.00 6DT6A 1.50 8810 2.50 47 6.00 DET18 28.50 ECH81 0.86 GZ30 1.00 PD510 3.65 3.00 5B -255M 19.50 6063 2.00 SP48 Z505S 15.00 6DW4 8805 1.95 50A5 1.50 DET23 35.00 ECH83 0.78 GZ31 1.00 PE1-100 4.95 215 6064 3.25 69.00 2520M 4.00 58-256M 9.00 5005 0.95 DET24 39.00 ECH84 0.89 GZ32 1.00 SS501 35.00 6E44 4.95 8F07 1.95 6067 1.95 PEN25 2.00 2521M 8.00 56-257M 9.00 50CD6G 1.15 DET25 22.00 ECH2000 1.50 4.50 ST11 1.50 6E47 2.50 1002 125 6072 4.20 GZ33 PEN4ODD 2.50 27000 5B -258M 14.50 DET29 32.00 ECL80 0.60 GZ34 2.15 STV280/40 3.00 5C22 6EA8 2.50 10DE7 2.50 50EH5 1.50 6080 8.50 PEN45 3.00 Z749 0.80 125-00 DF91 0.70 ECL82 0.65 GZ37 4.50 11.95 6E88 1.75 10F1 0.75 50JY6 2.95 PEN45D0 3.00 Z759 19.85 5.1180E 1895.00 6080WA 9.50 DF92 0.60 ECL83 2.50 HAA91 1.00 STV280/80 6EM5 2.50 10GK6 1.95 52KU 2.00 PEN46 2.00 Z8000 5R4GB 3.50 DF96 0.85 ECL84 0.74 HABC80 0.90 PEO6-40N 19.95 3.00 10P14 2.50 53CG 15.00 6132 10.00 42.00 2803U 18.95 5R4GY 3.50 6EM7 2.50 DF97 1.00 ECL85 0.119 H8C90 0.75 SU42 4.95 574 5.95 10P18 0.78 61SPT 4.50 6136 2.50 PFL200 0.95 TB2.5/300 2A1000 12.50 6E07 1.95 DH63 1.20 ECL86 0.80 HBC91 0.80 PL21 2.50 5Ú4G 2.50 7581 3.50 61468 9.50 ZA1001 1.50 6EU8 1.75 1OLD12 0.65 DH77 0.90 ECL805 0.139 HF93 0.75 PL36 0.95 85.00 5Ú4G8 2.50 75C1 2.50 6157 2.50 TB2-300 45.00 ZA1002 1.50 6EV7 2.95 11E3 DH79 0.56 EF37A 2.00 HF94 1.50 PL38 1.50 5V4G 1.25 55.00 83 8.50 6158 3.20 DH149 2.00 EF39 1.10 183-2000 ZC1040 8.00 6EW6 1.50 1246 3.95 HK90 1.06 PL81 0.72 2M1005 5Y3GT 1.95 84 3.00 6201 6.45 DK91 0.90 EF41 3.50 HL2K 4.95 395.00 8.00 6EW7 4.50 12406 1.50 PL81A 0.72 ZM1020 524GT 0.85 85A1 6.50 6205 6.95 DK92 1.20 EF42 3.50 8.95 6F1 2.00 12ÁG8 1.50 HL23DD 4.00 PL82 0.60 TBL-2-300 ZM1021 8.00 6/3012 0.70 85A2 1.50 6211 2.50 EF50 2.50 H141 275.00 6F5 4.95 12ÁL5 1.00 90AV 10.00 3.50 PL83 0.52 ZM1023 7.95 6A/203K 9.00 6267 4.50 DL35 2.50 EF55 4.96 HL42DD 3.50 6F6 2.50 12476 0.95 PL84 0.78 TD1-100A ZM1041 14.00 647 4.95 90C1 2.70 6350 3.50 0L63 1.00 EF70 1.20 HL90 0.70 25.00 6F6G 2.00 12477 1.15 9oCG 13.50 PL88 1.00 ZM1082 9.00 648G 1.50 6360 4.50 DL70 2.50 EF71 1.50 HL92 1.60 TD03-10F 35.00 12AT7WA 2.50 PL95 1.75 2M1084 10.00 6ÁC7 2.00 6F7 5.50 90CV 12.50 6386 14.50 DL73 2.50 EF72 1.20 HL133/DD 3.50 TD3-12 4.00 12406 1.50 PL302 1.00 ZM1177 9.00 6AF4A 2.50 6F12 1.50 91AG 9.00 6545 8.50 DL91 1.50 EF73 1.00 HR2 4.00 P1.345 12.50 TDD4 5.50 6F13 3.00 12AU7 0.65 92AG 19.50 0192 0.95 EF80 0.55 ZM1202 55.00 6AG5 1.50 6550A 10.95 HY90 1.00 PL500 1.10 TP25 1.50 6AG7 6F14 1.00 12ÁV6 1.95 92AV 12.50 DL93 1.10 EF83 3.95 ZM1263 4.00 1.95 6688 6.50 HVR2 3.00 1.1504 1.15 TSP4 7.00 6F17 2.75 12ÁV7 2.50 9541 6.50 EF85 0.50 ZM1612 3.00 6ÁH6 2.50 6870 11.50 DL94 2.50 JP9-74 60.00 PL508 1.75 TT11 1.50 6F21 2.50 12AX4GT 1.00 DL96 EF86 2.25 143 4.50 6414 2.00 6887 9.50 2.50 K3118 85.00 PL509 4.85 6AJ7 2.00 6F23 0.60 12.4X7 0.65 DLS10 13.50 EF86 Special 14C6 1.20 68836 9.95 KR6/3 4500 PL519 4.95 45.00 6ÁK5 1.50 6F24 1.25 12AX7WA 2.50 108C1 1.50 DLS16 10.00 Quality 3.15 TT21 1B3GT 1.95 6973 5.95 KTBC 700 PL802 5.95 45.00 6ÁK6 6F25 1.25 12ÁY7 3.95 15082 6.95 DM70 1.95 EF89 7722 1822 10.00 2.50 7025 1.50 KT33C 3.60 PL802T 3.50 6AL5 0.60 6F28 1.25 124Z74 1.95 150C2 1.50 2.50 DM160 2.75 EF91 1.95 T7100 57.00 1024 14.95 7027A KT36 2.00 P1820 2.95 6ÁM4 3.25 6F32 1.25 12B4Á 4.50 150C4 2.15 4.50 DV51 1.50 EF92 2.15 T7R-31 MR 16354 29.50 7032 KT44 400 PL5557 29.50 6ÁM5 6.00 6F33 17.00 12BÁ6 1.50 155UG 25.00 2.00 DY86/87 0.85 EF93 0.95 7059 KT45 4.00 PV32 0.60 65.00 6ÁM6 1.50 6FG5 1.95 128E6 1.95 18581 1.50 2.50 DY802 0.72 EF94 0.85 KT61 4.00 PY33 0.50 TY2.125A 85.00 101 2.50 12BH7A 2.50 7167 3.95 1.50 6ÁN5 2.85 6F07 2.95 211 33.50 EF95 KT63 2.00 PY81 0.70 TY4.400 85.00 1C5GT 2.50 12816 1.75 7189 3.50 EF97 0.90 6AN8A 2.85 6G6G 5.50 274A 15.00 E61L 12.00 KT66 OSRAM PY82 0.70 TY8--600W 1.75 128Y74 2.75 7193 7.50 EF98 0.90 6805 6GH8A 0.80 307 5.00 E82CC 3.50 15.00 PY83 0.70 365.00 1FD1 2.50 6408 0.85 12CA5 1.95 328A 15.00 7199 7.50 E83CC 3.50 EF183 0.85 1G3GT 2.50 6GK5 1.50 KT66 USA 9.95 PY88 0.65 TYS2/250 6AR5 5.95 12CX6 1.20 388A 17.50 7247 E83F 5.50 EF184 0.65 1K3GT 6GK6 1.95 2.95 KT66 GEC 14.95 PY500A 1.95 375.00 2.50 6408 3.95 12D068 3.50 42545 8.00 7360 13.50 E86C 9.50 EF730 1.80 1N2 6GS7 2.15 KT77 Gold Lion PV800 0.79 U18-20 2.75 4.50 6ÁSS 1.50 120W44 431U 4.50 7462 E88C 7.95 EF731 3.50 SGV7 2.50 3.50 15.00 10.95 PV801 0.79 U19 11.95 1N5GT 2.50 6456 5728 65.00 E88CC 3.50 EF732 3.50 2.50 6GW6 2.50 12DW7 2.50 7475 5.00 KT81 7.00 OB3-300 54.95 U24 2.00 1F28 25.00 6Á57G 4.50 705A 8.00 E88CCSiemans EF800 11.00 6H 1 9.50 12E1 17.95 7486 125.00 KT88 USA 10.95 OB3-1750 139.50 U25 0.90 114 0.70 6476 0.75 7084 8.00 Special 6.96 EFRO5S 13.50 6H3N 1.10 12E14 38.00 7527 85.00 KT88 G Lion 18.95 085-3500 495.00 U26 0.90 105 1.00 6478 1.75 715C 45.00 EF806S 14.50 6116 1.95 12GN7 3.95 E90CC 7.95 KT67 9.00 0E03-10 4.95 U37 9.00 1X28 1.40 6404 200 725A 275.00 EF812 0.65 6H6GT 1.95 121107 4.50 7551 6.95 E9OF 7.9! KTW61 2.50 0E08-200 041 6.95 122 8.95 6406 0.95 803 14.95 E91H 4.50 EFL200 1.50 6HF5 5.50 12HG7A 4.50 7558 9.45 0.72 KTW62 2.50 145.00 U50 2.00 267 1.50 6AV6 0.75 805 39.00 3.95 EH90 6H F8 2.50 12J7GT 3.50 7586 15.00 E92CC EK90 0.95 KTW63 2.00 0F40 65.00 U82 3.00 2822 69.50 6AW8A 2.50 807 1.95 E99F 6.99 6HS6 4.95 121(5 1.95 7587 29.50 EL32 0.95 KTZ63 2.50 OP25 1.00 1)191 0.70 2C394 32.50 6AZ8 85.00 E130L 25.00 5.95 6.14 2.15 12K7GT 1.50 810 7591A 4.95 EL33 4.00 L63 1.50 00E02-5 19.50 11192 1.00 2C3984 39.50 687 2.80 811A 15.00 6J4WA 3.15 1268 1.95 7609 47.00 EL34 2.25 L102/2K 6.95 OQE03-12 7.95 0193 0.65 2C40 37.00 688G 812A 35.00 E182CC 9.00 1.50 615 2.50 12SA7GT 1.95 7733 5.50 EL34 Mullard/ L120/2K 12 00 00E03-20 35.00 U251 1.00 2C42 29.50 68A6 0.95 813 23.50 E180F 6.50 LB7-20 6J6 2.00 12SG7 4.75 7788 Philips 4.50 95.00 00E06-40 U801 0.75 2C51 0.75 66A7 4.50 2500 E186F 8.50 LS9B 6.95 45.00 UABC80 0.65 6.1864 3.95 12SH7 1.95 7868 EL36 1.95 2C53 32.00 68Á8A 3.50 8290 14.50 3.95 E188CC 7.50 M502A 60.00 00V02-6 19.50 6JE6C 4.95 12SK7 1.95 8012 EL37 9.00 UAF42 1.00 2CY5 1.50 15.00 E1T 15.00 00V03-10 5.50 UBF80 EL38 4.75 .pppp 0.80 2D21 1.50 E280F 19.50 M537A 90.00 00V03-10 UBC41 2.95 EL41 3.50 2D21W 2.50 E283CC 10.00 M5143 156.00 Mullard 15.00 UBC81 EL42 2.00 1.50 2E26 7.95 E288CC 13.50 M8079 8.00 00V03-20 UBF89 0.60 WE ARE MOVING ON 1ST JULY 85 EL81 6.95 2J42 93.00 M8082 7.50 25.00 UBL21 1.75 TO OUR NEW DISTRIBUTION CENTRE E810F 25.00 EL83 5.95 2K25 27.50 E1148 M8083 3.25 00V03 -20B UC92 1.20 1.00 EL84 0.75 CALLERS WELCOME E1524 M8091 7.50 32.00 UCC84 0.70 2625 Raytheon 8.95 EL85 4.50 EA50 1.00 M8096 300 OQV06-40A UCC85 000 75.00 OPEN MON-THUR 9ÁM 5 30PM FRI EL86 0.85 EA76 1.95 M8098 5.50 27.50 UCF80 1.00 2K26 95.00 9AM-5 OOPM EL90 1.75 EA79 1.95 M8099 5.00 00V07-50 UCH21 1.20 3A/107B 12.00 ' 24 HOUR ANSWERPHONE SERVICE ' EL91 6.00 M8100 5.60 63.50 UCH41 2.50 3A/1084 9.00 EABC80 0.70 EL95 1.75 ACCESS & BARCLAYCARD PHONE M8136 7.00 00203-20 UCH42 2.50 34/1098 11.00 EAC91 2.50 EL153 12.15 ORDERS WELCOME EAF42 130 M8137 7.95 42.50 UCH81 0.65 3A/11013 12.00 EL183E 3.50 M8161 6.50 OS75.20 1.50 3A/141K 11.50 EAF801 2.00 UCL82 1.75 UK ORDERS P&P 50p PLEASE ADD EL18P 3.50 M8162 5.50 0575/40 3.00 3A/147J 7.50 EB34 1.50 EL360 6.75 UCL83 2.50 15°° VAT EB41 3.96 M8163 5.50 0S92/10 5.00 3A/167M 10.00 EXPORT ORDERS WELCOME EL500 1.40 M8190 4.50 OS95/10 4.86 UF4/ 1.15 3A2 3.95 EB91 0.85 EL504 1.40 UF42 1.15 CARRIAGE AT COST EBC33 2.50 M8195 6.60 OS108/45 4.00 3Á3A 3.95 EL509 5.25 UF80 1.75 SPECIAL E8C41 1.95 M8196 5.60 00150/15 5.95 3M 110 PLEASE SEND YOUR ENQUIRIES FOR EBC81 1.50 EL519 6.95 M8204 5.50 QS150/30 1.15 1,F85 1.20 3AL5 0.95 QUOTATIONS FOR LARGE REQUIREMENT': EBC90 0.90 EL802 3.85 M8223 4.50 0S150/45 7.00 U'F89 2.50 3AT2 3.35 EBC91 0.90 EL821 8.50 M8224 2.00 OS1200 3.95 1.144 3.50 3132 3.00

CIRCLE 50 FOR FURTHER DETAILS. ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com by Andrew Ray B.Sc., Intelligent Interfaces Ltd Case study in interface design Development of the Syscon 6 interface for using Commodore peripherals with a BBC computer illustrates the sometimes overlooked ratio between software and hardware design effort.

It is a popular misconception that puter. Firmware makes sure that filing system. However, random- microcomputer interfaces are a the user does not notice any dif- access filing systems have always complex plug and socket and that ference between using the Com- had to be supported by applica- their design time is equal to the modore peripherals and the disc - tion programs running on the time taken to make the necessary drives and printers normally used host computer. electrical connections. with the BBC computer. The Discs are formatted such that The Oxford dictionary desc- resulting interface software gives outer tracks have more sectors ribes an interface as an area of increased data storage capacity, than those closer to the centre. interaction between two sys- data security and flexibility. Tracks are reserved for a direc- tems. This wider definition There are two separate inter- tory of files and a block -allocation becomes more applicable as sys- faces in Syscon 6; both can func- map, or bam. The dos includes tems grow in complexity, parti- tion concurrently as data is trans- error-checking, e.g., read -after - cularly when distributed process- ferred to and from the disc in write verification. ing is involved. As the area of blocks and to the printer a line at a Disc operating system com- interaction grows, emphasis time. Firmware for the printer mands are sent by the computer moves from interface hardware to interface allows Commodore to the disc unit as strings of Ascii interface software; this descrip- printers to print a normal upper characters. When a dos com- tion of the design of Syscon 6 is an and lower case character set. mand has been executed an illustration of this trend. error -status message, also a str- Syscon 6 allows Commodore ing of Ascii characters, can be Fig.1. Software sections of disc drives and printers, now Commodore disc -unit design read by the computer. the interface for controlling often found collecting dust in Commodore peripherals using educational establishments, to To appreciate the design of the a BBC computer. be used with BBC the microcom- disc interface, CDISK, one needs BBC computer d.f.s. design to understand both the Commo- dore disc unit and the BBC com- The BBC -computer disc filing puter disc filing system, the system is totally integrated into BBC computer BBC computer d.f.s. paged rom filing system the main computer. An 8271 disc interface calls interface calls Over the years, Commodore controller is used with software in has produced a variety of disc a 'paged' rom. This simple but units, all designed as intelligent effective design results in rapid subsystems with two micropro- data storage and retrieval. Discs cessors. One processor unit, are formatted with ten sectors described as the file-interface per track which gives 100Kbyte CDFS controller, handles a filing system communica- per side for 40 -track drive or routines tion with the host computer twice that for an 80 -track one. through the IEEE488 interface. There are two distinct areas of The second processor acts as a interaction between the BBC disc controller. The processors computer operating system and CDFS communicate through 4Kbyte of the d.f.s. The obvious one is the filing system shared memory used for data data command -line interpreter. After Commodore dos buffering and operating -system the d.f.s. has been selected by interface routines work space. *DISC, other commands such as The Commodore disc operat- *BACKUP, *COPY, etc., are ing system, or dos, is in the disc passed by the operating system unit. All versions support primi- to the filing system for interpreta- Hardware driver tive direct -access commands tion and execution. routines such as those for reading or writ- The less obvious interface is ing a block of data, and later ver- used by languages and applica- sions support a relative -record tion programs written in assem- 58 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com I I u

bly-language. These make use of transferring data to the disc unit operation. The interface system operation, the pointer is updated. seven specific operating -system in blocks. is flexible in operation as the Closing the file channel. Here, calls for reading/writing data Efficient filing system opera- sequential catalogue files, data the CDFS writes any valid data bytes, filing information etc. , and tion depends on how data storage track/sector list blocks and data and data track/sector buffer to `OSWORD' calls. is organized on the disc. After blocks can be stored anywhere on disc then erases the default cata- Data in a disc file is always considerable thought, we chose the disc, allowing a file to be logue file and writes the current stored contiguously. To retrieve the following method. CDFS cat- extended at any time. Optimal catalogue file. Lastly, it erases a file, the only information alogue information, load add- use of disc space is made as then writes the current system required is the file start sector ress, execution address, etc., is blocks are only allocated as file if no other disc write channels and length. Disadvantages of this stored in a dos sequential file. required and freed when not. are open. storage method are that disc sur- These sequential catalogue The maximum number of files face faults cannot be tolerated files are referred to by an on the disc is limited only by the Having decided how data was to and that frequent file writing and extended file name which CDFS dos directory capacity and ranges be organized on the disc and deletion can cause empty gaps pads to 14 characters using from 151 to 224, depending on determined filing -system opera- between files. To fill the gaps, a spaces. The file name is preceded the disc -unit model. tion, the software design could be *COMPACT command has to be by the CDFS directory character completed. The software sec- used. and followed by a space if the file tions are clearly defined. There The first two sectors on the is unlocked or an 'L' if the file is are two interfaces to the BBC disc's first track hold d.f.s. cata- locked. Each catalogue file con- CDFS operation computer machine operating sys- logue information. Only having tains up to eight two -byte track/ tem (mos). First is the paged - two sectors limits the number of sector pointers to blocks which This is how a file is created and rom interface which handles files per disc side to 31 and file can, in turn, contain up to 128 written to using CDFS auto -start and auto -boot opera- names to seven characters, two -byte track/sector pointers to Opening the channel. This is tions, OSWORD calls and com- which can be irritating. All files the data blocks. Thus the maxi- done in response to an OSFIND mands not recognized by the are treated by the d.f.s. as a mum size of a CDFS file is 8X 128 call normally resulting from use mos, such as *CDISK and sequence of bytes. Extremely blocks or 256Kbytes, provided of a Basic OPENOUT function. *CPRINTER. fast random access filing is that the drive can hold that CDFS first checks availability of The second interface handles achieved by using a pointer. amount. an open channel, checks file the seven filing -system calls, During operation, CDFS main- name validity and checks that OSFIND, OSBPUT, OSBGET, tains a pointer for each open file there is no previously opened OSGBPG, OSFILE, OSARGS and CDISK interface design which points to the next byte to channel to a file of the same OSFSC. Most of the commands be read from or written to. CDFS name. It then reads the system used by CDISK are similar to After studying the Commodore determines the data track/sector file if there are no channels those provided by the Acorn dos and Acorn d.f.s. it was poss- list block, the data block and the already open to the same disc. d.f.s., but some offer addtional ible to draw up the Syscon 6 position of a byte in the data block During this operation, the disc is features and there are some extra CDISK filing -system specifica- from the pointer. initialized if necessary and the commands like *BLOCK. tion. CDISK would have to have Commodore dos sequential fil- write -protection state is deter- all the facilities of the Acorn d. f. s. ing system commands and facilit- mined. Next, CDFS determines and, to be of use in educational ies are used to locate and update whether the file exists, and if so, Conclusion establishments, it would have to the catalogue file while direct - checks that it is unlocked and be capable of transferring pro- access commands are used to deletes it. Lastly, it writes the For the sake of brevity, I have not grams written on a BBC compu- read and write data track/sector default catalogue file on disc to included a detailed description of ter with the Acorn d.f.s. to a com- list blocks and the data blocks reserve space. the software. Nevertheless, I puter with CDFS without modifi- themselves. The dos block -allo- Reading and writing data. To hope that you have gained some cation. cation map, barn, is automati- increase speed, CDFS maintains appreciation of the ratio of sof- Commodore dos only fully sup- cally updated during sequential two buffers for each open file in tware to hardware design time, ports sequential files, so most of file operation. By using the dos the computer memory. The first which in this case was around the design effort went into a ran- block -allocate and block -free contains a section of the data 100:1. dom-access capability for CDFS. commands during read and write track/sector pointer block and In any interface design, this Following aspects of the disc unit operations, CDFS ensures that the second a data block. When- ratio is a function of the mismatch design were carefully considered. the allocation map is kept up to ever the pointer crosses a data - between the interfacing systems. Data transfer speed between date, avoiding conflict between buffer boundary, the data block is In this case, the mismatch was the host computer and disc unit is sequential and direct -access written to disc. In the same way, considerable. Although this is limited for two reasons; the disc operation. whenever the pointer crosses the only an interface between a unit uses software for IEEE488 General catalogue information boundary of a data track/sector, single -user microcomputer source and acceptor handshakes, is stored by CDFS in a sequential the data track/sector pointer operating system and an intelli- and disc commands are sent as filing system. block is written to disc. The least - gent disc -subsystem capable of Ascii character strings rather The drive type is used to avoid significant pointer bits specify the undertaking one task at a time, than as a sequence of binary dos directory tracks and deter- next position in the data buffer to the area of interaction between bytes. However, as the disc unit mine data -block size.. CDFS for- be written to. After each write the two systems is large. is an intelligent subsystem, the mats a disc using the dos NEW number of commands needed is command and then writes the Table 1. CDFS catalogue file format. Catalogue information, reduced. Some operations, such system files to it. Backup is car- load address, execution address, etc., is stored in a dos as formatting a disc and searching ried out by formatting the disc in sequential file. for named files require only a the destination drive and then single command. copying each file in turn from byte contents We considered that the effects source to destination. of limited data transfer rate on DOS read -after -write verifica- &00 - &03 load address, I.s. byte first data storage/retrieval time could tion identifies a bad block and &04 - &07 execution address I.s. byte first &08 - &OB extent I.s. byte first be reduced by efficient communi- CDFS then excludes it from fur- &OC - &OF attributes cation. This was achieved by buf- ther use, allocates the next free &10-&1F track/sector list block fering in the host computer and block and repeats the write

ELECTRONICS & WIRELESS WORLD OCTOBER 1985

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by K.L. Smith Switched -mode Ph.D. power supply Last part of the instructional series on d.c. supplies is a practical description of a switcher to provide 13.8V at 13A.

In this, the last part of the Power Table 1 lists the quantities with secondary turns we must use Supplies series, I describe a fly- the values relevant to the opera- back switcher - again to show tion of this design. V, S how the theory is applied and to V 1-S-n see if it works. There should be enough detail to enable anyone The choke This gives a ratio of 15.1:1 at the interested to gain some hands-on nominal V, of 340V and output of experience and perhaps embark A core large enough to store the 13.8V, and requires 6 secondary on a design of their own. energy (or in other words, handle turns. I wound half of these ben- I have deliberately chosen the throughput) is required. Two eath the primary and the other cheap, easily obtainable compo- Mullard Ferroxcube-E cores type half on top - with a non -shorting nents. You can find the switch (a FX3609 were chosen and should copper foil screen between each BU126) for less than a pound and be ample for P = 180W. The winding. The secondary has to the control chip (TDA2640) for a dimensions of the cores used are handle 13 amps and a bunched couple of pounds or so, in the given in Fig. 1(a) and (b). The winding is the best answer. I used advertising pages. The technol- ferrite material is type A16 (3C8) 13 strands of 24 s.w.g. copper ogy is therefore a straightforward and the absolute maximum flux enamelled wire, all in parallel on application of the ideas to pro- density allowed before saturation each 3 -turn half-secondary. duce the following specification: at 100°Cis just over 300 millites- One or two points arise in the power output 180 watts (13.8V las. The pair of cores can handle design. The first is the difference at 13A) the required absolute peak flux of between the absolute maximum flyback mode, double -wound 126mWb. flux allowable in the core, and the choke Using the data collected, the working peak flux under normal switching frequency, 16kHz. calculation proceeds via the two circumstances. A safety factor is equations. Throughput, VA = given by: Fig. 1. Dimensions of Mullard I chose a flyback -mode circuit to Ferroxcube Cores. At (a), introduce the slightly more com- 180X10-6X0.5X7.5 max type FX3609 as used in the plex detail necessary for its 1.72 (1.7X 10-8X 1.3X 125X 10-3X 1.4 power choke. At (b), the design: a forward converter small "U" cores type FX3605 should be simpler, should you ¡max was used in the volts per turn employed in the driver with to experiment with one, g 0.4 expression. The normal transformer. Both are made although a 73X10 -6.16X103 appears in the for-e storage choke is (1+03_42\2 1.4 throughput from type A16 (3C8) required, so there is probably not mula. material, iSmax = 310 mT, a lot of simplification in it. There is a tertiary winding lla = 1000. = 190 VA placed on the choke for sensing

Establishing parameters This result indicates that the required 180 watts should be 55 The two important formulae comfortably obtained. 38 required are quoted: The second equation gives the r-17-{ required volts per turn to support the peak flux, at f = 16kHz. VA = AwFWPW l > From this the number of turns on 19 f p`m1u,FR (1 + T3,12 the primary is easily found. In 28 practice, I used 4 volts per turn and with an input level of 360 fl volts, this rounded off to 90 turns ' BAef . . . (l0A) (1 +71) for Np. In a flyback circuit, where the E mark to space ratio is not unity 25 All dimensions and are in mm (i.e. our "8" differs from 0.5), the output voltage at any secondary FX3609 FX3605 V 271 cmax f (9A) = is not simply the turns ratio dif- (a) (b) Turn 1 + 11 sm,n ference. Therefore to find the

ELECTRONICS & WIRELESS WORLD OCTOBER 1985 61

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09 R23 T3 C R2. C1, N ,\AA, it\ 2 D12a,b R18

[26 '930 R4 C15 R12 C28 C29 R8 If'J F- 'R13 29 :\A, C23

25 'R9 D1 -D4 h C3- C6

1 T' [2 moms -,- T IC1 R15

O

R

3

aC91 5- C67, '14 TT? t 1

Fig. 2. Circuit diagram of the voltage level to enable the choke. The optimization of the oscillatorcontrol component con- power supply. feedback system to control the a. c. performance (i.e. the induct- nections. C11, R5 and R6 produce output stability. The flyback ance) therefore requires a gap in a switch rate of 16kHz here. The choke factor rl was chosen to be the magnetic circuit. As I pulse width modulated output 0.4: thus, full control is main- mentioned in earlier articles, appears at pin 6, feeding the base tained down to a power output of Hanna curves are usually of the drive transistor, Tri. Pin 7 a little less than half the 180 employed to estimate this. My is a connection for "low feedback watts. At that point the current in approach was "experience tem- protection". Resistor R11 con- the choke winding falls to the cri- pered with experiment", in other nected to pin 13 reduces the duty tical zero value and the control words, I slid the cores apart very cycle to a small value if there is a circuit detects this and drastically carefully under power - and loss of voltage on pin alters the factor to keep the out- watched the slope on the current 10. put fairly level. But much stabil- wave being monitoring with an It is important to detect over - ity is lost, and the output smooth- oscilloscope until it showed the voltage. A sample is taken to pin ing is liable to worsen. Also, the shallowest decline. (This was dif- 8 via a rectifier network from the mode of control changes, and an ficult, as there was considerable sensing winding on the choke. audible whine may arise - from magnetic pull.) I then inserted The potential on pin 8 is com- the magnetostriction in the fer- paxolin shims of the required pared with the reference voltage rite core. thickness. on pin 9 from the 6.2V Zener (D6) There is a large d.c. compo- and if the level is exceeded, the nent in the windings of the power protection circuits trip. The regu-

Table 1. Design parameters and quantities for 180 watt Operation flyback switcher The full practical circuit is shown switching frequency 16 kHz in Fig. 2, with the printed circuit P, resitivity of copper at 20°C 1.7x10-8Qm layout in Fig.3. The TDA2640 m resistivity increase with temperature, (ref. 20°C) 1.3©204100°C s.m.p.s. control chip I chose is FR A.c resistance: d.c. resistance of windings being replaced by later types, (extra factor in 10A) 1.4 -6m2 such as the TDA1060, in up-to- Aw cross-sectional winding area (not window area) 180x10 date designs. Briefly the 2640 winding copper factor 0.5 mean turn length 125x10 -3m operates as follows (see Fig. 4),1. A voltage of +12V is required "maz8, absolute maximum peak flux density 300 mT on pin 1. I derived this via a Zener Acore magnetic core area 420 mm2 Smin duty factor (mains high) 0.36 diode (D5) from the main d.c. SmaM duty factor (mains low) 0.47 line. If the voltage falls below S duty factor (normal) 0.38 +8V on pin 1 then the protection minimum to maximum Po chosen to be. 0.4 circuits inside will switch off the supply. Pins 3,4 and 5 are the

62

www.americanradiohistory.com lation control system operates via Components pin 10. Again, the reference is the R, 2R7 8 W D, voltage on pin 9 and the pulse - R2 22k 5 W 02 2 A width modulator varies the drive C, 0.1 µF 600V R3 5k6 D3 Mains Bridge C2 µF waveform; i.e. the factor S to 0.1 600V R4 390k D4 maintain level output. If you look C3 1 nF R5 39k D5 12 V zener C4 1 nF at the circuit in the feedback loop, R6 10k D6 6V2 zener CS 1 nF R, 5k6 2% D, 1N4004 a number of actions can be seen: 06 1 nF R6 4k7 D8 75 V zener R13, R8 and R3 supply the sam- C, 225 µF 380V R9 1k D9 BY206 ple. The present RV, sets the C8 10 µF 10V R10 6M8 D10 BY210 level of output voltage. The com- C9 0.1 µF R11 82k D11 BY210 bination C13 and R1L improves the C10 10µF25V R12 10k D12 a,b BYV32 transient performance: C13 and C 1.7 nF R13 27k R10 is a feedforward network tak- C12 1µF R14 470R Tr, BSX21 C13 100 nF ing a sample of mains hum from R15 27k 2% Tr2 BU126 C14 1 nF the main d.c. feed to enable the P16 150k IC, TDA2640 C15 4.7 nF R17 1k modulator to compensate for it. Ct6 4.7 nF R18 3k3 T, mains filter Finally there is a shunt network, C,, 25 µF 380V R19 22k 5 W T2 see text C14 R8, which sets the gain of the C18 10 nF R20 3k3 T3 see text loop and obviates possible insta- C19 8.2 nF R21 5R6 bility. C20 0.47 µF R22 470R L, 10 µH Pins 11 and 12 sense any over - C21 4.7 µF R23 33R current through the switch - C22 100 pF R24 10k 9 W F, 2 A slow C23 330 nF R25 100R and turn off the circuit to protect F2 1 A C24 1.5 µF R26 1k it. The sample is taken across the C25 1 µF R27 2k2 9 W 1 ohm resistor, R27. The thresh- C26 1 nF R28 1R2W old is set by R31. C27 2.2 nF R29 330R The components C12 and R4 C28 1000 µF 35V R30 4k7 preset from pin 13 to the common line C29 1000 µF 35V R31 2k2 preset form a slow -start circuit. When switching on, the drive to the switch is gradually increased, reaching full drive after a couple 3 4 +12V 1 GND161 Ref V 9 of seconds. Thus, inrush surges 14 are avoided. Finally, the chip incorporates a TDA 2640 fault -condition counter. The Usci lator Comp number of restarts counted 2 10 before the circuit is turned off o/p voltage voltage permanently is set by C, on pin sense e' sense 15: after the final trip, the whole i er voitoge\ Pulse width supply must be turned off, then Remote Output 6 protection modu ator on again to restart. Pin 14 is a swit hing stage Ise 6i Pulse width remote -control point, left float- modulated ing here. o/p

e...... ^. Slow start Low output Current low supply V 6 sense Counter voltage /Over current protection reduction 2 - protectìan

13 I15

Fig. 4. TDA2640 contains Driving the switch advanced control and monitoring circuitry, as The variable -width voltage pulse outlined here. from pin 6 of the control chip requires converting into the appropriate current -drive wave- form to operate the BU126. I dis- cussed the reasons, and how the fast turn -on and reverse base- current turn-off waveform was produced, in part 5. The driver transistor Tr, is a BSX21 and stores energy in the

4 Fig. 3. Component side of the printed circuit board.

ELECTRONICS & WIRELESS WORLD OCTOBER 1985 6:1

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symbols self-explanatory. At a Snubber very rough level, with Vt) around 6 volts, AIB 100mA, V11 one volt The power transistor has to be and ST, 22 µs, L, works out at protected from voltage pusles about 1mH. This agrees with arising mainly from the leakage maker's figures'. inductance of T3. This is true At turn off, the base current especially for this circuit which must decline, then reverse. The has no energy -recovery winding energy for the reverse base cur- on the choke. Components C23, rent is supplied by the leakage R24, D10 and C26 with diode D11 inductance of T2. perform this function - called in Other components in the driver the USA "snubbing" circuits. stage include C22 and R20 which Resistors R24 and R26 dissipate a underdamp T2 as Tr1 goes off. large power and must be heavy This speeds up the rise and pro- duty types (9 W wire -wound). duces a slight overshoot on the base drive waveform to the BU126. Components Clé and C21 increase the reverse base current Final output at turn off and D55 clamps the top of T2 primary winding to prevents The last operation is to rectify and smooth the available pulses of Fig. 5. The driver transformer (T2) while the spurious turn -on pulses from maker's data energy at the output winding of regarding base current main switch is off. When the reaching the output switch. BSX21 goes off, the energy T3: fast diode pair BYV32 is requirement, given designed for this service. The graphically. stored in T2 turns on the BU126. The base drive current must total average current it can han- Driver transformer dle is 20A, which is for therefore decline as the field col- plenty this application. Output smoothing is lapses in T2. The secondary The construction of T2 is based achieved by assisted by C29, inductance must be large enough upon a pair of FX3605 'U' cores C25 to support the drive right to the (Fig. 1(b)). Its secondary was which are 1000 µF low -series - small 10 end of the on time the worst wound to have 0.8mH induct- resistance types. The - µII) choke L1 reduces the high case is when the duty cycle is long ance, found from frequency "edges" likely in the and there is a minimum V. Out- put current of the BU126 rises output of a flyback s.m.p.s.: it Ls = µ°CN ' 2 , '. N, = 26 turns over this time. Lowest forward was added empirically, not really 1 designed into the circuit for opti- base -current IstENt), must still perm- mum performance. Components keep the power switch into satu- where µa is the amplitude C1 the core factor for a and also help to damp ration up to the trailing edge. eability is C26 R25 pair of FX3605s. From maker's transient edges at the output From the maker's data, the base - and C1 winding. current requirement for the data, µa = 1000 = 1.2mm-1. These 26 turns were Finally, T1, C1, C2 and the BU126 is shown in Fig. 5. If the with small capacitors around the diode quantities are known, the wound outside the primary enamelled wire. The bridge help to suppress interfer- required inductance can be calcu- 36 s.w.g. primary some 75 to 80 ence flowing back into the mains. lated from supported References volts during the pulse, which was In a tightly controlled profes- 1. TDA2640 Control IC for Switched -mode (VD- VBE-IBR21) ST - Power Supplies Mullard Technical Infor- stepped down to a secondary sional design, the level of mains s borne inter- mation No. 19. DIB level of 5 to 6 volts, giving a turns and directly radiated 2. Television Switched -mode Power Sup- ratio of about 14:1. It was wound ference would have to meet the ply Using the TDA2640 White, L.M. Mul- where V1, is the drive voltage, and with 380 turns of 42 s.w.g. standards laid down, as I lard Technical Communications, July 1975. AIB is the current droop. Other enamelled wire. mentioned in part 1 of this series.

From page 48 variety of organic materials, par- Yet again, the problems are it would appear that advantage However, as experience indi- ticularly vegetable matter, into a more than formidable, but the could bé taken of existing agricul- cates, the difficulties do not end form of fertile soil, with a high solutions are not beyond the tural practice and of the slow - when the technological problems humus content, sometimes bounds of possibility. Briefly, moving nature of the process. are solved and water becomes known as a compound manure, from the production engineer's Export to other countries by sea available for cultivation of food and strongly reminiscent of the point of view, composting is a might well be done by means of crops. It has to be anticipated Black Land (alluvial soil) of the long process (full conversion, converted oil tankers with the that all soil will be completely English Fens. even with accelerators, takes 6-9 compost treated to make it more infertile, without even a trace of Composting, described as low- months or more.) As seen by the fluid, thus enabling existing pipe- humus being present; but again a cost biotechnology', depends for farmer, however, this is a normal line delivery techniques to be possible solution can be seen in its action on bacterio-chemical sort of time scale; and with the used. work done overseas on agricultu- conversion processes; and, as proposed scheme it might be pos- ral technology. At the beginning carried out in the UK on a domes- sible to make use of the farmer's of the century, a British project tic scale, using mainly kitchen experience and yet evolve some- was conducted in India on the waste, is virtually cost-free. It is thing more like continuous pro- References production of compost, and in therefore possible to envisage a duction by taking serially from 1. Young, R.E.: 'Managing research and which, incidentally, bullock carts large-scale operation being set groups of heaps graded according development', Wireless World, June 1985 were used to crush tough, woody up, initially in the UK, to produce to age. 2. Hooker, S.G.: 'Not much of an Engi- neer, Air Life Publishing Limited, Shrews- material before composting. In compost for replacement of Also from the production engi- bury, England, 1984 this instance the significance of eroded soil in regions denuded of neer's point of view, handling 3. Young, R.E.: 'Big -System automation composting lies in the fact that a trees and vegetation generally. poses a number of problems; but and telemetry', Wireless World, July 1985 64 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com ROBOTS E.M.S. POWER for EDUCATION SYSTEMS TRAINING MENTOR and System from INDUSTRY £495

featured in Practical Electronics - Sept. issue

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MENTOR DC servo desktop robot; 8 bit Extensive software Is supplied free with E.M.S. also manufacture chargers which range up control system; 300gm capacity; 420 reach. each robot. to 60 amps. NEPTUNE rd 6/7 axes 8/12 bit control Leads available for connection to BBC, system 2.5kg capacity. 1120mm reach. ZX Spectrum, Apple Ile, Commodore 64 and VIC 20. SERPENT LII 5 axes 12 bit control system For further details please contact: 2 kg capacity 400/650mm reach Most other micros are also easily usable with these robots. Robots programmed from keyboard or hand- E.M.S. Manufacturing Limited held simulator (model robot). Robots available as kits or ready built. Robots may also be taught by 'lead by the FMS (Flexible Manufacturing System( work Chairborough Road nose" method. cell additions also available High Wycombe . Please phone for brochure: 0264 50093. Bucks 1 1 4i West Portway Industrial Estate, Andover SP10 3WW, CYar"" Ie A private independent wppleatlaas and company giving prompt, Tel: (0494) 448484 personal service. CIRCLE 103 FOR FURTHER DETAILS. CIRCLE 133 FOR FURTHER DETAILS. Introducing...

WITH 'PERSPEX' SEE-THROUGH CYLINDERS! COMPLETE SYSTEM + 11 GHz SATELLITE TV RECEIVING EQUIPMENT UNDER LNA's LNC's RECEIVERS, FEED HORNS ETC. f1000! Dealer enquiries welcome For further details contact including software! HARRISON ELECTRONICS 22 MILTON ROAD, WESTCLIFF-ON-SEA, ESSEX SSO 7JX Tel: (0702) 332338

STEREO STABILIZER 11111111 )ni -'ad wate nymph)

NAIAD MICRO ELECTROHYDRAULIC ROBOT Rack frequency shifter for howl reduction in mounting BEING FEATURED IN WIRELESS WORLD November Issue public address and sound reinforcement Mono version, box types and circuit boards also available Please phone for brochure 0264 50093 SURREY ELECTRONICS LTD., The Forge, Lucks Green kvberne& West Portway Industrial Estate, Andover SP10 3 WW, Cranleigh, Surrey GU6 7BG .per pplleatluni A private and independent company giving prompt, personal service Telephone: 0483 275997

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www.americanradiohistory.com TG501 FUNCTION GENERATOR £295+VAT 005Hz to 5MHz, sine, square, triangle, ramp, pulse and haverwave waveforms; free -run, triggered or gated modes; variable start/stop phase, 19:1 symmetry range; variable DC offset; variable 5052 output; HL output; external sweep mode TG502 SWEEP/FUNCTION GENERATOR £495+VAT Main generator features as TG501 plus internal sweep generator; 1000:1 linear or 10,000:1 log sweep range; precise dial -and -enter setting of sweep limits; marker with variable duration and out -of -range indicator; variable sweep rate; single sweep mode; sweep reset and hold; sweep and pen -lift outputs. TG503 PULSE/FUNCTION GENERATOR £495+VAT Main generator features as TG501 plus normal, double and delayed pulse modes; pulse width variable from 5Ons to 50ms; -s WS delay variable from 100ns to 50ms; 10MHz capability in double al pulse mode; complement mode; symmetrical, positive -going or negative -going outputs with adjustable baseline. .Ìur For further information contact: Thandar Electronics Ltd, J London Road, St. Ives, Huntingdon, Cambridgeshire PE17 4HJ Telephone: (0480) 64646 Telex: 32250. 24,7f-x.thcndcr ELECTRONICS LIMITED CIRCLE 110 FOR FURTHER DETAILS.

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MICROPROCESSOR BASED DESIGN ELECTRONIC EQUIPMENT MANUFACTURE r c fikkaomaie AUDIO VISUAL SurTel EQUIPMENT FOR UHF RADIO TELEMETRY

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HOME OFFICE APPROVAL TO MPT 1309 * RANGE LINE OF SIGHT * TRANSMISSION RATE 1200 BAUD * SERIAL INPUT/OUTPUT * ROBUST WEATHERPROOF HOUSINGS (IP65) VDA's Modulators Matrices * OPERATES FROM 12 VOLT D.C. Cross Wire Generators Time/Date * LOW POWER DRAIN 250mA Generators Split Screen Generators * OPTIONAL BASE INTERFACE UNITS Comprehensive Design and Manufacture of Customer `Specials' LINK COMPUTER/COMPUTER/PERIPHERAL/INSTRUMENTATION - I - COST EFFECTIVE UHF RADIO MODEM - DICON ELECTRONICS LIMITED (A wholly owned subsidiary of Telefusion Plc) MICROMAKE ELECTRONICS Unit 8. Barrs Fold Close, Wingate Industrial Park, Westhoughton, Lancs. BLS 3XH. 1 THE HOLT. HARE HATCH. UPPER WARGRAVE. PERKS RG10 9TG Tel: 0942 611717. Telex: DICON 'G' 677493. TEL: 073522 3255 TLX. 849462 TELFAC G FAX: 0628 74928 CIRCLE 102 FOR FURTHER DETAILS. CIRCLE 144 FOR FURTHER DETAILS. 66 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com tools for DATAMAN 0 Lombard House, Cornwall Road, DORCHESTER, Dorset DTl 1 RX phone 0305 68066 telex 418442 micro engin e ering CIRCLE 141 FOR FURTHER DETAILS. I AST EPROW NOGAY J Copies eight EPRMS at a pass all 25 and 27 series up to 27256 EPROM type is set by switches erasure is checked automatically control is simple -- two keys liquid crystal display checksum facility 6 hex digits FAST or NORMAL programming PLUS VERSION also hasi serial RS232 program & check CTS or DSR handshake ASCII, SIMPLE HEX, INTELHEX MOTOROLA S or TEKHEX. GANG- OF- EIGHT e395 GANG-OF- EIGHT plus L445 AFFODA3L ATE Diagnoses bus troubles F201 hJITOR Helps mend micro boards Displays HEX on standard TV Z80 TTO3 Z80, 6502, 6800, 8085 with text -editing facilities Designed for Schools Council All covered by one product inserts and deletes to teach Z80 machine code Disassemblers included shifts and copies MENTA uses TV for display Plugs into micro socket bytes and blocks of code shows STACK & PROGRAM in HEX Hand-held probe identifies EMULATES EPROM in circuit ADDRESS, DATA and CONTROL using romulator lead supplied Editing facility includes lines at a touch. direct keyboard ASSEMBLER R5232 -output DISASSEMBLER

Prints a memory map Used to write & debug of an unknown system short machine -code routines showing ROM, RAM, I/O MENTA is a complete and EMPTY ADDRESSING SPACE controller with 24 bits of Ii used for RBTICS TEACHER's GUIDE, PUPIL READER Uploads and downloads MODULES (e.g. A to D; available using serial and parallel routines - RS232, Centronics NTA .. £99 PROGRAMS & EMULATES 2716 2732 2532 Useful for development particularly for piggy -back COYPTR 3AGÁIYS single -chip micros -ring for our BES` OFFER Adaptor is available OLIVETTI M21, M24 to program 2764 & 27128 with 10MB hard disk if req. LOGS all tests and responses AUTO-CAD & 1124 created this AD on PRINTER and ALPHA LCD "Our expensive equipment Non-volatile memory stays on the shelf also EPSON PX8 retains test sequences for weeks -- but SOFTY CHECKSUMS, RAMTESTS, is used every day" READS/WRITES MEMORY & I/O -- says big -budget customer EPROM ERASERS from 3 9 Reports location of SHORTS on ADDRESS and DATA busses Prints out memory contents SOFTY.. £1 95 3UY IT A\1 T YIT in ASCII, HEX or SOURCE CODE ADAPTOR... You cannot expect to mend £25 REFUND GUARANTEED microprocessor products with less postal expenses, if goods returned intact within 14 days a meter and a scope. PRODUCT IS USUALLY IN S7'OCK How many repairs would pay for your SuperDOL? TODAY DESPATCH IS F'OS:-_-;113I,E PHONE FOR A LITERATURE PACK VISA SuperDOC.. £395 VAT must be added to prices www.americanradiohistory.com DISHED TOROIDALS WASHER OUTER INSULATION The toroidal transformer is now accepted as the standard in industry, overtaking the obsolete laminated type. Industry has been quick to recognise the advantages toroidals offer in size, weight, lower radiated NEOPRENE SECONDARY WASHERS field and, thanks to I.L.P., PRICE. WINDING

Our large standard range is complemented by our SPECIAL DESIGN INSULATION section which can offer a prototype service with in l4 DAYS together CORE with a short lead time on quantity orders which can be programmed PRIMARY WINDING to your requirements with no price penalty. END CAPS

15 VA 50 VA 120 VA 225 VA 500 VA 62 x 34mm 0.35Kg 80 x 35mm 0.9Kg 90 x 40mm 1.2Kg 110 x 45mm 2.2Kg 140 x 60mm 4Kg Regulation 19% Regulation 13% Regulation 11% Regulation 7% Regulation 4% Why a Toroid? Smaller size & to meet SERIES SECONDARY RUS 2,010 6.6 416 4,010 6.6 10 00 6.012 12.12 938 8.016 25.25 10 00 weight No Volts Current 2,011 9+9 2 17 4.011 9+9 666 6.013 15.15 750 8.017 30.30 8 33 modern'slimline' requirements, 2.012 12+12 2 08 4.012 12+12 500 6.014 18+18 6 25 8.018 35.35 714 Low electrically induced 1 25 0.010 6.6 2,013 15.15 1 66 4,013 15+15 400 6.015 22.22 511 8.026 40.40 6 25 9.9 4 0,011 083 2,014 18+18 1 38 4,644 18+18 333 6.016 25.25 50 8.025 45.45 555 noise demanded by compact 0.012 12.12 063 75 2.015 22.22 1 13 4.015 22.22 2 72 6.017 30.30 3 8.033 50+50 5 00 equipment. 0.013 15.15 050 1 6.018 35+35 3 2' 4 2.016 25+25 00 4.016 25+25 2 40 8.042 55+55 54 High 0,014 18.18 042 2.017 30.30 0 83 4.017 30+30 2 00 6.026 40.40 2 81 8.028 110 4 54 efficiency enabling 0.015 22.22 034 2 2.028 110 0 45 4.018 35.35 1 71 6.025 45.45 50 8.029 220 2 27 conservative rating whilst main- 0.016 25.25 030 2 2S 2.029 220 0 22 4.028 110 109 6.033 50+50 8.030 240 2 08 taining size advantages. 0,017 30.30 025 2.030 240 0 20 4.029 220 0 54 6.028 110 2 04 6.029 220 102 625 VA Lower operating (encased in ABS plastic) 4,030 240 0 50 temperature. 80 VA 6.030 240 0 93 140 x 75mm 5Kg 160 VA 30 VA 90 x 30mm 1 Kg Regulation 4% 110 x 40mm 1.8Kg 300 VA Why ILP? x 0 45K Regulation 12% 70 30mm 110 x SOmm 2.6Kg 9.017 30.30 10 41 18% Regulation 8% Regulation Regulation 6% 9.018 35.35 892 3.010 6.6 6 64 5.011 9.9 8 89 * Ex stock delivery for 40.40 7 81 standard 3.011 9.9 4 44 9.026 1.010 6.6 2 50 5.012 12+12 6 66 1,013 15+15 10 00 45.45 3.012 12.12 3 33 9.025 694 240V range 1,011 9.9 1 66 5.013 15.15 533 7,014 18+18 833 3.013 15.15 2 66 9.033 50+50 6 25 1.012 12.12 1 25 18+18 4 44 5.014 7.015 22.22 6 82 5 68 Fast prototype service available 3.014 18.18 2 22 9.042 55.55 1.013 15.15 1 00 5.015 22+22 3 63 25.25 600 94028 110 568 3 1.014 3.015 22.22 181 weeks despatch for special 18.18 0 83 5.016 25.25 320 30,30 500 5.029 220 84 ; ,015 0 68 3.016 25.25 1 60 2 66 orders 22.22 5.017 30+30 35,35 428 9.030 240 2 60 3.011 30.30 1 33 016 25.25 0 60 5.018 35.35 2 28 ',J25 40.40 3 75 2 year no quibble 3.028 0 0 72 guarantee 1.011 30.30 0 50 5.026 40.40 2 00 7.025 45+45 3 33 3.029 220 0 36 * No price penalty for 5.028 110 1 45 7.033 50+50 3 00 3.030 240 0 33 5.029 220 0 72 7.028 110 2 72 call -oft orner 0 5.030 240 66 7.029 220 1 36 7.030 240 125

Prices including P & P and VAT Mail Order - P ease make your crossed cheques or pos al orders payable to ILP Post to: ILP Electronics Ltd., Dept. 3 VA Size VA Size Electronics Ltd. 15 0 706 160 5 1217 Graham Bell House, Roper Close, 30 1 767 225 6 13.75 Trade - We will open your credit account Canterbury, Kent. CT2 7EP 50 2 8.90 300 7 14.97 immediately upon receipt of your first 80 3 10.06 500 8 19.60 order. Tel : (02271454778 Telex: 96578G 120 4 10 65 625 9 22.30

For 110V primary Insert "O" in place of "X" in type number. For 220V primary (Europe) Insert "1" in place of lc in type number. For 240V primary (UK) insert '2" in place of "X" in type number. VISA IMPORTANT. Regulation - All voltages quoted are FULL LOAD. Please add regulation figure to secondary voltage to obtain oil load voltage. ELECTRONICS LTD.. CIRCLE 145 FOR F IRTHER DETAILS.

OPTO LED CLIPS 3 CT10E008' Dockffimer 17.40 8nm red 9 8nm red I 555 21 M1923 110 CT6000' t Programmable 3mm green 12 ánm peen 12 566 40 ML927 110 Timer 39.00 3mm yellow 12 Smm yeEOw 12 06114 Relay 101 for above 3.90 Rectarguar spare crow a 748 30 M1920 1.80 You can depend on XK101 Electron¢ Lock 11.50 'rogular Mat faceI AD500 3.30 MU/eat l 6.50 X0102' 3 -Note Door Clime 5.50 Red 15 Green 11 Yellow 11 4736916 190 41M74C915 96 06104 Solid State Switch 2.40 CA3080 65 MM7/C922 390 Bcobur K RasMg Red 50 X6112 Mons Moog Remote CA3130 85 MM74C926 tricolour Red, 4.90 Control 42.00 CA3140 40 NE567 125 r Round 32 Continuous 55 ICL7107 55668 X6113 MW Radio 5.50 Rectangular 45 ºm 210 IC11116 600 S5760 210 XKt26 DVMRhermometer 15.50 1174111111 55 MOC3120 110 511000K 4Ch Light 15.95 ICM7555 55 SA80529 3.50 Chaser 11071 170 MOC3040 I50 5111000K 4 -Ch Light Chaser 8.95 ICMe093 110 SA80603 2,50 ORP17 75 ME111 35 cLECTR, DLA11 Opto Input for above 70 IF351 40 S1440 1.95 Seven Segmem LEO Orsplars 013000K 3Ch sound to light 12.95 1E353 70 Sl441 1.35 now 3 cr 75 4 Cg 1 8" cc T0300K t 37,5 Touchhmmer 1.75 1E356 80 51486 115 1005005 ca 85 DIRECT DRIVE TS300K t 300W Touchswndr 1.75 LM324 50 SL490 2.05 1805015 ca 85 Display 100 to supply the fine L03000 t 301W ugltitfmmer 3.95 LM334Z 85 TBA800 70 TDR3000 t IR Remote Controlled 400V TR/ACS LM335Z 110 TBA810AS 90 ughtdnmmer 14.95 LM339 40 TDA1024 120 range & IA BA of test 5008' IR Transmitter for 49 50 LM348 55 TDA4290 1.98 124 TDR3INK Er MK1 4.50 85 IM358 48 T11161 10 TDE1K t Touchdlmmer En 2.50 8A isolated 65 164 95 LM380 1.20 11162 60 measurement TSA300K t Time Dahl' Touch 254 2.10 LM381 1.40 Ttló4 1.30 Switch (300119 5.00 BA sensitive 66 Dac 1e LM382 1.10 T1011 45 MK1 Thermostat 4.60 LM366 88 11012 70 gear by / MK2 Soled State Relay 2.60 SPECIAL OFFERS LM1035 195 1101/ 1.30 MK4 Proponwnal Temperature 2716 3.10 Z80A PIO 1.99 LM1458 34 TL0181 35 Controller 6.50 2732 3.20 Z80A CPU 1.99 LM2917 1.90 01162 48 MK5 Mains Timer 4.50 2764 4.20 6821 1.14 0.13900 68 UN 1.00 MK7 Sngledhannel IR Receiver 27128 7.50!! 1M3909 80 11110 50 124001 10.50 1313911 1.75 11507C 110 MK9 4 -way Keyboard 1.90 OMPONENT PACKS LM3914 2.65 TMS1121 850 MK10 16 -way Keyboard 5.40 LM3915 2.65 TMS1601 9.50 1 650 Resistors 17R 10M MK11 10 -channel 1.3 analogue 1M13800 1.10 002240 1.45 I0 per value 400 olp IR Recover 13.50 LS7210 4.75 3.021133 75 2 40 16V Electroly ics 10 1001.1 MK11 16 -channel IR Recover 13.50 LS1220 2.75 ULN2604 75 5 per value 3.25 MK1311,way Keyboard 4.35 LS1225 2.60 ZN411 00 3 60 Polyester Capacitors M014 AC Power Controller 5.20 MF1OC 7_97 Z14425 140 counters 0 01 li F 2506 5 values 5.55 M015 Dual Latched SS Relay 4.50 641922 3.03 Z71427 5.70 FREE 44 PAGE 4 15 Presets 100R IM 300 M106 Manspowered IR 641924 2.50 ZN428 4.50 5 30 Low Profile IC Sockets PRICED AND multimeters Transmitter 3.50 M1925 2.10 201034E 1.80 6 146 16 pin 240 50017 Snglechannel IR NOW IN STOCK SP0256417 4.15 6 25 Red lEDs ienmi 1 75 ILLUSTRATED Recover 112V) 10.50 scopes MK18 Coded IR Transmitter 6.60 We stock: VERO. CATALOGUE ON 96019 DC Controlled Audio VELLEMAN KITS, signal Amplifier 10.70 PANTEC KITS, REQUEST 'Includes box t Includes Irontpanel ANTED IRONS. Over 6000 items stocked generators etc. All kits include PCBs, components BOOKS FROM and assembly instructions. BABANI. T.I. For further details send S.A.E AND ELEKTOR. ELECTROVALUE LTD 28 St. Jude's Road, Englefield Green. Egham. ORDERING INFORMATION: ALL PRICES EX Surrey TW20 OHB Phone Egham (07841 33603. Telex 264475 ELECTRONICS VAT. FREE P&P on orders over 120 (UK CLUDE North Branch, Burnage Manchester M19 11 13 BOSTON RD onhl otherwee add 15 -0AT Overseas PSP Eurooe 680 Lane, 1NA LONDON W7 3SJ C.75. Bsewhere Lä50. Sad dlequelP0lBardaycadl Telephone 061 432 4945 Tel Orders 01 567 0910 Access No with order. Giro No. 52931/002 Please mention this publication when replying LOCAL AUTHORITY AND EXPORT C ENQUIRIES 015799794 ORDERS Shop Hours Mon Err gam 5pm WELCOME. GOODS BY RETURN SUBJECT TO I ; Ser 10am 1pm AVAILABILITY. J BRITAINS FOREMOST QUALITY COMPONENT SUPPLIERS CIRCLE 105 FOR FURTHER DETAILS. CIRCLE 126 FOR FURTHER DETAILS. 68 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com S.A. Cameron Call cost calculator by To conclude this series, a description of the software and the reprogramming procedure.

The call costing procedure must (Start of look -up table) + Stephen Cameron, who is 23, is read- Reprogramming take account of the many permut- 2 X ((Dist X Lmrate X Lmmode) ing for a B.Sc. in electrical and elec- ations of distance, connection + (Rate X Lmmode) + Mode) To reprogram for yourself, write tronic engineering at Brunel Univers- charge and tariff. down all the block information for ity, Uxbridge. An industry -sponsored For calls on the British Incrementing this address will initial and subsequent call units. student, he has worked for the past four years broadcast equipment, Telecom system, inland and give the block address reference Allocate a unique hexadecimal on international, there are 13 dis- for the subsequent unit. number to each unique block and radio and line development and com- tance zones, three charge rates The start address of the initial put them in numerical order into puting systems. and three modes. In all there are data block in the data block area the call data block area starting He qualified as an instructor in 117 combinations, but because of can be expressed as with block 00. Then using the for- Cadet Force signals while at the Duke repetition they can be stored in of York's Royal Military School, (Start of data block area) + 6 X mulas above, go through each only 80 Each block Dover. Spare -time interests include data blocks. (look -up block reference) combination and locate the look- consists of six bytes specifying up address for the unique data music, tennis and writing poetry. He cost and time; it may hold data for is publicity manager of the Brunel Consider an example. An oper- block references. initial call or for subse- University Industrial Society. the unit ator -controlled call (normal quent units. charge) at peak rate over 35 miles If every call category had costs 114p for the first three unique data for both initial and System parameters minutes and one-third of that for subsequent units, then 234 every succeeding minute. Accor- System parameter bytes can be blocks be would needed. Fortu- dingly, the bytes containing the altered by the user to control the nately, direct -dialled calls nor- initial unit information will be operation of the system. Parame- mally carry the same charge for ters beginning with Sc (see Table initial and subsequent units and Cost Time 3) are the addresses to which the so the storage requirement is 01 14 00 03 00 00 program will jump from the greatly reduced. scrolling message procedure now Consider the calculator's and those for subsequent units when the appropriate keys are 2Kbytes of ram. The combination pressed. This arrangement occupies 0.5K look -up table and Cost Time allows jumps to user -supplied block takes 1K, giv- the data area 00 38 00 01 00 00 routines within the ram space. It ing up to 256 two -byte combina- also allows expansion software to tions and 174 six -byte data These groups can be stored any- be accessed. The Adjump add- blocks. where in the call data block area. ress is the jump location used on The look -up table reference If we decide to make the initial pressing Reset after a telephone of bytes. consists two One points unit block the first block in the call has been made. These loca- to the address of the block speci- area (that is, starting at 20F016), tions are filled with default fying the initial charge unit, the then its reference will be 0016. addresses on bootstrap loading. other points to the block for sub- The subsequent unit block will be Stsps and Cadast are the start sequent units. the second block, with a start address of the data areas. By The is sufficiently flex- system address at 20F61ó and the refer- default they are 260016 and ible to allow any combination of ence 0116. 20F016 respectively. Initad is the distance, rate and mode; for Now we must place the refer- start address used by the repro- example there could be 16 Dists, ences 00 and 01 in the look -up gramming routine: by default it four Rates and four Modes or 28 table. But where? Dists, three Rates and three Table 1: for the B.T. tariff The value of Dist (for a call of Modes so on. Retes structure. The unit can cost and over 35 miles) is 0216 and the Now, how do we refer to the calls on any system in the Rate and Mode are also 021fi. We 0000 Cheap/economy initial and subsequent units 0001 Standard world. have the same Lmdist, Lmrate 0010 Peak look -up table? through the and Lmmode as before and so has - Modes -Distances. Each Dist, Rate and Mode plugging into the formula gives a binary number allocated to it 0000 Direct -dialled 0000 Local 0001 Operator -controlled, 0001 Under 35 miles (Fig. 1). Each of these factors has lower charge 0010 Over 35 miles a limit 200016 + 2 X ((2x3x3) + 0010 Operator -controlled, 0011 Over 35 miles, low -cwt routes - Lmdist, Lmrate and normal charge 0100 Channel Islands Lmmode which is the number (2X3)+2) = 205816 0101 Irish Republic, Isle of Man, calls to - -Special services. cellular radio subscribers of possible distances, rates and 0110 Intemationa charge bard A OD16, as the address where the initial 0000 None selected 0111 Intemationa charge band B modes: in our case, 316 and 0001 Advice of duration 1000 Intematlona charge band C 316 respectively. data block reference 00 is placed. and charpa 1001 Intematlona charge band D 0010 Credit-card call 1010 Internationa charge band E The address of the initial data The address reference for subse- 0010 Fixed time call 1011 Internationa charge bard F block reference in the look -up quent units, 0116, is stored at 0100 Personal call 1100 Intematlona charge bard G table is given by the formula location 205916. ELECTRONICS & WIRELESS WORLD OCTOBER 1985 69

www.americanradiohistory.com CALL COST CALCULATOR

26C0 Sc jump 1 Scroll message jumo store for Dist key (binary) ingly be subdivided into pounds mented by the Rate key or decre- 26C2 Scjump2 - fora Rate key (m.s.b./l.s.b.) and pence. mented by Dist. Carry is applied 26C4 Scjump3 - for Node key The special service (Sps) data only in the case of changes to 26C6 Scjump4 - for Start/stop key the 26C8 Adjump On addition jump location is separate from the normal cost- least significant digit. The Mode 26CA Stsps Start of Sps data ing as it represents a distance - key switches control from each 26CA Cadast Call data start address plus 26CE Initad Initial address for reprogramming -service element which can 26D0 Bootcnt Bootstrap control (bit) be treated as a connection charge Table 2: ram map. Addresses 26D1 State State control one-off additional cost to the are shown in hexadecimal 26D2 spare -a 26D3 Flaprd Flash period (binary) call. form. System interrupt 26D4 Buzprd Buzzer period for software monostable Each Sps cost occupies two variables should be used with 26D5 Mkt im1 Marker limit, seconds (b.c.d.) bytes of memory at the base unit care as they contain 26D6 Mk!im2 - hundredths of seconds 26D7 Lmdist Limit for distances etc. (binary) level. For British Telecom this important display counter 2608 Lmrate e.g. Lmdist=1016 if there are gives a cost range of 0 to 9999p. values, divider and sequencer 26D9 Lmmode 16 distances to be considered Should the Sps costs be far more 26DA Lmsps constructs as well as key -pad 26DB Totcos1-4 Total cost store, m.s.b.-1.s.b. (b.c.d.) than this, State bit 7 can be set, scanning information. Call 26DF Lstdist Lam distance store (binary) multiplying costs by 100 to give a type text is stored 26E0 Totuni1-2 Total &nits store, m.s.b.-I.s.b. (b.c.d.) of 0 26E2 Scmask Keyboard an mask (bit) range to 999900p in 100p sequentially as Dist, Rate 26E3 Prthold Pori hold control steps. and then Mode texts in 3,2,2 26E4 Cobuch Cost base unit character, e.g. P for pence If no Sps service is required the character blocks respectively. 26E5 Chxstr Checksum store (binary) 26E6 spare facility can be disabled by setting Areas 2000-21D0, 2600- 26EF spare State bit 5. 2630, 2680-277F are The data storage format fol- bootstrap -loaded from eprom Table 3: System parameters. points to the State control para- lows the pattern used previously. if Bootcnt (26D0) does not Address are in hexadecimal meter at 26D116. A look -up table the length of contain AAI6. form. Data format is shown Mklim bytes are used to Lmdist, accessed by the Dist in . change the end -of-unit indication parameter, has address refer- 2000 Look -up data bytes limit. They are initially set to give ences pointing to the start of Sps 20F0 (up to 0.5K) 40 seconds. data blocks twice the length of the 20F0 l Call data blocks The Lm- parameters are used number of services available. 21CF J (up to 1.5K, relocatable) Each Sps binary 21D0 for unravelling the packed number is the Spare characters in the call -type text offset in this data block. It points 25FF J to two bytes giving of Sps look -up table area. They indicate the limit for the cost 2600 and data blocks call -type selection and are used that service at that distance. The 2630 for data area access calculations. data blocks appear immediately (up to 0.5K, relocatable) Totcos, Lstdist and Totuni are after the look -up table. 267F Top of stack 2680 the storage bytesfor the running Introductory message text 26BF totals. On bootstrap they are all Programming procedure 26C0 reset to zero. l System parameters 26EF Before switching on, Certain bits in the state control remove the top panel of the instrument and 26F0} Sps text byte indicate to the system the 270F J (packed) link program pin to V+. position of the decimal point in D Switch on. The display immedi- 2710 Call -type text the cost data, with respect to the 274F (packed) ately shows the Initad address least significant byte. All costs 2750 and data at location in hexa- Spare are expressed in the cost base that 27BF decimal format. From here you unit (Cobu). An appropriate 27C0 can gain access to any point in the System work -space abbreviation for pence, for 27EB J -P memory map. If the system British users is stored in 27EC - crashes, this routine will always System interrupt variables Cobuch, 26E416. 27F7 J (virtual work so that corrections can be interface start) 27F8 made. 1 Display area 27FF f State byte Coat format Cobuch The flashing digit can be incre- bitl bit()

o 0 9 9 9 9 9 9 p 0 1 9999.99 p 1 0 9 9.9 9 9 9 p 1 1 .9 9 9 9 9 9 p

This decimal format applies also to the Totcos bytes. The floating- point format is used in the total cost and cost information display procedures . It features automatic suppression of leading zeroes and variable -justify for overflow. The time and cost display has a fixed format and displays no deci- mals unless bit 1 and bit 0 are 10 or 11. If a hundreds form of the base unit exists, as with the pound sterling, this will be indicated by All the electronic components are mounted on two printed bit 2 and the display will accord- circuit boards which fit into a standard plastics box. 70 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com Table 4: System control. The status byte 27F316 is used for inter- communication between the interrupt routine and the main pro- gram.

Bit description set (1) clear (0)

0 Key pressed new key no key 1 Timer control timer on timer off 2 Auto -repeat sustained single key entered 3 New number indicator intermediate number same number 4 Correct addition sequence add to total do not add to total 5 Flashing (1Hz) on off 6 Buzzer with flashing enable disable 7 Buzzer trigger trigger monostable do not trigger

Table 5: Cost data and display formats are controlled by the State byte at address 26D1.

Bit description set (1) clear (0)

0 Decimal point pos'n bit 0 see cost format table 1 Decimal point pos'n bit 1 see cost format table 2 Hundreds selection No hundreds hundreds 3 Decimal point left-hand right-hand 4 Total cost/total unit enable disable The instrument, based on a Z8O processor with 2K of ram, 5 Sps selection disable enable 6 Buzzer disable enable uses low-cost components thhroughout. The same hardware 7 Sps multiplier 1 100 could be used to implement a general i/o controller, for example in a security installatioon or central heatiing system. digit to the next. cally on switch -on. The Start/stop key toggles An indication of the total units between address and data con- used is displayed when the Start/ trol. Changes made by the user stop button is pressed during are not transferred to the dis- total cost display. Reprogramm- played address until Start/stop is ing of these displays can be dis- pressed to switch to address con- abled by State bit 4. trol. Addresses are incremented and read automatically during data loading with the Start/stop Display byte key. The Reset key returns the data The display character byte fol- at the current address to its old lows the standard bit -segment value. If Reset is held down then format. Bits D0 to D, correspond the address is reset to the Initad to segments a to h (as shown in address. the display board circuit diagram When programming is com- in the August issue). Setting any plete the user should ensure that bit causes it segment to light. the control byte Bootcnt 26D016 State bit 3 indicates to the sof- is set to AA16. This will disable tware whether the decimal points the bootstrap loader from over- in use are right-hand or left-hand. writing the altered data on subse- quent switch-ons. The unit may now be switched Assembler listing off and the D, link removed. The introductory message An assembler list of the software (which can be up to 64 characters is available for £3 from the author long) may be changed by writing at 7 Donnington Court, Worthy to. ram locations 268016 to Road, Winchester, Hampshire 26BF16. The purpose of this mes- S023 7BJ. The listing is in the sage is to show the user whether form of a 48 -page A5 -size booklet the system still contains the and includes detailed notes and updated cost and time data. It is comments. therefore wise to include in it an Component kits for this design issue date. are available from the sources The byte Chxstr (26E516) con- given in the July and August arti- tains a checksum of all the bytes cles. from ram locations 200016 to The calculator displays elapsed time and cost of calls in 263016. It is updated automati- progress and stores running totals in memory. ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com ThoArchor 280 cSI3C The SDS ARCHER - Thé Z80 based single board computer chosen by professionals and OEM users. * High quality double sided plated through PCB * 4 Bytewide memory sockets - upto 64k * Power-fail and watchdog timer circuits * 2 Serial ports with full flow control * 4 Parallel ports with handshaking * Bus expansion connector * CMOS battery back-up * Counter -timer chip * 4 MHz. Z80A OPTIONS: * SDS BASIC with ROMable autostarting user code * The powerful 8k byte SDS DEBUG MONITOR * On board 120 / 240 volt MAINS POWER SUPPLY * Attractive INSTRUMENT CASE - see photo. * 64k / 128k byte DYNAMIC RAM card * 4 socket RAM - ROM EXPANSION card * DISC INTERFACE card Mereoci Data &tam Ltd Sherwood House, The Aveitme, Farnham Common, Slough SL2 3JX.Tel. 02814- 5067

CIRCLE 138 FOR FURTHER DETAILS.

`SPECIAL Prices are as at going to press but may fluctuate, VALVES QUALITY please phone fo firm quotation. V.A.T. included. VIDEO TERMINAL BOARD A1065 1.40 EF91 1.60 PL36 1.10 1A3 1.40 3BW6 6.20 6Y6G 0.90 A2293 8.80 EF92 2.90 PL81 0.85 114 0.80 6BW7 1.80 6Z4 0.70 A2900 13.75 EF95 0.95 P182 0.70 1R5 0.80 6C4 0.70 724 1.90 AR8 0.75 EF96 0.60 PL83 0.60 1S4 0.65 6C6 1.20 906 2.90 80 characters X 24 lines* ARP 0.70 EF183 0.80 P184 0.95 1S5 0.65 6CH6 8.20 11E2 19.50 * ATP4 0.60 EF184 0.80 PL504 1.00 1T4 0.65 6CL6 2.75 12A6 1.00 B12H 3.90 EF812 0.75 PL508 2.40 1U4 0.80 6CW4 8.50 12AT6 0.70 Requires ASCII encoded keyboard and monitor to CY31 1.40 EFL200 1.85 PL509 5.85 1X28 1.40 6C X8 4.60 12AT7 0.85 DAF96 1.25 EH90 0.85 PL519 5.85 2X2A 2.50 6CY5 1.15 12AU7 0.60 make fully configurable intelligent terminal. Uses 6802 DET22 28.50 EL32 1.10 PL8021SE12.95 3A4 0.70 6D6 1.50 12AU6 0.95 DF92 0.80 EL34 1.80 PV80 0.70 3ÁT2 3.40 6F6 1.60 12AX7 0.65 micro and 6845 controller. Program and character DF96 0.70 4.55. PY81 /800 0.85 3828 12.00 6F6GB 1.10 12846 0.90 DH76 0.75 EL37 5.20 PY82 0.65 19.50' 6F7 2.80 1213E6 1.25 generator (7 X 9 matrix with descenders) in two 2716 DL92 0.60 EL82 0.70 PY88 0.60 306 0.60 6F8G 0.85 12BH7 3.00' Ds/86/87 0.65 EL84 0.80 PY500A 2.10 3E29 19.00 6F12 1.50 12E1 18.95 EPROMs. Full scrolling at 9600 baud with 8 switch DY802 0.70 EL86 0.95 00V03/105.95 3S4 0.70 6F14 1.15 12J5GT 0.55 E92C 2.80 EL90 1.00 10.00 4832 18.25 6F15 1.30 121(70T 0.70 selectable rates. RS232 interface. E180CC 8.25 EL91 6.50 00V03-204 5R4GY 2.20 3.20 12K8GT 0.80 EA76 2.25 EL95 0.80 27.50 5UAG 1.40 6F23 0.75 1207GT 0.60 Bare board with 2 EPROMS and program listing EABC80 0.80 EL504 2.70 00V03 -25A 5V4G 0.75 6F24 1.75 12SC7 0.65 - EB91 0.60 EL509 5.85 36.50 5Y3GT 0.95 6F33 10.50 12SH7 0.65 £48 plus VAT. Assembled and tested Send EBC33 1.15 E1519 6.90 00V06/40A 5Z3 2.80 6FH8 17.80 12SJ7 0.70 -£118 EBC90 0.90 EI821 8.20 28.50/49.50 5Z4G 1.25 6GA8 1.95 12S07 1.45 details EBF80 0.60 EI822 9.95 QV03.12 5.75 5Z4GT 1.45 6GH8A 1.95 12S7GT 0.85 for or CWO to: EBF 0.60 ELL801SE12.80 SP61 1.80 6/30L2 0.90 6H6 1.60 12Y4 0.70 EBF89 0.80 EM80 0.85 TT21 32.20 6407 0.70 6JU6 5.85 13D3 2.80 EC52 0.65 EM87 2.50 TT22 29.50 6ÁC7 1.15 0J4 1.35 13D5 0.90 A M Electronics EC91 4.40 EY51 0.95 UABC80 0.75 6ÁG5 0.60 6J4WA 2.00 19405 0.85 Wood Farm, Leiston, Suffolk IP16 4HT EC92 1.85 EY81 0.65 UAF42 1.40 6AH6 1.15 6J5 2.30 1963 11.50 AM ECC81 0.95 EV86/87 0.60 UBF80 0.70 6AK5 0.65 6J5GT 0.90 906 8.50 ELECTRONICS ECC82 0.60 EY88 0.65 UBF89 0.70 6AK8 0.60 6J6 0.85 19H5 39.55 Tel: 0728 831131 ECC83 0.65 EZ80 0.70 UCC84 0.85 6ÁL5 0.60 6J6W 2.80 2001 0.80 ECC84 0.60 E81 0.70 UCC85 0.70 6AL5W 0.85 6JE6C 5.50 20E1 1.30 CIRCLE 11 FOR FURTHER DETAILS. ECC85 0.60 GM4 5.90 UCF80 1.30 6AM5 4.20 6JS6C 5.90 20P1 0.65 ECC88 0.80 GY501 1.30 UCH42 1.65 6AM6 1.50 6K7 1.45 25L6GT 1.60 ECC189 0.95 GZ32 1.05 UCH81 0.75 6ANBA 2.50 6K08 5.50 2524G 0.75 Andelos 68000 SBC ECC804 0.90 GZ33 4.20 UCL82 0.95 6404 4.40 6KD6 4.60 35W4 0.80 ECF80 0.85 GZ34 2.75 UF41 1.35 6A05 1.30 616M 4.60 05A21.40,2.55' * Ideal for students, or as a target board * Expansion interface UF80 0.95 6A05W 2.20 807 160/2.40' ECF82 0.85 GZ37 3.95 6L6GC 3.70 for ECF801 1.05 KT66 14.50 UF85 0.95 6AS6 1.15 6L6GT 1.95 812A 21.80 development * Low cost EPROM Programmer - simply ECH 2.25 KT81 7.00 ÚL844 0.95 6AS7G 4.95 6L18 0.70 813 * Currently in use in Universities, plugs in ECH42 1.20 KT88 23.00 UM80 0.90 6AT6 0.90 6LD20 0.70 28.50/68.50 ECH81 0.70 ML4 2.80 UM84 0.70 6AU6 1.25 6L06 5.90 8298 24.00 Technical colleges, and Government * True 16 bit, 10MHz, for high speed ECH 0.80 ML6 2.80 UV82 0.70 6AV6 1.25 607G 1.30 8324 8.90 departments processing ECL80 0.70 N78 9.90 UY85 0.85 6AX4GT 1.30 6SA7 1.80 866A 5.05 ECL82 0.75 0A2 0.70 VR105/30 1.25 6AX5GT 1.30 6507 1.80 866E 9.80 * 4K/16K/32K/64K RAM, up to 32K * Comprehensive monitor (optionally with ECL85 0.80 OB2 0.80 VR150/30 1.35 6BA60 6SJ7 1.80 931A 19.80 EPROM, on board assembler) in 2764 EPROM ECL86 0.90 PCL82 0.95 X66 1.80 0.70/1.207 6SK7 1.40 954 1.20 EF37A 2.15 PCL84 0.90 X61M 1.70 6849 3.45 6SL7GT 0.85 955 1.20 * 24 parallel I/O lines, RS232 serial * Assemblers and cross assemblers EF39 1.50 PCL86 0.75 Z759 19.00 60E6 6SN7GT 1.60 956 1.20 interface available for 68000 and Z80 hosts EF80 0.65 PCL86 0.75 2749 0.75 0.65/120 6S07 0.95 5763 5.75 PCL805/850.95 Z800U 3.45 6BG6G 1.60 6SR7 4.60 6060 1.95 EF83 3.10 10MHz 68000 SBC with 4K RAM, Monitor in 16K EPROM EF85 0.60 PD500/5104.30 Z801U 3.75 60J6 1.30 6V6G 1.50 6080 5.30 £295 + VAT EF86 1.25 PFL200 1.10 Z803U 16.00 6807A 0.85 6V6GT 1.30 6201 5.20 10MHz 68000 SBC with 16K RAM, Monitor in 16K EPROM £305 + VAT EF89 1.60 2.80 Z900T 2.45 6SR7 4.80 6X4 1.50 6146 10.35 10MHz 6X5GT 0.65 6146B 10.35 68000 SBC with 32K RAM, Monitor in 16K EPROM '£415+VAT VALVES AND TRAN SISTORS 8068 12.50 10MHz 68000 SBC with 64K RAM, Monitor in 16K EPROM '£435+VAT NEW PYE 9001 0.95 Telephone enquiries for valves, transistors, etc: EPROM programmer card, plug in £95 + VAT retail 749 3934, trade and export 743 0899. EQUIPME NT 9002 0.95 9003 0.95 Assembler/Disassembler in EPROM, plug in, FIELD TELEPHONE, CABLE TYPE D10 & SPARES includes monitor £50 + VAT FIELD TELEPHONES TYPE V. Tropical. ,n metal cases. HARNESS "A" & "B" CONTROL UNITS "A" "R" Cross assembler for Z80 hosts/Assembler for 68000 hosts phone 10 -lino MAGNETO SWITCH -BOARD. Can "J1" "J2." Micr phones No 5, 6, 7 connectors. won( with every type of magneto telephones. frames. carrier set s, etC. 32K/64K prices subject to alteration - hopefully downwards! POSTAGE: E1'E3 50p; E3-í5 61p; £5-£10 80p; £10 -E15 E1.00; £15-20 f 1.50 Minimum order E1.00. Andelos Telephone: (0635) 201150 (ELECTRONICS LTD.)170 Goldhawk Rd, LondonW12 Systems COLOMOR Solina, Bucklebury Alley, Cold Ash, Newbury, Berkshire RG16 9NN Tel. 01-743 0899 or 01-749 3934.0pen Monday to Friday 9 a.m.-5.30 p.m. CIRCLE 111 FOR FURTHER DETAILS. CIRCLE 31 FOR FURTHER DETAILS. 72 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com Polyphonic keyboard 2 Digipoly's t.t.l. processor circuit and microcode program. by D.J. Greaves B.A.

The instrument has two proces- assembled using the instruction sors - an 8088 microprocessor set described last month. Features and software availability for control functions and a t.t.l. The first three instructions of Digipoly is -note polyphonic digital musical instrument processor for note generation. the microcode increment the P - an eight with a five keyboard ,ransposable over a nine -octave There are 18 instructions in register low -order section and -octave Digipoly's microcode program, the next three the high -order sec- useful range. It includes List1, which execute sequentially tion. At address six, the wave o Comprehensive envelope generator controls and then start again. The final from the waveform table is sam- o Vibrato and tremolo control instruction, INCV, causes the pled and this is multiplied by the o Midi interface program to be run on each sound VOL, V register in the ramaining o Hundreds of front-panel selectable waveforms channel in turn. instructions. At address 16, the o Battery -maintained memory for 16 user -defined voices Frequency of the master clock computed result is sent to the o Rotary control for adjustment of many parameters is divided by the length of the pro- output d -to -a converter. locked in gram and by the number of voices Each channel sends its output Note frequencies are not rigidly as divider type to give the sample rate at the to the same converter and the organs. A detune facility introduces a variable amount of scale error. audio output d -to -a converter. value is latched there until the Digipoly can be for With a 5MHz master clock rate next channel sends a value. built around £175 excluding case. this is This gives a discontinuous Software is available iin various forms from the author at 5 waveform. Summation of the Grovely Way, Crampmoor, Romsey, Hampshire S05 9AX. A 5 000 000/(18X8)=35kHz. eight channels into a single con- fifty -page listing of the 8088 source program is £3 and a 40 - An assembler written for the tinuous audio wave is performed track disc for the BBC microcomputer, holding source, object is Programmed 2764 microcode language in BCPL pro- by the integrating behaviour of and related files, £4 (single density). eproms containing the 8088 object code and a bipolar prom duced the code in List 1, but mic- the analogue low-pass filter fol- rocode can easily be manually lowing the converter. containing the t.t.l. processor code are £6.50 and £4.00 respectively. Please include £1 for UK postage List 1 Microcode of t.t.l. processor is only eighteen bytes long. and make cheques payable to D.J. Greaves. Brave readers can obtain a copy of the hexadecimal listing by sending a large stamped addressed envelope and t * Microcode software for the DigiPoly TTL processor. * a cheque for £1.35 to our editorial offices. Please t make this cheque payable to Business Press This version uses the wrap around on the V International. register to set the number of oscillators. The instuction after LOOP is assumed to execute. The HOST instruction is assumed to be performed as a side effect of the INCV instruction.

t * The multiplication is performed using a quarter t squares algorithm. The amplitude value is 0..63 and t the waveform table ranges -64 to 64. t 2

* A x B r. 4 = (A + B) - (A - B) t The square table is indexed -128 to + 127 t and gives values in the range 0 to 63

00 00 LOAD PL,V get low order part of note phase 01 12 ADD FL,V add on the frequency (Intergrate) 02 80 STORE PL,V 03 01 LOAD PH,V repeat with high order 04 53 ADC FH,V including the carry from the low order 05 81 STORE PH,V 06 OA LOAD WV,A look up the result in the waveform table 07 8F STORE E3 08 04 LOAD VOL,V get the amplitude of this oscillator, 09 6F SUB E3 take the difference, OA 08 LOAD SO,A and square it. OB BE STORE E2 Save in register 2.

OC 04 LOAD VOL,V Now calculate OD IF ADD E3 the sum of them, OE 08 LOAD SC'.A square the answer, The large circuit has left little OF 6E SUB E2 plus the square of the difference 10 86 STORE DACO giving the answer. space for text in this issue. We 11 AO LOOP hope to find room for more 12 B0 INCV move to next voice and perform HOST description in the next article t instruction. which includes details on the Midi bus. ELECTRONICS & WIRELESS WORLD OCTOBER 1985 73

www.americanradiohistory.com POLYPHONIC KEYBOARD

74 LS74

12 Q IC36b Clock 11 input 0 10 MHz

LOAD

15 11 14

1 7,10

9 IC2 A Bus 18 21 CK r LS161 T "O A0A7 11 14 1C18 1 A4-A6 LS245 l_ LZA6 ti

IC6 19 2K x8 13 1 ram 11 15 12 11 8 7 5 4 1 2 i Ao CK 5 6 23 20 Aim-- IC12 6 10 22 IC If.4 157 2fl. 9 13 12 19 6349-1 LS374 11 13 12 Microcode prom 12 4 15 1146115 12 17 16 14 18 19 A8 CE

19 15 10 1 Index Instruction register I register 1,7, 10 14 2 18 17

Build link 3 4 14 15 IC13 1113 4 ICn T6 13 17 ,1 4-- ,4 20 23 5 12 11 LS161 244 244 --s 19 NOP CLR LOAD 18 ICs LS154 Opcode select CK 2 9 15 19 -AO LOOP INCV ST RE SUB ADC ADD 13 11 13 9 6 17 2 11 12

11 C2 1126 119

10 IC11 1( 74LS126 13 11 -A6 12

GO -0 A6 -A4 Midi data I119 74LSO4 191 19 16 15 12 116115 12 19 16 15 12

1 11 1 CK' IC28 GO -C 5 ó C LS373 2

18 18 17 14 13 117114113 18 17 14 1 7 6 -DO - xu 7 D3 D6 D4 D3 -DO OO-D7 13 LS373 0 Bus 4 14 17 1126 18 D7 CK 3 iCK 11 IC19 5 12 D 1119 1 4 11 LS74 GO -E

16 / BUSY

74 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com 1

a -to d conversion logic IC

13 13 12

11 12 IL33

10

3 11

2 2

7 4 5 3,6 11

2 9¡

T D0-03 6 00-D3 23 10IAO'A3 AO -A3 21 11 03 12 19 13 100nS D Bus A3 IC7 IC17 TMM o 14 D4'D7 LS181 LS374 2016P 12 T a.l.u. 13 7 15 A4 -A7 a') Low order A4 -A7 1 17 17 16 1 B0 22 18 19 AO -A3 20 2 12 13 18 Accumulator

11 9 20 IC20 16 4 5 3.6

7 4 5 6.3

04 9

07 n 11 0 IC 8 3 710 DO 91-1-I-16 51-I-1-12 LS181

1036 1 IC46 u. 74L S 00 4 15 LS245 A Hìgharder

1

11 I -1-I-114 151-1-1-119 A 7 22 A7 A0 20

2 1 18

8 1 A Bus IC20

10 IC35

1 8 10 9 9 1,4

D 3CK

arry bit DAC1 Available for expansion

11 3 CK 12 Ls.b Remaining connections for 1037 shown later 5 11 6 10 D03 8 IC 9 9 IL27* This discrete high-speed t.t.l. 13 LS 374 12 8 I1AC0801 D Bus 14 15 7 processor was developed 17 16 specifically for Digipoly but is r-14-D7 1B m s general enough in design for many other applications. Its purpose is note generation. 126c Microcode software for the ten -instruction processor is stored in a bipolar prom.

ELECTRONICS & WIRELESS WORLD OCTOBER 1985 i5

1 www.americanradiohistory.com PCIXT - PERIPHERALS EX -STOCK INVERTERS TRANSFORMERS 12/24 V DC -240V AC Mainboard B - 103 4 Layer PC/ EPROM WRITER CARD up to MAINS ISOLATORS 50/25V or 25-0-25V 30/15V or 15-0-15V 100W £65.15 XT £294 128K £149 Pri/Sec 120Vx2 245V Tap Secs Volts 2x15' Tap Secs. Volts 250W 0198.00 MEGA Mainboard PC/XT £249 MODEM CARD V21/V23 CCITT AA/ (60-1000VA Tap Secs) available 5, 7, 8, 10, 13, available 3, 4, 5, 6, 8, 9, 500W £260.00 15, 17, 20, 25, 30, 33, 40, 10,12,15,18, 20, 24, 25,27 1000W. £414.00 SUPER Mainboard PC/XT £249 AD £169 VA price p&p '20 6.11 1.70 20-0-20 or 25-0-259 30 or 15-0-15V 2000w 0620.00 256 M/FUNCT. FLOPPY DRIVE CONTROLLER (4 40 9.96 1.89 309 15V Price P&P 4000w. .1200.00 50V 25V Price P&P 100 11.63 2.10 0.5 1 3.35 1.36 1par,1ser,cl, cal ,OK £169 DRIVES) £75 0.5 1 4.34 1.47 CONSTANT VOLTAGE 200 16.47 2.36 1 2 454 1 48 2 5.28 1.50 384k M/FUNCT. 6 -WAY (SEE ILL), TEAC FD-55B half ht 320K floppy 250 19.92 2.77 1 2 4 734 169 TRANSFORMERS1% A 350 24.64 2.84 3 6 8.50 1.45 Spite -free stable mains OK £289 dr £135 3 6 10.36 196 A 1 500 30.69 3 10 M 4 8 10.15 99 25000 0148.000/01000 4 8 14.80 2 22 512 RAM EXPAND (2 DIP RS232 SERIAL I/Face, !port 50- 55.65 4.70 P 5 M 10 12.55 2.10 50004 £201.93010 6 12 18.91 2.30 1500 71.79 5.95 6 P 12 14.20 2.30 1KVA 0300.500/A SWITCH),OK £95 9600 £49 8 S 16 26.75 2.86 2000 86.38 6.35 8 16 19.00 2.36 0590.950/A 10 20 31.74 3.20 S 2KVA.... Parallel printer card £39 SERIAL Async Rs232C, 2port 50 - 3000 121.12 OA 10 20 21.92 2.46 12 24 37.99 3.36 3KVA. C95/.í50/q 6000 256.77 OA 12 24 24.36 2.63 Parallel card with 64K buffer 9600 £69 4KVA 01173.000/A 115 or 240V sec only 15 30 27.96 3.20 5KVA 01470.000/A (OK) £109 GAMES ADAPTER £39 20 40 37.42 5.14 400/440 to 200/20011 CT 6604 01697.550/A Monochrome (text) display card £119 AD/DA 12bit 16ch-A/D, lch-D/A £139 60/309 or 30-0-309 VÁ60 Price AUTOS 7.5KVA 01796.750/A 1 Pri 2x12011. 23300 Tap PC Express/Intelligent Research 83K Cherry Style KEYBOARD .... £129 9e P9í 105, 115, 220, 230, 240V 10kvA í348£3489000/0 Secs. Volts available 512K £798 TRANS -NET NETWORKING 100 11.88 2.10 For step-up or down 200 16.47 2.36 6, 8, 10, 12, 16, 18, VA Price P&P AVO SPECIAL Titan Accelerator 128K £609 BOARD £450 250 19.92 2.52 20, 24, 30, 36, 40, 48, 60, 80 5.08 1.49 OFFERS Titan Accelerator 512K £729 NetMail Software £550 350 24.64 2.84 24-0-24 Or 30-0-30V, 500 30.69 3.10 150 7.36 9 00117 0105.00 60V 30V Price P&P NetSPOOL Software £250 1000 55.65 4.20 250 8 96 1.76 DÁ211 40.00 0.5 1 493 1.58 500 13.96 2000 86.38 5.50 2.76 002000 65.00 NetDISK Disk Server Software £150 2 7.51 1.60 1000 23.84 2.90 COLOUR/GRAPHICS 3000 121.14 OA I POP £1 . VAT. NetDMS 2 4 9.66 2.00 1500 29.58 3.35 Data Management 6000 258.77 OA Full range 000 8 WOOERS A 6 13.96 2.10 2000 44.34 4.20 Card (2 layer) Software £175 available. 4 M 8 15.91 2.31 3000 75.22 5.10 NET BOOT ROM for floppyless 5 P 10 20.11 2.36 5000 113.11 OA COMPOSITE COLOUR/rgb ops £50 24/12V or 12-0-12V 6 12 22.95 2.78 2 x 12V Secs. Pri. 240V 8 s 16 32.26 3.20 CASED AUTOS WW MODEM PROJECT 10 Monitors £149 NET STARTER KIT £975 120 24V Price PAP 20 37.55 3.47 240V Cable Input Transformers T1, T2 12 24 43.28 3.68 USA socket outlets SUPER COLOUR/GRAPHICS Card (4 0 3A 15 2.53 .90 T6.90 pair inc VAT, P&P

1 1.30 layer) PC, PCXT, PCAT (NOTE: We can supply most 05 3.45 VA Price PAP METAL OXIDE '7W 2 1 4.46 1.36 20 7.57 1.59 5% RESISTORS 01/100 COMPATIABLE £399 of the above as 4 2 5.15 1.70 80 9.81 1.69 MINIATURES 12, 20, 33, 41, 75, 390. 430, 3 1 76 6 0.07 150 12.70 1 99 MONOCHROME CARD A Amp Pace GRAPHIC for Sec' P96 2150 51061, 1k, 1k3, UNPOPULATED boards 8 4 9.43 1 82 15.47 78 560, lkl, 3-0-3V 0.2 3.26 96 2 VERSION II single parallel port 10 M 5 10.31 2 05 1k6, 1k8, 2k, 3k, 3k9, 15k, Off.) fi>2 1A.2 3.121.30 500 25.38 2.90 12 P 6 11.43 2 15 1000 16k, 24k, 27k, 39k, 56k, standard £229 0-0-9 0.1 2.72 96 35.43 3 97 16 8 13.62 2 33 82k, 100k, 110k, 120k, 5 0.33x2 2.53 96 2000 63.49 4.76 20 10 16.33 2.66 9.2 8-9/<2 5.2 3.53130 3000 91.14 OA 130k, 150k, 200k, 220k, 30 15 22.79 2.85 MULTI I/O CARD - 5 WAY!!! Dual 8-9x2 10.2 4.482 31 270k, 300k. P&P 20p. DISKETTE SALE 60 30 46.67 4.50 CABLE 15452) URM76150521 15x2 2.2 2.53 96 RECTIFIERS floppy controller interface 83 41 53.76 5.50 SPECIALFR BRIDGE 12-0-12 05 3.11 96 NASHUA DS/DD £14. box of ten F1 Man. lA 400V .32 Asynchronous RS232 serial comms 15e2 3.551 30 96/48V. Pri 2x120V 2002 2A 200V .52 UNBRANDED DS/DD 96 TPI. £14. box 20,12 Whde stocks last. port Parallel printer port, games Secs 2 x 36/48' VAT 35A 100V £3.00 15-20.2 9A 4.341.70 with of ten 60,72,84,96,36-0-30 TO 1258 500V 03.62 adapter Clock/Cal battery 15-27x2 5 5.881 70 PLEASE ADO 15% VAT or48-0-48V 1TEMSAFTEA PAP backup £249 DX45 lockable 100p0 DISKETTE 15-27 2 lA 7.66 50 ALL BOX £17. 72/96 36/48' Price P8 0-CT15V 5 2.66 96 1 2 9.38 1 522 0 -CT 4A 7.281.08 BARRIE EPROM WRITER CARD up to DX50 lockable 50p0 DISKETTE A 4 15.42 2.31 ELECTRONICS LT 128K £149 BOX £15. 6 18.68 2.52 WINDING SERVICES Unit 211, Stratford Workshops 3VA t015KVA 2/3 phase P 18 23.84 3.36 Burford Road, London E15 2SP 384 MULTIFICATION S 12 42.38 3.68 StocklItems`By Return.Tel: 01-555 0228 (alines) PC/XT CASE 16 46.23 3.98 CARD SDI WAY!!! WW 6 - B - Slot CIRCLE 46 FOR FURTHER DETAILS. 'Hinged lid 64K to 384K RAM Memory Includes hardware RS232C Serial Port £ 95.00 "Real Time Clock/Calendar with H.P. EQUIPMENT Battery Backup 2 - HP8690B SWEEPER MAINFRAME £550.00 6 HP8693B PLUG IN 4-8 GHZ 650.00 RAMDISK & PSPOOL Software PC to XT CONVERSION - 'Optional games port 4 - H018692B PLUG IN 1.7 - 4.2 GHZ 650.00 KITS 9 HP8491A ATTENUATOR 20DB (NEW) 50.00 "Built & Tested £195.00 - FOR IBM AND COMPATIBLES 15 - HP3420 NULL VOLTMETER (6 DECADE) 250.00 17 - HP8746B S -PARAMETER TEST SET 2500.00 -LAYER PC/XT 56 FLEXIBLE 450.00 4 NEW FAST CONTROLLER!!! - HP11605A ARM 55 HP7221B PLOTTER (RS232) (HP 1-13) (A3) 4 COLOUR 950.00 MAINBOARD WESTERN DIGITAL 1002 SWX-2 - 57 HP86242A SWEEPER PLUG IN 5.9 -9-0 GHZ 1250.00 SEGATE ST -506 STANDARD.£199.00 - 64K to 1MB ON BOARD 59 - HP7040A X -Y RECORDER A3 950.00 88 Fully Compatible Slots 10 MEGABYTE MR -521 1/4" TEKTRONIX TEST EQUIPMENT Built & Tested £295.00 1 ANALYSER C/WITH ALL ACC'S 10 MHZ 40 GHZ 3500.00 WINCHESTER HARD DRIVE, 2 - - 491 SPECTRUM - HEADS AVERAGE ACCESS 12 - 604 XYZ MONITOR HIGH RESOLUTION 650.00 RAM CHIP SALE! ! ! 85ms £375.00 24 - 1485R T.V. WAVEFORM MONITOR PAL NTSC ETC. 2950.00 4164 64K DRAMS 150ns £1.49 each 44 - GMA 102 C.A.D. STORAGE SCREEN MONITOR (NEW) 26" 950.00 48 GMA 103 C.A.D. STORAGE SCREEN MONITOR (NEW) 26" 1100.00 (upgrade PC/XT and compatibles) 20 MEGABYTE MR522 5 1/4" - 60 - 7704 4 SLOT 250 MHZ MAINFRAME 2250.00 041256 256K RAMS 150ns £5.49 each WINCHESTER HARD DRIVE, 4 - (upgrade OLIVETTI M24, COMPAQ HEADS AVERAGE ACCESS PHILIPS TEST EQUIPMENT 1/F) 950.00 DESKPRO etc) 85ms £550.00 55 - PM3181 XY RECORDER (A3) 50 UV SENS (IEE448 22 PM5532 G/07 PAL SYNC GENERATOR P.O.A. 4128 (Piggyback) Upgrade IBM PC/ - HARD 23 PM5539 T.V. COLOUR ANALYSER 1200.00 XT £5.99 each DRIVE CABLE SET ... £25.00 - CO -PROCESSOR INTEL 8087 -2/- UPGRADE 130WATT POWER OTHER EQUIPMENT 3 £139.00 SUPPLY £135.00 41 - PERKIN ELMER 5900 LASER GAGE TO 0.8 UM RESOLUTION, MAX RANGE 45 METERS TEMP + PRESS CONPENSATION. TROLLEY MOUNTED, DIGIT DISPLAY - PRINTER BCD 0/P ETC. FOR CALIBRATING N.C. MACHINES, 4950.00 Prices exclude VAT and DELIVERY LINEAR TRANSDUCERS ETC 650.00 terms on application. 33 - B+K 2209 SOUND LEVEL METER - 34 - B+K 1613 OCTAVE FILTER SET 150.00 32 - RFL INDS 3265 GAUSS METER 200.00 27 - VERSATEC V-80 HI-RES PRINTER - PLOTTER 3950.00 52 - SMS 3000 8X300 DEVELOPMENT SYSTEM 1500.00 21 - ZILOG 2DS-U Z80 DEVELOPMENT SYSTEM 1500.00 II]IIFW 16 - INTEL MDS-1 (INCOMPLET) TO CLEAR 295.00 Business Systems Ltd. 7 - WANDEL + GOTERMAN TFPM 42 TFPM 43 TRANSMISSION TEST SET AS NEW CONDITION '550.00 10 - MARCONI TF801 AM SIGNAL GENERATOR 10-470 MHZ, EXCEL Unit M, Charlwoods Business Centre, CONDITION 250.00 Charlwoods Road, 63 - GOULD ADVANCE MG520 SU 20A MINITURE SWITCHING P.S.U. 22.50 East Grinstead, PHONE 0223 68990 FOR FURTHER INFFO OR APPOINTMENT. West Sussex, RH19 2HH (0342) 24631 tlx: 957547 VESCOUNIT 2, DITTON WALK, CAMBRIDGE.

CIRCLE 47 FOR FURTHER DETAILS. CIRCLE 32 FOR FURTHER DETAILS. 76 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com by Martin Allard Electronic mailbox B. Sc. (Hons) Construction tips and line interface circuits complete the description of a self-contained electronic message system.

A plated -through printed circuit has different refresh require- square wave, and confirm that and the three roms are available ments; the slowest available the shape does not change when to constructors. The printed cir- devices will be suitable for the the input level is raised to 1V. cuit is designed to fit into an RS application. This also applies to Monitor test point two and adjust cabinet type 509-620. This the roms and the interface chips. the timing potentiometer so that board, the mains transformer, To reduce dynamic consumption, the logic level is on the point of and the line -isolation transformer the system runs at a relaxed clock changing states. are all attached to the front panel, speed but this does not limit its The clock is set by use of a spe- leaving only the backup battery operation in any way. The 1nF cial command and an internal fixed to the base of the cabinet. capacitor in the receiver monost- switch which protects it from Other components fixed to the able should be polystyrene; other being changed inadvertently. The panel are the three leds indicating capacitors are not critical. command format is `power', `on-line' and `attention', The mailbox can be connected t0000 two push buttons to manually directly in parallel with a tele- 10 The relays are RS type 346-851 switched as in a normal modem, and the switch for the clock is RS because any sounds picked up by Martin Allard has an honours type 336-674. The only compo- the handset cannot cause data where leap status is eight for leap degree in computing science Over the nents not mentioned in the circuit errors. year, four for leap year + 1, two from Essex University. years he has worked in 100n There are only two adj ust- for leap 2 and one for leap diagram are numerous year + psychology research, gas decoupling capacitors which ments to be made in the modem year + 3. For example, to set the pipeline instrumentation, should be monolithic ceramic circuit. Inject a sine wave of clock to 23:57 GMT on 9 Decem- operating systems design and types. They are shown in the lay- 10mV peak -to -peak at 1700Hz ber 1984, the string would be digital video, including the out drawing which will be sup- across the line side of the trans- t0000753290021810. The trim- single-handed design of a plied with the printed circuit. former, and monitor test point mer on the clock crystal should be digital PAL-NTSC standards The 64K rams can be any type one. Adjust the offset poten- adjusted at intervals of a few converter, all done from his except the Texas variety which tiometer to obtain a symmetrical cottage in Devon. He recently left that business, convinced that it is the road to madness, and is now an independent broadcasting and communications consultant. One of his current projects is the construction of solar - powered community f.m. radio stations in Nepal and Sri Lanka, in conjunction with UNESCO and Arthur C. Clarke. Martin still owns the working automatic telephone exchange which he designed at the age air of 11. Messages entered into the mailbox from a computer or terminal are sent immediately or later on while you're asleep. The message can even be held until the destination caller rings you.

ELECTRONICS & WIRELESS WORLD OCTOBER 1985 7

www.americanradiohistory.com ELECTRONIC MAILBOX

days, and the clock should be been taken notice of however. of this design if interest justifies reset until it is found to be runn- The control wire called DCD is it, and would therefore like to ing accurately. in fact a far more reliable form of hear from prospective users. The Principles of the electronic mail sys- remote control than anything firmware rom has plenty of space tem were discussed in the August a issue and hardware in the September Uses of the system provided by simple modem, and for enhanced facilities in it, and issue. it is being used to switch compu- one use of the board would be to Computing appears to many ters on and off when an incoming arrange for firmware upgrades. It people to be a solitary pastime, call is received. As with all other is my belief that the underlying but when the power of modern aspects of the system consider- standard is sufficiently sound to data communications is added it able attention has been paid to remain compatible with potential becomes an interesting social making it fail-safe. future versions possessing many activity. Fundamentally, the mailbox more features. This system is intended to pro- provides a cheaper, faster and A double -sided plated -through vide a mail service and a remote more reliable way of getting mes- printed circuit for this design is terminal service which are suffi- sages to a specific destination available from Combe Martin ciently reliable and easy to use than centralized systems such as Electronics, King Street, Combe that one can concentrate on the Prestel, Telecom Gold, Easylink, Martin, North Devon EX34 OAD, message being sent, and forget and the hobbyist bulletin boards. for £23 including UK/overseas about the way that it is being It does have the social disadvan- postage and v.a.t. Analogue signal paths. On delivered. Because the writing tage that one cannot spend one's A set of three programmed the receive side, the limiter and reading of mail is all per- telephone bill idly browsing roms is available from Mallard is followed by an exclusive -or formed off-line at no cost in com- through other people's corres- Concepts Ltd , 13 Southdown gate generating pulses on munication time, messages tend pondence. However it is a general Avenue, Brixham, Devon TQ5 both edges of the waveform. to be much longer and more lei- purpose real-time communica- OAP for £34.50 including v.a.t. These pulses are integrated surely in style than conventional tions system as well as a way of and postage. A guide giving and sliced after passing electronic mail. There are no delivering private mail, and as more detailed information on the through a monostable i.c. arguments about whether or not such is well suited as a means of use of the system is also available Data for transmission is was received a I the message - the accessing common database. free of charge from the same add- buffered after passing sender always knows the answer. am considering setting up a bul- ress on receipt of a large s.a.e. through a simple filter. One doesn't know whether it has letin board specifically for users

-I-5V

Red o Tele- phone line Blue

lWhite ZN428E R33 15k °/P

5k6 Test point 1

Offset 100k 1

+5V Timing 'n100k R42 100k 013 - - +5V 1 13 15 1n 114 1032 R43 5k6 R48 5k6 R44 R45 /c32 o Test point 2 9 5 1(31 R46 3 12 4k7 470k 470k 4538 1 Rx data to 6854 11 l 140ps C14 C15 016 4 2 7n 1n8 150p 1/2392 1/2 392 R47 5k6 1

78 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com TRACER -A new Robotic Teaching System from LJ

The new LJ TRACER Robot provides a cost- effective introduction to the world of Robotics. This ruggedly constructed XYZ robot features both stepper motor and closed -loop servo motor drive. The TRACER can be driven by any microcomputer with a suitable TTL level I/O facility. The TRACER is supplied with a pcb Assembly Task Kit (as shown) and a 3 colour pen -plot kit.

LJ Electronics Ltd Francis Way For full details of this Bowthorpe Industrial Estate and other LJ products Norwich, NR5 9JA. England send for our catalogue Tel: (0603) 748001 Telex: 975504

CIRCLE 100 FOR FURTHER DETAILS.

SMALL SELECTION ONLY LISTED Etc £100 to £150. MA250 - 1.6MC/S to 31.6 MC/S RING US FOR YOUR £100. MA1350 for use witt RA17 receiver £100. MA259G Precision frequency standard 5MC/S - REQUIREMENTS WHICH MAY BE 1MC/S - 100KHz £100 to £E0. Panoramic Adaptor IN STOCK RA66 £150. RA137 and RA37140t convertors 10 to 980KC/S. RA2181ndeperdent SSg unit £50 RA98 SSB-ISM Govertor C50. RA121 SS8-IS8 convertor £15. (pantechnic) - EC964/7K Solid Plate - single channel - SOB - malns or battery -1.6 to 27.5 MC/S and 400 to 535KHz £100 with manual Plessey PR e55Gon Solid State 60KC/Stape - 30MC/S £400. Creed 75 Tae rioters - Fitted tape 13:47:Punch and gearbox for 50 and 75 bands-110colls AC supply - In original tmesporttray sealed in polythene - Ilk new £15EA. Redilon TT/1 Audio Teleprinter con- vertor receiver solid state - supply 110 or 240AC - Made for use with above lelepinter enabling print-out r ,e r of messages recleved from nee Input of communica- design manufacture and supply tion receiver£15 with circuitlested.RedifonTTlOCon-

as above but Includes tralways L no. 4451-Oscilloscopes -£750.stocks alReco changingsmit Tektronixes Portable Battery or Mains Oscilloscope. SE Laboralo- POWER AMPLIFIERS 415 - 100MC/S TM Sang hm0 Sabre des 111 Oscilloscope - Solid State General pur- - 111 14 channels £350 Tra.atel Matrixer printers pose-Bandwidth DC to 18/20MC/S at20MV/CM- - AF11R- 5 level up to 300 Bands for Dual Channel - - HIGH POWER ASSEMBLIES - telrinter paper £50 to £100. Trans- Rise time 19NS Calibrated Sweep Calibrator - - - telAH11RnplainAs above butalsc level ASCII (CCITT No Display 1OCMSxBCMS- Power AC -95 Volts to 100- CONTROL CIRCUITRY 2 and CCITT No. 5) Like new £100. Army field tele - 190 Volts to 260 or 24 Volt DC battery - Size. e 15dets. enFng Ln i stoon W.25.5.CM - H25.5CCMS - 56CMS Deep - £6phono on type and quantity P.O.R.c. on WT11.4KGS - Carrying handle - Tested in faircondi- 10 Telephone Cablending hall mile canvas containers Lion with operating instructions £120.00. - p g £20. Night viewing Infra -red AFV periscopes -Twin for application in Eyepiece - 24 volt dc supply £100ea. Original cost to government over £11,000ea. Static Murton - 12 or J : ' 24 volt input- 240 volt AC sisewave output -various l ï M wattages P.O.R. XY Motors and pen recorders various INDUSTRY - P.O.R. Ferrograph series 7 Tape recorders mono £100, stereo £150 Signal Generators various - PUBLIC ADDRESS TF995IA3 £60. TF801 D/es- IOMC/S to 485MC/S £90 TF144H/A4 £90. TF1060/2 £60. HP606A - £90 £140 HP608£50 HP614A £100 HP0188 £100 HP620A £100. HI -Fl Marconi TF10648/5 £100 TF791 Deviation meter £100 ,- * TF893A Power meter £50 Aerial mast assembly 30ft s s-inswithplete 16ft seandaltomountontop- {., < er .-11411 guyropes-ghuyropgh es insulators - Baseand Spikes etc_ in heavy available _.-... duty carrying bag - new £30 Raul frequency counter Type 836 £50 Tektronix plugs ins- 1A1 £50.102 £40, Latest Bulk Government Release - Couor OscIllo- 1A4 £100 MESO. All items art bought direct from H. M. scope CDU only. Solid stategeneral Government being surplus equipment: Price is Ex OFF THE SHELFS purpose bandwidth DC to 35MHz al 5MV/CM - Dual works. S.A.E. for enquiries. Phone for appointment Channel - High brightness display (8x10cm) Full for demonstration of any ittms. Also availability or delayed time base with gated mode - Risetime IONS price change. V.A.T. and carriage extra. CUSTOMISED - Illuminated graticule - Beam finder - Calibrator 1KHz squarewave - Power 100 - 1200.2000 - 250 C A D DESIGNED volts AC - Size W 26CM -41CM deep - WT 12.5K.G. EXPORT TRADE AND QUANTITY carrying handle - colour blue - protection cover front DISCOUNTS GIVEN containing polarized viewer and camera adaptor plate JOHNS RAD10 10274) 684007 - probe (1)-Mains lead. Tested in Fair condition with WHITEHALL operating instructions -í15g.00. WORKS, 84 WHITEHALL ROAD, tel. 01.361.8715 132 High Road Communication Reuevers. Racal500KC/S to3OMC/S EAST BIRKENSHAW, BRADFORD in 30 bands 1MC/SWIDE - RA17 MK11 £125. RA17L BD11 2ER telex 266 873 New Southgate above £200receiversNew Metal Louvred Cases for above £25. All rotelreri are air tested and calibrated in PANTEC G LONDON N11 1 PG. our workshop - supplied with dust cover - operation WANTED: REDUNDANT TEST EQUIPMENT - instructions - circuit - in lair used condition. Racal RECEIVING AND TRANSMITTING EQUIPMENT - Synthesisers (Decade frequency generators) MA3SOB VALVES - PLUGS SOCKETS SVNCHROS Solid Stale for use with - MA79 - RA277 - RA7218 CIRCLE 19 FOR FURTHER DETAILS. ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com * COMPUTER PERIPHERALS * * * NI -CAD BARGAINS * * RALFE ELECTRONICS 10 STREET, LONDON, NW1 TEL: 01-723 8753 1.6MB 8" FLOPPY DISC DRIVES New ax -equipment but little -used. re -chargeable Nickel -cadmium CHAPEL - batteries at traction of L P Stock DEAC Type 10000K 6 Cell Button -stack (7.2V) Measures 21.2" Diam Capacity 1AEI Price each BRAND NEW At a surplus price, Fully Shugart compatible 'MFE C3. - Inc vat (pp 25p) CORPORATION' Model M-700 DOUBLE -SIDED industry standard 8" 1.5MBytes Power DEAC Type 600DKZ 3 Cell Button -stack (3.6V) Floppy disc drives. Double -density, up to Measures 1;x17 Dram Capacity 600mAH. Price requirements ±50 and + 24V 4 1.1A. 240V. AC 50Hz.

it PRICE 8 HANDBOOK. each f 50 inc vat (pp 25p) LOWEST EVER, £160-INC. VAT,CARRIAGE ** STEPPER MOTORS ** DRE 4000A DRIVES Brand new stock of "ASTROSYN' Type 20PM- Data Recording Equipment Model 4000A 5 + 5 MB Top - AU55 stepper motors. 28V DC. 24 steps per rev. loading disc drives re stock. Brand new including full 15 oz -in torque ar 100PPS. Body length 21/2 technical manual. Few remaining £250 each + VAT. x diameter 2 , shaft 1/4 dram 41/4- spirally TEKTRONIX 454 dual trace 150M Hz 1650+VAT threaded. Weight 16oz. Price each E11. 50 - -RAIL LINEAR PSU's (P&P TEKTRONIX 475dual -trace 100MHz t2K+VAT * MULTI * 50p). Connections supplied. INC VAT TEKTRONIX 0932A dual -trace 35MHz £325+VAT HEWLETT-PACKARD1707AduaI 75MHz C650+VAT Recent stock of brand new COUTANT E5M-Series Power Supplies at regulated, stabilised DC DYNAMCO D7100 dual - trace30MHz f200+ VAT surplus prices. Model ESM15.2 giving DRYFIT BATTERIES 5V 150 and ±120 to ±150 4 1.5A each and an un - GOU LD 0510008 dual - trace 20MHz £200+VAT outputs ® stabilised 24V 4 2A. 240V AC input. Measures 54&11 Fully Brand-new. u -used. Sonnenschein Dryfit A300 sealed TELEOUIPMENT 3- trace 06315MHz C275+ VAT enclosed. In original cartons with handbooks. £45 each -0. VAT 1+ lead -acid re -chargeable batteries at a surplus price. 12V carriage 1.13AH (RS No..59e-966 f17) OUR PRICE £8.50 inc vat. t5) AMPLIFIERS (pPC1). 1000 WATT AUDIO Also available small quantity of automatic standby units Incorporating the above battery. Inbuilt mains-failure ST506 WINCHESTERS change -over, charger, ideal for burglar alarm systems etc. £25 each (ppC2). AMPLIFIER MOO 10500-0 available ex -stock In superb. little - H 8 H PROFESSIONAL AUDIO POWER We nave in stock genuine SEAGATE ST506 5'4- Winchester disc n includes Dual -Channel 500.500W. OHO ESCAP DC MOTORS used condition at vastly reduced price Specificati drives sold in little used. fully functional condition complete with response. 10Hz-20KHz 0.005% IMO 0.02%. Output impedance 2.5-16ohms. Frequency ±1db OEM manual Formatted capacity 5MB. Swiss -made 6VOC =tars with 70 1 reduction gearboxes be c nfiguted to DC response). Forced air cooled precision 1NB. For industrial applications these amps' can PRICE £225 Inc VAT. carriage and manual. giving final drive speed of 16RPM ,u 6V Diameter 2'bcros x 4cms Rack mount x 3.5" Ht. ossipators for reliability and cool operation. Size 19' Also available 10MB version va £275 Inc. long. INC. VAT 8 CARRIAGE C5.25 PRICE PRICE ONLY C295. - INC VAT AND HANDBOOK (pp C I (NB.: List price over 0700.1 iSmall quantities only don't delay') IN -equip tested 8 guaranteedi * SWefDI-MODE POWER SUPPLIES * DATRON Model 1051 DIGITAL VM MARCONI Fully tested and guaranteed switch mode power 8 SHUGART DISC DRIVES e5. TEST supplies by Gould/Advance. Farnell etc. ©1 EQUIPMENT ' ' GENUINE SHUGART MODEL Woes in 60Amps 035 Oit, ._i (i:. i á 1 SA800. Solt sectored sngle- -1955 33 . Waxes io 150 035 IIiE,.. 7 ^d sided industry standard 8' 12Volts also. . f45 -oily reconditioned test equipment. t floppy disc drives. 800kB Sy ,c 103A. f95 90 day guaranteed. storage. Supplied in excellent 30V ís100 L15 105. Mr I, oigitat voltmeterdigit LOr with Options Idled condition. uttleused. Removed rr. 1 I T2000Audosig(gen/attenuator £200+ t, AC yourand Resistance Mr Isar- rv .,our £2200 Little Muld.rail 5V4A8 -15V 75A.ea. 030 Dom fully Iunehonal equipment. VAT u VAT PRICES ARE VAT POST INC. ed «r clr. C500 NB.. THESE 8 F ü Price including VAT. carriage 12700 Universal bridge 0250+VAT and Zerox of handbook- T95 DISPLAY SCOPES 'It313 u%Un versal bridge . C250+VAT * * CROSS -HATCH GENERATORS * * 11868 Universal bridge ... E125. VAT £250+ Airmen/Racal 4 -channel display oscilloscopes tor WAYNE KERR Autdbalence Universal bridge Model B641.. VAT colleges. educational etc. 17' CRT DC - 10Khz. Fully TF893A AUDIO POWER METERS TO 10W LABGEAR COLOURMATCH CM6004PG. operational.. f125, -VAT 085 Slit (1VAN Inductance budge Model R4000 Measures L to 11 1111 UHF television pattern generators '12905 SINE SQUARED PULSE 8 BAR wrIn drscnmrn ntrnoot 0 572uH 0375, VAT giving cross -hatch, dot and greay scale MAINS CONDITIONERS GENERATOR C250 patterns Fully tested and guaranteed. T12604 ELECTRONIC VOLTMETER £150 Constant-vollage tr ansformers NOW JUST £20 inc VAT 8 p&p. * INSTRUMENT COOLING FANS * GOULD 1.5KW220V.. . 0125+ VAT (pp í1O) HEWLETT-PACKARD LOGIC ANALYSER 1602A £250+901 CENTRONICREGUVOLT 220V 2KW £200+ SWEEPGENERATOR 220MHz.. . £150+VAT Ail loos availaole ex -stock and GUARANTEED KNIGHT 3- VAT (pp £15) EDDYSTONE Communications receivers SONY PRESTEL TERMINAL+PRINTER £750+VAT 770R/1 Covering 19-165MHz &0150 230V 10W 5 -Blade 34;x1' NEW C7 CENTRONICREGUVOI T 220V3KW £350+ ,tic vat pup - BAUSCH 8 LOMB METALLURGICAL MICROSCOPE 0500+ Covering 150- 500MHz í19S 'in770012 115V 13W 5 -Blade 3¡'3;x1- NEW C6 VAT (pp t15) VAT 115V 4)'4)x17 5 -Blade NEW CB TESTER 0150+VAT 11507W 47 3 -Blade WHISPER C5 AIRMEC 20KV IONISATION 209.. COMPANIES PLEASE NOTE That we would be very pleased to receive your invitation to tender BRUEL8 KJ0ER DEVIATION BRIDGE 1504. f95 230V 40W Papst 350187Hr. Ex -equip. £13 for your surplus or redundant equipment. Contracts offered for factory contents removals on PHILIPS PM6661 80MHz 8 Digit Erect counter £125+VAT regular basis All prices Include VAT (pp + 50p)

CIRCLE 48 FOR FURTHER DETAILS. PINEAPPLE SOFTWARE Z80 CONTROL Z80 with CARDMASTER CPU Programs for the BBC model 'B' with disc drive 4M1 -1z Z80 CPU FREE updating service on all software CP/M compatible User transparent MULTI -TASKING Up to 38K EPROM & 16K RAM DIAGRAM Watchdog crash protection RS232 8 RS422 Comms A program which allows you to store very large diagrams - up to 39 mode C 2 ' Z80a PIO (one uncommitted) - view or edit them by SCROLLING thecomputer screen around over any screens and On board bus buffering part of the diagram. Power -on jump hardware Euro -card constuction FEATURES 'he CPU card is supplied with a powerful three-way operating system MCP - The Multi -tasking Control Program version the MCV monitors. Commands include Single -Step and Break-point setting. Draw diagrams, schematics, plans etc MONITOR/DEBUG - An enhanced of MIRROR - MIRROR connects the CPU card to your C/PM computer. via the link. in such a way as to give the illusion of C/ in any aspect ratio, e.g. 10*3, 212 PM running on the CARDMASTER CPU card. MIRROR itself is a two part program which effectively gives CARDMASTER screens. direct access to your disk drive. (DISCS WITHOUT DISCS') Only £178.00 bunt and tested including the software subsystem. Access any part of the diagram rapidly by entering an index name, e.g. TR6, R5 etc., to display a specific section of the CUB MICROCONTROLLER diagram, and then scroll around to any Z80 CPU __ other part of the diagram using the 4 o Z80a PLO's (64 I/O lines) cursor keys. Z80a CTC 4K Battery backed RAM 2K sup.)

w Up to 128 Icons may be predefined for 4K EPROM (2K MCV2.0 sup.) each diagram,ll e.g. resistors32 Powerful monitor (MCV2.0) - Eurocard construction etc., in full mode 0 definition, up to 32 awNulaIEBBBnIIB>rNs The is the ideal solution where a trend alone controller Is required. The CUB lully supports pixels horizontally by 24 vertically. very popular CUB microcontroller the powerful Z80 mode 2 interrupt structure. Single-step 8 breakpoint commands in MCV2.0 provide excellent debuggIng louis The CUB is available built 8 tested or as a bare PCB Hard copyonan printA4sizoeutssheet,in varyingcompati printble sizes up tol8modedot 0 £28.75 PRICES: Built 8 Tested £104.95 Manual only £4 50 i}.L with most matrix punters. all inclusive CMR16 MICROCONTROLLER features including, selectable display colours. ZBOA CPU Supplied only on Many other comprehensive line drawing facilities, TAB settings, etc. 4 ° Z80a PIO's (64 I/O lines) - 407/807 disc Z80A CTC compatible Disc contains sample diagrams and two versions of the 64K Dynamic RAM All orders program, one of which will work from a 16k sideways RAM 8K EPROM sent by return 4 Channel AID converter of post. Comprehensive instruction manual Real time clock MCV1.0 Multitasking monitor RAM). In The CMR16 is a very powerful multitasking control system featuring all the facilities of the CUB (except B/Backed is with the 4 channel 10 bit A/D converter. PINEAPPLE SOFTWARE, 39 Brownlea Gdns. addition. the CMR16 has RS232 and a massive 64K RAM. Data agiusition simple PRICES' Built 8 Tested £219.75 Bare PCB £40.00 Manual only £5.50 Seven Kings, Ilford, Essex IG3 9NL Prices Include carriage Please add VAT @ 15%

GNC ELECTRONICS Little Lodge. Hopson Road, Theinetham, Diss, Norfolk IP22 1JN 01-599 1476. Telephone: Diss (0379) 898313 CIRCLE 40 FOR FURTHER DETAILS. CIRCLE 34 FOR FURTHER DETAILS. 1985 80 ELECTRONICS & WIRELESS WORLD OCTOBER

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Parallel processing is possible, Ram -rom input/ which is why it is called the Spider: if an event is caught in output controller the 'web' it is acted upon, A combination of 'sideways' another event triggers the ram and rom -based software system and its presence noted. expands the capabilities of the The first event has its data fully BBC Micro into control secured and the processor is applications. The Spider adds a then free to deal with the number of commands to BBC second or subsequent events. Basic to allow easy access to Different versions are available external devices and has uses in from the simplest, Spider -B at laboratories or in industry for £65, which communicates real-time control. Applications through the user and printer include measurement and ports to Spider -X at £115, recording systems, burglar working through the 1MHz bus. alarms, aids for the disabled Spider -E, also £ 115, interfaces and energy optimizing systems with the Control Universal for industry and the home. range of Eurocard control and The device is provided on a monitoring devices. Paul Fray butterfly board which plugs into Ltd, Willocroft, Histon Road, the 6522 user v.i.a. socket. Cambridge CB4 3JD. EWW201

Frequency spotting laser Instantaneous measurement and analysis of any number of incoming r.f. signals is possible with the use of the Bragg cell developed by Marconi Research labs at Great Baddow and available through GEC Research. The Bragg cell uses acoustic energy generated by the incoming signal to deflect or modulate a laser beam passing through a lithium niobiate crystal. The angle of deflection of the beam is proportional to the frequency of the signal and thus it is a simple process to determine that frequency. The cells are said to have much potential in optical signal processing and spectrum analysis. It could also be used to unscramble the signals from be expanded to 7.5Mbytes. be networked together and can a frequency hopping radar or Modular Four bit -mapped v.d.us are communicate with H -P series radio, or to follow the available medium or high 200 and 500 systems over a frequencies in order to jam workstation resolution, monochrome or 10Mbit/s Ian. Two IEEE 802.3 them. The cells are available in A choice of central processing colour. Standard cabling options may be various versions with units, displays, application Like most of the H -P range, used: The first can link up to 30 bandwidths from 60 to software, programming these computers are particularly systems over a distance of 2000MHz and centre languages and peripherals are a designed for control and 185m, the second can provide frequencies from 0.16 to feature of the Hewlett-Packard measurement applications and a connections to 100 computers 2.9GHz. GEC Research Ltd, series 300. The modular number of analogue and/or at distances of 500m. East Lane, Wembley, approach enables the user to digital interfaces are available A typical entry-level system Middlesex HA9 7PP. EWW211 start on an entry-level system along with the appropriate will cost about £5164 while the at relatively low cost and software. Series 300 will run top of the range costs ten times upgrade as and when required most of the series 200 as much; lower than the Series by the addition of a faster applications software and an 200 which are superseded by c.p.u. or a higher -resolution integrated word processor/ these computers offering better display. All of the software, and spread-sheet/database package performance. Measurement the peripherals, remain is available as well as electrical Design and Manufacturing compatible. The c.p.u. is either and mechanical engineering Systems, Hewlett-Packard Ltd, a 10MHz Motorola 6810 or a programs. Peripheral devices Miller House, The Ring, 32 -bit 16.6MHz 6820. A include digitizer tablets, mice, Bracknell, Berks RG12 1XN. megabyte of ram is standard mass storage, printers and EWW206 with either processor and may plotters. The workstations can ELECTRONICS & WIRELESS WORLD OCTOBER 1985 81

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circuit conditions and provides Digital Lc. tester the correct supply and input Many i.c. testers need voltage levels. The test may be 'personality' modules to tell the repeated indefinately to instrument which i.c. it is simulate soak testing and for testing, but an instrument from the detection of intermittent ABI Electronics includes test faults. The makers claim that it algorithms for a wide variety of is possible to test 1000 devices i.cs which are held in memory in a hour on the instrument and and can give instant results on is therefore ideal for 'goods all the 74 series of t.t.l. inward' testing, while the price devices, the 4000 range of c- (£573), the makers say, is mos devices and a number of within the means of many memory and interface chips. educational establishments who The instrument can identify the may wish to test a `job -lot' of device and test it, thus enabling i.cs purchased for students' the identification of unmarked designs. devices. It can also test itself. The makers also manufacture Data from space experimental speech digitizer giving telemetry information on Any new device or custom chip a low-cost 16 -channel logic Automatic satellite telemetry can be accomodated as ABI will analyser (£299). ABI board Amsat 2 and c.c.d. tv receiver and information camera signals. supply the appropriate Electronics Ltd, Unit 21, decoder is represented by the software. Aldham Ind. Estate, Wombwell, Using suitable software, acronym Astrid and describes which is available from Amsat The i.c. tester emulates in - Barnsley, S. Yorks S73 81IA. the functions of Astrid EWW209 -a UK, the data can be decoded to complete satellite receiving allow the graphic display of system with built-in decoder, satellite tracks over maps, error enabling signals to be received detection of received data, disc and data displayed on a home storage of data for computer computer. analysis and data presentation In operation, it receives all of particular telemetry the data transmitted by the channels. The software also Uosat satellites and allows the inclusion of the latest automatically records it on a orbit information to enable the standard tape recorder. The accurate prediction of satellite recorded signals are then fed positions. back into Astrid to be decoded Astrid comes complete with into ASCII format which may be an aerial and feeder, power read through the RS232 serial supply unit, test tape, manual, input on a computer. Signals and connecting leads. It costs may also be decoded `live'. £149 from MM Microwave Ltd, Information transmitted from Thornton Road Ind. Estate, the satellites include news Pickering, N. Yorks Y018 7JB. bulletins, satellite status data, EWW207 experimental data, messages on an electronic mailbox, and orbit Amsat UK is at 94 Herongate information. There is an Road, London E12 5EQ.

with 2Kbyte and 8Kbyte static Lithium -backed rams and may upgrade existing boards for memory retention memory without any change in the Over 10 years is the quoted design. Manufactured by Dallas retention of these memory Semiconductors, the DS1213 modules when c-mos static ram sockets are available from is used in the DS1213 `smart' Joseph Electronics, socket. The socket incorporates Westminster House, 188 a lithium cell and a control Shirley Road, Solihull, W. circuit. The socket may be used Midlands B90 3AQ. EWW203

Miniature v.h.f. required at 5V is 12.5mA. The amplifier is housed in a TO -12 amplifier package and will work as Working over a range from 5 to specified over a temperature 250MHz, the Watkins -Johnson range of from -54 to +85°C. EA51 can provide a typical gain Watkins Johnson International, of 17dB with less than 3dB Dedworth Road, Oakley Green, noise. The v.s.w.r. output is Windsor, Berks SL4 4LH. 1.2:1 and the direct current EWW202 82 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

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A superb range of innovative loading and duplicating technology Worldwide

the leaders Tape Automation Ltd, Unit 2, River Way, Harlow, Essex CM20 2DN. Telephone (0279) 442946, Telex 265871 MONREF G quoting Ref: 84: AUL001.

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CIRCLE 128 FOR FURTHER DETAILS.

POWERTIIAN IDIOTIC W011t CIII SYSTEM COMPLETE ROBOTICS EDUCATION AND TRAINING PACKAGE :.

Custom-tailored accessories enable VAX to be incorporated into a comprehensive work cell environment. 32 1/0 lines can control auxiliary units and monitor sensors. Rugged, reliable and exceptionally accurate, IVAX is suitable for tight industrial use as well as for educational purposes.

4,0 se On and tiainmo The bench top robot operates on a closed pack* WAR is the SCARA {Selective loop system to simulate virtually any Compliance Assembly Robot Arm) with the industcal application. 4 axes and an Powertran pedigree. With fully integrated independent gripper are operated by a software and coursework, IVAX is the perfect programmable controller, either as a-self- tool for robotics education and training. contairted unit or under the control of a host microcomputer

CIRCLE 36 FOR FURTHER DETAILS.

ELECTRONICS & WIRELESS WORLD OCTOBER 1985 83

www.americanradiohistory.com SOME IDEAS NEVER SELL... but our new innovations do! Crotech 'scopes are chosen for use throughout the electronics industry and in education for their reliability and ease of use. .

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The innovations.. . * Component Comparator * Triple Output DC Source

plus.. . * 20MHz Bandwidth * 2mV/div Sensitivity * 4Ons/div Timebase * TV Frame and Line Trigger * Add and Subtract * X -- Ymode . and very affordable at £312.00* For free details call: "(exc VAT) Crotech instruments Limited 2 Stephenson Road, St. Ives, Huntingdon, Cambs. PE17 4WJ 32/10/4/1 Telephone: (0480) 301818 CIRCLE 104 FOR FURTHER DETAILS. THE THERMOMETERS

HAZ40 Types K, T Differential HAZ30 and J available Low battery indication 0.5% accuracy 0.2% accuracy 120°C to 820°C 2000 hour min battery life - 30°C to + 200°C - + 1°C resolution 3 year Guarantee 0.1°C resolution HAZ20 £45.50 £63.50 0.1% accuracy - 100°C to + 1370°C 0.1°/1° resolution HAZ SERIES Autoranging Sealed tactile keyboard Min and Max hold RS232 and Centronics Automatic segment test Output option Splashproof design £95.50

ä.- VIXEiflHrTECH LTn LINI The cheapest! 17 Amberley Road, £29.85 0.2% accuracy - 120°C to Bostal Heath, + 820°C 1°C resolution London SE2 OSG. 01-310 4233

CIRCLE 45 FOR FURTHER DETAILS. 54 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com NEW PRODUCTS

are told: the contacts are rated Socket for the at lA with a maximum resistance of 30mohm at 10mA. leadless All 68 contacts are accessible A low -profile socket, type IC75, from the sides of the socket to is only 7mm high and 33mm enable testing under loaded and may be used for any conditions. The socket may be /c®` square 19)lf81 Jedec A or B 68 -way leadless used at up to 150°C. Radiatron CHANNEL MENA CLEAR AUTO/ SEANCn Sst chip carrier. The contact design Components Ltd, Crown Road, MANUAI. and cantilever -action lid ensure Twickenham, Middlesex. IF 1E S5 good electrical performance we EWW210 I! ru

automatic search facility with a CB at 934MHz memory for the positions of 8 934MHz never caught on as specific channels as well as rapidly as the 27MHz band for manual selection of any CB, partly because a: this channel. The receiver is wavelength the equipment claimed to be highly sensitive needs to be more precise and with 20dB quieting sensitivity therefore more expensive. It is of less than 0.711V and a signal/ seen by many to be the more noise ratio better than 40dB. discerning band, free from the made by Kyocera in Japan for many 'cowboy' operators who Mike Devereux Music Ltd, it is dominate the 27MHz band. A distributed at £355 by CB transceiver, the Cybernet Telecomms, 189 London Road, 1, offers 20 channels at Portsmouth, Hants P02 9AE. this frequency. It has an EWW220

Commodore the best value for money of any home computer. upgrades The same company has also The Commodore C16 computer produced their own extended can be augmented to a 64K Basic, MCT Basic, for the machine by the addition of a CBM64 which incorporates the ram board from MCT of commands found in the much Norwich. The board plugs into improved Basic of the C16. The the computer internally, leaving product is available on cassette the cartridge part free, and for £ 10.95 and on disc for enables the extended memory £14.95; a rom version will be to be used with Commodore available "in the not too distant C16 and Plus -4 programs (but future." Micro Component not those for the CBM64). At Trading Co. Group House, £59.95 inclusive, MCT claim Fishers Lane, Norwich, Norfolk the 64K machine represented NR2 lET. EWW217 back-up from the STE bus Multi -tasking 0S9 standby power line. The STE bus has access to 64 board pages of 56Kbyte ram and 1K of A development board, the SC09 input/output locations any of from Arcom, brings together which may be accessed by the the STE bus with the 6809 6809. The i/o is memory processor and the 0S9 mapped and code running in operating system. The single any of the STE pages may have Eurocard includes four memory access to peripheral devices. sockets, three 16 -bit Interrupts are accepted from programmable timers, an a.c.i.a. any two of the bus's attention for RS232C communications, request lines. The processor and an STE- bus arbiter. acts as a 'master' on the bus, The 0S9 is a multi -tasking using its arbiter to grant access system which can access a disc to one or two other temporary controller through the bus or masters. The control system communicate with a target rom - includes facilities for the based system; it can be processor to scan the bus and replaced with a machine -code deduce the amount of memory monitor. The memory sockets available and identify the take two 24 -pin and two 28 -pin connected modules on start-up. devices and may be used with Arcom Control Systems Ltd, any combination of rom and Unit 8, Clifton Road, ram. Ram may have power Cambridge CB1 4BW. EWW204 85

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Heat -sensitive applying the liquid crystal paint, provides a test current of about thus allowing the colour change Current tracer 0.55V at 50kHz which can then paint to show more clearly. The right Unskilled operators can trace be traced with the probe. combination of liquids to give faults in complex circuits with Shorts and partial shorts can be A three -bottle kit of liquid the required temperature the Polar Toneohm 580. Such is traced by following the current crystal thermographic paint colour -change can be applied on the claim for this instrument path around the circuit. It gives provides temperature coverage a test piece and assessed which has a sensitive magnetic - an audible tone so the operator from 58 to 117°C to non- against a printed calibration field probe that can detect small can concentrate on the circuit destructive thermography. spectrum provided. currents such as the flow under test without needing to Spectratherm may be applied to Temperature can be resolved to through an i.c. substrate or look at the instrument. £176 any dark and preferably non - within 0.5°C under laboratory within the layers of a multi - from Antron Electronics Ltd, reflective surface. conditions. The kit costs layer p.c.b. Hamilton House, 39 Kings Semiconductor packages in £25.30 from Redpoint Ltd, The instrument also has an Road, Haslemere, Surrey GU27 shiny finishes may be darkened Cheyney Manor, Swindon, internal power supply that 2QA. EWW212 with a black felt pen before Wilts SN2 2PS. EWW219

------.M.. .e...... - ...... e....e...... c...... c.-..-0. _...... :. ..accc..ee.. e cece...... 7.._ 'dramatically' reducing the Give it a tweek contact resistance. It is claimed A liquid that is claimed to cut to offer improved reliability in down or eliminate problems any electrical or electronic caused by poor contacts is equipment. It comes in a 7m1 called Tweek. It is not a dispenser for £15 and, as it cleaner, says the distributor, needs to be used sparingly to but a non-conductive fluid that give of its best, 7m1 should go Count up to built-in 10:1 ratio attenuator works by filling in the surface a long way. Fulcrum (Europe) reduces h.f. noise components imperfections and improving the Ltd, Valley House, Purleigh, 100MHz to prevent false counting. Input metal -to -metal contact and Essex CM3 6QH. EWW208 Capable of measuring sensitivity is 20mV up to frequency, period, frequency 100MHz. The period function ratio of input channels, time averages periods for three intervals and unit count, the cycles before displaying a value. Circuitmate ÚC10, may be used A self -check function test the in audio and computer internal timebase generators servicing, cordless telephone and counters. £216 from repair and for calibrating Beckman Industrial Ltd, function generators. With a Electronic Technologies frequency range of 5Hz to Division, Mylen House, 11 100MHz, the instrument is also Wagon Lane, Sheldon, provided with four time -gate Birmingham B26 3DU. selections from 0.01 to 10s. A EWW215

tablet Digitizing switched stream, at 1 to 200 Initially designed for Siemens as coordinate pairs per second. A a high -quality, low -resolution single 12V supply is taken in input device, the Videograph 1 through the RS232 connector. is now available in the UK. The Typical configuration of tablet, working area is 320mm square stylus and RS232 interface with a resolution of 0.1mm. costs £499. Dicoll Datasystems The output can be binary or Ltd, Bond Close, Kingsland ASCII, serial or parallel, up to Estate, Basingstoke, Hants 19200baud, point, stream or RG24 OQB. EWW216 86 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com TOP LOADING STEREO CASSETTE MODULES HIGH QUALITY REPLACEMENT This month we feature some fantastic Limited quantity of brand new stereo cassette units, as used in hill music ,f bargains. Our standard range of centres etc. All have auto stop. CASSETTE HEADS professional quality kits and cassette decks is still expanding, along with new lines in Video heads and power supplies. Our FREE list gives details 1 of these and many other lines. ALL BARGAIN ITEMS INCLUDE VAT 8 POST.

Do your tapes lack treble? A worn head could be the problem. Fitting one of our replacement heads could restore performance to better than new! Standard mountings make fitting easy and our TC1 Test Cassette helps you set the azimuth spot-on. We are the actual importers which means you get the benefit of lower prices for prime parts. Compare us with other suppliers and see I The following is a list of our most popular heads, all are suitable for use on Dolby machines and are ex -stock. HC20 Permalloy Stereo Head. This is the standard head fitted as original equipment on most decks £5.11 HM90 High Permalloy Head. A hard-wearing, higher per Deck type 858B.Has RiP Grcwts, 12v DC motor. 3 -digit formance head with metal capability.... 08.06 counter 029.32 HS16 Sendust Alloy Super Head. the best head we can find. Dedi type 811C. As above but with Dolby noise reduction. Fully wired Longer life than Permalloy, higher output than Ferrate, fantastic withtwin VU meter, level controls, pilot lights and DIN socket 044.73 frequency response £9.91 Deck type 828A. Deck mechanism only as used in both above. produced H0551 4 -Track Head for auto-reverse or quadrophonic use Full by one of top manufacturers. Fitted Japan's high quality stereo R/P head specification record and playback head £9.73 MODEM OPTICAL ISOLATOR UNIT andFernte erase. 12v governed DC electronically motor.... £11.27 Please consult our list for technical data on these and orner Sperry Univac M4000 optical isolator unit, designed to provide Cassette Doorto fit any above. £4.02 Special Purpose Heads. excellent electrical isolation between data terminals employing Deck type 111D. Complete module with record and play electronics. 3- MA481 Latest version Double Mono (2/2) Record/Play head. high voltages and modems. Full isolation up to 2.2Kv with a max line digit counter, AC drive motor and cassette door £21.73 speed of 9600 baud. Complete unit is 4'h" high, 9'2" wide, T deep Replaces R484 £8.90 and weighs5"elbs. Power supply is 240v 50Hz at 20 watts. Fitted with COMPLETE STEREO TUNER MODULE SM166 Standard Mounting 2/2 Erase head. Compatible with 25 way "D" connectors for RS232C/V24 input and output 3 Band. LW/MW/FM Stereo Tuner fully assembled on PCB 165 x 85mm. above or H0551 4 Track head. C5.90 OUR PRICE ONLY 079 95 Supplied with Ferrite Rod Aerial, stereo LED and band switch fully wired. H524 Standard Erase Head. Semi double gap, high effi- 12vOC Supply. TU560-Tuner Price Only 07.99 ciency . £1.50 LIQUID CRYSTAL DISPLAY WATCH MODULE Drive accessories with 2 knobs, tuning drum, window and scale... £2.99 With LCD display, 2 pieces of Polarising material, backlight diffuser, Special pricefor both items bought together E9.70 H561 Metal Tape Erase Head. Full double gap £4.90 micro lamp, precision crystal, trimmer, battery contacts and open microcircuit. Untested. 5for£1 CLOCK/TIMER/FREQUENCY METER PARTS Special otter of the fabulous MSM5524 clock, timer and frequency HART TRIPLE -PURPOSE TEST PLESSEY MAINS INTERFERENCE SUPPRESSORS meter chip. MSL2318 prescaler chip and 6LT09 5 -Digit fluores- CASSETTE TC1 Filter unit for mains borne interference. Max current 1.5A. Our Price, display. These are the 3 primary components for a complete One inexpensive test cassette enables you to set up VU level. new timing and frequency display system covering the long, medium, brand only £2.27 head azimuth and tape speed. Invaluable when fitting new Item, short and FM wavebands. Total cost of these parts is normally Same Store soiled only £1.61 heads. Only £4.68 plus VAT and 50p postage. over C25. OUR SPECIAL OFFER PRICE ONLY 013.68 10W POWER AMPLIFIER MODULE INF230 Data on MSM5524 and MSL2318 70p Tape Head De -magnetiser. Handy size mains operated unit Mullard LP1t73 Amplifier module. Needs 24v DC Supply to gives 10 INF260 Application Circuit 20p prevents build up of residual head magnetisation causing noise 4 112 x watts into ohm speaker. Size x 70 29mm. Complete with heat Crystal 3276.8 KHz £2.18 on playback .. 04.54. sink. Only £2.40 complete with Data. Curved Pole Type for inaccessible heads _. £4.85 SLIMLINE AXIAL FANS ALPS FF317U FM FRONT END Send for your free copy of our LISTS. Overseas please send 2 Beautiful, precision made High Quality variable capacitor tuned FM Crouzet precision made 93mm Front End with Dual -gate MosFet. Covers full FM range of 87 to 109 MHz. IRCs ro cover surface Posl or 5 IRCs for Airmail. square and only 25mm thick 12v supply ONLY if required packing and insurance follows: £5.15 Circuit 35p. equipment fans, Mini Frilac Type Please edd part cost of post, as V80. 2700 RPM 115v 50Hz 13W. INLAND OVERSEAS in operation and RADIO FM IF AND Very quiet Orders up to 510 - 50p Please send sufficient to craven CAR STEREO DECODER for high power amplifiers. Miniature PCB with 10.7MHz ceramic filters, 2 -transformer ratio ideal Orders £10 to 049-£1 these cost around Sur face or Air Post IC Normally Orders over E50 - £1.50 detector, Ax010 noise suppression and TCA4500A advanced stereo required decoder IC. Only needs front end to make FM tuner or car radio. £14 each. OUR PRICE ONLY £6.46 Complete with circuit. Incredible value at Only £1.99

Personal callers are always very welcome but 24hr SALES LINE ALL PRICES EXCLUDE VAT 1111 please note that we are closed all day Saturday (0691) 652894 UNLESS STATED

CI RKW I K is a lightpen or trackerball driven CAD package orientated to the production of schematic drawings, such as circuit diagrams, flow charts, power systems, pipework diagrams and many similar professional and engineering batapen applications. Using this on screen menu driven program you can turn your BBC micro into a powerful CAD system capable of producing high quality drawings easily and quickly. An ordinary 80 column dot-matrix printer is all that is required for output and a unique graphics routine allows a multiple screen drawing to be printed in one pass. Lightpen version £19.95 Drawings up to 2 screens high by4 screen wide may be produced and new sym- Trackerball/lightpen version.24.95 bolic shapes may be created on an enlarged scale even while the drawing is in Graf pad/lightpen version £24.95 progress. Up to 640 different symbols may be used at any time. The drawings are Datapen lightpen £25.00 in high resolution mode 4 with no restrictions on position and symbols and text Marconi Tracker ball with may be joined, overlaid, rotated and inverted at will. Block move and copy com- Micro -Draw program £59.50 mands, logical erase and self straightening lines are some of the useful features ICON drawing program £60.50 included with this program. Parts lists of symbols used may be generated and ATARI Trak-Ball with BBC printouts can be obtained of the unlimited libraries. 3 versions available; Datapen lightpen, trackerball and Grafpad, the latter two interface £33.00 also include the lightpen version. The drawings produced on any version are completely interchangeable and the difference between versions is one of speed of drawing. All prices include VAT & postage. Please send your cheque/P.O. to: S.A.E. FOR FURTHER DETAILS. Dept. WW Datapen Microtechnology Ltd, Kingsclere Road, Overton, Hants. RG25 3JB. Tel: (0256 770488)

CIRCLE 30 FOR FURTHER DETAILS.

Lynwood GD1 VDUs: Intelligent Green micro controlled, RS232, printer port, 101 key k/b. Full Video enhancements. ONLY £149+£15 P&P (S/H) Electronic Burroughs MT686/7/TD710: Intel l igent Green 12' V DU with 3 micros and 64K store. RS232. Programmable... Only £199 Corporation new or £149 S/H + £15 P&P ni Open Chassis Video Monitors from above VDUs £40+7.00p&p THRULINE® Directional Wattmeters Mu ltirai l Switching PSUs from above 5v 4A 12v+24v £25+£7.50 TERMALINE® RF Coaxial Load Resistors Data General 6012 VDU's very attractive display working RS232 with integral 73 key k/b either dumb terminal mode or page TENULINE® Attenuators and accessories buffered Only £120.00 + £ 15.00 p&p from stock Centronics 306 Line printers: Professional fast (120 cps), superb quality 80 column printer. Parallel i/f ONLY £99+ £15.00 P&P Osborne Executive Portable CP/M system with oodles of software. Twin floppy Aspen Electronics Limited drives £900+£15 p&p Diablo 630 Daisywheel printer. OEMi/f NEW £599+ £15 P&P The exclusive UK representative for Bird Electronic Calcomp 565Drum Plotter, l0thou steps. ONLY £450+ £10 P&P 2/3 Kildare Close, Eastcote, Ruislip BECKENHAM PERIPHERALS LTD Callers welcome We also buy Middlesex HA4 9UR by appointment 01-468 5582 redundant peripherals Tel: 01-868 1188 Tlx: 8812727 34 Rodwey Roa Kent 13JLromley CIRCLE 90 FOR FURTHER DETAILS. t.1RC1-E 140 FOR FURTHER DETAILS.

ELECTRONICS & WIRELESS WORLD OCTOBER 1985 87

www.americanradiohistory.com Hitachi Oscilloscopes the highest quality from £299 the most competitive prices +VAT

Hitachi Oscilloscopes provide the quality and performance that you'd expect from such a famous name, with a newly -extended 14 model range that represents the best value for money available anywhere. V-212/222 20MHz Dual Trace V-65(1 60MHz Dual l imebase V-223 20MHz Sweep Delay \'- I(151) I00MHz Quad l race (illustrated) V-1070 100MHz Four Channel V-209 20MHz 'Mini -Portable V-1100 1(X)MHz DMM 'Counter V-422 40MHz Dual Trace V-134 I0MHz Tube Storage V-423 401MHz Sweep Delay VC -6015 10MHz Digital Storage

V -S09 S01MHz ,blini -Portable VC -60l 1 40MHz Digital Storage

1 Prices start at (299 plus vat (20MHz dual trace) including a 2yr. warranty. We hold the range in stock for immediate delivery.

For colour brochure giving specifications and prices ring (04801 635711 Thurlby-ReItech, 46 High Street, Solihull, yy .Midlands, B91 3TB. CIRCLE 122 FOR FURTHER DETAILS. The world's most advanced low-cost bench multimeter! Thurlby 1905a £349+ VAT A complete high performance bench DMM

51/2 digits; 0.015% acc; 1 pV, 1 m i-2 1 nA. Full ac and current functions as standard A sophisticated computing and logging DMM Linear scaling with offset; null/relative Percentage deviation; running average dBV, dBm general logarithmic calculations Limits comparison; min and max storage 100 reading timed data logging RS232 and IEEE -4.88 interface options Thurlby Electronics Ltd New Road, St.lves, Cambs. PE174BG III Thurlby1 Tel: (0480) 63570 designed and built r, Britain CIRCLE 123 FOR FURTHER DETAILS.

Now Thurlby makes logic analysis affordable ! from the Thurlby LA -160 £395 +vat 16 data channels, expandable to 32 Clock rates up to 20MHz 2,000 word data acquisition memory Non-volatile reference memory Data state and logic timing displays Binary, octal, decimal or hex formats Powerful search and compare ' ' Hard copy data ' ;. i blpYS cers Icroprocessors lC QYv . . - rs standard mnemonics used QY1a m 02, Z80 and 6800 presently available With otl Simple connection to the microprocessor N Full capture using 32 data channels An essential instrument All memory/stack operations are shown An oscilloscope and logic probe are not enough to unravel the Branch addresses are calculated complexities of today's eiectronic equipment. A logic analyser has Extra uncomitted channels available become the essential tool for both hardware and software engineers. Indeed a logic analyser is as important for the observation of logic Now, with the launch of uP disassemblers, a complete 32 channel signals as an oscilloscope is for the observation of analogue logic analyser system with disassembler software and personality signals. module is available for £658.

Unfortunately the high cost has made logic analysers unavail- Contact us now for full technical data and prices. who now able to many could benefit from them, but the Thurlby Thurlby Electronics Ltd LA -160 puts a sophisticated and versatile logic analyser within the IIIThurlbyl New Road, St.lves, Huntingdon, Cambs. reach of everyone. designed and built in Britain PE17 4BG, England. Tel: (0480) 63570

CIRCLE 124 FOR FURTHER DETAILS. 88 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com A FULL HOUSE DISTRIBUTING A GREAT DEAL

G igital °SciUoscp 9ue Power supplies D.M.M.'s Paxton Function generator ar Frequency couriers Instruments *St Á'Jà% Distributors of ` Electronic Test Bloc 1 Instrumentation

. Unit B1 /. ^,. Pixmore Industrial Estate, 1; ;; ' :C Avenue, ' ,t Pixmore 11i rr" Letchworth, rrl'rt ,;-. Herts SG61JJ .`' it Phone: ,". ' :í i 0462 685648 0462 678811

CIRCLE 94 FOR FURTHER DETAILS.

zThe Wings Appeal It's easy to Fund helps to maintain e, the RAF Association Home for Disabled Give as complain about and Chronic Sick. Care is essential for they those who have served advertisements. their country and who are in need. So please help by But which ones? giving all you can for an emblem in WINGS WEEK Every week millions of advertisements in September or send a appear in print, on posters or in the cinema donation to show that Most of them comply with the rules you care. contained in the British Code of Advertising Practice. To : Royal Air Forces Association, Appeals Dept., (DS) Portland Rd. But some of them break the rules and Malvern, Worcs. WR14 2TA.

warrant your complaints. I enclose a donation of If you're not sure about which ones they forte Wings Appeal Fund. are, however, drop us a line and we'll send you Name an abridged copy of the Advertising Code. Address Then, if an advertisement bothers you, you'll be justified in bothering us. The Advertising Standards Authority. Please tick if receipt required If an advertisement is wrong,were here to put it right. or information on RAFA Space donated by ASA Ltd, Dept 2 Brook House,Torrington Place, London WC.LE 7HN Electronics & Wireless World

This space is donated in the interests of high standards of advertising. ELECTRONICS & WIRELESS WORLD OCTOBER 1985 89

www.americanradiohistory.com ERS - PRINTERS - PRINTERS - PRINTERS SUPER DEAL? NO - SUPER STEAL TELETYPE ASR33 TERMIPRINTER THE FABULOUS 25 CPS "TEC STARWRITER" DATA I/O TERMINALS // Industry standard, combined ASCII 110 baud printer, keyboard and 8 hole paper tape punch and reader. Made to the very highest spec the TEC Standard RS232 serial interface. STARWRITER Ideal as cheap hard copy unit FP1500.25 features a or tape prep. for CNC and NC very heavy duty die cast machines. TESTED and in good chassis and DIABLO type print mechanism condition. Only £235.00 floor giving superb stand £10.00. Carr & Ins. £15.00. A massive purchase of these desk top registration and print a fraction printer terminals enables us to offer you quality. Micro -processor of its on gloat cost. these quality 30 or 120 cps printers electronics offer full at a SUPER LOW PRICE against their DIABLO/QUME command compatability and rule contro via CPM WORDSTAR EX NEWS original cost of over £1000. Unit ETC. Many other features include bi-directional printing, switchable 10 or 12 pitch, comprises of full QWERTY, electronic full width 381 mm paper handling with up to 163 characters per line, friction feed keyboard and printer mech with print rollers for single sheet or continuous paper, internal buffer, standard RS232 serial SERVICE PRINTERS face similar to correspondence quality interface with handshake. Supplied absolutely BRAND NEW with 90 day guarantee typewriter. Variable forms tractor unit and FREE daisy wheel and dust cover. Order NOW or contact sales office for more enables full width - up to 13.5" 120 information. Optional extras RS232 data cable £10.00. Tech manual £7.50. Tractor Compact ultra reliable quality built unit column paper, upper - lower case, Feed £140.00. Spare daisy wheel £3.50. Carriage & Ins. (UK Mainland) £10.00. made by the USA EXTEL Corporation. standard RS232 serial interface, internal Often seen in major Hotels printing up to vertical and horizontal tab settings, the minute News and Financial inform- standard ribbon, adjustable baud ation, the unit operates on 5 UNIT rates, quiet operation plus many other SUMMER OFFER ONLY £399.99!! BAUDOT CODE from a Current loop, features. Supplied complete with manual. RS232 or TTL serial interface. May be Guaranteed working GE30 £130.00. connected to your micro as a low cost GE1200120 cps £175.00 printer or via a simple interface and filter Untested GE30 £65.00 Optional floor to any communications receiver to stand £12.50. Carr & Ins. £10.00. DIY PRINTER MFCH enable printing of worldwide NEWS, TELEX and RTTY services. SEMICONDUCTOR Brand New surplus of this professional printer chassis gives an Supplied TESTED in second hand outstanding opportunity for the Student, Hobbyist or Robotics condition complete with DATA, 50 and 'GRAS' RAGS" constructor to build a printer - plotter - digitiser etc, entirely to their 75 baud xtals and large paper roll. own specification. The printer mechanism is supplied ready built, TYPE AE11 Mixed Semis amazing value contents Many features 50 Column ONLY £49.95 include transistors digital, linear, IC's, aligned and pre tested but WITHOUT electronics. triacs, diodes, bridge recs, etc. etc. Spare paper roll for AE 1 1 £4.50 include all metal chassis, phosphor bronze bearings, 132 character All devices guaranteed brand new full optical shaft position encoder, NINE needle head, 2 x two phase 12V TYPE AF11 R 72 Col. spec with manufacturer's markings, fully stepper motors for carriage and paper control, 9.5" Paper platten etc. + Ribbon £65.00 guaranteed. TYPE AH11 R 80 Col. a to the unit's capabilities!! 50+ £2.95 100+ £5.15 etc. Even manufacturer's print sample show ASCII/BAUDOT £185.00 Overall dimensions 40 cm x 12 cm x 21 cm. TTL 74 Series. A gigantic purchase of an Carriage and Insurance £7.50 "across the board" range of 74 TTL series Sold BRAND NEW at a FRACTION of cost ONLY £49.50 + pp £4.50. IC's enables us to offer 100+ mixed "mostly TTL" grab bags at a price which two or three chips in the bag would normally cost to buy. Fully guaranteed all IC's full spec. 100+ £6.90, 20,000 FEET OF ELECTRONIC 200+ £12.30, 300+ £19.50 AND COMPUTER GOODIES ENGLAND'S LARGEST SURPLUS STORE- SEEING IS BELIEVING!! CENTRONICS DEC CORNER MAO TAPE DRIVES 710 PRINTERS Ex RENTAL Heavy duty full width Many EX STOCK computer tape drives and spares by carriage printer up to 132 columns on PDP 1140 System comprising of CPU. 124k 17" fan fold sprocket fed paper. 60 cps memory & MMU 15 line RS232 interface. PERTEC, CIPHER, WANGO, DIGIDATA, KENNEDY print speed with standard RS232 or 20 RPO2 40 MB hard disk drive. etc. Special offer this month on DEI Cartridge tape mA loop interface. Supplied in TESTED TU10 9 track 800 BPI Mag tape drive, dual used condition with data ONLY £85.00 track system. VT52 VDU, etc. etc. Tested and drives ONLY £450.00 each. carriage and insurance £10.00. running. £3,750.00 FOR DETAILS BA11-MB 3.5" Box, PSU, LTC £395.00 CALL DH11-AD 16" x RS232 DMA interface £1,900.00 COMPUTER/SYSTEM CABINET a PSU MAINS FILTERS DLV11-J4 x interface EIA £350.00 All in one quality DLV11-E Serial. Modem support £190.00 computer cabinet with integral CURE those unnerving hang ups and data DUP11 Synch. Serial data i/o £650.00 switched mode PSU, mains filtering, and twin fan glitches caused by mains interference with D0200 Dilog - multi RK controller £495.00 cooling. Originally made for the famous DEC PDP8 professional quality filters. SD5A match- DZ11-B 8 line RS232 mux board £650.00 computer system costing thousands of pounds. box size up to 1000 watt 240 V KDF11-B M8189 PDP 1123 Made to run 24 hours per day the psu is fully Load ONLY £5.95. L12127 compact PLUS £1,100.00 screened and will deliver a massive +5v DC at 17 amps, +15V DC at completely cased unit with 3 pin fitted LA30 Printer and Keyboard £80.00 socket up to 750 watts ONLY £9.99. LA36 Decwriter EIA or 1 amp and -15v DC at 5 amps. The complete unit is fully enclosed 20 mA loop £270.00 with removable top lid, filtering, trip switch, power and run leds MS11-JP Unibus 32kb Ram £80.00 mounted on ali front panel, rear cable entries, etc. etc. Units are in MS11-LB Unibus 128kb Ram £450.00 good but used condition - supplied for 240v operation complete with EPROM COPIERS MS11-LD Unibus 256kb Ram £850.00 full circuit and tech. man. Give your system that professional finish PDP11 /05 Cpu Ram, i/o etc £450.00 for The amazing SOFTY 2 The "Complete only £49.95 + carr. 19" wide 16" deep 10.5" high. Useable area Toolkit" for copying, writing, PDP11/40 Cpu, 124k MMU £1,850.00 16" w 10.5"h 11.5"d. modifying and RT11 ver 3B documentation kit £70.00 listing EPROMS of the 2516, 2716. RK05-J 2.5 Mb disk drives £650.00 Also available less psu, with fans etc. Internal dim. 19"w, 16"d, 10.5"h. 2532, 2732 range. Many other functions KL8 JA PDP 8 async i/o £175.00 £19.95. Carriage £8.75 include integral keyboard, cassette inter- M18E PDP 8 Bootstrap option £75.00 face, serial and parallel i/o UHF modulator VT50 VDU and Keyboard ELECTRONIC ZIF socket etc. - 20 mA £1 75.00 ON ONLY £195.00 + pp £2.50. VT52 VDU and RS232 interface £250.00 'DIS EQUI MENTTS "GANG OF EIGHT" intelligent Z80 OUN controlled 8 gang programmer for ALL Due to our massive bulk purchasing programme, which enables us to bring you the single 5v rail EPROMS up to 27128. Will Give your VT100 a Birthday!!! best possible bargains, we have thousands of ICs, Transistors, Relays, Caps, PCBs, copy 8 27128 in ONLY 3 MINUTES. Internal Brand New VT100 Keyboards Sub -assemblies, Switches etc. etc. surplus to OUR requirements. Because we don't LCD display and checking routines for only £85.00 have sufficient stocks of any one item to include in our ads we are packing all these IDIOT PROOF operation. Only £395.00 + items into the BARGAIN OF A LIFETIME. Thousands of components at giveaway pp £3.00. prices. Guaranteed to be worth at least 3 times what you pay. Unbeatable value and "GANG OF EIGHT Same 1000's of EX STOCK spares for. PLUS" spec. as perhaps one of the most consistently useful items you will every buy!!! Sold by above but with additional RS232 serial DEC PDP8, PDP8A, PDP11 systems & weight. interface for line loading peripherals. Call for details. All types of down data from Computer equipment and spares wanted for 2.5k1s £5.25 + pp £1.25 5 kls £6.90 + £1.80 computer etc. ONLY £445.00 + pp £3.00 PROMPT CASH PAYMENT. 10kIs £11.25 + pp £2.25 20kIs £19.50 + pp £4.75 Data sheets on request 1000's of other EX STOCK items including POWER SUPPLIES, RACKS, RELAYS, TRANSFORMERS, TEST EQUIPMENT, CABLE, CONNECTORS, HARDWARE, MODEMS, TELEPHONES, VARIACS, VDU'S, PRINTERS. POWER SUPPLIES, OPTICS, KEYBOARDS etc. etc. Give us a call for your spare part --eier' requirements. Stock changes almost daily. Don't forget, ALL TYPES and QUANTITIES of electronic surp Ius purchased for CASH

CIRCLE 129 FOR FURTHER DETAILS.

9 0 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com

a-?-- J. IcOMPUTER WAREHOUSE FAR%Li THE "ALLADINS CAVE OF COMPUTER AND ELECTRONIC EQUIPMENT ; New EX -STOCK INTEGRATED CIRCUITS NOT LINE DATA BASE SCOOP 4164 200ns D RAMS 8 for £14.95 411 6 300 ns £1.50 PRINTER / TERMINAL 2112 £10.00 2114 £2.50 2102 £2.00 8118 £2.50 A MASSIVE purchase of these attractive stand alone EPROMS 2716 £4.50 2732 £3.00 2784 £4.95 terminal units enables a SUPER BARGAIN offer. Made by 27128 £5.50 6800 £2.50 8821 £1.00 68A09 £8.00 the US GENERAL ELECTRIC CORPORATION the GE 8809 £10.00 8085 £5.50 8088 £15.00 8251 £7.00 f MODEL 30 features a standard QWERTY 80 key 8748 £ 15.00. *DISTEL©* electronic keyboard coupled to a quality built matrix :The ORIGINAL FREE OF dial up Thousands of IC's EX STOCK send SAE for list. CHARGE data printer with variable 3" to 9.5" forms tractor. The printer is base. Buy, browse or place YOUR OWN AD for capable of continuous duty printing, with up to 120 :goods or services to sell. 1000's of stock items, characters per line. Standard RS232 interface accepts RECHARGEABLE BATYF1tIES spares and one off bargains. Updated daily. ASCII data at 110, 150 or 300 baud. Ideal for Terminals, Dry Fit MAINTENANCE FREE by Sonnenschein 8 Yuasa ON LINE NOW. CCITT, 8 bit word, no parity. Data loggers, local label printing, or just as a printer!! Sold A300 07191315 12v 3ah as RS 591-770 NEW £13.95 For TESTED with data ONLY £95.00. Also available with A300 07191312 6v as RS 300 baud modems call 01-679 1888 3ah 591-360 NEW £9.95 For TWIN MAGTAPE CASSETTE unit for data capture, data A300 07191202 6-0-5v 1.8ah as RS 591-382 Ex Equip 1200-75 baud modems call 01-679 6183 preparation etc £150.00 Carriage £10.00. £5.99 3.6v 100 mah PCB mount as RS 59t-477 NEW £1.00 DISC O14I VES COOLING FANS Japanese Hal eight, rack Keep your not partsCLOL and RELIABLE wrtn COLOUR AND MONOCHROME 80 double sided our range of COOLING FANS disk drives by TEAC, TOSHIBA etc. Sold as ETRI 128LF21 240v 5 NEW with blade equipment tan 90 day guarantee ONLY£125.00. Dim. 80 x 80 x 38mm £9.95 MONITOR SPECIALS SUGART SA400 SS FH 35 TRK £55.00 ETRI 88XU01 Dim. 92 x 92 x 25mm SIEMANS FDD100 SS FH 40 TRK £75.00 240v equipment fan, complete with finger `SYSTEM ALPHA' 14" COLOUR MULTI INPUT MONITOR carriage on 51/4" drives £5.50 guard NEW £9.95 made in the UK by the famous REDIFFUSION Co. for their own professional Brand NEW metal cases with internal PSU etc GOULD JB-3AR Dim 3" x 3" x 2.5" compact computer system this monitor has all the features to suit your immediate and for above drives, below cost!!! very quiet running 240v operation. future monitor requirements. Two video inputs: RGB and PAL Composite Video, NEW £8.95. allow direct connection to the most makes micro DSKC 1 for 2 HH or 1 FH 51/4" drive £39.95 BBC and other of computers BUHLER 69.11.22 8-16v DC micro miniature and VCR's An internal + pp £4.50 DSKC 2 for 1 HH or 1 FH 51/4" drive speaker and audio amplifier may be connected to your £29.95 + pp £4.50 re'.ersiblefan. Uses a brushless servo motor for systems output or direct to a VCR machine, giving superior sound quality. Many extremely high airflow also silent running and other features included PIL tube, 8" Refurbished standard units. Matching BBC case colour, Major controls on guaranteed 10,000 hr ife. Measures only 62 x front panel, Separate Contrast and Brightness- even in RGB mode, Two types of SUGART 801 SS £175.00 + pp 62 x £8.50 22mm. Current cost £32.00. OUR PRICE audio input, Separate Colour and audio controls for Composite Video input, BNC SUGART pppAR85gg11g DS pp ONLY £12.95 complete g£250.00 + £8.50 with data plug for composite input, 15 way 'D' plug for RGB input, modular construction MUFFIN -CENTAUR standard 4" x 4" x 1.25" TWIN SUGT851,2 n smarttcase, fans 110v OR 240v NIEW at £10.50 or tested etc etc complete with PSU etc, £595.00 EX EQUIPMENT 240v £6.25 or 110v £4.95. This Must be ONE OF THE YEAR'S BEST BUYS 8" DRIVE PSU for 2 drive units £45.00 1000's of other fans Ex Stock. Supplied BRAND NEW and BOXED, complete with DATA and 90 day guarantee. Call for Details. Post E. Hard Disk Drives Packing on all fans £2.00. SUPPLIED BELOW ACTUAL COST- ONLY £149.00 DRE/DIABLO Series 30 2.5 Mb front load, DECCA80 16" COLOUR monitor. RGB input £525.00, Exchangeable version £295.00 QWERTY KEYBOARDS Little or hardly used manufacturer's surplus enables us to offer this special ME3029 PSU for above £95.00 Manufacturer's BRAND NEW surplus. converted DECCA RGB Colour Video TV Monitor at a super low price of only 44/DRE4000A, B 5+5 Mb from ALPHAMERIC 7204/60 Full travel ASCII, for £DIABLO £99.00, a price a colour monitor as yet unheard of!! Our own interface, safety 60 key with parallel output and strobe. modification and special 16" high definition PIL tube, coupled with the tried and CDC HAWK 5+5 Mb £795.00 £39.95 CDC 9782 80 Mb RM03 tested DECCA 80 series TV chassis gives 80 column definition and picture etc £2500.00 DEC LA34 Uncoded keyboard with 67 quality found only on monitors costing 3 TIMES In fact, PERTEC D3422 5+5 Mb £495.00 OUR PRICE. WE quality gold plated switches on X-Y matrix- GUARANTEE you will be delighted with this product, the quality for the price, RODIME 10MB ST508 Winchester NEW ideal micro conversions etc £24.95 has to be seen to be believed. Supplied complete and ready to plug direct to a £299.00 AMKEY BASF MPNK-114 Superb word processor BBC MICRO computer or any other system with a TTL RGB output. Other 8172 23Mb Winchesters, as seen chassis keyboard on PCB £ 199.00 single with 116 features are: internal speaker, Modular construction, auto degaussing circuit, keys Many features such as On board Attractive TEAK CASE, compact dimensions only 52cm W x 34 H x 24 D, 90 day Carriage on other drives £ 10.00. Micro, Single 5v rail, full ASCII coded guarantee. Although used, units are supplied in EXCELLENT condition, ONLY Unless stated all drives are refurbished with character set with 31 function keys, £99.00 + Carr. 90 day guarantee. Many other drives and Numeric keypad, cursor pad and 9800 baud DECCA 80 16" COLOUR monitor. Compositve video input Same as above spares in stock- call sales office for details. SERIAL TTL ASCII OUTPUT!! ONLY model but fitted with Composite Video input and audio amp for COMPUTER, £69.00 with data VCR or AUDIO VISUAL use. ONLY £99.00 + Carr. REDIFFUSION MARK 3, 20" Colour monitor. Fitted with standard 75 ohm composite video input and sound amp. This large screen colour display is ideal MODEMS 111\\AA111Ate/ eee IOWMM Join the communications revolution with our Mlt\AAriAMAAUAaU e BIM» for shops, schools, clubs and other AUDIO VISUAL applications. Supplied in AS super range of DATA MODEMS, prices and t11l1111111AeL1A121011111teletel ee eale NEW or little used condition ONLY £145.00 + Carr. specifications to suit all applications and tAeleelelelaeelelAe see budgets... ffl BUDGET RANGE EX EQUIPMENT MONOCHROME video BRAND NEW State of the art products. i`.;- monitors. All units are fully and set DACOM DSL2123 Multi standard 300-300, Carriage on all Keyboards £3.50 cased for 240v standard working with composite video 1200-75 Auto answer etc £268.00 inputs Units are pre tested and set up for 80 column use on BBC micro etc Even DACOM DSL2123AD Auto dial smart when MINOR screen burns exist- normal data displays are unaffected. modem with multi standard AUTO SPEED KGM 320-1 B/W high bandwidth input, will display up to 132 x 25 lines. detect, and data buffer with flow control PLESSEY VUTEL ££1g2" 5 etc £385.00 Manufactured by fag.8R SCREEN version of KGM 320-1 Only £39.95 DACOM DSL2123GT The CREAM of the PLESSEY Ltd this 9" KGM 324 GREEN SCREEN fully cased very compact unit Only £55.00 intelligent modems, auto dial auto call index compact unit, only 9" HITACHI VM-906E/K Black and White screen £49.95 buffer etc etc £498.00 slightly larger than a STEEBECK SB1212 V22 1200 baud FULL telephone features an Carriage and insurance on all monitors £10.00 DUPLEX, sync or async optional auto dial, all in one TELEPHONE, £485.00 24 x 40 character CRT TRANSDATA 307A Acoustic coupler 300 screen, VIEWDATA- D.C. POWER SUPPLY SPECIALS baud full duplex, originate only, PRESTEL modem, GOULD OF443 enclosed, compact switch mode supply with D regulated outputs of Keypad RS232 £49.00 and electronics to run as a fully +5v @ 5.5a, +12v @ 0.5a -12v @ 0.1a and -23v @ 0.02a Dim 18 x 11 x 6 cm. 110 or fledged PRESTEL ':erminal or telephone. 240v input BRAND NEW only £14.95 Ex BRITISH TELECOM full spec, CCITT, Ready to plug direct into a BT 600 type jack GOULD G6 -40A 5v 40 amp switch mode supply NEW £130.00 ruggedised, bargain offers Sold TESTED with socket and instantly connect you to GREENDALE 19A -BOE Switch mode 60 watt open PCB with a fully regulated DC data Will work any PRESTEL etc. Many other features include on MICRO or system with output of 5v @ 6 amps, and three semi regulated outputs of +12V, -12V +15V @ upto 1 RS232 interface. Memory dialling, Recall button, Off line screen amp Dim only 11 cm x 20 cm x 5.5 cm. Similar to RS 591-994. 110 or 240v AC input. DATEL 28 300 Baud Modem see SPECIAL data storage, Picture expand, Standard TESTED ex equipment. Only £24.95 OFFER. Mullard LUCY chip set, Integral 5" JVC crt AC -DC Linear PSU for DISK drive and applications Constructed a rugged monitor, SYSTEM on MODEM 13A 300 baud unit, only 2" high fits etc etc Designed to sell to the ALLOY chassis to continuously supply fully regulated DC outputs of +5V @ 3 amps, -5V under phone. CALL mode only £45.00 EXECUTIVE at over £600!! But from @ 0.6 amps and +24v @ 5 amps Short circuit and overvoltage protected 110 or 240 V DISPLAY, ANEW MODEM 20.1. 75.1200 baud. Compact unit BRAND AND BOXED at AC input. Dim 28x 12.5x 7 cm NEW £49.95. for use as subscriber end to PRESTEL only £99.00 for DTMF tone dial or £140.00 Carriage on PSU's £3.00 TELECOM GOLD, MICRONET etc £39.95 for standard DIAL PULSE version. + pp £6.50 Carr. £8.00. MODEM 20.21200-75 baud. Sameas20-1 but for computer end, £85.00 + pp £6.50 DATEL 2412 Made by SE labs for 8T this two SPECIAL 0 S OM 0 VDU TERMINALS part unit is for synchronious data links at 1200 purchase these BRITISH D Standard VDU data entry terminals at give away or 2400 baud using 2780/3780 NEW or little used 2B data modems allows US to make the FINAL prices!! protocol etc Many features include 2 or4 wire REDUCTION, and for YOU to join the exciting world of data QUME OVT108. Current product, state of the art working self test, auto answer etc terminal with detachable keyboard, 12" green COST OVER £800 Our price ONLY £199 communications at an UNHEARD OF PRICE OF ONLY £29.95. Made !o screen, 2 page RAM, TVI 925 emulation, 25 x 80, + pp £8.00 the highest POST OFFICE APPROVED spec at a cost of hundreds of Clock Swivel and tilt base, Printer port, Function DATEL 4800 RACAL MPS4800 baud each, has all the requirements for data base. keys etc BRAND NEW and BOXED AT ALMOST modem, EX Bt good working order, ONLY pounds the 26 standard HALF PRICE Only £425.00 £295.00 + pp £8.00 business or hobby communications. All this and more!! AJ510 - EX RENTAL Z80 controlled, 15" SUMMER OFFER 300 baud full duplex Z CALL. ANSWER and AUTO modes green screen 24 x 80 display, graphics, cursor MODEM TG2393. Ex BT, addressing, printer port etc Very good condition Up to 1200 baud, full Full remote ' RS232 interface control Standard serial TESTED complete with manual only £225.00. duplex over4wireor half duplex over2 wire line CtITT tone standards NOW OMLYL> Built in test switching ONLY £85.00 PER PAIR + pp £ 10.00 ADDS 520-Dumbterminal used 12" b/w screen Supplied with full data -, EY9.95 240v Mains operation RS232 interface and printer port. TESTED. For more information Modular construction y, fil. 1 year full guarantee ONLY £125.00 CONTACT OUR SALES OFFICE Direct isolated connection r, Just 2 wires to comms line Carriage on terminals £ 10.00 100's of other terminals in stock BT 600 Jack plug and cable £2.25 Carriage and Ins. £10.00 CALL for more details.

All prices quoted are for U.K. Mainland, paid cash with order in Pounds Sterling PLUS VAT. Minimum order value £ .00. Minimum Credit Card order£/0.00. Minimum BONA FIDE account orders from Government Depts., Schools, Universities and established companiesE20.00. Where post and packing not indicated please ADD £1.00 + VAT. Warehouse open Mon -Fri V 9.30.5.30. Sat 0.30-5.30. We reserve the right to change prices and specifications without notice. Trade, Bulk and Export l'1 1 32 Biggin Way, Upper Norwood, London SE19 3XF 1=1_1_IhT ii w- tI I\ Li 111 Telephone 01-679 4414 Telex 894502 Data 01-679 1888 la ELECTRONICS & WIRELESS WORLD OCTOBER 1985 91

www.americanradiohistory.com C ITZENBERGEI+ AERITALIA AVIONICS GROUP Electrical & Magnetic I= I E S r7,Z..,,...::, ,'Z' :o,""" Field Sensor System. Low Frequency Power Amplifiers Covering Frequency: DC Power Amplifiers 20Hz-1 GHz & 1-18GHz. With Simulation of all power supply units from 100VA to 100KVA. nine optional sensor heads. TYPICAL APPLICATIONS (electric and magnetic fields) Radiation hazard measurements in near and far 0 field conditions Transmitter antenna evaluation and field pattern - measurements Transmitter antenna tuning for maximum radiation CIRCLE 23 FOR FURTHER DETAILS. APPLICATIONS Monitoring electromagnetic environment in areas where electrb- Research & design of electrical and electronic equipment with either variable explosive devices, or weapon systems are stored or fixed frequencies and voltages. Quantitative "on the air" measurements Active steady mains simulation for sources of 50Hz, 60Hz, 400Hz, & 4KHz. R.F. interference measurements Capability to decrease & surge the voltage and shift the frequency. R.F. field strength measurements during EMI susceptibility tests (MIL - Mains simulation for MIL -STD -7048. STD -461-462, H.E.R.O. TESTS etc.) TESTING OF: Motors, chokes, capacitors, fluorescent lamps, transformers, Monitoring of installation sites for R.F. sensitive equipments (industrial A for all control & regulatory apparatus. synchronizers. calibrating source areas, ships, aircraft etc.) CIRCLE 24 FOR FURTHER DETAILS. Electro -Metrics Div. of Penril Corp. HIRE ELECTRO -METRICS EMC -50 500MHz-18GHz INTERFERENCE AND FIELD STRENGTH ANALYSERS Many Units from these r. manufacturers are e I included in our range di?, 6 6 oEl of EMC Hire facilities - Pre -selected down -converters will take It up to 26GHz & 40GHz. per day/week/month EMC -11 20Hz-50KHz EMC -25 10KHz-1 GHz

FOR HIRE SAE J551-461/2 CIRCLE 26 FOR FURTHER DETAILS. ASK THE BROCHURE FCCNDE/ANSI Impulse Generators CIRCLE 25 FOR FURTHER DETAILS. Electro -Static Discharge Testers A wide range of equipment Oar HIRE Ask for the HIRE Brochure

EMCO FISCHER Antenna Range Custom ` Communications ELECTRO -MAGNETIC INSTRUMENTATION A full range of current probes 20Hz to 1GHz.

Also injection probes. Magnetometers Models can be Magnetic Field Intensity Meters customised regarding ' Helmholtz Coil Systems internal diameters. ' Magnetic Field Generating Coils ' Antennas 20Hz-18GHz

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CIRCLE 27 FOR FURTHER DETAILS. CIRCLE 28 FOR FURTHER DETAILS.

For further Information on the above contact: ELECTRO-METRICS ELECTRO -METRICS LTD. TEL: (0767) 316767 41 Church Street, Biggleswade, Beds., SG18 OJS.

92 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com RECEIVER UP -DATE

receiver bandwidths ranging from 500Hz to 240kHz. Remote con- Communications receivers trol and data transfer are possible via a passive 20mA current loop. Also from Eska is a modifica- survey tion kit for the JRC NRD-515 Some additions to last month's receiver pictured last month. The kit includes extra filters to Philips have launched two multi - The Danish manufacturer 109.9MHz. Modes available are improve the set's selectivity and band synthesized portables, each Eska is returning to the market s.s.b., f.m. (broad and narrow - is claimed to increase the signal- covering 150kHz-30MHz plus the after a reorganization, and among band), radio -teleprinter, a.m. to-noise ratio by 10dB. It also f.m. broadcast band. the h.f. products announced by and phase -locked a.m., with true provides a phase -locked a.m. The D2935 (£170), styled as a the company is the RX99PL passband tuning. This versatile detector for distortion -free recep- portable, is a double-superhet transportable receiver. set has a two-line, 20 -character tion of a.m. stations even during with a liquid -crystal display, key- Frequency coverage is 15kHz alpha -numeric l.c.d. read-out, severe fading and interference. pad frequency selection giving to 29.999MHz plus a. v. h . f . range 99 memory channels, scanning, Eska Communications Systems storage for up to nine stations, of 144-176MHz and an unusually four independently -selectable A/S, Frederikssundsvej 274D, a b.f.o. for s.s.b. or c.w. recep- wide f.m. broadcast band of 60 - a.g.c. time constants and nine DK2700 Brenshej, Denmark. tion and an r.f. gain control. It can run on mains or battery power and it weighs 2.45kg. Among the additional features offered by the D2999 (£300) are three -speed electronic tuning using a knob as an alternative to the keypad, a digital field - strength meter, seven more memories, a search -tuning facil- ity and a switchable dual loud- speaker system. This model, which is described as a transport- able, weighs 4.11kg. The D2935 from Philips Eska's RX99 PL receiver

From page 36 selecting latch IC2 is treated as an for these dynamic memories can also feeds forward, bypassing the ence here is that in the newer i/o port clocked by an external take two forms, dependent on the delay chain. This is the early ver- devices there is no onus on the signal which, in the case of the state of the W line when CAS goes sion of CAS, made available for system to provide the refresh SC84, comes from the i/o board low. the 'CAS -before-RAS' refresh address. through pin c25. The lower seven Most microprocessors still cycles mentioned earlier. Selec- This 'CAS -before -RAS' signal bits stored in this latch combine have their write signals high at tion of the CAS type takes place in mechanism - just one of the with the lower 11 bus address the point when CAS goes low, so a dual 4 -to -1 -line multiplexer, advances being made in dynamic lines to form inputs to a nine a conventional cycle is generated ICx. Here the comparator output memory development - channel two - input multiplexer, where the memory outputs the and the higher order bit from the requires the slightly more com- IC3_5, providing row and column present state of the bit, i.e. the page register combine to select plex RAS signal. addresses to the dynamic mem- cycle begins as a read one. By which type of CAS, early or con- To keep the system simple, no ory array. setting W low before CAS goes ventional, is passed to which code is executed within the sili- It doesn't matter which add- low an 'early write' cycle occurs 256Kbyte memory block. con disc memory; it is purely a ress lines are paired up, or which in which the output pin of the In using a silicon disc, one rule store into which and from which multiplexer outputs go to which memory stays in a high imped- must be adhered to. Remember data is transferred. This means dynamic memory address inputs. ance state throughout the cycle. that the 'disc' is silicon and not that access to it will always be Upper system address lines All to This allows the data input and magnetic and so should the power interleaved with access to other A17 go into an eight -bit compara- output pins on the memory to be fail you will lose all of the data. areas of memory. tor formed from ICF , which gives connected together without any The rule is to regularly make The timing controller generat- an active output when the add- fears of bus contention - an back-up copies of any master files ing RAS and CAS for the silicon ress matches the switch settings arrangement which suits the bidi- on magnetic disc. disc produces conventional mem- and the SDSEL line is active. This rectional system data bus. A version of the SC84 operat- ory cycles when the disc is actu- line is the signal which maps the The main control signal indi- ing system, version 2.1D, is ally being accessed. It generates silicon disc into memory and may cating a memory cycle passes available which treats the silicon CAS -before -RAS cycles when- be selected to be active high or through buffering and a series of disc as drive E. For readers ever accesses at other addresses low by switch Ss. Output of the time delays to produce a slightly patching their own CP/M Bios, a occur or when the silicon disc is comparator is used to gate the delayed version for the RAS sig- DPB exists. The DPB sets the mapped out of the system. Thus inverted RD signal into the nal. A further delayed version number of sectors per track as 16 refreshing is guaranteed while dynamic memory W pins. switches the address -line multi- (sixteen 128 byte sectors yields the microprocessor runs and yet In SC84 an inverted read signal plexer and a yet further delayed the 2Kbyte of page/track) and minimal control signals are rather than the conventional one acts as the conventional CAS. zero offset, i.e. no tracks required. write one was used as the write Note that these signals are all reserved for system use as you Component ICI buffers the data strobe to the memories. The gated with the original one so that would never boot the system bus to and from the host system. advantage of this is that an 'early all signals go to their inactive from a silicon disc! Other para- It is permanently active and nor- write' is always generated. This state promptly at the end of the meters are by choice, although mally faces off the system bus type of write cycle is particularly memory cycle. the system uses a block and 16 toward the silicon disc. Page useful in that the write operation The memory control signal checked directory entries. ELECTRONICS & WIRELESS WORLD OCTOBER 1985 93

www.americanradiohistory.com ADVANCED LOW COST INirelésswörld SPECTRUM ANALYSER EDITORIAL FEATURES 1985/86 ISSUE íl: ___a PUBLICATION DATE DATE FEATURE a.- ...

*us ii is is Nov. 1985 Oct. 16th Modems Jan. 1986 Dec. 19th A to D & D to A Converters THE IFR A-7550 SPECTRUM ANALYSER Mar. 1985 Feb. 20th Computer Aided The A-7550 Spectrum Analyser is the most advanced, low cost portable Design spectrum analyser on the market today. Two powerful microprocessors, menu driven display modes and single function keyboard entry aid the user Equipment in the operation of all analyser functions. To further enhance the operational simplicity of the A-7550, the microprocessor system automatically selects May 1986 April 17th Fibre Optics and optimises the analyser's bandwidth, sweep rate, centre frequency dis- play resolution and the rate of the frequency slewing keys. An operator over- ride is also provided when non-standard settings are required. TO LEARN MORE ABOUTTHE A -7550's IMPRESSIVE RANGE OF FEATURES, CONTACT US TODAY. For more details regarding Fieldtech Heathrow Limited, advertising Huntavia House, 420, Bath Road, Fieldtech Longford, Middlesex, UB7 OLL. England. y_ Contact Bob Nibbs Heathrow Telephone: 01-897 6446 ï%lnüg Telex: 23734 FLDTEC G 01-661 3130

CIRCLE 13 FOR FURTHER DETAILS.

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ELECTRONICS & WIRELESS WORLD OCTOBER 1985

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DISPLAYED APPOINTMENTS VACANT: £21 per single col. centimetre (min. 3cm). Advertisements LINE advertisements (run on): £4.50 per line, minimum £30 (prepayable). accepted up to 12 noon BOX NUMBERS: £7 extra. (Replies should be addressed to the Box Number in the advertisement, c/o Quadrant House, The Quadrant. Sutton, Surrey SM2 4AS). October 1for November PHONE: IAN FAUX, 01 661 3033 (DIRECT LINE) issue 15% VALUE ADDED TAX NOT INCLUDED 1 Cheques and Postal Orders payable to BUSINESS PRESS INTERNATIONALLTD. and crossed.

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Professional Career Opportunities The Easy Way to look for your new job from the comfort of your own armchair. Our well qualified consultants will carefully match your requirements against vacancies. appropriate TAME (Mr/Miss/Mrs) We have many clients seeking Engineers and Technicians at all levels and we are particularly interested in hearing from you if you have experience in the following:- ADDRESS Signal Processing Technical Sales ATE Programming Radar Systems RF Development Real Time Software Your next step is to complete and return the attached coupon or POST CODE telephone John Prodger on 0442 47311 or one of our duty consultants on 0442 212650 during eve-ings or weekends. TEL NO

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ELECTRONICS & WIRELESS WORLD OCTOBER 1985

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r- CAPITAL APPOINTMENTS LTD CUT THIS OUT! THE UK's No.1 ELECTRONICS AGENCY Clip this advert and you can stop hunting for your next If you have HNC/TEC or higher qualifications and are technical appointment. We have a wide selection of the best looking for a job in design, test, customer service, appointments in Digital, Analogue, RF, Microwave, Micro- sales or similar fields: processor, Computer, Data Comms and Medical Telephone now for our free jobs list Electronics, and we're here to serve your interests. We have vacancies In all areas of the UK Field Call us now for posts in Design, Test, Sales or Service, Salaries to £15,000 pa at all levels from £6,000 - £18,000. 01 808 3050 1 (24hours) `Technomar& 1 Engineering & Technical Recruitment 1 CAPITAL APPOINTMENTS LTD 11 Westbourne Grove, London W2. Tel: 01-229 9239. 76 WILLOUGHBY LANE, LONDON N17 OSF 2 u (1935) 1 I------gla

Telecommunications Engineering Technicians Openings in Servicing and Maintenance ;"3`'?l Up to £9,317 r__ Our business is to install and maintain the communications equipment used by the Police and Fire Brigades in England and Wales - some of the latest you will find in operation anywhere. We have a number of vacancies Some at our Service Centres in various parts travelling of the country for Telecommunications will normally Engineering Technicians with practical be involved. skills in locating and diagnosing faults Registered disabled persons can of in a wide range of equipment from course apply. computer-based data transmission to The Home Office is an equal FM and AM radio systems. opportunities employer. The work provides excellent Salary will be on a scale £6,810 for extending your opportunities to £9,317 a year with generous leave with technical expertise, specialised allowance and pension scheme. courses and training to keep you up to date on developments and new Good prospects for promotion. equipment. There are also opportunities If you are interested in work- for day release to gain higher ing with us, please write for further qualifications. details and application forms quoting Applicants, male or female, reference WW/9 to: Miss M must be qualified to at least City & Andrews, Home Office, Directorate Guilds Intermediate Telecommuni- of Telecommunications, Horse - cations standard and possess a ferry House, Dean Ryle Street, current driving licence. London SW 1 P 2AW.

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u; ELECTRONICS & WIRELESS WORLD OCTOBER 1985

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SEEKS AN ENGINEER

QUALIFIED to HNC/HNC to varied Electronic perform Engineers - tasks in a friendly and challenging environment. ILR2 salary plus shift allowance. Whatyou want, where you want! Apply:- Chief Engineer, Piccadilly Radio, TJB Electrotechnical is a P.O. Boo 261, Personnel Services specialised appointments Manchester. service for electrical and electronic engineers. We have clients throughout M60 10U. PICCADILLY RADIO the UK who urgently need technical staff at all levels from Junior Technician to Senior Management. Vacancies exist in all branches of electronics and An Equal Opportunities Employer (43) allied disciplines - right through from design to marketing - at salary levels from around £6,000 -f20,000. OLYMPUS CAMERAS If you wish to make the most of your qualifications and experience and move another rung or two up the ladder we will be pleased to help you. require Technicians All applications are treated in strict confidence and there is no danger of

Olympus Optical Co (L IK) I -td, the your present employer (or other companies you specify) being made aware UK's largest distributor of 35mm of your application. cameras, requires additional technicians for their rapidly expanding micro digital product range. The ideal applicant should be self TJB ELECTROTECHNICAL Please send me a TJB Appointments Registration form: motivated and capable of working PERSONNEL SERVICES, under pressure with time ability to pre- 12 Mount Ephraim, Name pare training courses. Tunbridge Wells, Benefits are all that would be Address expected of a large multinational Com- Kent. TN4 8AS. pany: good salary, non-contributory pension scheme, lite assurance and Tel: 0892 39388 HI. TA. (861) (24 Hour Answering Service) Please telephone Mrs Jane Rockel for an application town and further information on 01-253 0513. OLYMPUS (54)

THE OPEN UNIVERSITY PENRHOS ELECTRONICS LTD in collaboration with BRITISH TELECOM COMPUTERISED AND Faculty of Technology PROGRAMMABLE CONTROL PENRHOS FOR INDUSTRY

RESEARCH FELLOW A GROUND FLOOR OPPORTUNITY EXISTS FOR COMPUTER AIDED FILTER DESIGN PRODUCTION ENGINEER Applications are invited for the three year post of Research Fellow, to work in the Electronics Discipline at the Open University on a SERC Collaborative Research Programme with British Telecom Research I. Qualifications - Micro Electronics HNC/D or Degree. Laboratories entitled 'A comprehensive Computer Aided Filter Design 2. Experience 2/3 years Z80, Motor Rola, 6,8000, System'. The System will be based on a DEC Vax Station Computer, Assembler, C,. together with a wide range of input/output devices. Penrhos Electronics is a fast growing company with a We are seeking applicants with a PhD in Electronics, Computer Science - a or a related area, and a background or interest in one or more of the World wide market. We require hardworking, ambitious areas of Computer Aided Circuit Design, Electronic Filter Design, engineer who would have his sights set on the Numerical Methods, Software (C,Fortran under Unix), and Man - * Technical Directors job * at the outset he would take Machine Interfaces. charge of a small team and be responsible for taking designs An appointment will be made on the Research Fellow I A scale, and modifications through prototype trials into currently £7520 to £ 12150; with an initial starting salary of up to £8920. productions. The post is available from 1st October 1985. Further particulars and an application form can be obtained from: Salary initially £8-11K with sizable increments on Miss M. Fordham (4867/2), Faculty of Technology, progress. The Open University, Walton Hall, Milton Keynes, MK7 6AA, or Telephone Milton Keynes (0908) 653941: Please reply in writing to: C.M. Griffiths, Managing There is a 24 hour answering service on 653868. Director, Penrhos Electronics Ltd, Westfields Trading Closing date for applications: 7 October 1985 (41) Estate, Grandstand Road, Hereford, HR4 9PA. (42)

ELECTRONICS & WIRELESS WORLD OCTOBER 1985 97

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Brighton THE START Heath Authority. OF Chailey Heritage Hospital. SOMETHING Rehabilitation Engineering Unit. NEW Medical Physics Technician If you are leaving College and planning a career in modern communications or if your present job lacks interest and Grade Ill or II.With a background in electronic challenge why not join us in GCHQ? and mechanical engineering to join an enthusiastic We are recruiting research team on a Spastics Society funded research project concerned with the development and duplication of special switches and interfaces for electronic aids and RADIO OFFICERS microcomputers for the severely disabled. This is a new who are after initial training will become members of an post, initially for three years. organisation that is in the forefront of communications technology. Government Communications Salary according to age, qualifications and experience on a Headquarters scale £6408-£9627. can offer you a satisfying and rewarding career in the wide field of communications. Training involves a 32 week Closing date for return of application forms is 31st October. course (38 weeks if you come straight from Nautical College) Further information and from: which will fit you for appointment to RADIO application forms OFFICER. Dr C.E.E. Senior Research Thornett, Scientist, or: Not only will the Mr R.L. Nelham, Technical Director, you find work as an R 0 extremely Rehabilitation interesting but there Engineering Unit, Chailey Heritage Hospital, North Chailey, are also good prospects for promotion opportunities for overseas travel and a good Lewes, Sussex, BN8 4EF. Tel. 082-572-2112 Ext 99. (46) salary. Add to this the security of working for an important Government Department and you could really have the start of something new. The basic requirement for the job is 2 years radio operating VIDEO SERVICE ENGINEER experience or hold a PMG, MPT or MRGC or be about to FOR obtain a MRGC. Registered disabled people are welcome to INDUSTRIAL VIDEO apply. EQUIPMENT - Salaries start at £4,988 at age 19 to £6,028 at age 25 and FARNHAM, SURREY. over during training and then £6,832 at 19 to £8,915 at 25 and over as a Radio Officer. Increments then follow annually to £12,328 inclusive of shift and weekend working E.S. Video have a vacancy for an engineer with service allowances. experience on low band `U'Matic equipment, Industrial V.H.S., single and three tube cameras. For full details and application form phone 0242 32912/3 or write to: _ The Recruitment Office A/1108 Attractive negotiable salery with car allowence and Free BUPA. - Priors Road CHELTENHAM (2806) Write with full details to: - Glos GL52 5AJ

Mr R N Woodward, E.S. Video, 5 Mead Lane, Farnham, Surrey. GU9 7DY 140)

pleasant, the surroundings are attractive, and the career COMMUNICATIONS prospects are excellent. Ideally we're looking for men and women who DESIGN have studied electronics or electronics related subjects to degree level w equivalent and have had some experience FROM START... of design, whether obtained at work or through hobby activities. Appointments will be made as Higher Scientific Officer (£7,435-£lO,O39) or Scientific ( )dicer (£5,909- £8,153) according to qualifications and experience.

For further details please write to the address givct i At 11.N1. Government Communications Centre below. It would be particularly helpful if an outline of we're using the very latest ideas in electronics technology your personal interests and practical experience could to design and develop sophisticated communications be included. systems and installations for special Government needs The Recruitment Officer, HMG(:(:, Hanslope Park, at home and overseas. Buckinghamshire MK19 7BH. With full technical support làcilities on hand, it's an environment where you can see your ideas progress tin initial concepts through prototype construction, test and evaluation, to the pre -production phase, with a ... TO FINISH chance to influence every stage. Working conditions are (2523)

98 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

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CLIVEDEN TEST ENGINEERS For full systems test on data - communications networks £8,000 + Wokingham SERVICE FIELD SERVICE ENGINEERS USA training on ATE systems. Suit experienced repair technician. £10,000 + car Woking TECHNICIAN ENGINEER To maintain VAX PDP11 & flight ENGINEER simulation systems. to £11,000 Middlesex TEST ENGINEER IN-HOUSE ELECTRONICS Fault -find data-proocessing equipment to componant level. Some systems involvement. Harpenden, Herts c£10,500 Herts. SERVICE ENGINEER Tektronix is at the forefront of innovative technology in electronics Mobile radiocommunications with an extensive product range unequalled in the industry. equipment. We have an opening for a Service Engineer to work in-house in our £8,000 + car Hants. & Central London Harpenden office. Working as part of a highly skilled team this represents an excellent opportunity to develop your knowledge of FIELD SERVICE ENGINEER electronics, and apply it our most in-house Digital/fibre optic communications to sophisticated range of network. Full training provided. test and measurement equipment. £12,000 + car S.E.London You should have a good practical knowledge of analogue techniques Phone/write/call Roger Howard C. and circuit theory, plus the ability to fault -find down to component MIEE, Cliveden Technical Recruitment level. If you can also bring some knowledge of digital techniques so Consultants, 92 The Broadway, much the better but this is not essential. Bracknell, Berks RG12 1AR. Tel: Bracknell (0344) 489489 (six lines) We offer a competitive salary, enhanced by a profit share scheme and (2598) fringe benefits. Excellent product and skills training is offered and there is good opportunity to advance within the company as we continue to grow and diversify. For more information and an application form, please contact Sue James, Human Resources Department, Tektronix (UK) Ltd, Fourth Avenue, Globe Park, Marlow, Bucks. VIDEO Telephone: Marlow (06284) 6000. ENGINEERING CO OPERATIVE Seeks 3rd full time engineer for

91111111111 II interesting and varied work in the independent and commercial sectors. Téktronix® S.A.E. for further details 11 11 111i1i , COMMITTED iO EX( El _EN( to: VET Ltd. c/o S.C.D.A. 135 Rye Lane, London SE15. (59) (44)

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ROYAL HOLLOWAY AND BEDFORD NEW COLLEGE UNIVERSITY OF PAPUA NEW GUINEA UNIVERSITY OF TECHNOLOGY Egham Hill, Egham, Surrey. TW20 OEX SUSSEX DEPARTMENT OF ELECTRICAL AND DEPARTMENT OF PHYSICS COMMUNICATION ENGINEERING 2 Grade 5 Technicians required for this ELECTRONICS TECHNICIAN (M/F) recently expanded department. SENIOR TECHNICAL INSTRUCTOR One to assist with the research into In the Psychology Laboratory in the nuclear Applications are invited for the post of Senior Technical Instructor, which will and microwave physices or Arts and Social Studies Area. In the crystallography be available from January 1986. Candidates should have a higher certificate/ and solid state first instance this will be a temporary spectroscopy. diploma/degree qualification and relevant industrial experience. appointment with a possibility of being One to assist in the running of the made permanent. Duties will include Preference will be given to candidates with teaching experience/ large undergraduate laboratories in maintenance and repair of computer qualifications and experience in communications systems or broadcasting. the modem Tolansky building. terminals and printers, installation and SALERY: Senior Technical Instuctor I K17,555 per annum, Senior Technical Applicants should be qualified in checking of wiring, installation of com- Instructor II K19,405 per annum (K1=Stg. 0.7215 approx), level of physics, applied physics or electronics puters, ordering and keeping stock of appointment depending on qualifications and experience. and have some laboratory or workshop spare parts. An interest in computing is experience. Applicants without desirable. experience would be appointed at a The initial contract period is for three years. Other benefits include a gratuity of 24% taxed at 2%. Appointment and repatriation fares for the staff member and family after lower grade and be instructed in Salary within Grade 4 - £6,106 to £7, 024 per annum (pay award pendiing), 18 months of service, settling -in and settling -out allowances, six weeks paid leave per laboratory techniques. year, education fares and assistance benefit schemes are available. according to age Salary on the scale £7101 - £8204 and experience. Detailed applications (two copies) with curriculum vitae together with the names inclusive of London allowance. Application form from: and addresses of three referees, and indicating earliest availability to táke up appointment, should received by: THE Please apply in writing stating age, Personnel Office, Sussex House, be REGISTRAR, PAPUA NEW GUINEA UNIVERSITY of TECHNOLOGY, Private Mail Bag, Lae, Papua new Guinea, by 11 qualifications and experience together University of Sussex, Falmer, October 1985 Applicants resident in the United Kingdom should with the names and addresses of two also send one copy to Brighton BN1 9RH. the Association of Commonwealth Universities (Appts.), 36 Gordon Square, London referees to:- the Personnel Officer. Closing date 18 October 1985. (47) WC1H OPF, from whom further general information may be obtained. (39) (60)

ELECTRONICS & WIRELESS WORLD OCTOBER 1985 99

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Services Sound and Vision Corporation Assistant Chief Engineer Product (UK & Overseas) Development Based at Chalfont Grove and reporting to the Chief Engineer (UK and Overseas) the main duties will include: Assisting in the day-to-day general and technical administration of Engineers UK non broadcast engineering staff. Dolby Laboratories, famous for its audio noise Recruitment and training of non broadcast engineers. reduction systems, was founded by an engineer. Administration and supervision of the general office for A company that believes in engineers and engineering department UK. engineering, we are small enough for individual Co-ordination and liaison with equipment manufacturers regarding contributions to be recognised yet well Post Design Services activity and equipment assessment. established with the resources to implement and Deputise for the Chief Engineer (UK and Overseas) in his absence. capitalize on innovations. We are looking for Senior and Junior Engineers, This is a managerial position and in addition to a competitive salary a who are probably electronics graduates, to staff a corporation car is provided which is available for personal use. Five weeks and two days annual leave. Good pension scheme and life new Product Development Section in the UK. assurance. Group BUPA scheme available. Reporting to the Managing Director, the group Applications are invited from suitably qualified personnel with at least will be responsible for translating agreed product 5 years experience of technical support for electronics or electro- 'outlines' into manufacturable units. The mechanical equipment at least 2 years of which should be in a emphasis is on creative engineering and design. supervisory or managerial capacity. Salaries will be competitive. Please apply to Mrs. D.B. Trigg, Personnel Manager, The Services Sound and Vision Corporation, Chalfont Grove, Gerrards For more information contact: Cross, Bucks SL9 8TN. Telephone: Chalfont St. Giles 4461. (49) Gary Holt, Dolby Laboratories Inc., 346 Clapham Road, London SW9 9AP 01-720 1111 (45) Dolby WANTED

RESILIENT BROADCAST ENGINEER ELECTRONIC DESIGN ENGINEER Pearpoint Ltd is emerging as one of the country's leaders in solid state area imag- ing techniques. To operate 20 Kw AM & FM Transmitters for "The Voice of To complement our ever expanding committment to new product development Peace" aboard the Peace ship in the Mediterranean. we are seeking to recruit a first class electronics design engineer. A thorough knowledge of the design and implementation of the latest digital electronics tech- Applications, including C.V. to: niques, coupled with an ability to understand the analogue aspects of the work would be a requirement of this post. The voice Peace, P.O. Box 4399, of Tel Aviv, Israel It is considered that candidates should possess the minimum of a 2nd Class Or call Israel (010 972) 03 245 560. Honours Degree in Electronic Engineering or a similar discipline. Renumeration will be by way of a first class salary and other fringe benefits. The company will shortly be moving to a greenfield development site in Alton, (37) Hampshire and would consider relocating a suitable applicant to the area. Please apply in the first instance to: Mr. A.K. Sefton Pearpoint Ltd 32 Woolmer Trading Estate SERVICES SOUND AND VISION CORPORATION Bordon ¢orpoint Hants GU35 9QF (50) VIDEO TECHNICIAN FOR WESTERN EUROPE An experienced and suitably qualified Video Technician is required to work in and around Dusseldorf, West Germany. Responsibilities will include the service and repair of video equipment (predominantly RED ROSE RADIO P.L.C. domestic) in our workshop in Dusseldorf with on -site along some visits The independent Local Radio Station for to areas in West Dusseldorf. FOR YOUR Lancashire has a vancancy for an A car is provided with this appointment. Engineer, Grade ILR2.

The successful applicant will enjoy a CLASSIFIED VIDEO ENGINEER wide variety of work including project design and development, technical FOR WESTERN EUROPE maintenance and Studio and Outside ADVERTS Broadcast operations. An experienced and suitably qualified Video Engineer is required for work in our workshop in Minden, West Germany. Responsibilities will Applicants should be qualified to PHONE include the repair and service of video equipment both domestic and Degree/HNO level in Electronics and have industrial with some on -site service calls. experience in broadcasting or a related The successful applicant should possess a good working knowledge of field. A clean driving licence is essential. 01 661 3033 U'matic V.C.R's and 3 tube colour cameras. Salary is in accordance with current ACTT Good salaries paid to right applicants. Please write or telephone for an rates. Apply in writing, including a full (IAN FAUX) application form to: C.V. to:- Dave Cockram, Chief Engineer, Mrs. A.R. Sive, Personnel Officer, Red Rose Radio PLC., P.O. Box 301, The Services Sound and Vision Corporations, St. Paul's Square, Preston. PR1 1YE. (38) Chalfont Grove, Gerrards Cross, Bucks SL9 STN. Tel: Chalfont St. Giles 4461 Ext. 221. (48)

100 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com Appointments r - i ELECTRONICS/SOFTWARE SOUTH PACIFIC i JOB OPPORTUNITIES i TECHNICAL AUTHORS PAPUA NEW GUINEA Howard Engineers produce maintenance and user manuals, to a high standard, for a wide variety of products, from large PAPUA NEW GUINEA ielectronics systems to software for personal computers. DEPARTMENT OF CIVIL AVIATION GROUND FACILITIES DIVISION We currently have vacancies for both trainee and experienced I Technical Authors. The work involves liaison with our clients, developing a detailed understanding of the product, REQUIRES- I organising and writing the handbook and co-ordinating the CHIEF ENGINEER . production of the finished text and illustrations. Ref No VIS/CAP,;

Prospective trainees should have a sound knowledge of SENIOR ENGINEERS electronics or computer software, acquired from format RADIO AND ELECTRICAL I education, job experience or a serious leisure activity, plus the Ref No. VIS/CN54 ability to express themselves concisely in the written word. TELECOMMUNICATIONS AND ELECTRICAL The company offers varied and interesting work, a pleasant TECHNICIANS I working enivironment and a salary commensurate with your Ref. No. VIS/CAJ56 knowledge and experience. TECHNICAL INSTRUCTERS RADIO ELECTRICAL Vacancies exist at our Gosport, Southampton and Wokingham AND offices. Apply in the first instance to: Ref. No. VIS/CA/56 DRAFTSMEN ELECTRONIC AND ELECTRICAL Ref No VIS,'CA/57 Carolyn Hatch HOWARD ENGINEERS LTD SALARY PACKAGE Grosvenor House Cumberland Place Engineers C£23000 - £24200 Southampton Technicians, Instructers and Draftsmen C£18000 - £22000 Hampshire 5O12BD BENEFITS Tel: (0703) 334332 Three year contract with possiblity of renewal. Free MARRIED/SINGLE accommodation. Six weeks annual leave. Return leave fare once per contract.

n, i EXPERIENCE Extensive background in Aviation Ground Facilities preferred. May consider those from allied areas if they have proven staff management and training experience particularly in a developing country. QUALIFICATIONS LOUDSPEAKERS Degree, HNC/ONC or equivalant. STEYNING SUSSEX Closing date for applications 20th September 1985 For full details and application forms please write or telephone the Recruitment Rare opportunities to join our progressive Dept. Papua New Guinea High Commission, research team developing high -end audio 14 Waterloo Place, London SW1 R 4AR. Telephone:01-930 products. 0922 Telex:Kundu 25827 n/ SENIOR PROJECT ENGINEER Candidates should have a good degree and at Inner London Education Authority least five years R&D experience in high quality drivers and loudspeaker systems, and be LEARNING RESOURCES BRANCH, capable of original thinking as well as following Production Division, projects through to conclusion. Television and Publishing Centre, Thackeray Road, AUDIO ENGINEER London SW8 3TB To work with Project Engineers in developing high TELEVISION ENGINEER quality drivers and systems. Some previous for Master Control Section (ST1/2) experience is desirable, but graduates will be This post is involved with the bulk production of colour videocassettes considered depending on ability and initiative. from 1" Ampex submasters. The successful candidate will be expected to operate the 1" machine, Working conditions are extemely pleasant, complete cassette machines (VHS, Betamax and U-matic) and label and check copies. He/she will have a good working knowledge with computer and laser interferometry facilities. of colour television principles and suitable experience and/or technical BUPA membership, canteen and other fringe background. benefits. Salary commensurate with ability/ Salary within the scale £6222 to £9327 + £1494 London Weighting experience. We are looking for dedication and Allowance. Further details, including full job description and application ambition recognising success with a bonus scheme. forms from EO/Estab 1B, Room 366, The County Hall, London SEI 7PB. (Please Please apply initialty in writing to the Managing Director enclose SA.E.) The closing date for completed application forms is B&W LOUDSPEAKERS LTD 30.9.85. This post is suitable for Job -share. Elm Grove Lane, Steyning, West Sussex nNa 3SA 1f ) This is a re -advertisement. ILEA IS AN EQUAL OPPORTUNITIES EMPLOYER. (16)

ELECTRONICS & WIRELESS WORLD OCTOBER 1985 101

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ARTICLES FOR SALE WANTED

Light beam modulation - mirror microgalvos. res.freq. 1625 £29.data £2. Marconi TF.1041 B. LINSLEY HOOD DESIGNS £69. Valves 3D22 £10, 5B254M £5. EHT Amplifiers Signal Generators WOUND COMPONENTS * MICROCOMPUTERS capacitors 6Kv, 680pí 75p ea. LCR Bridges. 0.1 °,a Complete custom built service for or wide -range £98. Tape speed stroboscope THD Analyser Millivoltmeter * PERIPHERALS £7.50. Radio frequency adaptor with probe for Details from: air core, self bonded, miniature Avo -8 £15'. Marconi TF 890 £65. Siemens ferrite wound components for * INSTRUMENTATION fault locator, multi -channel £45. Micro - TELERADIO ELECTRONICS electronic transformers, inductors, chokes etc. For fastest, best CASH offer, phone, spot welding heads £55. Kent Chromalog 2 £75. 325 Fore Street, Edmonton, Beckman Hydrogen lamp POWER SUPPLY £50. Write or phone COMPUTER APPRECIATION Tektronix Time -mark Calibrator £79. Hoffman London. N.9. OPE. Dynamic Balence Machine, electronic & Tayside Audio (Scotland) Ltd Oxford (0865) 55163 mechanical units £85. Low pressure regulators 0 (24) Unit 1, Dunsinane Ave Telex 838750 -100mBar £15. Quantity Ferrograph spares £75. Dundee D02 30N (2492) FM/AM generator. Pulse Sweep generators, Tel (0382) Tlx 76137 generator. Marconi Test Modulator HO 72 £59. 819997 Resistance/capacitance boxes. Variable standard LITESOLD SOLDERMATIC wave soldering (56) capacitors. Centrifuge. Marconi Noise Receiver TF machine - model 800, with 90 Kg of solder. 1225.A. £65. ph, Temperature & Fluoride -ion Complete with sturdy purpose made bench Excellent condition. £2500. electrodes Very large stepper motors suitable for When replying to classified power robotics etc.. £45 ea. Quantity of Tel: (05036) 2013. (53) chemicals, reagents, metals, electroplating etc GRUNDIG COMMUNICATION RECEIVER advertisements, readersare Mazda Sodium Lamp £5. VHF Frequency Standard Satellite £600 prof. Hardly used Superb Global Latest model 1984 £280.00 Ring £45. Three new automobile products. electronic, QUARTZ CRYSTALS OSCILLATORS AND Reception. recommended to take Carlos Olms 01 - 499 1673 after 6p.m. or steps mechanical and chemical, prototype stage easy & FILTERS of all types. Large stocks of standard weekend. (56) cheap to manufacture. etc. etc. items. Specials supplied to order. Personal and to protect their interests 040 - 376236 (2016) export orders weh umed - SAE for lists please. OEM support thru:- design advice, prototype before sending money WAVEGUIDE, Flanges and dishes. All standard quantities. production schedules. TEKTRONIX DAS 9109 sizes and alloys (new material only) from stock. Golledge Electronics. Merriott. Somerset TA16 (2519) 0010 LOGIC Special sizes to order. Earth Stations, 01-228 5NS. Tel: 73718 124721 ANALYSER OPTION A2, 01, 02 7876, 22 Howie Street. London SW 114AR.(2099) with 91 P16 Pattern Generator, 91A32 Acquisition and TO MANUFACTURERS, WHOLESALERS all probes. BULK BUYERS. ETC. £15,000 ono. E C COMPONENTS Phone: 099 389 8282 ext 155 We buy large and small parcels LARGE QUANTITIES OF RADIO. TV AND of surplus I/C, transistors, capa- (51) citors and related electronic ELECTRONIC COMPONENTS FOR DISPOSAL stock. Immediate settlement. SEMICONDUCTORS, all types, INTEGRATED CIRCUITS, TRANSISTORS, Tel: 01-208 0766 DIODES, RECTIFIERS, THYRISTORS, etc. RESISTORS, C/F, M/F, W/W, etc. FM & MW BROADCAST Telex: 8814998 CAPACITORS, SILVER MICA, POLYSTYRENE, C280, C296, DISC EQUIPMENT (2491) CERAMICS, PLATE CERAMICS, etc. ELECTROLYTIC CONDENSERS, SPEAKERS, CONNECTING WIRE, CABLES, A special range of high quality SCREENED WIRE, SCREWS, NUTS, CHOKES, TRANSFORMERS, etc. transmitters, power amplifiers, ALL AT KNOCKOUT PRICES - Come and pay us a visit ALADDIN'S CAVE stereo encoders, UHF repeater STEWART OF READING TELEPHONE: 445 0749/445 2713 links, compressors, antennas. 110 WYKEHAM ROAD R. HENSON LTD. Powers 10w to 1kw. READING RG6 1PL 21 Lodge Lane, North Finchley, London, N.12 Built to high specifications at an TEL NO: 0734 68041 (5 minutes from Tally Ho Corner) (16131 economic price. Meets IBA & Home TOP PRICES PAID FOR VARIOUS P.C.B's Chassis disk drives and cables Office specifications. G.W.M. RADIO ALL TYPES OF SURPLUS LTD. 40/42 Portland Road, for data general Nova 820 family of computers. Worthing, TEST EQUIPMENT Sussex. Tel: 0903 34897. Marconi Tel: 01-328 7987. (21) Full catalogue available. Atalanta Communication Receivers £25. Suitable COMPUTER EQUIPMENT, spares or re -build. Buyer collects. A. V.O. 8 with BRIDGES waveform/transistor analys- Cyberscan International, 3 Eastcote COMPONENTS etc. case and leads £70 inc. A.V.O. 7 no case £35 inc. ers. Calibrators, Standards. Millivoltme- ANY QUANTITY (52) Advance Signal Generator]-lA 15c/s - 50Kc/s View, Pinner, Middx HA5 1AT. £25 inc. Wayne Kerr Universal Bridge Type CT492 ters. Dynamometers. KW meters. Oscillo- Tel: 01-866 3300 (33) £80 inc.p+p. All prices include VAT. Satisfaction scopes. Recorders. Signal generators - guaranteed. (55) sweep, low distortion, true RMS, audio, TURN YOUR SURPLUS i.cs transistors RM, deviation. Tel. 040 376236. (2616) etc. into cash, immediate settlement. We also welcome the opportunity to quote for OPPORTUNITIES IN complete factory clearance. Contact THE SOUTH EAST COLES -HARDING & CO, 103 South Brink, Wisbech, Cambs. 0945 Sales Executives 584188. (9509) 10.6k basic + 6k OTE + car. More Sell Telecom Equipment in the city and N.W.London WANTED Test Engineers c9.5k SURPLUS ELECTRONIC COMPONENTS AND Hi -Tech Jobs All rounder with Analog Digital and some Microwave experience. Working In-house. EQUIPMENT Service Engineer We also welcome the opportunity to quote for £8000 - £_0,000 complete factory clearance c8k. B. BAMBER ELECTRONICS As a leading recruitment consultancy we have a wide Experience on Micro Processor Equipment to 5 STATION ROAD, LITTLEPORT, CAMBS. selection of opportunities for high calibre Design, Development, component level working In-house and in the Phone: Ely (03531860185 Systems and supporting staff throughout the UK. field. 2483) If you have experience in any of the following then you should In-house repair and systems support be talking to us for your next career move. vacancies. Salary Neg. Working for a ARTIFICIAL INTELLIGENCE IMAGE PROCESSING leading Dato Comms Company. MICRO HARDWARE & SOFTWARE GUIDED WEAPONS Field Service Engineer OPERATIONAL RESEARCH RF & MICROWAVE OPTICS WANTED MATHEMATICAL MODELLING SIMULATION C' c8k + car. HIGH To service and repair Micro Computers in the Test equipment, receivers, LEVEL PROGRAMMING SYSTEMS ENGINEERING field. ACOUSTICS & SONAR FLUID DYNAMICS RADAR valves, transmitters, com- SATELLITES AVIONICS CONTROL ANTENNA Technical Support ponents, cable and Opportunities exist with National, International and 10k plus. electronic scrap and quan- consultancy companies offering excellent salaries and career Supplying Technical Support to customers on tity. Prompt service and advancement. Digital Hardware cash. Member of A.R.R.A. For Free and Confidential career guidance call John Spencer Plus wide range of other Design Servicing or send a detailed C.V.. Please quote and Tech Support vacancies. reference WW/3. M&BRADIO c.V.'s to: 86 Bishopsgate Street Skyquip Technical Services Ian Darch, Leeds LS1 4BB 85 High Street, Winchester Hampshire. 5023 9AP Garnet Professional Services (AGY) 0532 435649 Tel: Winchester (0962) 69478 (24 hours) (2579) 10 Queen Victoria Street, Reading. or Tel: Reading (07341 588685 19956) TiSig.( t,dnt ref rurtrnent for Aerosace. Defence 8 Communications Industries (3)

11)2 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com Classified

SERVICES

CIRCOLEC HAVING DESIGN PROBLEMS? THE COMPLETE ELECTRONIC SERVICE THEN CONTACT OUR SOLUTIONS DEPT Artwork, Circuit Design, PCB Assembly, Test & Repair Service, Q.A. ANALOGUE 8 DIGITAL DESIGN - C.A.D. Consultancy, Prototypes, Final Assembly. Full PCB Flow Soldering PHONE 03E16-B32152J Service. IDESelfeLTV Quality workmansiip by professionals at economic prices. Please telephone G1-646 5686 for advice or further details. f8 i OR Williams P.C.B.Artwork, 49IWeetbourne TAMWORTH MANOR SE M Hone baurna, Evssfam, Wores, WRIT 5PT. 302-310 COMMONSIDE EAST, MITCHAM WRITE (1391) tel - 021 - 773 - 0913 DESIGN, DEVELOPMENT AND PRO- Unit A. N.E.W. 272 Montgomery St, TOTYPES. Digital and microprocessor DESIGN AND MANUFACTURE. ANA- Sparkbrook, Birmingham B11 1DS. based equipment our speciality. Proto- SMALL BATCH PCBs, produced from LOGUE, DIGITAL, RF AND MICRO- (2627) types and small batch production under- your artwork, also DIALS. PANELS, LAB- WAVE CIRCUIT AND SYSTEM DESIGN taken to the highest quality and with fast ELS. Camera work undertaken. FAST Also PCB design, mechanical design and turnaround. For details of our hardware TURNAROUND. Details: Orbitechnic Cir- prototype/small batch production. - and software services please contact: IB cuits, 38 Torquay Gardens, Redbridge, Adenmore Limited, 27 Longshot Estate, Electronics, 11 Broomshaw Road, Maid- Essex. IG4 5PT. Tel: 01-550 3610. Bracknell, Berks. Tel: Bracknell (0344) stone, Kent. (2635) (9794) 52023. (656)

cçtget! for your classified adverts (elfljt ring Ian Faux 01 661 3033

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ELECTRONICS & WIRELESS WORLD OCTOBER 1985 103

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GENERATORS TV TESTING: DIGITAL AND ANALOGUE i BLACK STARTHANDAR MULTIMETERS:'SCOPES: CLAMPMETERS: LEADER TRIOSALDETA INSULATION TESTERS: WOW/FLUTTER MULTIMETERS METERS:DISTORTION METERS:FUNCTION THURLBYSOARMETRIX PULSE ANO R -C GENERATORS:LCR BRIDGE: BECKMAN THANOAR DIGITAL CAPACITANCE: MULTIPLEXERS. PLUS LOW COST RANGE LOGIC ANALYSER: LOGIC PROBES: - COUNTERS: POWER SUPPLIES: COUNTERS O TRANSISTOR CHECKERS. ETC. 00 00 THANDAR BLACK STAR POWER SUPPLIES PLUS COMPONENTS: TOOLS: THURLBYPLUS LOW COST COMPUTER SOFTWARE AND RANGE ACCESSORIES: SEMICONDUCTORS: 301 Edgware Road, London W2 01-724 3564 INSTRUMENT HEflRY'8 404 Edgware Road, London W2 01-724 0323 CATALOGUE AUDIO ELECTROf1ICS ACCOUNT AND EXPORT ENQUIRIES 01-258 1831 Write, call in or phone. CIRCLE 118 FOR FURTHER DETAIIS.

N) INDEX TO Wi ele iiórid ADVERTISERS Appointments Vacant Advertisements appear on pages 95-103 PAGE PAGE PAGE Adenmore Ltd 34 Gemini Computer Systems Ltd .... Outside back Pantechnic 79 Advertising Standards Authority 94/89 cover Paxton Instrument 89 Airlink Transformers 26 Gould Electronics Ltd 44 Pineapple Software 80 AM Electronics 72 GNC Electronics 80 PM Components 56, 57 Andelos Systems 72 Powertran Cybernetics 83 Antex Electronics Inside back cover Hameg 55 Protek 39 Aymon Electronics Ltd 38 Happy Memories` 32 PSP Electronics Ltd 20/37 Aspen Electronics Ltd 87 Harris Electronics 34 Harrison Bros. 65 Radiocode Clocks Ltd 38 Bamber, B. Electronics 32 Hart Electronic Kits Ltd 87 Radio Component Specialist 2 Barrie Electronics Ltd 76 Henry's Audio Electronics ' 104 Raedek Electronics 39 Beckenham Peripherals 87 Henson R. Ltd 26 Ralfe Electronics 80 Black Star Ltd 49 Hilomast Ltd 34 Reprints 2 Reticon, EG + G 16 Cambridge Kits 49 ILP Electronics Ltd 68 Cambridge Microprocessor Systems 8 Imhof -Bedco 7 Shackman Instruments 8 Carston Electronics Loose insert Instrument Rentals 37 Sherwood Data Systems 72 Cavendish Automation 50 IQD 55 Sowter, E.A 50 Colomor (Electronics) Ltd 60/72 Spectra Strip 37 Computer Appreciation 26 JDR Sheet Metals 38 Stewart of Reading 60 Costar Ltd 17 Johns Radio 76/79 Surrey Electronics Ltd 65 Cricklewood Electronics Ltd 32 Crotech Instruments Ltd 84 Keithley Instruments Ltd 16 Tape Automation 83 Cybernetic Applications 65 Kemo Ltd 37 Taylor Bros. (Oldham) Ltd 49 Technomatric Ltd 12,13 Dataman Design 67 Langrex Supplies Ltd 33 Tektronix UK Ltd Inside front cover Datapen Microtechnology 87 Levell Electronics 3 Telefusion - Dicon 66 Digitask Business Systems 76 IJ Electronics Ltd - 79 Television 26 Display Electronics 90, 91 Lowe Electronics 2 Thacker, A.H. & Sons 7 Lucas Control Systems Ltd 34 Thandar Electronics 66 Electo -Metric Ltd 92 Thorn EMI Instruments 25 Electronic Brokers 6/10 Micro Concepts 7 Thurlby Electronic Ltd 88 Electroplan Ltd 37 Microlease PLC 37 Timebase 50 Electrovalue 68 Micromake Electronics 66 T K Electronics 68 EMS Mfg Ltd 65 Monolith Electronics 39 Triangle Digital Services 20 Essex Electronics Centre 60 Mowlem Microsystems 37 E & WW Edit. Feature List 94 Vesco 76 Newrad Instrument Cases 49 Vixen Hytech Ltd 84 Field Electric Ltd 20 Number One System 38 Fieldtech Heathrow Ltd 94 Waugh Instruments 7 Fulcrum (Europe) Ltd 2 Olson Electronics Ltd Reader reply card Wings Appeal 89

OVERSEAS ADVERTISEMENT AGENTS Japan: Mr inatsuki, Trade Media - IBPA (Japan), B.212. Azabu Jack Mantel, The Farley Co.. Suite 650. Ranna Building. France and Belgium: Pierre Mussard, 18 - 20 Place de la Heights, 1.5.10 Roppongi, Minato-ku 106. Cleveland, Ohio 4415 - Telephone (216) 621 1919. Madeleine, Paris 75008. Telephone: (03) 585 0581. Ray Rickles, Ray Rickles & Co., P.O. Box 2028, Miami Beach, Florida 33140 - Telephone (305) 532 7301. Hungary: Ms Edit, Bajusz, Hungexpo Advertising Agency, United States of America: Jay Feinnan, Business Press Tim Parks, Ray Rickles & Co., 3116 Maple Drive N.E., Atlanta, Budapest XIV, Varosliget. International Ltd, 205 East 42nd Street, New York, NY 10017 - Georgia 30305. Telephone (404) 237 7432. Telephone: 225 008 - Telex: Budapest 22-4525 Telephone (212) 867-2080 - Telex: 23827. Mike Loughlin Business Press International, 15055, memorial INTFOIRE Jack Farley Jnr., The Farley Coi. Suite 1584, 35 East Walker Ste 119, Houston, Texas - Telephone 1713) 783 8673. Drive, Chicago. Illonois 60601 - Telephone (312) 63074. Canada: Colin H. MacCulloch, International Advertising Italy: Sig C. Epis, Etas -Kompass, S.p.a. - Servizio Estero, Via Victor A. Jauch, Elmatex International, P.O. Box 34607, Los Consultants Ltd., 915 Carlton Tower, 2 Carlton Street, Toronto 2 Mantegna 6, 20154 Milan. Angeles, Calif. 90034, USA - Telephone (213) 821-8581 - - Telephone (416) 364 2269. Telephone: 347051 - Telex: 37342 Kompass. Telex: 18-1059. 'Also subscription agents.

Pnnted in Great Britain by Index Pnnters Ltd.. Oldhill. Dunstable, and typeset by Legendary Characters, South Street, Lancing, for the proprietors, Business Press International. Quadrant House, The Quadrant, Sutton. Surrey SM2 SAS. 2t Business Press International 1985. Wireless World can be obtained abroad from the following: AUSTRALIA and NEW ZEALAND: Gordon & Gotch Ltd. INDIA: A.H. Wheeler & Co. CANADA: The Wm. Dawson Subscription Service Ltd., Gordon & Gotch Ltd. SOUTH AFRICA: Central News Agency Ltd: Willian Dawson & Sons (S.A.) Ltd. UNITED STATES: Eastern News Distribution Inc.. filth Moor. Ill Eighth Avenue. New York, N.Y. IUUII.

104 ELECTRONICS & WIRELESS WORLD OCTOBER 1985

www.americanradiohistory.com . Tomorrows Soldering Technology Today. SKS ANTEX ha; a worldwide repitation for quality & service & for many years SOLDERING KIT has been one of the best known & most popular names in soldering. Always at the forefront of technology, ANTEX is continually researching new and Free 'How To Solder' bookMt and pack of solder better ways pf achieving more accurate, reliable, and cost effective solderirg. 01 ANTEX Soldering Irons, :he advanced design of the interface between the element-& the bit allows more efficient heat transfer to the bit and improved stability of the temperature at the point of contact with the work. Indeed, experiments have shown that an XS25 watt iron can be used for tasks where a 40 watt iron would normally have been required. ANTEX Soi;lering Irons exhibit except onally low leakage currents & heice are suitable 'or use on Static Sensitive Devices. Sophisticated temperature controlled soldering units have recently been added to the ANTEX range.

TCSJ1 Soldering Unit

sK5 Soldering Kit

TCSU-D Temperature -Contro led Soidenng Unit

Model C SK5 Soldering Kit. Contains - 15 Watts. Available for model CS 240v Iron, an ST4 TCSU-D 250, 220, 115,100, 50 or Stand and solder. Model CS -BP Elegant Temperature 24 volts. 17 Watts. SK6 Soldering Kit. Contains - 240 volts, fitted Controlled Soldering Unit with British Plug. Model model XS240v Iron, an ST4 with 50 W Iron (XSD) and / - 25 Watts. Available for Stand and solder. TCSU1 built around EERRANTI / 240, 220, 115, 100, 50, 24 SK5-BP and SK6-BP - Very robust temperature custom-made UtA. Range / or 12 volts. Soldering Kits as above with controlled Soldering Unit, Ambient to 450°C. Acc- Model XS -BP British Plug. with a choice of 30 Watt uracy ± 5°C. Zero / - 25 Watts. 240 volts, fitted (CSTC) Model CS or 40 Watt (XSTC) crossing switching / ca\` with British Plug. -17 Watts. Available for miniature irons. Detachable / 5 / e e5 ST4 Stand 240, 220, 115,'100, 50, 24 Range 65°C to 420°C. sponge Q\¢a5 ,. Paò - To suit all irons. or 12 volts. Accuracy 2% tray. CIRCLE 2 FOR FURTHER INFORMATION

www.americanradiohistory.com PICK AX

Every card's a winner. The versati 80 -Bus system can be used for a host of applications: Process Controle Batch Counting, Robotics, Colour Graphic Displays, CAD/CAM, CNC; In Manufacturing, Telecommunications Instrumentation, Laboratory Testing, Security Systems, Plant Control, Data Collection and Distribution. Also, in smaller companies it can handle Accounts, Payroll, Wordprocessing, Stock Control, Program Compilation and Data Base Management ... whilst still being able to run specialist applications. And because there is no wasted capacity with a Gemini, a system can cost a good deal less than you might think. With Gemini you can buy a complete system, upgrade your existing 80 -Bus system, or build your own. So when you've had a look at the pack of cards below, plug yourself into our dealer network to discover how opening a new pack of cards with Gemini will help

These represent just a small selection from our extensive range of cards. .

GM811 Z80 CPU board with serial and parallel I/O GM844 8 -way Backplane assembly GM813 Z80 CPU board with 64K dynamic RAM, GM845 6 -way Backplane assembly serial and parallel I/O GM846 3 -way Backplane assembly EV814 IEEE 488 interface board GM848 Multiple serial I/O board GM816 Multiple parallel I/O board GM849 Floppy disk controller/SCSI board GM824 8 bit A -D board GM853 Bytewide Eprom board 10828 High resolution colour graphics board GM862 256K dynamic RAM board GM832 Video controller board GM863 Static RAM board GM833 512K RAM-DISK board GM870 Modem board GM836 RS422 network interface GM888 8088 co -processor board GM837 Medium resolution colour graphics board GM839 Prototyping board GM841 Extender board Il Gemini GM842 Trackerball interface Computer Systems Limited Springfield Road, Chesham, Bucks HP5 1PU. CIRCLE 113 FOR FURTHER DETAILS. Telephone: (0494) 791010. Telex: 837788

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