'Review:

double-track disc drives, storing 143 kilobytes per disc. The disc drive mechanisms are very smooth and well Sharp's cut-above-average made, the 70-track format is unusual and non-standard in the U.K. and means that software which might otherwise be MZ-80K hardware regarded as standard, e.g., CP/M-based programs is not directly transportable The Sharp MZ-80K computer was first marketed in the recorder is controlled both by mechanical from other machines to the MZ-80K. keys and the system software. Like all the peripheral units forming U.K. in 1979; before that, it had been available only as a The tape counter is fitted in the cassette STOCK RCOISTÿTTON part of the MZ-80K system, the MZ-80 I/O kit in Japan. In the 18 months the machine has been on recorder and programs or data on the ttoo- AWN***** unit is housed in a smart steel case, sale in Britain, the price for a model equipped with 20K can be located accurately and STOCK €»«iu:»v containing a five-slot mother board and a reasonably quickly using #TO> V*H.U4T1W the fast forward .OUT or tmc* List discrete power supply unit. The mother RAM has substantially r t t««s ens fallen to £380. and rewind controls with the counter. The .outs AMI' . board uses double-sided connectors with .SUPPLICPS IU* data-transfer rate for the recorder is * 30 pins on each side. The pitch of the THE SHARP MZ-80K is advertised widely, The steel case of the computer is impressive it allows the 14 kilobyte connector appears to be 0.125in. a non- often with an emphasis on its suitability strongly constructed with a piano hinge Sharp Basic—tape to be loaded in about 1.5 U.K. standard. The I/O interface— unit is for business or office use. It is also used connecting the upper and lower sections minutes. connected to the MZ-80K by approx¬ for laboratory and industrial process which are normally secured by four On microcomputers, the keyboard and imately 18in. of shielded 50-way ribbon control by firms such as 3D Digital Design screws. The strut supporting the upper the visual display unit are the interface cable. and Development. Three units are section of the computer when it is opened between machine and user. The level of Part of the MZ-80K configuration is a available as part of the MZ-80K package; has a retaining thumbscrew on the lower ambient lighting in an office environ¬ real-time clock which starts counting from an input/output interface unit, a dual leg which can be screwed-in to prevent the ment, the reflections from a VDU screen zero when the machine is switched-on. floppy disc drive and a tractor-feed dot¬ and the angle at which it slopes, the ability The clock can be synchronised with GMT matrix printer. to separate the keyboard from the screen and could be used to control external reputation The commercial of Japanese Dimensions Weight so that a typist or operator can be devices. If personal computers are to very largely MZ-80K 41W 47D firms is based on often clever 28H 13kg comfortable are all important consider¬ continue their present penetration into the precision engineering and high-quality MZ-80IO 20 32 13 5 ations in designing a machine which will MZ-80FD 20 32 20 7 9 home market, it will be because they are MZ-80P3 41 38 19 10 allow a user to operate it for long periods seen to have a useful function around the by John Dawson without fatigue or unnecessary strain. house. Software serial numbers Similarly, a considerable amount of Sharp/Xtal monitor SP 1002 control during production. The ability of work has been done on the ergonomics of The Sharp MZ-80K. Machine durability Japanese ingenious Sharp tape Basic SP 502S the to write software Sharp disc keyboard design and this is apparent now Basic SP 601 S computer is, however, less certain. Xtal CP;M Version 2 21 in both computers and word processors The will have to run con¬ The high-quality engineering in, for Xtal CBasic Version 2 06 1 from firms like IBM and Logica at one tinuously — with tighter electrical- example, the MZ-80K double-track disc Dimensions are quoted in centimeters and end of the scale to more modest machines engineering and safety requirements — if, drives may suggest that the Japanese have exclude cable-bending radii Total power con- Tandy for example, it is to operate a burglar sumption for the four units is given as 2 1 5Watts such as the TRS-80 at the other. sought hardware solutions to compensate Those who use keyboards as part of their alarm, deal with incoming telephone calls, for their software failings. work develop strong preferences and this process the family budget, and act as a Table I. Equipment dimensions. The dimensions, weights and power allows room for variations such as the facsimile transceiver for letters and mail¬ consumption for the review equipment are extended front on the IBM 5120 machine order catalogues. The MZ-80K and its set out in table 1. The review MZ-80K had upper section of the case collapsing on which an operator can rest the palm of peripherals ran continuously for three been fitted with a Xtal CP/M adaptation. accidentally. his hand. These variations are made, days during the review period without The machine consists of four printed The visual display unit produces a however, within well-defined limits of signs of overheating or distress in any of circuit boards; the main CPU board, tape white-on-black image 40 characters wide good design. the units. recorder, keyboard, and visual display by 25 lines deep in an eight-by-eight The keyboard of the MZ-80K is Software has two important parts; the unit/audio frequency amplifier. The CPU format. A wide range of graphics markedly at variance with the rest of the program itself and the accompanying board is the largest and is mounted inside characters are available including elec¬ machine, is outside any concepts of good documentation. Good documentation is the base of the steel case with the other tronic symbols for drawing circuit design and surely can be neither intended not the myth it often seems to be and boards mounted on the upper section of diagrams on screen and a good number of nor used for serious typing. The spacing companies such as Hewlett-Packard, IBM the case. games and general-purpose shapes. The of the keys is the same as an ordinary and Rockwell produce excellent written The power supply is enclosed within a lower-case letters have true descenders offices typewriter 0.75in. from key explanations to support their products. ventilated metal case and is mounted and there is a pseudo-high-resolution centre to key centre— but the relative The U.K. armed forces also understand beside the CPU board. Power is supplied graphics capability which will display 50 positions of the keys—are non-standard the importance of clear, simple and through a two-pin connector which is by 80 pixels. although the board uses a normal concise English in their instruction standard for all the units in the system at Both the stability and definition of the QWERTY lay-out. manuals. the rear of the computer and display excellent, although Comment on the CP/M manuals there is a are there was In particular, the position normally Sharp’s MZ-80 P3 dot-matrix printer. second opening, with a screwed metal some pin-cushion distortion in the picture occupied by the space bar contains the supplied with the Xtal adaptation for the cover, which allows access to a 50-pin symmetry on the review machine, which cursor control, carriage return and insert/ syncrasy whenever text is being entered. the print head to traverse the full width of Sharp should start on a long rising note of Scotchflex connector. The CPU bus is meant that the last six characters on the delete key in addition to a small space key. The MZ-80P3 printer is a tractor-fed the paper and return. hysteria and frustration. The abundance brought out to the connector and is the right-hand side of the bottom line were The key-tops are transparent plastic caps dot-matrix printer capable of handling The print-head prints in one direction of jargon and virtual absence of worked sole signal input and output pathway to almost illegible because they had curved marked with graphics characters as well as paper widths from four to lOin. The only and will produce 80 characters per examples throughout the CP/M the computer the 50 lines are shown off the screen. the alpha-numeric characters. The main normal characters are printed in a six-by- line on lOin. paper. The printer accepts documentation made the system almost diagrammatically— in figure 1. This fault is not apparent on two other alpha-numeric markings do not stand out seven dot format and there are no parallel eight-bit ASCII data and will wholly obscure for a user without access The MZ-80K has a three-octave sound newer MZ-80K machines where the clearly enough which makes identification descenders on lower-case letters. The produce 255 ASCII and graphics to a source of CP/M folklore. generator and a real-time clock which is picture symmetry is good good enough of a particular key more difficult. printer will produce double-width characters. There is an 80-character print Moreover, the CP/M 2.21 version fitted re-set when the machine is switched-on. for you to take direct photographs— of the Under the original Sharp monitor, the characters in a 12-by-seven format and the buffer inside the MZ-80P3 and it is to the MZ-80K is still cluttered with There are pre-set controls for the VDU screen and use them as slides in lectures. keyboard also has non-standard print-head is driven across the paper by a possible to lose the last line of print under sediment from the past. CP/M origin¬ and the volume of the internal loud¬ The cassette tape recorder in the MZ- functions. Lower-case letters are pro¬ peg in a slotted drum. This has the some circumstances in which case it may ated, for example, with machines which speaker mounted on the front edge of the 80K uses a pulse-width modulation duced after the SML/CAP key has been important consequence that the print- be output, disconcertingly, at the top of used Teletypes for input and output. printed circuit board below the VDU. The recording technique and transfers pressed but the comma and full stop keys head must complete a full line’s travel the next print run. Consequently, the delete key on the Sharp CPU board has vacant connections for a information at 1,200 bits per second. A then produce characters with umlaut however short the line printed. In other The MZ-80FD floppy disc unit contains repeats characters entered on a line in re-set switch. mechanical tape counter is fitted and the accents. This is an infuriating idio- words, a line-feed character still requires two 5!4in. single-sided, single-density, (continued on next page)

67 66 PRACTICAL COMPUTING May 1981 PRACTICAL COMPUTING May 1981 Review1

lacking in both the Sharp versions of (continuedfrom previous pane) mnemonics, also denying the use of the Conclusions A | B reverse order, erasing them from the line additional Z-80 specific instructions, Basic. AIS 1 . G The MZ-80K is mechanically and The Sharp Basic manuals are bad memory at the same time. To correct a many of which are particularly powerful. • • AM 2 INT electrically well designed and constructed translations but offer many examples to mistyped letter in the word MUSACBOX, When the disassembler is used to list Z-80 AI3 G with the exception of the keyboard. illustrate individual instructions and you must either delete the whole line or code, it produces the results shown in 3 pro¬ Particularly at discount prices, the gramming techniques. delete and type the following: figure 2 in which the double question AI2 , « MREQ • machine offers an impressive specifica¬ MUSACBOXXOBCA1CBOX marks presumably indicate instructions A 1 I S G The service manuals for the MZ-80K tion. • which is then entered as MUSICBOX. beyond the scope of the disassembler. AI0 6 IORQ and printer are excellent — a stark Although the machine has no inherent The Research Machines CP/M version 1.4 Research Machines, once again, has A9 7 G • contrast — containing fault location input/output capability, the Sharp bus is flowcharts, has a patch which simply erases a letter written a Z-80 assembler called ZASM for A8 8 RD test programs and waveform well buffered and is readily available for when the delete key is presed and I wonder its own CP/M package. I found the A7 9 G illustrations for various test points as well proprietory or home-built expansion as diagrams. how this anachronism has survived into editor program difficult to use and, when A6 10 WiT the usual circuit units. The Sharp machine language manual is the 2.21 version offered by Xtal. I was unable to make one instruction AS 1 1 G • The machine needs a re-set switch for good apart from poor-quality More seriously, the assembler/dis¬ perform any function at all, the manual A4 12 Ml • translation. assembly language and machine-code assembler included on the CP/M disc is compounded my confusion. A3 13 G The Basic Sharp system back-up is not programming as there is no way out of • an 8080-based program which demands One good feature in the CP/M adapt¬ A2 14 HALT the worst of its kind but it is far from loops or Halt (76H) instructions other adequate and cannot match in any way that the user should learn a new set of ation to the MZ-80K made by Xtal is its Al IS G than by switching the machine off, when the documentation supplied with, for modest claim to have made “what we A0 16 RESET the RAM contents are lost. example, the Apple II. Figure 2. consider to be some standardisations and G 17 G The MZ-8FD floppy disc unit. A volume control on the outside of the The keyboard prohibits the use of the improvements on the ... keyboard”. The D7 IB G • • case would improve the usability of the The printer matches the system both in MZ-80K in any environment where typists DDT UERS 2.2 SML/CAP key toggles between upper- D6 19 G • computer. its graphics set and styling but is definitely will switch from a normal typewriter to and lower-case and lower-case characters D5 20 G The MZ-80K, floppy disc, printer not in the van of equipment. the computer and back again. are given their normal ASCII value. Full DA 21 G • combination can be locked up in too There is often much to be said for A word-processing package for the -LI200 stops and commas can be typed normally D3 22 G • • many ways; for example, if by accident, using a well-tried and reliable design MZ-80K would appear a wasted effort as in both upper- and lower-case mode and, D2 23 G there is stored in a disc directory two rather than a bug-ridden designer's dream the machine does not seem suitable for 1200 CALL 1BDA as far as is possible by altering software, Dl 24 G quotes without an intervening space, and in those terms, the MZ-80P3 is a business use of this kind. C, the keyboard is greatly improved when the DO 25 G 1203 MUI 01 attempting to save any file by any name successful, hard-working printer machine is running CP/M. but as On the other hand, the bus is well Mark gives error 42, i.e., tried to register under such, its price is high. • 1205 CALL 1BC9 Xtal supplies the Rodney Zaks CP/M Bus Connector Detail buffered and the computer strongly an existing name. 1208 LXI B, 1DF7 handbook with Xtal CP/M discs and • The Xtal Basic tape is good value for constructed, and with the addition of D-A Figure I. MZ-80K connection details for the The price/performance ratio of money, releasing and offering manuals. Although the book provides an • the RAM an and A-D converters of the kind produced 120E: DAD B 50-way system bus. Sharp peripherals is not the same alphabetic list of CP/M commands in class enhanced instruction set. by 3D Digital Design and Development as the MZ-80K itself. The MZ-80 I/O When Xtal incorporates a standard among others, the MZ-80K offers good 120C SHLD 1C3F presented consistently, the text is often a leaflet supplied with the tape has some • interface unit is expensive for what it does printer routine into its tape Basic, I hope hardware value for laboratory workers 120F NOP paraphrase of the original manuals rather information about port numbers, relevant and although the floppy disc unit is well it will include a command to print the who wish to than a complementary overview and memory locations and an example of a control experiments and for 1210 LXI H.-06A4 made, it also looks expensive in com¬ contents of the VDU screen a com¬ engineers, most of whom introduction to the system. printer subroutine. A major advantage of — will be unable to parison with other reputable units. paratively rare but valuable facility type. 1213 MUI A,FF the Xtal Basic is the additional program touch 1215 XRA M Tape Basic — Xtalbug — which allows machine-code 1216 M0U M? A The Sharp tape Basic is supplied with modifications and insertions to be made -L the machine so the main question in a to the Basic interpreter. The facility is review must be whether the additional powerful, well worth having, and a Announcing 1217 JMP 0705 cost of the Xtal Basic is worthwhile. complete contrast to the jealous approach ? DIRTY MAINS ? Without sacrificing any instructions or taken by Sharp, which prohibits the user Day 121A NOP suffering any loss of speed, the Xtal from taking even a security copy of the Is the mains supply Next deliveryof 1218 NOP Basic occupies 5K less RAM. There are master tape, both in writing and in the to your computer more than additional software. 1210 HOP 12 commands as dean as it could be? packed into the reduced interpreter Also on the second side of the Xtal tape computersupplies, 121D NOP including the following: is a conversion program for translating 121E NOP DEEK DOKE programs recorded in Sharp Basic to Xtal PRINT @ ON ERR GOTO/GOSUB Basic. The program worked successfully 121F NOP WAIT SPEED The MF 10A accessories and cables! although the one command not trans¬ 1220 ??= 20 POP POS Anything in Inmac’s new Catalogue can be in your Computer AND OR and NOT lated — GET — required some syntax MAINS FILTER UNIT Room tomorrow (2 days to Northern Ireland). Even faster in an 1221 SUB B 1FTHEN ELSE changes in the converted program. There emergency! There’s a wide range of over 500 top quality 1222 NOP The Xtal Basic works with six signifi¬ are suggestions for modification in the attenuates noise and accessories, supplies and cables to choose from, many of which are cant figures instead of eight, but has an Xtal manual. hard to find elsewhere. A direct telephone line offers you an 1223 MOU B? B extended exponential range. The PRINT The major improvement in disc Basic is high voltage transients. instant, trouble-free ordering service, with advice always available. -L @ command in the Xtal Basic allows that it permits sequential and random- Everything covered by the Inmac no-nonsense graphs and tables to be plotted easily access storage of data on disc and Guarantee ofSatisfaction. The 10A capacity self contained unit with 1224 NOP on screen and is accompanied by less snow contains two commands — CHAIN and IF YOU DON’T BELIEVE US- “i fuse, neon, and on/off switch than the more primitive Sharp POKE SWAP — which allow whole programs to TRY US! 1225 = 08 offers a low cost solution to H,9210 command. A disadvantage for some be called from a disc, with execution and For FREE Catalogue, telephone Runcorn 1226 LXI prospective buyers will be the lack of any existing variables transferred to the new mains borne interference problems. 1229 '?ÿ?= 10 printer routine in the Xtal Basic. program. The SWAP command returns (092 85) 67551 Telex 629819 INMAC G or write to: 122ft LXI H,4212 The documentation with the Xtal Basic the first program to the CPU at the ~ c,e tape consisted of a printed pamphlet completion of the second, and the first Price £68 each (ex VAT) INMACLTD., Dept C, 81 1 122D MOU describing the general features of the program continues its execution. 18 Goddard Road, Astmoor Industrial , 122E NOP language and its application to the The error handling of the disc Basic is Data sheet available from: Estate, Runcorn, Cheshire WA7 1QF. 122F DAD B Nascom computer and a photocopied enhanced greatly in comparison to the 1230 “i 10 booklet setting out modifications specific tape version. There are one or two ALAN KIDDLE ASSOCIATES LIMITED = to the Sharp version. additional instructions but no PRINT Fairlight House, London Road 1231 STAX B There are instructions adding USING command or IF THEN ELSE, 729 for to the Hounslow, 1232 MOU B,B Basic instruction set in the original both of which might have been expected Middlesex TW3 1SE. Nascom booklet and the conversion in a disc version. Phone 01 543 0179 Telex 965649 • Circle No. 159 • Circle No. 160 68 PRACTICAL COMPUTING May 1981 PRACTICAL COMPUTING May 1 98 1 69 COMPUTERS CRYSTAL ELECTRONICS Decisions! Decisions! CC ELECTRONICS Who do youturnto? THE SKY’S THE LIMIT

Up to now there hasn't been anybody willing FOR YOUR SHARP MZ80K with enough to give you impartial advice, on which SHARP CP/M 2.21 (XTAL) type of microcomputer wordprocessing and/ or CP M is the trade mark of Digital Research system is right for your business. We at Petalect have made it our business to give you that help. A This sophisticated interactive program study of the market has meant that we can offer development system will give your you a wide selection of systems to meet most applications, at a cost that is not going to burn a BUSINEJESS/INDU potential. hole in your pocket. Basic CP/M facilities include: They range between £1,000 - £15,000 and Dynamic file management • Fast assembler include the best known names — Commodore, • General purpose editor Advanced debugging utility Sharp, ACT, • • Hewlett-Packard and Apple. All (XTAL) backed by our reliable after-sales service. So YOUR SHARP CP/M 2.21 PACKAGE INCLUDES before you make a decision, chat with us first. • Hardware modification (if fitted by a SHARP dealer does NOT break the guarantee) • SHARP CP/M 2.21 (latest version) on disc • XTAL Monitor and ll • 7 Digital Research manuals • CP/M Handbook (by RODNAY ZAKS) • 12 months guarantee and up-dates TOD fÿQCESSlh IF YOU ARE A SHARP MZ80K OWNER, CP/M 2.21 (XTAL) IS A MUST FROM £200.00 Ask your SHARP dealer for further details or contact CRYSTAL ELECTRONICS CP/M SOFTWARE HOUSES-XTAL CAN HELP YOU ESTABLISH YOUR SOFTWARE ON THE SHARP Computer Maks the Members of Retailers Association & Apple Dealers Association right choice, Shop open 0930-1730 except Saturday & Sunday right from the start. [PCTALCCTi !ÿÿÿcoMnjTtnswd 40 Magdalene Road Torquay Devon, England Tel 0803 22699 Telex 42507 XTAL G 32, (P), Chertsev Road. Woking, Surrey GU21 5JE Tel Woking 69032/21776 . Accen and Barclaycard welcome.

• Circle No. 281 • Circle No. 282

BASIC INTEGER COMPILER FOR COMMODORE SYSTEMS

• 50-150 times speed of Commodore Basic. • Several extra low-level commands for precision Any length variable names. I/O programming, eg DELAY, SETB1T, MOVE, • etc. Single dimension string and integer arrays. • Automatic into Full Integer arithmetic Sc logical (1 byte variables) inscrnon of code interruPt • * routine. for extra speed. Variables can be individually set to reside at any Code Sc Data can be set to reside anywhere in • • memory. location allowing direct access to page zero I/O ports, etc. i Many facilities for interface with Commodore • Full logical file handling. Basic programmes. • Compiling speed of 3 lines per minute. • New commands can be added to Commodore • Basic automatically using WEDGE statement.

Suite includes resident compiler, disk compiler, editor, loader and debugger. Editing environment and language similar to Commodore Basic. Produces ready-to-run 6502 Machine Code.

Detailed Manual £7.50 inc. VAT Compiler: 3000 series £150.00 inc. VAT ...... 8000 series...... £150.00 inc. VAT

5 Oxford Street Woodstock Oxford 0X7 1TQ Telephone: Woodstock (0993) 812838 • Circle No. 283 162 PRACTICAL COMPUTING May 1981 Computer Hardware at Cash & Carry Prices.

SHARP EQUIPMENT Model User Ram exc.VAT Sharp MZ80K 20K RAM Sharp MZ80K 36K RAM Sharp MZ80K 48K RAM Sharp MZ80FD Sharp MZ80P Printer Sharp MZ80I/O Input/Output Unit

FREE LEDGER & STOCK CONTROL PROGRAMME WITH EVERY COMPLETE SHARP SYSTEM, i.e. 48K Sharp, Twin Floppy Disk, Printer and I/O Unit COMMODORE EQUIPMENT Model User Ram exc.VAT inc.VAT 3008 (4008) 40 Col. PET 8K Mem. 378 434.70 3016(4016) 40 Col. PET 16K Mem. 462 531.30 3032 (4032) 40 Col. PET 32K Mem. 585 672.75 8032 80 Col. PET 32K Mem. 755 868.25 3040 (4040) 347K Disk 585 672.75 8050 1M Byte Disk 755 868.25 4022 Printer 357 410.55 8024 Printer 975 1121.25 C2N Cassette 47 54.05

VIC and ATARI equipment - available Mid-May -ring or write for full details. Every machine sold by Computer COMPUTER Supermarket is fully tested before despatch and is absolutely complete with instruction SUPERMARKET manual and tape, including free 13 amp plug 3rd Floor fitted on mains lead. Douglas House All goods sold with full manufacturer's Queens Square warranty and subject to conditions of sale. Corby Northamptonshire Copy available on request. All machines sold Telephone (05366) 62571 are full U.K. Standard. Telex COMPSU 341543/4 • All prices exclude VAT. FREE delivery • anywhere in U.K.

PRACTICAL COMPUTING May 1981 1 75 PRICE BEATERS! READY TO USE SYSTEMS •Business System £2295 •Accountants System £2295 •Finance House System £2500 •Word Processing System £3000 •Hotel System £2500 Payroll System £2295 • + VAT Systems include: SUPERBRAIN, PRINTER, INTEGRATED SOFTWARE, FULL DOCUMENTATION. + MULTI-USER SYSTEMS You lucky AppleIIowners- AVAILABLE. by adding RHrlMI-jl you WE ARE THE EXPERTS! can havethe only Contact: 0924 82636 PO approved ANPAC SYSTEMS computer connection MARTIN HOUSE 92 CANAL LANE MARTIN STREET LOFTHOUSE GATE With Appletel you can link your present Apple II BRIGHOUSE WAKEFIELD computer direct to Prestel for just £595 plus VAT - which is a major cost saving for a start. Add in these other major advantages and you'll really appreciate • Circle No. 342 what the complete Owl Computer package can do for you! ★ Save on telephone bills by storing pages from Prestel on a floppy disc - screen them up on Apple II when you're ready. ★ Programme the unit to automatically call up a MZ80 48K sequence of pages, and store them for later examination. OUR PRICE £460.00 No gimmicks, No give¬ Write your own BASIC programs process ★ to aways. Just good Prestel data as well as send commands to Prestel. value for money Cass. ★ The full keyboard means you can use Prestel THIS MONTH'S STAR BARGAIN I/face to maximum advantage for sending messages Sharp PC-1211 Pocket Computer £15.95 £82.00 Appletel is now available in colour TRS-80 0 Expansion Interface Units £173.87 For full details on 16K Ram Upgrades (same day service) £30.00 what Appletel can Disk, Drives, Singles, Twins 40-80 track do for you, and £236.00 the name of your from nearest dealer. For TRS-80 and Video Genie please phone Stringy Floppies TRS-80 £169. V/Genie £179 or write. Video Genie 16K Level II £299.00 CREDIT FACILITIES AVAILABLE ON ALL PURCHASES OVER £150 00 (written quotations on request) We fully support the products we sell. TOP QUALITY 5 %" Floppy Disks £156 each. Cassettes, Drivers, Tapes, Books, Paper, Cables, Software for Entertainment, Business and Educational purposes. C.W.O. Please add VAT and carriage. Personal caters welcome Computers T— T Owl ICRO-CHIP SHOPS L. D. MORGAN £t CO. LTD 18 Hadham Road, Bishop's Stortford Computer Systems Design XI 91 FRIARGATE, PRESTON, LANCS Herts CM23 2QR 197 WATERLOO ST., BLACKPOOL Head Office: Tel: Bishop's Stortford (0279) 52682 190 LORD ST., FLEETWOOD Tel. Fleetwood 79511/79480 • Circle No. 341 • Circle No. 343 1 98 PRACTICAL COMPUTING May 1 98 1