','Ïii'l'iiIi'I.i ANUARY 198160p High -Quality FM Tuner Project Universal Digital Tacho Computer Interface - Micro to Mainframe! Astable Design - A Fresh Approach 94999 8K ON BOARD MEMORY! 2 MICROPROCESSORS 5K RAM. 3K ROM or 4K RAM, 4K ROM (link Z80 the powerful CPU with 158 instruction, including selectable). Kit supplied with 3K RAM, 3K ROM. all 78 of the 8080, controls the MM57109 number System expandable for up to 32K memory. cruncher. Functions include +, - /, squares, roots, logs9xponenti , trig functions, inverses etc. 2 KEYBOARDS! Range 10- to 9 x 19 to .8 figures plus 2 exponent 56 Key alphanumeric keyboard for entering high level digits. language plus 16 key Hex pad for easy entry of machine code. EFFICIENT OPERATION Why waste valuable memory on sub routines for GRAPHICS! numeric processing? The number cruncher handles 64 character graphics option - includes everything internally! transistor symbols! Only £18.20 extra! MEMORY MAPPED high resolution VDU circuitry RESIDENT BASIC using discrete with extended mathematical capability. Only TTL for extra flexibility. Has its 2K own 2K memory used but more. powerful memory to give 32 lines for 64 characters. than most 8K Basics! - KANSAS CITY low error rate tape interface. 1K MONITOR resident in EPROM. PSI comp 80 SINGLE BOARD DESIGN Even keyboards and power supply Z80 Based powerful circuitry on the superb quality double scientific computer sided plated through -hole PCB. design as published in WIRELESS WORLD COMPLETE KIT Cabinet size 19.0"x15.7"x3.3". NOW ONLY Television not included in price. The kit for this outstandingly practical design by John £225 + VAT Adams published in a series of articles in Wireless World really is complete. Included in the PSICOMP 80 scien- tific computer kit is a professionally finished cabinet, fibre -glass double sided, plated -through -hole printed circuit board. 2 keyboards PCB mounted for ease of construction, IC sockets, high reliability metal oxide resistors, power supply using custom designed toroidal transformer. 2K Basic and 1K monitor in EPROMS and, *ETI VOCODER* of course, wire, nuts, bolts, etc. KIT ALSO AVAILABLE AS SEPARATE PACKS Fir b.s. seamen wk. wish Is spread tesir psrcksa sr Wilda p.raallsed eystaa te. kil is .eil.de n supra. picks ry. PCA III" x 12.51 £43.20. Pair et kepards £34.50. Firawa. i. EPRUNS £30.00. Tirade! trad.raAr 171 pear apply clap 17.00. Wild leery r.kpd. ud. lr.. dal. really CODER leaieelly lidabll £20.50. P.B. Ill !really alas. eF steer .Aryls Herd cwpn.r Iesldies OHIO SUPERMAR01s, wild k s..1. redly WIOd. Otea packs lined i. ter FREE CATALOGUE. PSI COMP 80 Memory Expansion System Expansion up to 32K all inside the computer's own cabinet! By carefully thought out engineering a mother board with buffers and its own power supply (powered by the computer's transformer) enables up to 3.8K RAM or 8K ROM boards to be fitted neatly inside the computer cabinet. Connections to the mother board from the main board expansion socket is made via a ribbon cable Mother board: Fibre glass douole sided plated through hole Panel size 19.0" x 5.25". Depth 12.2". P C B 8.7" x 3.0" set of all components including all brackets, fixing parts and ribbon cable with socket to connect to expansion plug £39.90 14 CHANNELS! 2 OSCILLATORS! 8K Static Fibre glass double sided plated through hole NOISE GENERATOR! VOICED/UNVOICED RAM board P C 8 5.6" x 4.8" £12.50 Set of components including IC sockets. plug LED PPM METERS! DETECTOR! and socket but excluding RAMs £11.20 2114L RAM (16 required) £5.00 SLEW RATE CONTROL! Complete set of bdard. components. 16 RAMS COMPLETE KIT ONLY £195 + VAT 8K Fibre glass double sided plated through hole ROM board - PCB 56"x48" £12.40 Kit includes FREE foot control and test oscillator! Set of components including IC sockéts. plug Like all our kits the t I I VOCODER really is complete fully finished metal work, professional quality and socket but excluding - ROMs £10.70 components (all resistors 2% metal oxide), nuts, bolts, etc. even a 13A pluglKits also available as 2708 ROM (8 required) - £6.00 - separate packs - See our Free Catalogue. Complete set of board. components. 8 ROMs £66.50 OUR CATALOGUE IS FREE! WRITE OR PHONE NOW! POWERTRAN ELECTRONI PORTWAY INDUSTRIAL ESTATE ANDOVER, HANTS SP10 3NM (STD 0264) 64455 PRICE STABILITY: Order with confidence. Irrespective of any price changes we SECURICOR DELIVERY: For this optional service (U.K. mainland only) add £2.50 will honour in this advertisement until February 28th, 1981, If this month's (VAT inclusive) per kit, advertisement is mentioned with your order. Errors and VAT rate changes excluded. SALES COUNTER: If you prefer to collect kit from the factory, call at Sales Counter. EXPORT ORDERS: No VAT. Postage charged at actual cost plus E1 handling and Open 9a.m.-12 noon, 1-4.30 p.m. Monday -Thursday. documentation. U.K. ORDERS. Subject to 15% surcharge for VAT. No charge is made for carriage, .S or at crentur rate if changed._ MANY MORE K ITS ON PAG E I PM Tuner SIN Project Universal Digital Tacho Computer Interface - Micro to. Mainframe: FEATU RES Asttrbie Desíÿrc- A Erwin Approach ec DIGEST 9 New news is good news MICROBASICS 17 Monitoring programs SPOT DESIGNS 27 And a couple of other spots AUDIOPHILE 29 Sound seasonal ideas I/O INTERFACE 43 Computer talk ASTROLOGUE 54 Win The Spaceflight Directory READERS SURVEY 57 Audience .:.NEWS., ...PROJECT& participation DESIGNER'S NOTEBOOK 72 555 astables Watch the birdie p.88 SLR ELECTRONICS 88 Watch the LED birdie TECH TIPS 96 Circuits from your very own selves ELECTRONICS TOMORROW 102 See -SAW filters PROJECTS MULTI -OPTION SIREN 22 Noises and infinitum UNIVERSAL TIMER 36 Seconds out LED TACHO 49 Light up your revs AUDIOPHILE FM TUNER 62 Spot the tuning POLYSYNTH 77 The makings of a motherboard FOIL PATTERNS 110 Rub down foils INFORMATION Once upon a time p.36 NEXT MONTH'S ETI 15 What's in February BINDERS 19 Issue protection ETIPRINTS 109 Rubbing down PCBs COME AND JOIN US 112 Calling all camera operators .:::.::.s>:>::::.:.:.::.:.::;:::::s;::« ..,;<:::;;;r:.:;:.:.:,r::..:.;: <:::::. ii+if:££iF:5ii5::::i :'ii::{ii:ïéiii%:º%wi:ire:n:`rñ.,:er..d%iJ.a;v.g <:,!i.d Spot the tuning p.62 f.Y.i3P.dre Ci3sstNtNNeryrwmiq Head pnutPhN!5e: Rqpkµpyrs tin Cie.wÆrMUM. Lecture kexw.ns ' itfÏt? Electronics Today is normally published on the first Friday in the month preceding cover date. MODMAGS LTD 19e) All material is subject to worldwide copyright protection. All reasonable care is taken in the preparation of the magazine contents, but the publishers cannot be held legally responsible for errors Where mistakes do occur, a correction will normally be published as soon as possible afterwards. All prices and data contained in advertisements are accepted by us in good faith as correct at time of going to press. Neither the advertisers nor the publishers can be held responsible, however. tor any vanations affecting price or availability which may occur after the publication has closed for press ISubscription Rates UK 110 including postage Airmail and other rates upon application to The hi-fi supermarket p.29 ETI Subscriptions Service, PO Box 35, Bridge Street, Hemel Hempstead, Herts. ETI JANUARY 1981 Why the Sinclair ZX80 is Britain best-selling Built: £9995 Including VAT, post and packing, free course in computing, free mains adaptor. Kit: £79.95 Including VAT, post and packing, free course in computing. This is the ZX80. A really powerful, full -facility computer, matching or surpassing other personal computers at several times the v. '19) %`1AM .eum\\\\ "® price. 'Personal Computer World' gave it nQ\\iu>\\\\\ 5 stars for 'excellent value'. Benchmarktests \p-.-\\\`_iuu say it's faster than all previous personal computers. Programmed in BASIC -the world's most popular language -the ZX80 is suitable for beginners and experts alike. And response INTEGRAL FUNCTIONS from enthusiasts has been tremendous - S TR $ PEEK- usFe over 20,000 ZX80s have been sold so far! L$$ E 'es - `ÉN Powerful ROM and BASIC interpreter 4K BASIC ROM offers The kg, HOMEO 4\ \ RU T\\\\ remarkable programming advantages: \ST,A \ NE Unique 'one -touch' key word PR/4",*ene\ entry: the ZX80 eliminates E0/;' \e4keÄ\ Gor óKe a great deal of tiresome \\0/41 typing. Key words LEAR Gosua\erT Eoil\\e (RUN, PRINT, LIST, e,ae\c CS Rer etc.) have their own \\ R\\\\\ single -key entry. \\\ \ Unique syntax check. \\ A`\\\\l\ \`l. l'li .. , A cursor identifies errors immediately. Excellent string -handling capability - takes up to 26 string variables of any length. All strings can undergo all relational tests (e.g. comparison). Up to 26 single dimension arrays. FOR/NEXT loops nested up to 26. Variable names of any length. The Sinclair teach -yourself BASIC language also handles full Boolean BASIC manual arithmetic, condition expressions, etc. If the specifications of the Sinclair Randomise function, useful for games ZX80 mean little to you -don't worry. and secret codes, as well as more serious They're all explained in the specially -written applications. 128 -page book (free with every ZX80). The Timer under program control. book makes learning easy, exciting and * PEEK and POKE enable entry of machine enjoyable, and represents a complete code instructions. course in BASIC programming -from first * High -resolution graphics. principles to complex programs. * Lines of unlimited length. Kit or built -it's up to you Unique RAM In kit form, the ZX80 is pleasantly easy to The ZX80's 1 K -BYTE RAM is the assemble, using a fine -tipped soldering iron.