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lorn hardware conversion Vinters: a layman's guide Micros and matlis Atom with BBC Basic Beeb sound

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Sb- ^- CONTENTS MARCH 1983, NUMBER EIGHT

Editor 3 News 67 Atom analogue converter Tony Quinn 4 Caption competition Circuitry and software by Paul Beverley Editorial Assistant 71 BBC Basic board Milne 8 BBC update Kitty Barry Pickles provides a way round David Allen describes some Managing Editor some of its limitations Jane Fransella spin-offs from the TV series Competition Production 11 Chess: the big review 75 Simon Dally offers software for Peter Ansell John Vaux compares three programs TinaTeare solving his puzzler with a dedicated machine Marketing Manager 15 Beeb forum 79 Book reviews Paul Thompson and Pascal Ian Birnbaum on programming Promotion Manager among this month's offerings Pal Bitton 19 Musical synthesis 83 Printers for beginners Publisher Jim McGregor and Alan Watt assess First part of this layman's guide Stanley Malcolm the Beeb's potential by George Hill Designers and Typesetters 27 DIYIightpen GMGraphics, Harrow Hill 89 Back issues and subscriptions Joe Telford shows you how in a Graphic Designer to get the ones you missed, and hardware session of Hints and Tips How Phil Kanssen those you don't want to miss in Great Britain 33 Lightpen OXO Printed 91 Letters by ET.Heron & Co. Ltd Software from Joe Telford Readers' queries and comments on Advertising Agents Lightpen multiple choice 39 everything from discs to EPROMs Computer Marketplace Ltd 41 BBC assembler 20 Orange Street 95 Official dealer list London WC2H 7ED Tony Shaw and John Ferguson Where to go for the upgrades 01-930 1612 addressing tackle indirect and support Distributed to News Trade the 45 Micros in primary schools by Magnum Distribulion Ltd. is put under scrutiny 72-8 Fleet Street, Maths London EC4Y 1 HY. 51 Software review Tel: 01-583 0961 Three educational packages Telex: 893340 Magnum G. worthy of consideration Published by Addison-Wesley Publishers Ltd. 53 Microprimer review 53 Bedtord Square, How good is the MEP's package? London WC1 B 3DZ Heather Govier finds out Telephone; 01-631 1636 Telex: 881 1948 57 Software review ISSN: 20M7002 7 Eight packs for the Beeb ^Addison-Wesley 63 User groups Publishers Ltd 1983 64 Atom ROM review Bruce Smith gives his opinion of the Ross toolkit Cover design by Mike Milne Subscription Information For UK Subscriptions, send your cheque or postal order How to submit articles made payable to Addison- You are welcome to submit articles to the Editor of Acorn Userior publication. Acorn User Wesley Publishers Ltd to: cannot undertake to return them unless a stamped addressed envelope is enclosed. Acorn User FREEPOST Articles should be typed or computer written. Black and white photographs or trans-

BKT (Subscription Services) Ltd parencies are also appreciated. If submitting programs please send a cassette or disc. Douglas Road, Payment is £50 per page or pro rata. Please indicate if you have submitted your article Tonbridge reviews and information to: The Editor, Acorn User, 53 Bedford Kent TN9 2TS elsewhere. Send articles, England Square, London WC1 B 3DZ. Tei: (0732) 351216 Telex: 95573 Coming soon in Acorn User: • Games listings • Language ROMs for the Beeb • Software reviews • • Programming in primary scfiools • Discs tested • Musical micros • Graphics Annual subscription rates • Atom EPROM blower • Printer guide • UK £15 permission otlhe publisher. The publisher Europe £18 All righls reserved. No pari ol Ihis publication may be reproduced without prior writlen £20 cannot accepi any responsibility tor errors in articles, programs or advertisements published. The opinions expressed on the Middle East publisher, Lid, or pages ol itiis journal are those of the authors and do not necessarily represent those ol the Africa The Americas and £22 Acornsotl Ltd, Rest of me World £24 Acorn, Acomsofl: and the Acorn symbol are the registered trademarks ol Acorn Computers Ltd and Acornsofr Ltd Official 13[DB Dealer BBC DISC SYSTEM /Z700 Disc Interface inc. 1 .0 operating System £95 Installation £20 Model B £399 BBC Single Drive (100K) ipriceincludes VAT. Can. extra£8l £230 + £6 Carr Complete Upgrade Kit E50 BBC Dual Drive (BOOK) Installation £15 £POA Individual Components also A wide range ot "Software from Acorn, available. BBC and others for education and fun in slock. Ait mating connectors with cables in stock. *^ 'VIEW BBC Word Processor ROM BOOKS Basic Programming on BBC £5.95 Teletext Adaptor 30 HR Basic (NEC) £5.95 Let your BBC teach you to Program £6.95 2nd Processor (6502) + 64K RAM £170 BBC Micro Revealed £7.95 Assy. Lang. Program on BBC £8.95 2nd Processor (Z80) + 64K RAM £170 Program the 6502 £10.75 6502 Games £10.75 Phase Phone to Check Delivery Details on New Add-ons 6502 Software Design £10.50 INo VAT on Books - El p&p/book) WIDE RANGE OF SOFTWARE HELD IN STOCK For Full Details of Add-ons for BBC SEND or PHONE FOR OUR BBC LEAFLET Send for our Leaflet

BBC COMPATIBLE BVa" DISC DRIVES DISKETTES

These are TEAC mechanism fully compatible with BBC. They are in packs of 10 supplied with independent power supply and housed in BBC Single Sided 40 tracks £15 matching cabinet. Single Sided 80 tracks £24 SINGLE DRIVES: 100KE180 200KE255 400KE345 Double Sided 80 tracks £32 DUALDRIVE: 200K£36a 400KE480 800KE610 p&pC2/pack

Carr- C6/Single drive t8/Dual drive, DisC Cable: Single £8 Dual£12 PRINTERS NECPC8023BEC EPSONMX80&100F/T3 SEIKOSHAGP100A • 80 Cols. 100 CPS • Proportional • MX80: 80 Cols. 80 CPS • MX100: 136 • 80 Cols. 30 CPS • Self Testing • Hi-Res Spacing • Hi-Res & Block Graphics Cols. TOO CPS • Bit Image Printing Graphics • Standard & Double width • Bi-directional Logic Seeking • Forward • Hi-Res Graphics • Bi Directional Logic characters only & Reverse Line Feed • International & Seeking* International Characters £185 + £6 Carr. Greek Alphabet • Auto underline • 32 Print FONTS • Auto underline • Super & Sub Scripts • 2K Built-in • Super & Sub Scripts buffer MX80 F/T3 £325 + £8 Carr. £320 + £8 Carr MX100 F/TE425 + £10 Carr.

Please send SAE for our detailed price list of electronic and computer components

MONITORS Kaga 12" Colour Monitor RGB Ferguson Cassette Recorder £250 + £8 Carr. £26 + £1.50 Carr. Microvitec 1431 14" Colour Monitor Kaga 12" Antiglare Green Monitor Cassette Leads £269 + £8 Carr. £107 + £6 Carr. 7 pin DIN 3 jacks £3.50 Microvitec 2031 20" Colour Monitor Hi-Res 12" Green Screen Antiglare 7 pin DIN pin DIN + jack £4.00 £389 + £8 Carr. Monitor £99 + £6 Carr. it We carry a wide range of connectors and assemblies. Microprocessors, RAMs, EPROMs, Crystals, etc. Price Lists, Leaflets available on request. Large stocks enable same day despatch on most orders. Special pricing for dealers purchasing in quantity.

PLEASE ADD 40p p&p & 15% VAT Technomatic Ltd (Export: no VAT. p&p ! Cost) Government Colleges etc. welcome. MAIL ORDERS TO: 17 BURNLEY ROAD, LONDON NWIO lED Orders from Depts. & SHOPS AT: 17 BURNLEY ROAD. LONDON NWIO Detailed Price List on request, - (Tel: 01-452 1500, 01-4506597. Telex: 922800) ^ Siock items arc normally by return of post. 305 EDGWARE ROAD, LONDON W2

ACOHN USER MARCH NEWS

Second processor timings BENCHMARK timings from Acorn for the BBC micro with a 6502 second processor Source of comparative timings and the benchmarks them- take the machine from third to selves is Microprocessors and IVIicrosystems (October 1 978 vol2 with first place in the top ten speed no5) an update from World ratings for micros. (October 1981). The benchmarks are listed in order accord- ing to benchmark 7, According to October's the Olivetti M20 was PCW, 7+8 top in ail the machines they reviewed. The BBC micro

came third, with the DAI 3MHz BBC in 6502 0.42 1.73 4.95 5,25 5.51 8.46 13,18 3.08 16.26 second. Second Processor 2MHzBBC 0.61 2.6 7.43 7,88 8,27 12,69 19.77 4.62 24.39 Even more interesting is a price comparison. The DA! 1 MHz Atom Basic 0.50 5,07 9.49 10.8 13.85 19,14 31.06 is no longer sold in Britain, 4MHz 380Z TDL 1.4 6,5 13,2 13-9 15.0 22,3 31.6 6.2 37-8

the Olivetti costs over 4MHz Osbourne 1 1,4 4.4 11,7 11,6 12.3 21,9 34.9 6,1 41.0 the with £2000,. and Beeb 4.77MHz 8088 IBM 1.5 5.2 12.1 12.6 13.6 23,5 37.4 3,5 40.9 the 6502 second processor 1MHz BBC in ATOM 1.21 5.20 14,86 15,75 16.53 25,39 39.54 9,24 48.78 about eeoo. Vic20 1.4 8.3 15.5 17.1 18.3 27,2 42.7 9.9 53.6 The second processor Applesoft 1.3 8,5 16.0 17.8 19,1 28,6 44.8 10,7 55.5 uses the same eight-bit chip Pet2001 1.7 9,9 18,4 20.4 21-7 32,5 50,9 12.3 63.2 as the Beeb - a 6502 micro- 1 MHz 6809 TRSCOL 2.0 11.3 22.2 23.9 27.0 41.5 61.1 13,0 74.1 processor. It is this which performs all the calculations ZX81 fast mode 4.5 6.9 16.4 15.8 18,6 49,7 68.5 22,9 91.4 within the machine. ZX Spectrum 4.8 8.7 21.1 20-4 24,0 55,3 80.7 25.3 111.0 As well as increasing the ZX81 slow mode 17.7 27.2 65.3 63.0 74,2 199,3 275.6 91.6 367,2 machine's speed by about •Olivetti Iwl20 1.3 4.0 8,1 8,5 9.6 17,4 26.7 1.6 half, the second processor BBC 1.0 3.1 8,2 8.7 9.1 13,9 21.4 5,1 means an extra 64k of RAM can be used. The processors' cycle times are related to their clock frequencies as follows: 6502 cycles per second equals clock frequency Two more second pro- Z80 cycles per second equals clock frequency divided by 2.5 cessors are planned, based 6809 cycles per second equals clock frequency on the eight-bit Z80 and 32- 8088 cycles per second equals clock frequency divided by 4 bit 16032 chips. Develop- Thus a 2MHz 6502 is vaguely equivalent to: 5MHz ZBO. 2MHz 6809, 8MHz 8088.

ment of these is not as far The 1 MHz timing applies to Atom and Acorn System versions of BBC Basic. advanced, but engineers at Acorn are already comparing *These two timings are from PCW (October 1 982), The timings are not strictly comparable with the 32-bit system to mini the figure above as PCW used a pre-production BBC machine. Also, the BBC machines computers, never mind timed themselves in the Acorn figures. micros.

Micros in intensive care snow dates D The Manchester Home A HOSPITAL is so delighted Computer Show opens its April 22 24. with its four BBC micros that doors from to Midland Hotel is the it is planning to buy a dozen The more. StThomas'sHospital venue. Details from ASP, in London installed the first 1 45 Charing Cross Rd, of its micros in an intensive London WC2H OEE. care unit. D Artificial Intelligence and The consultant in charge Education is the theme of a believes hospitals could conference to be held at easily afford to equip their Exeter University on April intensive care units with 16-17, Seymour Papert (as the BBC micro - and save in Logo) will be there and money. tutorials will be held on Pro/og St Thomas's plans to use and Logo. the three other micros to Details from Masoud monitor heart-related prob- Yazdani, Computer Science, lems, artificial kidney sys- Exeter University, Physics tems for renal dialysis and Building, Stocker Rd, Exeter incontinence in children. EX4 4QL. Tel: (0392) 77911 Other possibilities for ext. 2 1 6. the Beeb's use are being O Bristol University is explored by the hospital running several courses administration. It could, for using BBC micros. Contact example, store every detail D, Wilde or Mrs. L. Skinner, of a patient's condition as Extramural studies, 32 an addition to medical Tyndalls Park Rd, Bristol records. BS8 1HR. Tel: (0272) 24161

ACORN USER MARCH NEWS

Telesoftware launch due Memory

THE BBC's telesoftware Ceefax, explained that mod- part in the earliest tele- back-up service could be ready for ifications to his computers software projects and is an April launch. Acorn's which transmit teletext infor- undertaking research to A BACK-UP memory device complete. 'The teletext adaptors were on mation were assess its value in education. should now be available for show at January's BBC BBC end is ready to start A third source of soft- the BBC micro. Greenwich micro trade exhibition and broadcasting when we want,' ware is the general public. Instruments have developed are starting production. he said. 'People are already sending an adaptor for their NVR64, Software available will Teletext is a process be in a steady trickle of to store the Beeb's memory whereby information trans- educationally-biased, with 50 listings,' said Clayton. Graham once the power is switched programs coming the mitted by BBC's Ceefax and from 'We are negotiating a very off. Microelectronics ITVs Oracle can be accepted Education small payment and have The adaptor plugs into and stored by a micro. This Programme and eight from produced guidelines for the 1 tVlHz extension bus and removes the need for a Brighton Polytechnic, It will writers.' will be available with the special set be changed fortnightly at However, TV and means the main prob- necessary software from software can be broadcast first, but this frequency will lem is still the BBC's late February costing about and downloaded into a be increased as the number inability to pay commercial £25. The NVR64 itself costs of users grows, computer directly. rates for telesoftware as it is £375. Graham Clayton, head of Brighton Polytechnic took unable to charge users. The device has 64k of usable memory, protected by an internal lithium power Reject call system for up to 10 years. The manufacturers claim it DO YOU have something in is exceptionally fast common with Einstein, Winston programs load and save in a Churchill. Puccini, Rudyard fraction of a second - and Kipling, Jimmy Young or due to the absence of Margaret Thatcher? They moving parts, is suited to have all been rejected at hostile environments. some time or other. Contact Greenwich If you have any funny, Instruments at 22 Bardsley cruel, kind or eccentric Lane, Greenwich, London rejection letters, Peter Knight SE10 9RF. Tel: (01) 853 wantstousetheminabookof 0868. rejection stories. He'll be offering a bottle of champagne for the best Beeb Forth entry - you should send your stories to: Peter Knight, toolkit (Acorn User), FREEPOST. A FORTH toolkit has been London SW6 5BR. produced by Level 9

Computing. It is designed to DIglta-pIc enhance their 'r q Forth' for the BBC micro. The toolkit THE Digitiser System, for has about 200 functions and the BBC model B. can is supplied on cassette for reproduce pictures and £10. diagrams or can be used to Smiling beauty prize The toolkit is divided into produce original designs. sections, any of which can The user traces a picture and be loaded as needed. Some little the co-ordinates are stored in WE couldn't resist holding a 'balloon' of the functions include: a the computer. competition about these two smiling beauties. 6502 assembler, turtle The digitiser costs £98, They are (left) Chris Curry, joint managing director graphics, double-numbers, with a joystick an additional of Acorn and David Alien, produce of BBC TV's cassette file handling and £48.95, both plus £4 Making the Most of the Micro. What do you think bit-pattern manipulation. Level Computing postage and packing and they're thinking or saying? A prize of software to 9 can VAT. Further be reached at 229 Hughen- details from the value of £20 is offered for the best balloons. B.S. Dollamore, den Road, High Wycombe, Burton Entries on a postcard please, addressed to Acorn Road, Castle Gresley, Burton- HP13 SPG. Tel: (0494) User and marked 'GRIN'. 26871. on-Trent, DEI 1 9HA. Tel: (0283)217905. light detectors. TV robot link to micro A pen operating system is Shop Clubs planned, to enable the Buggy

A IVI a nch ester- based software THE Buggy shown in the square by five inches high to be linked up to Logo company, is starting its own BBC's latest computer series and runs on three wheels packages and used as a users club. is soon to go on sale. driven by two stepper turtle. The NEC course

It costs £5 a year to join, This vehicle is designed motors. 'Interfacing and control sys- and members are entitled to to be controlled from the Economatics, who make tems' will include a teaching discounts of up to 30% on Beeb, and software will be the device, say it will cost board to drive the Buggy. tapes. There will also be a bi- provided to enable it to about £125, including 13 Details from: Economatics monthly newsletter. Details perform a variety of tasks, programs, and will be Education Division, 4 Or- from: Micro-Link at 830, Hyde from following lights to available in April. It comes in greave Crescent, Dore House Road, Gorton, Manchester mapping out boundaries. an 'easily assembled' kit Industrial Estate, Handsworth, M18 7JD. It is about five inches form and has collision and Sheffield S13 9NQ.

ACORN USER MARCH )1

MAIL OHDER AND RETAIL SHOP. TRADE AND EXPORT INQUIRIES WELCOME. GOVERNMENT AND EDUCATIONAL ESTABLISHMENTS OFFICIAL ORDERS WATFORD ELECTRONICS ACCEPTED. Carriage: unless staled otherwise, please add mill. 50p to all cash ordersl. \/ A T'^''P''ICABLE TO UK CUSTOMERS ONLY. ALLPRICES EXCLUSIVE OF VAT. DEPT BBC, CARDIFF ROAD, WATFORD, Herts, England V /-\ I PLEASE ADO 15% VAT TO THE TOTAL COST INCLUDING POSTAGE. SHOP HOURSi 9.00am TO 5 OOpm MONDAY TO SATURDAY AMPLE FREE CAR Tel Watford (0923) 40588. Telex: 8956095 PARKING. ACCESS ORDERS: Simply telephone through yatir order on Watlotd 50234 .'40589. BBC PC8023BE-C STAK-PAK NEC The unique com Model B £399 puter ijrogram filing and storage (carr £71 system. Made of tough black plasnc UPGRADE KITS. Upgrade vour Model A to these compact Mod. B with our Upgrade Kits and save drawer sections yourself C s s s hold two cassettes each and lock • BBCl 16K Memorv(8 «4816AP-3 lOOnSI £18.00 together vertically • BBC2 Printer User l.'O Port £6.98 to form miniature cabinets of any height. Each • Disk Interface Kii £65,00 BBC3 drawer section has two Agfa C12 Cassettes with • BBC4 Analogue I/O Kit £6.40 labels plus external index card. Five twin Paka (10 Bi-directional, BBCBSerialt/OKit £6-70 100 CPS, logic seeking, 80 Cassettes) £6.00 • BBC6 Expansion Bus Kit £6.10 columns, 7x9 Dot matrix, superscript & READY MADE LEADS for BBC • Printer Cable Readv made 36" £11.95 subscript, hi-res block graphics, underlining, • Complete Upgrade Kit Mod. A to Mod. B £43.00 true descenders. Tractor/ Friction feed, Re- CASSETTE LEADS: 7 pin DIN Plug

to 5 pin DIN Plug i 1 Jack Plug £2.00 verse linefeed, 2K Buffer, proportional spac- Complete range of Connectois & Cables available lor to 3 pin DiN Plug f 1 Jack Plug £2.00 ing, attractively finished £320 (£7 carr) BBCMicm. Send SAE for list. to 7 pin DIM Plug £2.50 to 3 pin Jack Plug £2,00 Interface Cable for BBC Micro £12 DISC DRIVES 6 pin DIN lo6 pin DIN Plug (RGB) £2,50 RIBBON CABLE LEADS 36" long TEAC BBC Compatible EPSON (Female Plug at one end, other end free) SK9 Printer Cable (26 way Female) £2,75 SKI I/O cable (20 way Female) £2.00

SK1 1 1 MHz Bus Cable {3A way Female) £3.20

SK 1 2 Tube Cable 140 way Female) £3,70

PRINTER LEAD 36" Ready made £11 Single DISC DRIVE Cable £8 Twin DISC DRIVE Cable £12 MISCELLANEOUS CONNECTORS

PIllC/S Sockets MX80FT/3 RGB(6pinDINI 30p 45p RS423 (5 pin Dominol 30p 40p FD50A- Uncased, Single sided, 10" Tractor & Friction feed, 9 *; 9 matrix, 80 Cassette (7 pin DIN) 25p 65p 40 track, 51", TOOK Ei:S col., speed 80 cps. Bi-directional, ht-res bit EC0NET(5pinDINI 15p 25p FD50A Cased, Single sided, image graphics. Subscript &- superscript. Ital- Padd1es(15pin'D') £1,10 £2.15 40 track. 5i", lOOK £150 ics & underlining. Only £324 (£7 carr) FO50A Cased with own Power Supply, IDC MALE Headers S'S40track,5r.100K £180 Printer Interface Cable for BBC £12 to fit aSC PC Board FO50A - Twin Cased with own PSU, 2x10 way (20 pin User PortI £1.00 Single sided, 40 track. 5;". 200K £350 2x13 way (26 pin Printer Port) £2.00 FD50E - Single case with own PSU. MX100FT/3 2x17 way (34 pin DISC (ntr) £2,35

>: 1 (34 1 Single Sided, 80 track, 5J", 200K £250 2 7 way pin MHz Bus] £2.35 15" Carriage, 1 36 columns, plus all thr; faciij- FD50E -Twin cased with own PSU, 2 J<20 way (40 pin Tube) £2.50 lies of MX80FT/3 Only £425 *^7 carr) Single sided, 80 track, 5; ". 400K £475 Official JOYSTICKS FD50F -Twin casedwiih own PSU, £11.50/pr Double sided, 80 track, 5]", 800K £725 LISTING PAPER Single Drive Cable for BBC Micro £8 Twin Drive Cable for BBC Micro £12 8^" or 9^" Fanfoid paper plain or ruled 10 Verbatim Diskettes, 51", S/sided £18 UTILITY ROM ( 1 000 sheets) £7 ( 1 50p carr) 10 Verbatim Diskettes. 5i", D/Sidsd £30 15" fanfoid paper (1 000 sheets) WEROM is WaKord Electronic's own most sophis- £9(150pcarr) ticated but easy to use 4K ROM based on BASIC

( for Acom straight into the ACORIM AP100A Teleprinter Roll (econo paper) £3 1 50p carr) extension ATOM. Plugs utility socket in an ATOM with floating point. The PRINTER special features are: MONITORS High Speed Tape Interface -Memory Dump, Modify Machine code breakpoints BASIC Error Trapping-READ, DATA and RESTOBE-Full BASIC Keyboard Scanner (BBC like) -FULL Disassembler - AUTO Line Numbering - PLUS: CHAIN, Cursor Movement, Loop Aborting — Easily Extendible further. Supplied complete with instruc- tions.

10" Trac- Special Introductory Offer: £9.95 tor Feed, 80 BBC WORDPROCESSOR PACKAGE Columns, 30 We offer a complete BBC Wordprocessor pack- GPS normal & MICROVITEC 1431. 14" Colour Monitor, age consisting of; double width RGB Input, (as used in BBC Prog.) BBC Model B'. Single TEAK Disc Drive (Twin Disc Drives optional) EPSON MX80FT3 PRIN Characters. Dot res graphics Price including connecting Lead TER IDaiseywheel Printer optional), ZENITH Parallel Interface Standard, £249.95 (carr £7) Hi-Res Green 12" Monitor (Microvitec 1431 Our price includes ZENITH 12" Green Monitor. Colour Monitor optional), A par:ket of 10 Dis- of PAPER ffl££500 SHEETS Excellent res. £80 (carr £7 kettes, 1000 Sheets Fanfoid paper. WORDWISE Only £175 (£7 carr) (the most sophisticated ROM Based BBC Word Processing software yet written), all the con- • SEIKOSHA GP250X 10" Tractor CASSETTE RECORDER & ACC. nectors, Cables, Manuals etc supplied. All you require is a mains outlet to have it up and Feed. 80 col. 50 GPS. normal & double running. width & height characters, RS232 & Top quality Sanyo Slim-line, portable Cassette For further details phone Martin on Centronics Interfaces standard. Recorder, Ideal for Computer use. Mains/ Watford 10923)40588/50234 £235lf:7carrl Battery operated. £24 (carr £1 • PRINTER CABLE to Interface above CI 2 Computer Grade Cassettes in library cases For BBC SOFTWARE and BOOKS see our printers to BBC Micro £11 40p advert on Page SO of tftis magazine.

ACORN USER MARCH NEWS

Subscription Autoprommer

changes THIS little box can not only SUBSCRIPTIONS to Acorn blow EPROWIs, but also run programs auto- User will, from the April issue, be handled by Brown, Knight matically on the Beeb. files and Truscott Ltd. Data can be loaded Their address and phone from and dumped to number are given on page cassette for all operating systems to 1 .2. It one. and they will deal with up runs subscription and back number on 25 or 21 volts and takes from enquiries from now on. power the Beeb. The price is £120 A new service they offer is plus the ability to arrange sub- VAT and postage. Details scriptions by credit card over from ATPL, Station the phone. Rd, Clowne 843 4AB. Details of back issues, a photocopy service and the arrangements for subscrip- tions are given on page 89. NEC to launch micro courses

THREE newcomputercorres- will be applicable to other ised '30-Hour Basic' because

Hidden message pondence courses are to be machines. Books of the courses it was not specific enough, released by the National Ex- will be jointly published with although this was mainly in this SOMEWHERE mag- tension College. the BBC. caused by a lack of BBC micros zine is a hidden message. The first two - 'Structured The NEC is now claiming when the course was written. We're not giving aw/ay any programming in Basic' and over 100.000 users for its This problem, graphically clues, but there's a year's '6502 assembly language pro- original course '30-Hour described by Richard Free- free subscription awaiting gramming' will cost £50 and Basic' released as part of the man in September's Acorn the first person to find it. be available this year, The third. BBC's Computer Literacy User, has now been overcome Send your answer on a 'Interfacing and control sys- Project. It has also arranged as there are now more than postcard, which must be tems' is not yet accepting for the City and Guilds ot 50.000 Beebs about posted, and we will not enrolments. London Institute to offer a Details of courses from: accept answers by phone. All the courses are based certificate in computer literacy. NEC, 18 Brooklands Avenue, So there! around the BBC micro, but Some people have critic- Cambridge CB2 2HN. BITS& BYTES

44 Fore SL llfracombe, Nth Devon. Tel: (0271 ) 62801

ACORN DEALERS, BBC, DRAGON, VIDEO GENIE SALES & SERVICE EPSON HX20 COMPUTER Model A/. £299 Atom Micros BBC Upgrade Kits BUY THE Cf:> Model Colour Monitors BBC printer interfaces bX_ £399 Seikosha GP100A 5^" Floppy Discs \P* As supplied to schools, Printers local authorities and C-12 Cassette Tapes government departments Epson Printers ZI7RITISH by the leading BBC/Acorn Cassette Recorders dealer & service cer>tre Monitors- 12" B/W Continuous Stationery Monitors- 12" Green Software ^^OMPUTER

b^" Disc Drives Software We supply all the extras:

IC/WP.S.U. a CASE) written to order F loppy diskt inierface + E'jonel netware interlace + voice synthesis Circuits •- Cartridge ROM PHCH mlertace + Allernatii/a high-level languages in ROM + PadOles + Casselle recorders + Black 8 white or colour monitors * lOOKsmgle-siaeddisRarive + 800 K double-sided dish d'lue + Dot mHlni printer + Daisy *heel prinier + Teletext or Pieslel acomsilion unit? PLUS computars, paripharala, printsri, aottwara, gsmas, books anil much, much more from laading makanat low prieot-atwayaaHailabla from your /oca' tlockiil: REPAIRS TWICKENHAM COMPUTER CENTRE LTD ,^TL7fxM.rs^coRN & SERVICE n Hulk M Ttrkllliliim MM^i TWI 4B1III 101-892 7866/01-191 16IZI To all Micros

ACORN USER MARCH 9

the one to watch

MODEL A/B

Cassette 1 : Star Trek/Candy Floss (very popular) £6.50 Cassette 2: Family Games (hours of fun) C4.50 Cassette 3: Mutant Invaders/ Breakout C6.50 Cassette 8: Model A Invaders (M/C) C5.50 MODEL B (or A+32K) Cassette 4: Beep-Beep (Super Simon Game) £4.50 Cassette 5: Beebmunch (full colour Munchman)£6.50 Cassette 6: Super Hangman (animated, educational) £4.50 Cassette 7: 3D Maze (fast and intricate) £4.50 CASSETTE (BCDB MODELBInvaders(orA+32K) (M/C) £7.50 CASSETTE 10 MICRO WORDPRO. (Cassette W.P. system).£10.50 CASSETTE 12 GAMES FLAGS. (Countries and Capitals). £4.50 CASSETTE 13 • All Programs will run on all HYPERDRiVE (M/C arcade). Destroy operating systems the Drone aliens in the caverns with • All software in stock before we your laser tanl<. £6.50 advertise CASSETTE 14 • Send SAE for Brochure STRATOBOMBER (M/C arcade). Keep the enemy fleet at bay in order to destroy the rogue star ships nuclear reactor. £7.50

CASSETTE 15 - LEAP FROG li^ The fabulous 'frogger' arcade game reaches the BBC micro. Superbly written full colour machine code version for the Model B (or A+32K). Help the frog cross the road avoiding the vehicles travelling at different speeds, and cross the multi current river to reach the safety of the lilly pads. The game gets progressively harder- perfect for arcade addicts Only £7.50 for MODEL B (or A+32K) ?^>*?^^'^«;

LYINCLUS'

J^aJKLTOUTrP

Softwa, gSt kpool, Lan UK Limited 253) 21^55

ACORN USER MARCH BBC UPDATE SPINNIN by David Allen, BBC producer

M.lost of the programmes in Making the Most of the Micro have now been shown, so this is a useful time to look at the software and hardware which is likely to be produced to support the series. In programme one, The versatile machine', we see a number of demonstration programs. One of these helps to explain how data gets from tape into the computer's memory when a program is loaded.

It was written by Ian Trackman and will probably be released by BBC Publications. The sound monitoring program and the pressure pad weighting- machine software (written by BBC engineers Steve Lowry and John Mitchell) may also be available. The BBC micro is used throughout the series to produce the closing superimposed credits, subtitles and names. This technique could be used on home videos. 'Getting down to Basic' is the first programme to show any coding. Although quite simple, programs have been written to

show good practice and it is likely these will appear on Ceefax.

At the end of the programme we see programs written for schools by the Microelectronics Education Programme, as well as one from the Welcome tape. The two MEP The BBC Buggy in programs will be transmitted free to action. This small viewers who have teletext decoders robot can negotiate attached to their BBC micros. mazes, follow lights 'Strings and Things', programme and draw pictures. It should soon be linked three, looks at how the computer to a Logo language, handles words and demonstrates a and may be used in an word processor. NEC course on control. We also look at procedures and The TV picture on structured programming. Ian Track- theleftwas setup using man demonstrates a patience- a technique developed playing program with excellent by BBC engineers graphics, and a couple of programs which has obvious which play a dice game. One of possibilities for home these has 'well' written, video. been and shows the principles of good structure; the other is a 'bad' program with poor screen display, and poor error trapping.

ACORN USER MARCH

L BBC UPDATE G OFF FROM THE

For those who want to learn businessman to produce a by the computer. It has a pair of more about structured programming financial model of his business. precision stepping motors, a light reader, an there is a second National Music, speech and 'intelligence' sensor, a macro barcode Extension College course coming make up programme seven. This elecromagnetically operated pen up called 'Structured Programming shows software which converts the and two touch sensors. on the BBC Microcomputer'. BBC machine into a music Software is being whtten which to, for Programme five, 'Keeping a synthesiser and demonstrates the should enable the buggy Record', helps to demystify musical equivalent of the word- example, map out its environment databases and shows a simple processor - a music editor which or find its way out of a maze as well friendly home database or 'record enables you to create music, as follow a light, negotiate its way follow bar-coded keeper' written by Ian Trackman, display il in 'proper' notation and round objects and instructions. We also see the BBC machine then play It back, with harmony. interrogating the New Yorl< Times The speech chip- immortalising Programme nine takes a second database using software whtten by the voice of Kenneth Kendall - is look at graphics, and various 'colour John Coll at Acorn. This converts shown in action, and this is now techniques such as the BBC machine into a 'smart available for the BBC machine. switched' animation effects are terminal' and enables you to use demonstrated as well as the use of the telephone to communicate with lightpens and graphics tablets. any mainframe computer capable Control is the subject of Programme 1 deals with of reading ASCII code. programme eight. In this we show communications. We look at the Programme six is about business how various simple sensing use of the machine with the networking 'inking applications. It contains a demon- devices can be interfaced to the telephone and stration of UltraCalc - a BBC- machine and how it can machines so they can communicate spreadsheet program similar to control mains operated devices. and share pehpherals, a subject VIsicalc. This software is important We also show the BBC buggy, a you will he hearing a lot more

because it enables the small wheeled vehicle which is controlled about.

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10 ACORN USER MARCH .

REVIEW

John Vaux set three programs for the his is a review of three chess programs for the model B BBC Beeb against each other- micro. As an interesting comparison, and a dedicated chess machine one of the dedicated chess machines has been included in the test. The review looks at how well the programs ptay chess from TAKES various aspects of this complex MICRO ON game. The three programs are from Program Power (abbreviated to PP), CHESS MACHINE Bug-Byte (BB) and Computer Concepts (CC). The chess machine

is the Mini Sensory Challenger (MSC). The programs loaded from m the tape with no trouble except that mm m the BB program is called mf A 'BEEBCHESS' on the tape and 'CHESS' in the instructions, 1 r™7 --V,, =?, Documentation in all cases gave adequate information about all the facilities, although presentation

1 i ranged from a glossy booklet with m ! '^ the MSC to duplicated pages with sS PP and CC.

1 H^ The facilities provided are wide ranging, with CC having the most

1 M (four typed pages of them). CC is 1 the only program which uses the mm1 _j_i^_^ function keys. All provide various Figure 1 . White to move Figure 2. White to move levels of play which can be changed at any time. All allow the m^ 'SS! Qh H setting up of a position for problem 1 H solving. Additional features include - saving and reloading of a game

1 printing a list of moves made, ffl playing 'Blitz' (provided by PP - you ^ 1 move in 10 seconds or you miss w L_J_^ your move!), changing the colour of the board and pieces (provided by ri 1 E^E9 CC), to name-a few.

,

r\ I he CC display is the clearest, 1 PP is reasonable but the difference ^^ ^^B HH n^H ^^^ ^^^ ^H mHmH m between the pieces is not great. BB Figure 3. White to move Figure 4. White to move shows quite clear pieces but the relative sizes can be confusing (for instance, the pawns are bigger than ^^^^^1 the king). MSC of course does not HI have a display but uses actual I pieces. Although these are small and fiddly they are quite easy to p differentiate. Clock display: BB has no clock, PP shows time taken for your moves p only, CC has a clock for both sides. CC can be set to play computer against computer, computer against human or .iT.C-: human against human (in M 1 the last case it monitors for legal moves). At any time that it is a 1 ^^^^^^^jSSi ^H human's move CC can be asked to Figure 5. Black to move Figure 6. White to move suggest a move.

ACriRN ll'^FR MARCH n REVIEW •-•

less reliable two performance. CC and MSC Nlow we come to levels of play. and sometimes plays MSC has four, one being the peculiar moves in the early stages. getting four correct and BB five. fastest and four being very slow. PP On one occasion SB's first move Figure 1 shows an example they has six levels indicating the was G8~F6, it's second move EG- all succeeded on, times being: PP (on number of half-moves or 'ply' GS and so after two moves it was (on level three) 25 seconds, BB searched. Thus a mate in two is back where it started! 3.99) six minutes, CC (on 3,0,0,4) 22 three ply {white-black-white-mate). Space does not permit me to go seconds and MSC (on level three) BB has main levels up to nine in detail into how well each 55 seconds. The solution is: A4-E4 indicating ply and sub-levels up to program handled the opening check, B7xE4i D3xE4 mate. Figure 99 indicating the number of moves moves, but BB was generally the 2 shows an example that only PP tried at each level. CC has no less least sound. solved in two minutes, BB (3,99) than four different level settings. A good way to test chess wrong in five minutes, CC (3,0,9,9) programs is to give them set wrong in 18 seconds and MSC (3) hese are called level, care, problem positions to solve, and wrong in one minute. The solution sublevel and speed, but these there are many books from which is: D5-A8 check, C8-C7; A8-B7 names do not really describe what such problems can be obtained. mate. they mean. All these settings PP was so good at mate-in-two, it provided by CC may be fun for the was put up to level five and given a experimenter but are too complex ^^me are specifically designed couple of mate-in-three (five ply) for the average user. to demonstrate the limitations of problems to tackle. At this level you Expensive chess machines have chess computers. Problems for this need something else to do while the more common standard review were extracted from books waiting. It 'beeps' when it has made it's solved both, in 49 opening move sequences stored in listed at the end of this article. move. PP one nearly three memory. For the first moves of Illustrations of some of the minutes the other in these stored openings they do not positions are included so that you hours. Figure 3 shows the first one - well your program need to 'think' and so move can try them on your chess see how chess immediately whichever level they machine or program to see how does! The solution is: E8-H8 check, check, are playing at. None of the they compare with those in this H7xH8; E3-H6 H8-G8; programs under review have this review. H6xG7 mate, facility, although a piug-in module Each program was given nine of openings is available as an mate-ln-two (ie three-ply) problems. optional extra for the MSC machine. PP was found to be particularly I was impressed at how well PP PP, CC and MSC playing white good at these and correctly solved handled these problems and of all prefer D2-D4 or E2-E4, every one on level three, times surprised at the performance the

apparently choosing randomly being from 10 seconds to eight others, I would have expected any between them. BB preferred knight minutes. Having moved, it displays program claiming to be good to opening B1-C3 or G1-F3. 'mate in one' to show that it consistently solve mate-in-two Playing black, PP, CC and MSC recognises the fact. None of the situations even if for instance the respond with sound moves. BB is others approached PP's mate-in- first move is a queen sacrifice,

ACORN USER MARCH I REVIEW

However, there were some white advances his A-pawn, the abandoned on move 27 after two

situations which PP couldn't solve. black king cannot reach it in time hours 40 minutes.

Figure 4 shows a problem that was to prevent it promoting. BB handled I was generally somewhat only solved correctly by BB. The this correctly at level 4.99 in 24 disappointed in the performance of

others did not realise that it is OK seconds, CC was correct on level all these programs. During tests, all

to let black promote his pawn to a 6,0,5,9, in five minutes. PP got it occasionally made stupid moves so

queen and then exchange queens wrong at it's top level and MSC was I do not think they would be good

resulting in a winning position with also unable to solve it. enough for the above average four pawns against nothing. They Only one BBC micro was chess player. They could all give

kept checking with the queen to available so I could not get the the less strong player a reasonable prevent the promotion taking place! chess programs playing each game at level two (each move

Figure 5 shows a situation where other, but I did play each program taking about a minute) and a a win is obtained immediately by against the MSC machine. Playing stronger game at level three (moves promoting the pawn not to a queen at level two, results were as follows: taking around three to five minutes). - but a knight. BB is apparently the Wise V PP. Three games played The MSC machine (£50) is no only one that is capable of under- PP won one, one was drawn by stronger than these chess programs,

promoting a pawn. Later it was MSC obtaining a stalemate while It is apparent that the strong player

discovered that when it is your PP was ahead on material, the other would need one of the expensive pawn being promoted B B asks game was abandoned about equal machines (£1 00 plus) to really what piece you want to promote to. when MSC tried to make an illegal challenge him.

The others all assume you want a move (maybe this was due to a Of the programs PP is the queen. mistake by me when transferring strongest - and also the cheapest the moves from one to the other). at £7.95, CC has the best display MSC V CC. Three games played - and the most facilities (£10). BB

^^omputer chess programs are MSC won all three. has it's moments but is the least - reasonably good at the opening MSC V BB. Two games played desirable of the three (£1 1 .50). game and come into their own in MSC won both. the middle game in that unlike Thanks to Ray Hodges Associates human players in complex situations of Maidenhead for the loan of the they rarely make mistakes. On the I hese games took from about half MSC machine, to Program Power other hand, they do not have an hour to an hour and a half each. and Computer Concepts Wbr the sudden flashes of inspiration and As PP was the only program to beat loan of their programs. The Bug- see combinations beyond their MSC, two games were played Byte program wa^purchased. normal horizon of searching. In the between them at level three. One The problems were taken from: end game, the look ahead required game was won by MSC in about How to get the most from your * - usually increases considerably two hours. In the other game PP tbhess computer by Julio Kaplan; with to pawns won the queen but failed to build especially respect The Computet Chess book by T.IX" racing with kings to promotion. on its advantage and the game just Harding; Hate yc^r own ctiess by Figure 6 is an example of this. If drifted on aimlessly. It was Donald B^S. _ - ^

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14 ACORN USER MARCH 2

BEEB FORUM

IAN BIRNBAUM sets out to improve your programming SOME FURTHER THOUGHTS techniques on the BBC micro. He will answer reader's ON BYTE PACKING questions and develop their ideas - as well as providing some of his own. But the real aim is for readers to provide l^ecember's Forum gave a few easy: for the ith point the the questions and answers. will paid for ideas on cutting down on storage coordinates are A%(I)DIV1 ,000,000, At least £5 be any tip published, with £10 space by packing bytes. I want now (A%(I)M0D1 ,000,000)DIV1 00. The for those which merit a one- return to this subject connecting mode is given by to and Stat award and £20 for real consider a different way of storing (A%(I)M0D1 00) DIVIO, and the humdingersi numerical information economically. colour by A%(I)MOD10. Send your hints or Suppose you wish to store in a We can do even better than this questions to BBC Forum, particular sequence the horizontal since we can include (lashing Acorn User, 53 Bedford London B 3DZ. and vertical positions of a pixel colours also, in the same amount of Square, WC1 PEease include a self- (using the Beeb's absolute storage. If the colour is flashing we addressed envelope If your references of 1280 by 1024), the shall use a negative number: contribution is to be mode of connection to the next otherwise positive. A function to do returned. pixel in sequence (ie whether solid line, dotted line, triangular filled or not connected) and the colour of Benjamin the connection (or the pixel itself if Finn earns not connected). We will code the for connection as 4 for not connected, £20 this tip on 1 for dotted, for solid, and 5 for using passwords triangular (the reason for this will become clear). And the colours are to 7, depending on mode: no Here is a very useful routine for and you wil flashing colours are included for have to enter one. If it inserting a password system into now. is correct all will be well; but a programs on the BBC model A or wrong password will cause the B. It can be placed anywhere message: (preferably at the start) in a method of storage rests on Syntax error Uur program, but nonetheless is Bad program our constructing a 10-digit number unlistable. formed by the four digits of the The program should be and you will find that your horizontal coordinate (X), followed renumbered to clear lines 0,1 and program has been erased! by the four digits of the vertical 2, and listing 1 entered. If ever you forget your coordinate {M) and the colour {C). password but Note that there should be no remember the line it is This done by computing is stored in, blank spaces before or after the just enter: 4- 1 ,000,OOOX + 1 GOY 1 + C and 0M REMs, and that you may insert 1 (or the line number used for the will fit into just one integer storage any phrase as a password instead password routine) and press location of four bytes, for the RETURN of PHRASE (line 1), maximum positive number per- Now you should enter the This will delete the offending missible is &7FFFFFFF or second line, listing below which and you may carry 2,1 47,483,647. Thus for example we on with the makes these lines invisible. If you program. can store coordinates of (963,45), a now list the program lines 0-2 connecting mode of 5 and colour 5 have disappeared, and there are To recover the as 963,004,555. And the number program if no traces of any alterations. a you mistakenly type in the corresponding to (1 200,1 021 ), However, when the program is wrong connecting mode of and colour 6 password, execute the run the computer will say: following: is 1,200,102,106. Each combination Password? has a unique number corresponding ?PAGE=1 3:?(PAGE+3)=1 to it and each number has a unique

Listing 1 . combination corresponding to it (assuming the combination is possible). 1 INPUT"PaBsuiord? A$: IFA$<> "PHRASE" !PAGF = 0;RUN This is an economical way of 2REMJ23456 storing data. For example, to store Rest 3 of ppograrri. . . data on 100 connections requires Listing 2. just over 400 bytes of storage using A = PA. ;$f A+.5 ;-^3TRI^^r^

ACOHN USER MARCH 15 BEEB FORUM

Program 1. 32000 DEF FNENCODE(X%,V%Jv|v^c%);; LOCAL N -'n I, f \ A, 32010 IF CX>7 THEM Uy.^CX h^nX---1 Fi ^F h'

32020 ^"^^ U-OO000Q%XXviOOtYX--^-ir)%r\z^.cy ) >{.rsj '^''^^ N-^=-i j'op^-S"''' THEN — 200000000o''e

Program 2. 320^)0 DEF PRGCDECODE ( IX) 32010 XF I>;<'0 THEN rx^H Ff SE r"''--'^> 32020 " I%-ABS

Program 3. 32000 DEF PROCPLQT(XX„yx,MX,CX) 320i0 BC0L0,C%;;PLDT(5-^-i6){cNX).XX„V 3^020 ENDPRGC

this is given in program 1, called PROCPLOT (X%,Y%,M%,C%) is FN ENCODE (X%,Y%,M%,C%); in such procedure in a given program SHiFT-LOCK AND program 2 a procedure PROC- 3. It should now be clear why we DECODE (1%) is given. The fur^ction chose the numbers we did for the CAPS-LOCK CONTROL is used to encode the information connecting modes.

(the parameters are horizontal It is possible to squeeze even Many people have asked whether it coordinate, vertical coordinate, more information into these four is possible to control the Shift-lock connecting mode, and colour- this bytes. The sixth digit from the right and Caps-lock keys from the time from to 15). Since there is will always contain or 1 . It follows program. The answer is 'y^s', but only one value to be returned, a that we can additionally store there are two problems: the method function is the most convenient information on a further variable is conditional on which operating way of returning the information. with up to five values, in this sixth system is in use; and you will not digit position. Moreover, if we really be able to use your program across want to pack the bytes, we can the Tube without modifications. Ihe procedure in the second store information on another The general syntax is as follows: program Is used to decode the variable with two values, this time in information. Notice v^^e need four the first digit position on the right. ?B%=&10sets Shift-lock; sets Caps-lock; global variables to return the But you might now feel economy is ?B%=&20 ?B%=&30 releases both locks: information, Conforming to our being carried too far! ?B%-&40 sets both locks. ideas in December's issue, we use The most important use of these

as a prefix for the globals with procedures is to save and retrieve In OS Version 0, B%=&D8 : in OS obvious notation to correspond to graphics information from tape or Version 1,B%=25A, An easy way to the parameters in FNENCODE. If disc. This may facilitate the creation ascertain which OS is installed we want to plot the points of an economical 'look-up' table of directly from the program is to immediately we do not need the data to speed up plotting, for execute: globals. Instead we can the pass example. But other uses are IF ?&FFFE = 164 THEN <0S 0> values to a plotting procedure. possible. ELSE <0S 1>

16 ACORN USER MARCH What do you do if your BBC Micro goes wrong?

If you value your BBC Micro and your money you can now purchase extra one and two year full guarantees direct from us or via most Acorn dealers.

If your Micro is still under warranty, just fill in the expiry date on the coupon* a'nd the guarantee will start from that date.

We carry a full stock of parts and should your

computer malfunction we will repair it within five days of receipt.

A full one year guarantee costs just £18.40 And a full two year guarantee costs just £27.60

If your Micro is already faulty, and out of

guarantee, we will repair it on receipt and issue a full years guarantee for £29.90 or a full two years guarantee for £39.10. Please state fault when sending micro. For you and your BBC Micro's peace of mind send the coupon today

& Please tick service required. Warranty Expiry* Date / /83 n I enclose £1 8.40 for a full 1 years guarantee If applicable I enclose £27.60 for a full 2 years guarantee

n I enclose £29.90 for an immediate repair and a full 1 years guarantee

full D I enclose £39.10 for an immediate repair and a 2 years guarantee Surname Access Card No

Initials Make/Model A/B Address Serial No Send remittance to: Cambridge Processor Services, or telephone your access card number 25 Parsonage Street, Dept. A to Madingley 210212 Cambridge CBS 8DN.

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ACORN USER MARCH .

MUSIC

Jim McGregor and Alan Watt assess the values MUSIC ON and limitations of the sound facilities on the BBC micro, and show A MICRO how it can be used for serious instrumental synthesis

Can the sound and envelope on successive comp ession^ and the micro be used for serious rarefactions of air. This BSrfessure BBC j instrumental synthesis or are they variation can be convertep/' into a

just for fun? What is Instrumental variation of electrical curj^t as4^ synthesis and can a computer function of time,Asing a transducer make violin sounds like Yehudi such as a miCTcyDhone, and /the Menuhin? electrical current dt^signal displayed The answer to the first question on an oscilloscope. ThiWgives us is a qualified yes, and this article an idea of what sounds'^ look like explores the BBC facilities, and when converted into suqjj a signal. their values and limitations in 'Seeing' sounds then provides a

Figure 1 . instrumental synthesis, drawing on useful bridge between the\ aural Pure tone middl; some musical physics to try and impressions of sounds an^ the put them in perspective. We will no! numbers we have to suppl^ to a go into detail on the meaning of the computer program to generate the parameters in the envelope sounds. Various examples are

statement, but rather concentrate shown in figure 1 on how the parameters influence A pure tone has a regular sounds. Also at this stage we will sinusoidal appearance and can /v^vVv^ concentrate on the amplitude only be generated perfectly parameters in the envelope electronically or mechanically (or statement. electromechanically) by a device The answer to the second such as a tuning fork. Musical question is also yes. Given instruments do not generate pure Middle C on the BBC micro sufficient resources there is no tones but a complex mixture of technical reason why a computer pure tones, each mixture a function could not accurately reproduce or of many variables, the most copy a master musician playing pedominant being the instrument eight bars of a Ivlozart violin type and the player. An oboe concerto on a Stradivarius. This produces a mellow smooth tone, a

may seem surprising, and it would trumpet a much harsher cutting be pointless - a tape recorder is a tone. better device for listening to Yehudi Sound generated by the BBC

IVlenuhin. However, providing suf- micro is not a pure tone either. It is

ficiently fine measuring devices are a distorted square wave (figure 1),

available to capture every subtle which is why it sounds 'electronic' nuance, change in intensity, pitch, rather than instrumental. Its other Bottom C on the BBC micro harmonic envelope, etc, a perfor- less than desirable characteristic is

mance could be reconstructed from that it changes shape as a function computer controlled fragments. of frequency or pitch, This means The real point of instrumental the character of the sound changes synthesis is to make a computer with frequency, sound like a traditional instrument or make unique sounds unlike any Uifferences in sounds produced existing instrument. by different musical instruments -

Perhaps it is best to introduce or in the sounds produced on one sound by tying up the aural instrument played by different impressions or qualities of sounds players - can be quantified by two with visual impressions. Any sound mathematical models. Rock music extract is a pressure variation with time, or page 22

ACORN USER MARCH 19 GEMIN

It can do a powerful job for yot

Here's a range of software for the independent businessman that's designed to harness the p)Owcr of your micro to deliver the vital information you need in all key areas UMITED of your business. A breakthrough on both price and SPECIAL performance, each program is fully tested and comes with all OFFER the documentation t>ack up you need. "Gemini's range of software is in the vanguard of £19.95 ." at . . Buy iust any two programs the releases for 'serious' micro users and take one at £19.95 (WhkJi Micro and Softwafe Review) FREE! SPREADSHEET ANALYSIS BEEBCALC £19.95 CASH BOOKS ACCOUNTS m DRAGONCALC £19.95 PROGRAM FOR FOR BBC AND DRAGON 32. Spreadsheet BBC MICRO. . .£95.00 processors have proved to be important ^^o| \ r^^'^,^ tools for using micros in business, scientific of the innovative business One most and domestic financial applications. programs on the market. Most serious ^tg^^ \ Without any programming knowledge at all, you may:- r^^^^ J accountancy packages are written and * Set up a computerised spreadsheet, with chosen row and column names. coded by professional and competent * Specify formulae relatins any row or column to any ottier. programmers. The Gemini Cashbook Accounting * Enter your source data and have the results calculated. * Save the results on tape (or disk - BBC) for later reloading and manipulation. program was written by practising Chartered Accountants and * Print the tabulated results in an elegant report format. programmers. This is a coded by professional and competent * Experienced users may access saved files and write their own reporting or fundamental difference. graphics presentation programs for the results.

This practical program is simple to use and will replace your Some typical applications:- manual cash and bank records and by giving you instant * Small business accounting applications, e.g. profit and loss statements and cashflow projections, break-even analyses etc. management information, it may even put your accountant out * Investment project appraisal - anything from double glazing to oil rigs! of job I + Comparing renMease/buy options With exceptionally exhaustive user documentation, full * Processing the results of scientific experiments or field studies technical back up and product update policy this program will * Engineering calculation models * In fact, anything that involves repeated re-calculation of results presented in increase the efficiency and profitability of your business. Take a tabular or spreadsheet format. look at the Information this program will provide. Program Availa t>Mity Chort — * summary of VAT information to enable you to complete your i"dsrrfioolt Won! (ommcEciaP Mdiir-.I VAT returns DrfCflbeft*: Ccifrul SlflH^mcnTi D

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INVOICES AND STATEMENTS . . . £19.95 DATABASE. . .£19.95 Compatible with most micros. Sec table. Ideal for the small Compatible with most micros. See table. The program that business, A complete suite of prosrams together with everyone needs, the most valuable and versatile in your

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Sisruture. I Gemini. FuiK^kMul Software specialists, 9 Salterton Road, Exmouth, Devon. Wi\jtJ^\yC^^ 9 MUSIC

Flute: isoUted note Vibraphone: isolated note

Frequency Hz

Time (sees)

Figure 2. Harmonic envelope of Attack Sustain i Decay clarinet playing continuous note of S23HZ Figure 3. Piecewise linear approximations to instrumental transients

First consider a note played on one with the highest amplitude, and the sound of a conlinuous note on an instrument and held ai a steady the relative amplitude of the other a particular instrument would need volume. This exercise carried out harmonics define a harmonic many more than three tone on a trumpet will sound totally envelope. The overall shape of this channels, and all of these would different from the same continuous envelope gives a note a have to produce pure sine waves. note played on an oboe. This is characteristic sound, and this There is, however, another because the mechanical design of shape varies generally with the important consideration in the an instrument causes vibration frequency of the note and the way sound a particular instrument modes at different frequencies and an instrument is played. Even the makes that the BBC computer can the different mechanical designs same note on the same instrument synthesise accurately. This Is the mean that different instruments can produce different envelopes amplitude envelope. Above we exhibit varying vibrational strengths depending on the way it is blown. considered a continuous note, but at different modes. A continuous note played on any instrument can musical notes are not continuous. They start and stop, some more be considered to consist of a series I he varying mechanical designs abruptly than others, They take a of superimposed sine waves all of instruments produce completely certain time to build up and decay. having different frequencies and different harmonic envelopes. These times are characteristic of amplitudes. This is sometimes Computer synthesis of continuous different Instruments. called a harmonic envelope. The tones of different instruments can harmonic envelope for a clarinet is be achieved by playing pure sine Figure 3 shows one of a series shown in figure 2. waves of different amplitude and of isolated notes at the same The diagram indicates that this frequency simultaneously. The frequency played on a flute, note is made up of a sine wave capacity for the BBC computer to together with one of a series of undulating at 523 (the frequency of do this is, however, limited as it has notes played on a vibraphone (a top C) plus a number of other sine only three tone channels, and the tuned percussion instrument like a waves or harmonics undulating at tone generated is not a pure sine xylophone with metal bars). The twice, three times, four times etc, wave, but a square wave, already waveforms show that the undulations the fundamental frequency of 523. possessing its own harmonic the instruments make (that The fundamental sine wave is the envelope. To convincingly reproduce themselves can be synthesised

Program 1. Turns keyboard into 'piano'

ENVELOPE 1. . ENVELOPE ...." 2, ' ' ENVELOPE 3 140 SOUND &H. O. 150 O ENVELOPE A, .....' SOUND Z<12. O. 0.' O 5 160 IE natet ~ THEN currnote* 10 octave = = betj FALSE : envelope = ELBE -is" CLirrnote* = note* 20 teys* = "ZSXCFVBBNJMK.L / 170 UNTIL currnote* = ^O *FX 11. 1 175

40 «FX 12, 1 180 *FX 12.0 45 190 END 50 currnote't=GET« 200 60 REPEftT 2IO DEE PROCcheckforstops 70 FROCchBckforstops 220 ao 230 Je i^:::^i;v-';^^^>^ ^hen enop^c 9i:i bOUND 240 I, envelope, pitch. 255 100 250 IF "^'" '^"^"^ INSTR,-:234". CMrrnoteS) no REPE^T^^" ^-nvelap.,p,tcM.4B.255 THEN 120 note* = INI-;eY«(2) 260 REPE.^Trir.:L:f:%"^;r^^"~'*^^'"-'' 130 270 UNTIL nDtet< >t:Lirrnotet 2B0

22 ACORN USER MARCH MUSIC If'

from a number of pure tones) have organ or piano, with the keys on the their amplitude controlled by the row above behaving like black transient characterisitc of the notes where appropriate. Key C instrument. The amplitude of the represents middle C. The 'effect' undulations build up, sustain and keys 1, 2, 3, 4 select one of four decay. The attack time on the flute envelopes for playing subsequent

(the time it takes the sound to build notes and the P key {P for Plain) up to a maximum} is much longer causes subsequent notes to be than the attack time for the played without an envelope. The vibraphone. The sustain lime of the key (0 for Octave) causes each flute is longer than that of the note to be played tog. her with the vibraphone. (Although sustain time note an octave above (using the In a v^'ind instrument depends on same envelope for both notes). In the player, figure 3 shoves the the the program inner REPEAT loop 1,1, musician sound produced by a causes the SOUND statement to be 0,0,0,0,0,0, instructed to play as short a note as played UNTIL the key is no longer 20,-20,0,0,126,0 possible.) A piano, essentially pressed or UNTIL a different key is percussive, has a transient that pressed. The IN KEY parameter exhibits a fast build up and long defines the length of time the

sustain. This is almost the opposite program is to wait and see if a key

of an organ where the note takes a is pressed. The value of this longer time to build up but decays parameter has got to be as small sharply as the air supply is abruptly as possible, (so playing the keys cut off. In tact a tape recording of a fast is possible), but greater than piano played backv^ards will make the repeat rate at which characters Figure 4. Variation in amplitude organ sounds and vice versa. are sent by a continually depressed controlled by the envelope vi/hich a note builds is to The rate at key. The repeat rate decreased statement. Oscilloscope trace up and decays and how long it is its smallest possible value using a starts on the third increment sustained for can be controlled *FX call (see User Guide). The accurately by the envelope effect keys are checked by statement, but the undulations PROCcheckforstops, in between whose amplitude is controlled are each note being played. A variety square waves and not pure tones of stops could be examined by or 'trumpet-like' or 'clahnet-Iike' extending this procedure. The envelope statements (eight possi- undulations. Approximate instru- procedure also has to absorb the bilities) for each note in the mental synthesis is still possible variable number of characters that chord. and this demonstrates that transient will be sent by a stop key due to • playing chords where each note control or control over the the increased key repeat rate. in the chord is controlled by a amplitude envelope, is just as You can define up to four different envelope statement

important as (if not more important envelope statements and these can (4x3x2 possibilities per three than) the harmonic envelope in be incorporated Into a number of note chord). determining the unique sound of effect keys. Some suggestions are: • Adding chanel effects. an instrument. • single notes with a selected Alternatively, program 2 can be There are other subtle factors envelope (four possibilities). used to experiment with the effect involved in the recipe for an • chords can be played with two of the amplitude envelope by instrumental sound but we have not or three sound statements playing tunes from DATA statements the space to go into them here. selecting one of the four (Acorn User December). The code

f\{ this stage it is useful to introduce a program that will play Program notes from the keyboard and also 2. Sets up envelopes from DATA statements

change the characteristics of the 10 tempo = 1 note played as soon as an 'effect' 20 INPUT aa, ad, as, ^r , ala, aid key or 'organ stop' is pressed. You 30 ENVELOPE 1,1, 0,0,0.0,0,0, can then play tunes from the ''^ '^^ ""^ "^' ^^"^ ^^^ keyboard and instantly change the 40 REPEAT sound produced by pressing an 50 READ note, duration 60 'effect' key, just as you would on an IF note-255 THEN envelope-O electronic organ. The structure of ELSE e?nve}. ape'=l the program is amenable to BOUND 1, envelope, not^ f«mr,^*^ ' ^--ePmpo*dL,rat i on extension. SO UNTIL note=-l 90 Program 1 causes the keys on 100 the bottom row of the keyboard to DATA behave like the white notes on an

ACORN USER MARCH 23 MUSIC

10 durat i on - 'j 20 ENVELOPE 1.1, 0.0,0,0,0.0, -20. 126. -20, '-20. i-?(, Ml Table 1. ENVELOPE 2,1. 0,0.0,0.0.0. " Envelope parameters for some instruments 90, -20, -20i -20. 90 60 35 ENVELOPE 3.1. 0,0,0.0.0.0 ' ^^'' ~^°' ~^^'- ^-f'- 126. W 40 FDR bar = 1 TO 16 4S FOR triplet = 1 TO 2 50 FOR note = 1 TO 3 126 \2b ion ELfct 60 envelope 126 l] ^""^^ = l ELSE 176 50 ElffCt 70 SOUNDsnnwn'r' envelope 1J6 -4 -1 126 1D0 Acoua o. envelope. 4. duration -b -2 1Z6 126 Acous SO NEXT note =>0 NEXT triplet -6i 63 1?6 Organ 100 FOR note = 1 4 U -6J 5i 126 Wind TO no Sl-.'ND O, 3, 4, duratian»3/2 120 NEXT ate 150 NEXT bar Program 3. R hythmic effects

255 is used to represent rests. This statements if detune the 20 ENVELOPE 1,1, we means only two items of 0,0,0,0,0,0, octaves: information are needed per musical aa,ad,as,ar,ala,ald 80 SOUND 1, envelope, note, entity (note or rest) in tfie DATA tempD*duration 30 ENVELOPE 2,1, statement. 90 SOUND 2, envelope note + 50, 0.0,0,0,0,0, tempo*duration Figure 4 is an oscilloscope aa/2,ad,as,ar,ala/2,ald/2 100 SOUND 3, envelope, note + 97, photograph of an isolated note tempo*duration generated using: 80 SOUND 1, envelope, note, Using a common percussive ENVELOPE 1,1. duration * tempo envelope, this will give the sound of 0,0,0,0.0,0, 90 SOUND 1. envGlope*2, note, a West Indian steel band - oil 20.-30,0,0,126.0 tempo * 2 drums tuned to octaves but This is an inverted 'V envelope exhibiting less than perfect tuning. taking seven increments to build The parameters In the echo Finally, program 3 demonstrates up and seven to decay, the attack envelope can be made a function the use of channel in conjunction rate being equal and opposite to of the main envelope parameters to with a percussive envelope to the decay rate. If this was control the echo effect. Again produce a rhythm from a mono- compressed in the horizontal or experiment yourself, tone percussion instrument. The time direction so the steps were not rhythm is shown in figure 5, and if so apparent, it w/ould begin to look you don't know what this is from like an instrumental envelope. /\s discussed above, it is not only reading the dots then play the amplitude envelopes are the transient behaviour Some of a note program. now given together with a very that gives it its chracteristic Figure 5. Rhythm for program 3 approximate subjective description instrumental sound, but its of their sound or effect. All the harmonics. We can add harmonics envelope statements in this article to a program generated note, but are only suggestions. The emphasis only two. Also bear in mind that the is on relating envelope parameters BBC tones are not sine waves and JlJIjm to the produced sound and in that is why, no matter how hard you giving frameworks for experimenta- try, all notes will sound 'electronic'. tion. With some imagination and Now in real harmonic envelopes, Note also in program 3 the use patience you should produce not only does the amplitude of two envelope statements to pleasing and original sound. change as a function of the simulate that the emphasis can The envelope parameters in frequency of the harmonic but so either be an amplitude change or table 1 are meant to be used with does the attack rate of the the note played on another drum, A t=1. In the top part of the table, harmonic. We can control this program like this could be merged percussive envelope values are easily in a program: into either the tune playing program given, in the bottom part wind or the keyboard program to add a 20 ENVELOPE 1,1 rhythm is instruments' values are suggested. 0,0,0.0,0,0, section. This rhythm Note that for the wind instruments aa,ad,as.ar,ala,ald intended to show the variations values of aid are greater than ala 30 ENVELOPE 2,1 possible within a bar, using 0,0,0,0,0,0, and ad is positive. A long slow emphasis from different envelope aa/2,ad,as,ar,ala/2,ald/2 is statements in conjunction with attack continued into the decay 40 ENVELOPE 3,1 phase. 0,0,0,0,0,0, channel 0, rather than something aa/3,ad,as,ar,ala/3,ald/3 that Gene Krupa would play! In the next issue we shall W.'e now move on to consider the continue with treatment of the pitch 1 90 SOUND , envelope, note, effect of using two or three sound envelope and look at tempo ' duration some statements under envelope control. too SOUND 2, envelQpe*2, note + mathematical and syntactical ele- An echo effect can be achieved by 48 tempo • duration ements of music structure that using a second sound statement 110SOUND3,envelope*3, note + enable you to get your machine to 96, tempo * duration under a different envelope control, do something more interesting than but using the same sound channel. Other simple effects can easily be playing the ubiquitous 'Green- A suggesting is: attained with octave sound sleeves' from a DATA satement. #

24 ACORN USER MARCH Software Savers

Tlie most advanced word processing WORD PROCESSOR progrann written in machine code and permanently stored on a ROM which PACKAGE plugs into your BBC computer board, ONLY (Model B only). This program contains many advanced features including £25. 50 access to existing programs, and is undoubtedly the best value for money. [including VAT and Delivery) If you are not convinced, we guarantee to refund your money and postal expenses.

BUSINESS PROGRAMS GAMES

Sales Ledger £10.00 Backgammon £10.00 Filing £10.00 Space Invaders £7.00 Purchase Ledger £10.00 Pucman £7.00 Payroll £10.00 Space City £7.00 Invoicing £10.00 Gambling Video £7.00 Home Accounts £10.00 Star Trek £10.00 Stock Control £10.00 Directory/enquiries £10.00

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EXAMPLES (all for the BBC 32kl AVAILABLE NOW- ANGLE Set of 4 graded programs with superb graphics C8.95 demonstrating Angle as 'turning', degrees, names of MUSIC (for Model A or B) E8.00 various angles, how to use a protractor, with questions to check understanding. Even measures angles direct from Enables your micro to play any music which you choose the screen. Ages 8-14, to type in, using a simple notation, An up to 3 parts. INKOSI Be an African King! If your strategy is good you may stay Comes complete with demonstration pieces including E5.95' for 10 years, but watch out for the Witchdoctor. "The Entertainer' (needs 32K) and a Bach composition. Colourful simulation with great graphics and sound- Ages 10-adult. We challenge anyone to produce better sounding music INVISIBLE MAN Draws and labels a grid, and displays a man who on the BBC micro. £5.95* disappears! Feed in co-ordinates to find him in the time

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26 ACORN USER MARCH HINTS AND TIPS

Joe Telford builds a be solved: construction of the touch pad in the prototype circuit. hardware, and writing suitable In addition to the wires from lightpen for £17 and software. Before doing either, look sensor to paddle connector, we writes the software at the input/output facilities of the take wires to the outside surface of BBC micro to find a suitable port or the pen. These are connected to an to run it on the BBC input channel. Normally I would go analogue input and effectively micro- with or for the user port. However, measure skin resistance. Under without the Tube examining the ADC (analogue to software control we can make digital converter) port circuitry these contacts behave tike a shows a possible connection. switch. Notice also that we have a

Figure 1 shows the paddle and 100k (100,000 ohm) resistor, which lightpen (ADC) connector. Notice makes a potential divider. We that pin 9 is marked LPST B, and develop a voltage of about 1.8v this is the light pen strobe input. across the user's finger, when Our first priority is to ensure a TTL touching the contacts (about the type input goes to this pin when same as a single battery in a torch). our lightpen is held to an illuminated section of TV screen. WARNING: Ensure the ADC The RS catalogue of electronic reference voltage is not at mains components, shows a device which potential, and Ihat you do not touch can be used: the pin photodiode live wires while using the lightpen. {RS number 303 292} at £6.33. Neither the author. Acorn User nor Acorn will accept responsibility in The high sensitivity of the pin the event of an accident involving photodiode allows a range of using mains electhcity with this screen intensities to be received, If lightpen. It is designed to operate the pen does not seem to react to at voltages of 1.8 volts and 5 volts the screen, the remedy is often only. simply to increase screen bhghtness on the TV. Figure 3 shows the constructed The value of this is that a simple lightpen. The connector to the ADC circuit can be constructed, which port is a 1 5 pin 'D' connector allows a slim biro to be used available from most BBC micro Figure 2 circuit for the pin shows a stockists, RS or Farnells, The photodiode. The tag on the pin connecting wire is five core photodiode identifies leads 1 ,2,3 stranded wire, and about four feet when aligned with its diagram in typical lightpen picks up light will be needed. Again, any figure 2. given out by the TV screen. The pen electronics dealer should sell this. sends an electronic signal into the The touch sensors can be made micro, where circuitry decodes the from two copper strips (half-inch position on the screen at which the Veroboard} which after soldering, hile pen is pointing. Software can Wf constructing a prototype, I can be glued on the pen barrel. access this input, tailor it to the decided the pen's facilities would Soldehng the light sensor is screen mode and allow the user to be enhanced if it could move a easy, providing you use pliers to play games, draw and 'paint', cursor across the screen. When dissipate heat from the sensitive design layouts, select multiple that cursor was in the correct pin photodiode (figure 4). Once the choice answers, update and alter position, pressing a switch would leads are soldered they need to be information using a menu, or indicate this to the computer. A individually insulated with tape. interact with graphic simulations. keyswitch on the keyboard would The pen itself can be any size

And these are just a few do, but this defeated the which allows the light sensor to fit applications. philosophy of having a self inside its empty barrel. Once the There are two main problems to contained lightpen. Hence the sensors are glued in place, the pen

Figure 1 . Connections to ADC (analogue) socket. Based on User Guide

ACORN USEH MARCH 27 DIGITISER SYSTEM" Designed for use with the BBC Model B Microcomputer

^^^^^^H|^^ '"'**U|||jjflQ

The P.L. Digitiser System enables you to reproduce complex pictures and TO: Dollamore Castle Gresley, diagrams, or produce original designs,^quickly, easily, and accurately. B, S. Ltd, The package consists of the 'Graphics Digitiser' incorporating a tracing pad Burton-on-Trent, Staffs DE11 9HA (mapped out by rectangular grid) 256mm « 205mm and the 'Control Please supply the following: Program' () which handles the information passed from the digitiser to the microcomputer. Qty Description Cost VALUE

P.L. DIGITISER C109.50 1 WIDE RANGE OF INSTRUCTION scale may be increased or reduced BLOCKS. Instruction blocks by making just two inputs, Post & Packing CA.OQ enable: boxes and circles of any STORAGE. Pictures may be saved size to be constructed by specifying V.A.T. @ 15% on cassette or disc file or two probe positions; filling area TOTAL reproduced by a line printer. with chosen colour; drawing of irregular shapes using chosen FULL COLOUR. The range of Each Digitiser is supplied with cassette Control Program and resolution; outlining defined area in colour facilities offered by the BBC comprehensive operating instruction manual. different colour and varying line micro is easily handled by the thickness; creating lines in Digitiser, in modes 4 and 5. Please charge on Access/Visa Card Horizontal, Vertical or Angled ACCURACY. The probe position is modes, with parallel lines in repeat No continuously displayed on the or multiple repeat styles again in screen and fidelity of image to selected thickness; write and Signature original drawing is very accurate, position text, NO KNOWLEDGE OF BASIC Name COMPLETE EDITING FACILITY. REQUIRED. Users can very easily Mistakes can immediately be erased Address and quickly familiarise themselves and rectified. with the P-L. DIGITISER SYSTEM,

RELOCATION AND SCALE. TM-B, S, OollatTiDre Ltd. Castle Gresley. Images may be relocated simply by Bunon on Trent, Staffs DEI) 9HA. inputting two probe positions and Telephone: Burton on T ten I (0283) 217905

\y^ m .».^^ The London ACORN-BBC Centre Suppliers to Schools and Colleges Atom: Full hardware and software support. Maintenance Contractors Tapes: BBC: New Showroom: Model A £299 Top Tape; see adverts in Radio Times, OFF Records would expect you to buy Model B £399 OFF Records beats all published prices. best value. Spend some time in the Memory up-grades £21 .99 Stationery: relaxed atmosphere of our new Repair service and component supply Moore Paragon main agents. Large showroom to find out exactly what you selection of continuous stationery, Printers: are getting for your money £215 forms and labels. SeikoshalOO OFFware: Epson MX80FT/3 £385 Books: CHAR Al D for the design of a block of 4 SCM Daisywheel £485 Browse through the Computer Book characters in any graphics mode Deparlment for educational, scientific Cassettes : including mode-7. Outputs VDU23 and business applications, Matched Cassette Recorders £26 commands, teletext commands and Monitors: printer commands to screen or printer 12" Green Screen COMPUTER HOUSE together with actual design. Substantial (Hitachi/Phoenix) £110 58 BatterseaRlse software with more than 20 well- 12" Colour (Kaga) £255 documented commands. Indispenstble Clapham Junction 14" Colour (BMC/Cable) £255 for graphics work, Discs: London SW111HH £7.50 p,p,& VAT incl- TEAC40-track £199 Telephone 01 -223 7730 ATlLITYcontains seven essential Shugart twin 40-track £299 routines forthedisc based Atom: TORCH dual disc drive with Z80 COPY, -QOPYT, -COPYD. "RENAME, < M»nuli-v rrcKr* BH Cltpham jEinili processor, 64K RAM. CP/M and Bni 19, 3',39, a&.ilB, eS, ", 17! 'PURGE. -BACKUP, 'AUTORUN. T'kltv Cljptt#n CorniTion FREE software £780 *J £25p.p-&VATincl, SI JOHNS HIU. LAVENDER HILL Eprom programmer: Vacancy: Specially designed for BBC, Programs tW¥ llKI)4m»N... OFF Records are looking for a bright 12 different Eproms including 27128, spark with good knowledge of both

Includes screen software £95 (A3. SOUTH CIRCULAR) BATTERSEA RISE, SW11 software and hardware. Initially a (dealer enquiries invited) Saturday |ob with a view to full-time

Add 15%VAT to all prices. Carriage extra. employment.

28 ACORN USER MARCH ^^ HINTS AND TIPS

•^ Figure 3. Wiring for prototype Figure 4.

Pliers used to dissipate heat while soldering

^tnoWkKB

Insui^tinii fapo

cap can act as a shade to improve though we are especially interested Together these tell us where the accuracy. This fits over the light in registers 16 and 17 which lightpen is pointing. We get sensor and has its end cut to let in contain information about the numbers from these registers even light from the screen. lightpen. Register 16 holds the if the lightpen isn't pointing at the The total cost of this last pen most significant byte of the location screen, or indeed isn't even (buying new equipment}: of the lightpen and register 17 plugged in. Type this program: holds the least significant byte, 10?&FE00=16:P.?&FEai Putting them together gives us a 20?&FE00=17:P.?&FE01 number which relates to the Order Item Cost Supplier Now plug in the lightpen, hold it position of the lightpen on the no about five inches from a 60W bulb screen. 303 292 Pin photo- E6.33 RS and type RUN. The program will diode print two numbers. Remove the pen 140 822 15 pin D plug £2,61 Farnells U,'nfortunately. the 18 registers are from the lamp quickly and type 140841 15 pole £3.99 Farnells not directly memory mapped in the RUN again. The same two numbers D cover micro. However, 437 of should appear, 140496 5m cable £1.85 Farnells BBC page This indicates the CRTC has 100k ohm £0,03 Tandy the User Guide gives a hint on how memorised the last known pen Vi watt etc. to access the registers which we resistor need. position. To test the pen with a TV program Old pen to suit £0.00 Location &FEOO is memory screen, simply LIST the a + VAT £2.22 mapped to the address register of couple of times, turn up the bhghtness and hold the pen on a Total £17.03 the CRTC and location &FEOO is memory mapped to the register file part of the listing. Type RUN. Two different numbers should appear. of the CRTC. So, if we put a number from to 17 into location &FEOO Move the pen to another part of the If nothing else, readers can see then location &FE01 effectively listing and type RUN, Another pair most commercial lightpens are not becomes the CRTC register of numbers should appear. If this is tremendously overpriced, although indicated by that number. the case we are ready to begin -if you made say 100 pens they For example, type; writing software. If not. check the would each cost about £1 4. connections on the D connector, ?&FE00=16;P.?&FE01 At this point, we have our light the pin photodiode itself. ?&FE00=17;P.?&FE01 and port, pen to plug into the ADC Program 1 is an essential

except nothing happens. This is Readers will see that each line procedure to run the lightpen. It is because we have to use software to produces a number in the range called by PROC. quopen which get at the other end' of LPSTB. to 255, ie, a byte-sized number. regards the screen as a series of The other end is connected to a fairly high powered chip inside the Program 1. Lightpen BBC micro. Not, as we might procedure expect, the ADC chip, but the 6845 X290mFPH0C quapen CRTC, 6845 is the integrated circuit 1295LDCAL o'f f sc-t w:j. ., dth, -sca-t e number and CRTC means cathode i.iUOof-fset-lS42:width-80:sr.^]p.= l ray tube controller. This works in 1305REPEAT combination with the video ULA to control the screen in a number of ways. One of the tasks of the CRTC t.S20:

is to handle the signal picked up 1 --':' 3;.25??.FE00^--- J. 7 s 1 open !>-^F En j. by the lightpen and to generate a 1330penpos=INT(fh:i.pen*2564.iopen>-nffc.pt) unique number for each screen l-^-l^.Jpeny=penpD!iv DIV width location it reads. i340penx-INT( /=.ra] p^ registers i.i4bUNTIL The CTRC contains 18 ADVAL ( 1 ) /:l 6->1.on numbered to 1 7. Each is used by .1.35OEN0F>ROC the BBC micro in different ways.

ACORN USER MARCH 29 HINTS AND TIPS

Table 3, Contents ot 'scale' for Table 1 Contents of 'offset* Table 2. Contents of 'width' for each mode for each mode each screen mode Scale= Mode Width Maximum resolution Mode Mode Offset (to access single characters) 7 10248 7 40 single character 6 3076 6 40 single character 7 1 6 5 2820 5 40 half character 1 5 4 2820 4 - 40 single character 2 4 3 2054 3 80 single character 1 2 1542 2 80 quarter character 3 1 2 1 1542 1 80 half character 4 1542 80 single character 1 2 1

character sized locations as for text resistance. A suitable value should page &FE (*FX151 means wnte to handling. It returns the position of be between 50 and 300, sensitivity page &FE). It is identical to 7&FE00 the lightpen in two vanables, penx increasing as the value decreases. = 1 6 except it is Tube compatible, and peny. These can be used in the The idea of the touch pad is that 1050 A%-^&96:X%-1 means set

TAB function. If for example the the pen can be held against the A% to &96 and X% to 1 In lightpen is pointing at line 7, screen until the user is confident preparation for calling a machine character position 14, then penx the pen is correctty place. Then, code routine. Don't worry! Acorn will contain 14 and peny will hold 7. pressure on the pad will conclude have written the routine for us. Hence a program line; the procedure, and return the latest 1055 hipen-(USR{&FFF4)DIV&FFFF) PRINT TAB(penx,peny);"P" values of penx and peny to the AND &FF calls a machine code body of the program. It acts as a subroutine which places A% in the will print 'P' in front a on the screen safety catch to prevent spurious accumulator and X% in the X- of the lightpen. garbage enthes. register of the 6502. The &FFF4 The procedure uses the special start location of the subroutine vanables 'offset' and 'width'. The indicates this is an OSBYTE first is essential to find the top left r^rogram 1 is the procedure on (operating system byte) call, and screen position. Because of which other programs included in with parameters A%^&96 and hardware timings etc. when the this issue are However, the based. X%^1 it reads the contents of CRTC returns the pen location, it is lightpen is device which will still a location 1 of page &FE in the I/O between 1000 and 10248 higher be used when readers upgrade to a processor (BBC micro). The result than expected depending on the second processor at the other end of the USR statement is a number screen mode. To correct this, we of the Tube. Unfortunately, the which is made up of four bytes: (i) subtract the 'offset' value from the region of I/O in the memory BBC program status register, (ii) Y combined contents of CRTC micro will not move along the Tube, register, (iii) X register, (iv) the registers 1 6 and 1 7. This is done in and so such commands as; accumulator. line 1330, Alter line 1295 for each P.?%FE01 The rest of the line; mode using table 1, which lists the DIV&FFFF) AND&FF contents of 'offset' for each screen may print a value, but certainly not mode. the value of the CRTC register file. extracts the single byte we need, that in the Y register. Program 2 performs just as I next special he variable which program 1 except it is Tube users must set up for each screen compatible. The lines which allow Uines 1060 to 1075 perform the mode is 'width'. This is the this compatibility are 1040 to 1075. same functions as 1040 to 1055 resolution of the lightpen across An explanation of these is as except they produce the contents the width of the screen, and table 2 follows: of 'lopen'. shows this for each mode. The last The procedure is set for a 1040 •FX151,0,16 of the special variables is 'scale', particular screen mode by line This enables the lightpen to access means place 16 in location of 1010. The three most common the screen in whole characters. Again, 'scale' needs setting for l':iOODEFPRDC_quapen lOlOLOCftL Program of + EE:-t, width, scale 2. Tube compatible each mode (table 3), I030REPEAT ^ 1040*FX151 .0, .16 Lines 1 305 and 1 345 form a l050A7.=,196ix-.'.= l loop which allows the CRTC to continually update penx and peny. 1070f\y.=S,96iXY.= l This continues until a touch pad is i0751apBn=(U3R(?.FFF4,DIV .^FFFF. AND .^,FF pressed and is tested by; !u9upbn).-penpas DIV fjidth UNTILADVAI_(1}/16>100 "°^ WXdth)/ErMe) lllMUNTIL!;V-nMxr^'^^''P^"P°^ADVAL(l)/16MOO The value 100 may need adjusting 1 i::oENDPRoc as it is an analogue of skin

30 ACORN USER MARCH HINTS AND TIPS

2. Program 3. Relies modes I have used are 7,4, and lOMQDE? on the target approach From the tables we can see these 20CLS modes require the following 30PRINTTABC1.0„5) ; "PEN IS AT" 1 0: amendments to line 01 40>; =RND ( ) : 39 y =RND ( 1 ) + 1 o 50PRINTTAB(>;,y) ;CHR$(?55) 1 01 Ooffset=1 0248:wicltti=4C:scale=1 60PR0C for mode 7 quopen 1010offset=2820:width-40-.scale=1 70VDIJ7 for mode 4 aOPR:iNTTAB(IO,7> pen;-! pp-ny 1 01 Ooffset^l 542;width=80:scale=4 90PR I NTTAB ( >; , y ) ; CHR* i^.r^) for mode 2 .l00t=O-IhE+I00' tlOREPEAT UNTIL TIME^t The second version of the 120G0TD40 relies on *FX calls not procedure lOOODEFPROC quopen available before OS 1.00, so I will lOOSLQCAL of f-et, width, scflle refer to the first version of the l!.'10Dffset-10243:width=4O:c:if-^-[p.,, procedure from here onward. 1015REPEAT Because the pen needs screen 1020: light, there are two techniques 1025?>?.FE00::=16: hi pBn-^:-7U--E>-')i which can be used. The first is to 1030: light up only the parts of the screen 1035??.FE00-17:lape^n = ':^,''.FEO] which contain information for the 1040penpc.s=INTUhipen*256+lDpen? -offset) UJ4^peny=penpoB pen to work on. For example the DIV width 1050pBn>! = message: IIMTapenpaEs MOD wi dth> /scale) 1 055UNT I L ADVAL U, ) / 1 6 > 1 OO PEN HERETO GO ON >@< 1 060ENDPRDC is followed by a target (a bright character) at which the pen must 10liaDE4 be aimed. 20VDUI9,0,7,0;0;r Program 0; sCLS 4. 30PRIIStTTAB(i!"),fi) This approach is useful in a ; 'PEW IB AT' Background approach 4.0PRQC quQpen" question and answer session, or in 50VDU7 a program where the lightpen A0PRlWTTAEit4/7)penK peny selects from a menu. In a game of 70PRINTTAB(pen)i,peny) ;CHR$(4-:') 30t=TIME-+-10a computer draughts however, the 90REPEAT UIMTtL TIME>t sight of 24 targets might be more 100GaT040 than a trifle offputting. llOREPEAf UWTIL TlME>t 120GaTD40 The second technique is best lOOODEFPROC quope^n used after experimenting with the lOOSLDCAL offset, width target approach. In this approach 10l0of1^Eet=2320:width=4O:BcalP=l the whole of the screen is 1015REPEAT 1020: bhghtened, normally by CLS after 1025';'!; = rNT(

useful, and with practice can do auto repeating. The program again aw/ay with the delay loop altogether. needs the lightpen procedure given "rogram 3 demonstrates the The only other point about this earlier. For mode 4, line 1 01 of the target approach by randomly program is that it needs the light procedure will need altering to: choosing targets in the lower half pen procedure given earlier. For offset=2820:width=40:scalG=1 of a mode 7 screen. When the mode 7, line 1010 of the procedure light- I of lightpen is held to a target and the hope to continue the use the will need altering to: touch sensor pressed, the location pen into drawing, painting and gen- offset=1 0248:width=40;scale=1 feel of the target is printed. To avoid eral design. Readers who do not auto repeating by people who are Program 4 demonstrates the able to construct either design from slow to remove their fingers from background approach by allowing this article should be able to buy one to point the pen anyv^^here from a number of sources, including touch pads, I have included line 70 the user which is intended to give the user a on the mode 4 screen. When the Acorn. Components from RS and positive feedback on pressing the lightpen is held to the screen and Farnells catalogues may be ordered touch sensor. Lines 100 and 110 the touch sensor pressed, the through electronic dealers or TV also ensure the user has one location of the target is printed plus repair shops. second's grace, before GOTO40 an asterisk in the actual position. begins to auto repeat. This program uses the same • Next month; how fast does a disc Users will find the sound cue approach to prevent users from drive?

ACORN USER MARCH 31 . !

F I NANCIAL BBC Model B GAMES

THE WORLD TRAVEL GAME

I or 2 Players. Choice of dame, Excit ing , Tense, Competitive and even Educational' xxxxx

Travel the World; Journey by air, rail and road. Exchange currencies; Buy souvenirs; Book tickets. Cope with hijacks, strikes, robbery and other problems inherent with travel.

Visit countries as diverse as Russia &the Falklands.

Your aim isto collect 6 souvenirs & return to LONDON intact'' -£6.95 -

GREAT BR I TAI N LTD INHFRI T ANrP

You are RM. Gt. Uncle Arbuthnot and Chancellor of is dead. 'Great Britain You stand to inherit !

You must select the A 2 pari game. Prove your Party you wish to represent financial and your aim is to stay accumen in Part 1 by investing wisely at in office for as long as possible. You must control the stock and metal markets; if desperate try the inflation and unemployment, maintain th exchange casino or the horse races. If you are successful you rale, introduce social reforms and stay popular. The will enter the world of big business in Part 2. Find game is split into sectors; country profile, shopping the secret formula for paradise cola: manufacture basket, budget day, reform opportunities, manifesto, and market the drink; cope with strikes, fires, frauds, and most important election nights (a telling time) cash shortages, etc. Your ultimate aim is to become A COMPLEX GAME THAT YOU WILL NOT TIRE a millionaire! A MAMMOTH GAME PACKED OF IN A HURRY FULL OF FEATURES -£5.95- -£5-95- See Reviews in: Acorn User Dec '^82 Trade Enquiries Welcome Personal Computer Jan '83 Special Deal for Schools Simon W. Hessel Wept a) IS Lytham Court, Car d^well Crescent Sunninghill, Berks.-Tel: Ascot 25179 24hr Despatch —One Year Guarantee— Money-back if not satisfied.

32 ACORN USER MARCH : ::: 1 ' ::::::::::; -

HINTS & TIPS

program 0X0 BY LIGHTPEN THIS demonstrates the you. It relies on the 'background' use of the lightpen in a game technique. Players have to input format, can be used as a basis for their names from the keyboard, for

further development, for example to convenience, although all input make the computer play against after this is by lightpen.

i-OHEmt-it.i^tt*:t.t*.ttt*it*tt*ttikt 20REM* 530 SOREM* LIGHT PEN 0X0 590REPEAT 40REM* 600; 50REM* Uz) J Telford 1 time 150 REM LARGE X AND 710: 1 60 720REM Now check for 1 win 70VDU23 , 227 , , 255 , , , , , , 730 .130VDU23, 223, 0, 0, O, 0, 0, 0, 0, ?5=v 740PR0C check i90VDU23,229,l,i: 1,1,1,1,1,/ 750 200VDU23,230, 123, 128', 123, 123, V^Q 760REN decrement no o-f- goes le-ft 128, 123, 128 770 2107DU23,224, 1,2,4,8, 16,32,64,128 730ng=nq-l 220Vr>U23,225, 123,64,32, 16,8,4,2,1 790

230VDU23 , 226 , 1 29 ,66,36, , , 24 24 36 , 66 , 1 29 800REM 1-f at 240: end then Win = -"1 310REM to indicate a draw 250REM SPACE FOR PLAYING BOARD AND 820 260REM AND 2 SYMBOLS X s. D 330IFng = AND win ---^ = 270 win I 840 IF w.n > 2S0.DIM THEN PRDC win board (3,3) , Ch$ (2) S50IF win = --1THEN PROc""draw 290 360: 300REN PUT X AND D INTO stnres 370REM I-f -the program qet--^ 3 1 '. hen- 330REM then win =^' in 320DATA 22S, 32, 224, 10, 3, 8. 8, 32 S90REM IE keep going 330DATA226, 32, 10, 3,3, 3, 224, 32,^^'^^'"225 900 340Ch*C0)='"':FaRI-/.-l TO 1?' 9iOUNTIL win 350READ data 920 360Ch$ (0) =Ch$ (0) +CHR* (data) : NEVT 930REM The game i -.^ 370DATA224 D-ver check: -far , 227, 22S , ,10,3.3,8, 730 y.2 940REM another go, 330DATA229, 10,8,3,8,225,223* '^'"'4 950 390Ch*(l).= ""sPGRI/:=i TO 17 960PRINT TAB (5, 26) 400READ data <' 970PRINT"Pen to ; -for 1 another 4 OCI--,* ( 1 ) -Ch* ( 1 ) +CHR!ti go. ( data > : NEXT 930REPEATSPR0C 420: guopen 990UNTIL pen;. = ,t5 AND peny 430REM FINAL SET UP 1000: 440REM F= Player to go lOlOREh Go back to 450REM l>;,ly = beginning last location o-f pen 1 020 46(.)REM win= tests -far win/draw 1030VDU7:G0T0 ~ 520 470RLM ng number of goes 1040: 480 1050REM Draw Board and -fill array 490F-*^0 1060: 500Dj:m name?$ (2) 107ODEFPR0C_Boflrd 510PR0C_nair.f?s 1080MGVE336, 320: DRAW3^6, 864 520CLBS PROC_BDard 1 O90M0VE528 , 320 : DRAW523 5301 x=0: y=0 , 864 1 1 10OJ1DVE132, 496: DRAW7()4, 540wi, n-0: nq=9 496 1110tMDVE132,6Sa:DRAW704i6S8 550: jv.- H-20F0R 1 JO 3 560REN Now repeat -for 9 gaes 1130F0R I7„== 1 TO 3 570REM or until a W3. nner -t 140bDard ( J7., rX) ^-9 1 150NEXT:NEXT

ACORN USER MARCH 33 ::: :: :: ) : e ) )

HINTS & TIPS

1 t60ENDPRDC

i .1 70 17S0t^^0i:FGR 17.^=^1 TO 3 11S0F?EM copy array to Fjcreen 1790t = t-f-boardCl, n.90: 17.) 1S00NEXT:IF t=0 win=l:ENDPROC 1200DEFPR0C_printbQard laiOIF t=3 win=2:ENDPR0C 1210F-"DR jy..:^ 1 TCi y, 1820t==0:FOR I7.= l TO 3 I220F0R 1%:=: i TO 3 1830t ^ t+board<2, 1230IFbDard— 9 THFN I ?60 ia40NEXT:IF t-0 wi n= 1 : ENDPROC 1240PRINTTAB< r7.*6H a'/C*6) ; 1350 IF t=3 win=2:ENDPRDC 1250PRIMTCh* (board (J7.„ T7.) ) ia60t.^^=0:F0R 17,= ! TO 3 12iONEXT5NFXT lS70t = t+baard ,1270ENDPR0C (3, 17.) -tGaONEXT:IF t=0 wi 1 12Q0: n= : ENDPROC ia90IF t=--3 win=2; ENDPROC 1290REM get players namps "^ '"} = :! 1 : FD R J 7. = 1 t n --t 1 300 i910t - t+board

13501JNTIL LEN(name*(0) ) VI 1960NEXTSIF t-0 wi n-l .- ENDPROC 1360CLS:REPEAT:PRIMTTAB(S, 10) ; 1970IF t=3 win=2:ENDPR0C ; 1370PRINT"Who is " ; " "; Ch* U ) 3.9B0t^0:F0R J7.".t TO 3 13a0INPUTname$(I) 1990t = t+bDard(J7-„3)

1390UNT.IL L.EN (nameit < 1) ) >! 2000NEXT:IF t-0 wi n=l : ENDPROC 1400CL.SsRRIMTTAB(5,20) ; 2010IF t=3 win=2: ENDPROC 1 '1. 10: 2020t=0:FOR J7.= l TO 3 I420REM get pen location to start 2030t =s t+fooard (J7,,| J7.) 1430: 20401MEXT:IF t-0 wi n-l : ENDPROC 1440PRINT"Pen here to begin. i > ' 2050IF t=3 wiri=2sENDP''RGC 14'50REPEAT:PR0C quopen 2060t=0-^FOR J7.= l TO 3 i460lJMTlL p(H-i>;=27 AND - peny=20 2070t t-f-board ( J7;^ 4-J7) 1470VDU7 20B0NEXT:rF = t-0 win J, 1: ENDPROC 1 4aOENDPROC 2090IF t = 3 win--2: ENDPROC 1 490 2100ENDPROC 1500REN gc-^t each players qn -from 2110: 1510REM Lp. 2120REn mease o-f a w:in. 1, 520 2 1 30 1530DEFPRac go 2140DEFPR0C win

lS40PRlNTTAi'(5,2) ; ' ' ' STRING* (30, 2150PRINTTAB(5,2) : STRING* (7^0, ' l^i50PRlNTTAB(5.2) ' ;namf.?$iF) ; " •^ 2 1 60PR ( I NTTAB , 2 ) ame-li -: go" 5 ; n w i n 1 ) 1560REPEAT:PR0C guapen " is the Winner" 1570UNTIL 3:NT(pen;-;/6) > 2I70F0R L-1 AND TO 5: FOR S-50 TO 1 OO INT(pen>i/6)<4 AND 2 1 SOSOUND.^: 1 1 - INT (peny/6) -m-) AND . 1 S , S , 2 1 lNT(peny/6)<4 2 90NE X T : SOLIND , , 1 ., a ISaoIF INT(peny/6.):=;ty AND 2200NEXT INT ':pen>:/6) =1 h G0TG1S60 22 1 OENDPROC 1590IF boarcl(lNT(peny/6) , 2220:

INT(pen>:/6) ) = -9 2230REM In ca-^-B o-f a draw board ( INT ;pe?ny/6) „ INT ^pen-! /6) ) 2240 s F :S0UND1,~1S,S0*(F+-1) ,R ^GGTOl 620 2250DEFPRGC draw ELSE S0UND0,-l^.s 106„3 2260PRINTTAB:t playpr 16f.50: 2310ENDPRGC 2320: 1660F=1-F 2330REM The .1.&70REM copy lightpen Procedure this go into last no 2340: 1.6a0REN location-; 2350DEFPR0C_guDpen 1 690 2360LGCAL of f set , wi dth , seal 17001y-IMr(peny/6) : 1 >;-INT (pen;; /63 2370of f 171.0ENDPR0C set = 2320: width-40:Brale=--l 2330 REPEAT 1 720 23.90??.F£00=16:hipen = ?S(FE01 1730REM Check -for vn n by c-ach 2400??.-FE00- 17:1 Gpen = 1740REI1 Player, horizontal, ??,-FEO 1 17SUREM Vertical, 2410penpos=INT(hipen*256+lDpen-o-f + set) diagonal. 2420pt=ny=penpos 1 760 DIV width 2430pen;.: = INT( (penpos MOD wi dth) /seal e) 1770DEFPRGC check 2440 UNTIL ADVAL ( ], ) / 16>,t OO 2450ENDPR0C

34 ACORN USER MARCH 1

p|I1Io)(g|(I)(a)@QQ;SQO@III(I)(I)(o)OG}QGO ® Attention all ATOM Owners !! — B Announcing the Software

SPACE FIGHTER (12K COLOURI Super Hrgh speed "Defender" game. 5 types of intelligent aliens. Repeating laser cannon, smart bombs, hi-score, rankings, tionus points. 6 skill levels Eiciting sound effects £6,95. INVADER FORCE n2KI Terntic version

of Space Invader' 'I types of invadets, (12KI Full feaiure. Cheis (12KJ Improved graphics, plavs ASTROeiRDS (12KI NEW version of Cowboy Shool-Out mother ship, great sound, hi score, 6 player, arcade shooting game. black or while, mid game leuel changes, this uicrectibii; GALAXIAN type game. two skill levels £5.95 sound effects. Screaming Superb graphics and sound ES.95 look ahead up to eight moves, Fantastic ATOMSTOHE (12K NOT M'CI oHensive, normal and defensive play. missiles £t swooping bird "men NOW Stock-Cat n2K) HI RES. Two Player Database filing ft printing program, passant' SPEED OPTION. £5.95- around any different race Ten sub-levels, castling. En by DOUBLE contest of 16 excellent value at only C6,95 player Rejects illegal moves. Take back ADVENTURE (12K NOT MIC) tracks. Steering, acceleration and moves and action replay with take over ALL THE INTRIGUE AND braking controls. Set the level of PLEASE NOTE: WE Set up problem games. C6.95, FRUSTRATION OF A MAIN FRAME difficulty for dnve r and ch oose the no, ARE AUTHORISED Hyparfire (12K colour! Aliens have ADVENTURE! Great skill and of laps £5.95 o over run six planets. Obieci to clear imagination are reguired to play this DEALERS FOR ACORN ATOM, Ihom Super high speed action. Four exceilem game and you may still never defender ships. Hit alien luel dumps and exhaust all the possibilities C6.95. BBC MICRO & DRAGON 32 alien ships Aircraft ladar shows Please add Sbp order P 6 P t VAT at 15% lilacemem of approaching ships. Thiuster conliol— including diagonal LTD. ^^ movement. Best sound effects yeti E6,95 ATOM 8/8A REGENT STREET, Cj Dog Fight 112K) Eicidng, two plays: G combat piogram in HI RES Graphics. SPECIAL OFPER CHAPEL ALLERTON your aircraft carriers and Defend attack Deduct E1 per cassette your opponents Engage the enemy LEEDS LS7 4PE. when ordering Q fighters m a battle to the death £5.95 Tel. (0532) 683186 G k two or more. y P O

ACORN USER MARCH 35 THE PROFESSIONAL SOFTWARE PEOPLE Multiple Choice Question & Answer Pack

• Specially designed for educational users

• For use with the BBC Model 'B' multiple choice Micro computer questions and • £25.00 including VAT and P& P answers pack Pack Contains • Instruction manual for BBC model B • Master input mode • 3 Reception modules, each display questions and answers in a format wcr suitable for students of different abilities and age groups • Blank tape for data. THE PACKAGE CAN BE USED BY STUDENTS FROM AGE 6 UPWARDS BY SELECTINCTHE MOST SUITABLE RECEPTION MODULE, IT MAY ALSO BE USED IN BUSINESS FOR APTITUDE TESTING AND IN THE HOME FOR EDUCATIONAL QUIZZES. Word Processing Pack • A simple to use tape-based word processing package • Ideal for the small business or Mil li home user

• For use with the BBC Model 'B' Micro computer Word • £70.00 including VAT and P & P. Pack

v/cr

Minefield • An entertaining family game • Try and cross the minefield without blowing yourself up!

• 3D graphics on Model 'A' and 'B'

• Only £5.95 including VAT and P & P.

70;EDUQUEST 7 Thames Avenue Windsor Berkshire 5L4 1QP Tel: Windsor (07535) 58079 Please send me: (Tick as required) Multiple Choice Pack^ Signature. Word Processing Pack D Name Minefield Model 'A' G Address. Model 'B' n

/ ericlose cheque for £ or charge my Access/Visa/Trustcard Account No:

36 ACORN USER MARCH . Together Mike Chalk and Kansas bring you the first major

arcade game for the BBC Micro . . Caiacfic Tmesmp

Those ever circling, swooping, diving Firebirds of the famous arcade machines, brought in all the glory of the BBC Micro's colours and sound. Many programmers of many machines have tried to emulate the arcade game, Firebird, but nobody, the Americans included, has managed to get the circling, swooping firebirds on a computer. Only Mike Chalk It is incredible how the Firebirds peel away, circle around in numerous positions on the screen, then suddenly sweep in to attack, all the while raining down their bombs.

Even if you manage to dodge all their bombs whilst shooting them down, it is as though they realise they will not get you this v^ay, for vwithout warning they'll take kamikaze action and come straight for you! Then come the Astro Blasters, shooting down a solid energy bolt, to fry you completely, in adition to their own brand of super bomb. Oh, you can fire at them, but a solitary hit will have no effect whatsoever on these nasties. As though Firebirds and Astro Blasters are not

I nough, as the game progresses, come the Megon Bombs. With no less than three hits needed to destruct! And you can't dodge them easily either, as their explosions spread.

Though the game starts with just the Firebirds, it As exotic illustrations usually hide third rate programs, here is the progresses level after level, until ultimately the actual screen as seen during an advanced level of play. screen is full of Firebirds, Astro Blaster, Megon Bombs and other bombs raining down, until you are completely annihilated. Top score table of course. In full machine code. From Kansas - and only from Kansas £9.50 'Vat and post paid

to you want ^ ^ q^nsas Brand leader in microcomputer software Tel: 0246 850357 Kansas City Systems, Unit 3, Sutton Springs Wood, Chesterfield, 844 5XF.

ACORN USER MARCH 37 A

COMPUTER MAINS INTERFACE Five Computer controlled 13 Amp socket outlets, each capable of SIR Computers Ltd switching loads up lo 13 Amp. Allows implemenlation of Industrial and Home automation systems without electrical experience. All outlets fiave indicator ligtils wfiich make the unit ideal for Educational use. Easy to use. just plug in to a 13 Amp socket and into CARDIFF your Computer and then load the Demonstration Cassette provided. Low voltage or mains inputs can be supplied to allow your computer to monitor limit switches, thermostats, flow detectors, pressure Agents for Acorn, BBC and TORCH Computers switches etc.

* lor BBC(B), PET, VIC. COM64, NASCOM E65 BBC * BBC (A) £69 Model A wilh 32K RAM >ind VIA 13.^9.00 Optional Extras — Model A with i2K RAM, VIA and (oystick port 1354.00 * 2 l\1ains Input Ports £7 Model B £399.00 Other options available. Hardware and Software available for most Model B with di^c jnlerface £509.00 applications.

Single inOK disc drive , £249.00 Dual 2x lOOK disc dnve £389.00 BBC ANALOGUE INTERFACE The disc manual and ulililie'; disc are both included. Allows your Computer to monitor and plot variables such as voltage, current, resistance, pressure, weight, temperature, speed, lighting Disc interfacL'foi ihc BBC Micro (kiU £ 95.00 and sound levels, pH etc, (fined) £110.00

Uf)^r,idc ol BHC MndH A lo \i £ 90.00 * Interface adapter with 30V dc and 300V ac £66 plug in Modules Please telephone for uji to date information on Prestel, Teletext, speech * Extra plug in (Modules (up to 4 may be fitted) synthesis, second processors, etc. AC Modules 300V, 30V, 3V E12 DC l^odules 300V, 30V, 3V £12 TORCH Computers Temperature IVlodule and Detector E20 Z-ftO Disc Pack for the BBC Microcomputer £895.00 Other Modules available, including Input and Output ports. S. A. E. for This uni! connects to the BBC Micro in the same way as a normal disc details. drive, but as well as offering a dual 2x400Kdisc drive for use under BBC

BASIC or other languages it provides the option of using the wide range BBC UPGRADES of CP/M software available lor business jnd data processing apiilications. * 32K Memory Upgrade £21 The lirmw.ue supplied with the machine allows switching fjei ween BASIC * User/Printer Port £8.75 and CPN, a powerful operating system developed from CP/M 2.2. * Analogue Port £7.70 In addition to the disc pack a second processor is supplied. This js a Z- RBG Serial I/O Kit £8.70 80A with its own f)4K RAM i..Md, communli ating wilh the fiS(l2A in the Tube/Bus Kit £7.00 BfiC loniputei through the 'Tube', Typicilly (he speed of execution of Recorder lead with any type plugs £2.00 programs under the twin-processor system is increased by up to 50% * All Accessories include demonstration programs. compared with a conventional single-processor computer. All prices include p.p. & VAT A third processor, the 16 bit 680(X), will shortly be available. TORCH rF240 £2795.00 COMPUTER ACCESSORIES (Ex. VAT) This an extension of the BBC microcomputer/Torch disc p.ii k system, 69 Well Heads, Thornton. Bradford 8013 3SJ available In a single unit. The conipuier contains a BBC-based peripheral Tel; (0274)833742 processor connected to the main Z-flO computer, a dual 2 x400k disc drive as described above, a high resolution (80 character) colour monitor

and a complete British Telecom approved 1 200 baud modem. It is the only microcompuler which has been granted permission for direct connection 4 Greenbarn Way to the Public Swiclhed Telephone Network both in the UK and the United Slates. Blackrod

The TORCH can communicate either directly with another TCJRCI I or with vinually any other type of computer via Prestel. Using the Gateway Lancashire facility of Prestel it is possible for the TORCH to access vast amounts of information stored by pri>Jate organisations on public database systems. BL6 5TA The Mailbox facility of Prestel also allows the use of electronic mail,

TORCH As above but wilh a 10 MB hard disc drive. CH240/10 R O D AT Tel 0204 694265 TORCH CHi40/2! As above but with a 21 MB hard ilisc drive.

Peripherals A CONCEPT IN SOFTWARE PUBUSHING Seikosha GP lOOA printer £ii9,(H) NEW Epson MX 80 F/T type 3 pnnter £3fi9.00 NEC PC 8023 printer £389.00 BEEBTikPE Mlcrovilec 14" RGB Monitor £299.00 Kaga 12" RGB Monitor £280.0(5 Tired of typing published program listings Sanyo 14" RGB Monitor £260,00 into your BBC Microcomputer? Fed up paying high prices for lliyh resolution 12" black/green monitor £ H5.()0 mediocre software? Now BEEBTAPE is here with a wide range of Software software without typing!

We currently hold in stock programs Irom the lollowing sup|)liets; BEEBTAPE is a bi-monthly cassette of Acornsoft Level 9 Software programs to run on your BBC Microcomputer. Each issue A & F Software Molemerx covers a broad range of Bug Byte MP Software contains at least five programs and Computer Concepts Program Power interest Our launch issue has two great games, Crawler and Digital Fantasia Salamander Software - Runners, a critical path analysis program and two utilities Golem Software for All 1|K Software Su|jerior Software one which dumps blocks of memory either to the screen or a printer in hex format, and another, called Sound Workshop, Unfortunately we are unable lo supply software by mail except as part which gets the best out of the SOIMB and ENVELOPE commands of a larger order. by continuously displaying all parameters on screen and Delivery by InteHink of any of the above ilems £ 1(1,(10 [Jn/ess ot/ierwise sliifed all prices inc/fjde VAT. allowing them to be edited, compared and tested.

BEEBTAPE is available by annual subscrip- SIR Computers Ltd tion at £21 or a sample issue for &5- At five programs per issue 91 Whitchurch Road you will receive at least thirty programs in a year. That's 70p Cardiff per program. Teiephone (0222) 21341 ACCESS TELEPHONE ORDEBS WELCOME

38 ACORN USER MARCH : :: : " ) i

MULTI-CHOICE (called distractors) need to be pro- program. Next rewrite the data lines in duced so they are believable, and order 'question', 'answers', 'correct This prog ram is a multiple choice quiz. should always indicate the problem answer number'; eg: It contains 10 questions relating to experienced by the child who gives )" 1490 DATA'This is Qu the BBC micro. All input during the that distractor as an answer. They 1500 DATA"ans1","ans2" program is by lightpdn and readers should also statistically attract a per- 1510 DATA"ans3","ans4" will note the use of sound cues for centage of children answering the 1520 DATA-ans5",3

correct/incorrect answers. test. Note the 3 indicates Ihat answer 3 is As the number of BBC micros in The first thing to change would be correct.

schools is continually increasing, I the title on lines 520 and 530. The only Do this for each of the questions as should mention that teachers who other amendments would be to needed. The last DATA line must be wish to use this sort of program must changing the data, which begins at DATA"END". The program will auto- give adequate thought to the data to line 1490. To change the data, simply matically score for quizzes of any be employed. The incorrect answers delete from 1490 to the end of the number of questions.

20REM* * 490ENDPR0C 30RE'M t MULT I -CHOICE QUIZ 40REM* 500 510DEFPR0C_.tltJ,e 50REM!t: HGR LIGHT PEN 60REM* "Multiple Choice Quiz" 520PRINTTAB!9„ 10) ;yeT 70REM* a, TELFORD 1933 low*; SO REM* 530PRINTTAB(10, 12) ;yellow*? "Far the BBC Mi(::ro„ " 100MODE7 S40PRINTTAB(9,lS)r'Ren here to start 3 "target*; f UOREM Set error chec ing " 120 ON ERROR GDT0300 550REPEAT: PRDC quopen 560UNTIL pen>::=29 AND t30REM Startup Progrrr.m peny=lS' 140DIM 570VDU7 yl DC (5) „ answpr* (5) .ISOREPEAT 58OEMDPRon 160REST0RE 590 1.7OPR0C setup 600DEFPR0C,_getquest i on i^ 180PR0C,__title J. OREAD q$:iF q*:=:"END" FNDPPQC 620F0R a7.=r.i 190REM Laop through questions ro 5 630READansweriE 200REPEAT ( JX 2.10PR0C qetqueBtion 640NEXT A50READ correct answer 220IFqi$="ENn" DONE"- GOTO 260 230PR0C_di 660ENDPR0C !5p.l ay quest i nn 670 240PR0C^gG?tanswer 6aODEFPR0C__d 250PRDC check^mswpr i sp 1 ayquest i on 2A0UNTIL DOME 690CLS 700no.„Df,_, 270PR0C,„_5core quest ions^^no o<- qne=^ti Dn^^-;+ 71ypRINT=-r6-vdt5 " "QueKtion Nq: " I FNc-sg ;| 280UNT L a i n ( T'* ) = NO 290CLSE 72oPRINT;nD_Df_questiGnssTAB':20) PRINT^- "Bye" : END ; 730PRINT"Score: 300CLS: REPORT^ PRINT" at ERL " ; no corrert 74(,.iPRINTred$-STRINS*(3S, " ") 310PRINT^' "BVG>" = END 7'30PRINTTAB(0,vlDc 320 (0) ) n n$™ 760F0R 330REM NOW FOR PROCS J7,=^ 1 TO 3 340 770PRINTTAB(0,yloc(a%));"]n,target$-T 78oPRINTTAB(5,ylcK:(JX) 350REM Procedures ) ;ven,nw*ii Btart hf?re 790PR.lNTan5wer* 360DEFPR0C setup iJX) 370CL3 300NEXTJ/, aiOPRINTTAB(0,13)-'Pen 3g0F0R J7. = TO 5 to line of L or r ec t an -^^wer " 390READ yloc (JX) 320ENDPR0C 4 GONE XT S30: 4 1 0nD_.Gf .^quest i ons=--0 a40DEFPRDC_getanswp^- 420no__CQrrec:t=0 SSOREPEATs PROC, quopen 430DONE -^ OAOUNTIL pm-^y.:=yj or 440red$^=CHR$ (129) AND ( i > peny<^:^y|ac (5) > 450green*=:^CHR* (130) B70VDU7 460yel 1 ow$==CHR* (131) SaOENDPROC 470target-*:^^CHR$ (25fi) 890: 4S0ENVEL0PEU0.2,-2,2,6,]2,6,1':'7 O o' 900DEFPR0C_ chec k an swer -127, > ' 12.^.>,0 910IF ylDc ':correctanswer)~peny THEN PROC.^ correct ELSE PROC... wrong

AOORN USER MARCH 39 :: : e : ! : 51 4 3

HINTS & TIPS

920PR0C_CDnt: 930ENDPRDC 153.0DATA"The 6502", "The 730" 940: 1520DATA"Tho 6522", 1 950DEFPR0C correct 530 ;; 960SDUMDi, i, ],49,3 1540DATA"What is the type of I/O 9T0n(:)__c Drr port used by ec t-no c or r ec t + ] the BBC Micro?" 9aOPR:[NTTAB (0, 20?; Qreen$; i550DATA"The 620S VIA", "The 8255 PIA" "That was correct" 1560DATA"The S,25S V.TA"., "The 65?-^ VIA" 990EMDPRDC !,570DATA"The 652? PIA", 4

1 (jOC) : t 53>::) lOlODEPPROC wrong 1590DATA"Which Chip allows the 1.020SOUNDO,-12, 106,8 use of I the Light Ppn-'" 1030PR,!:WTTfiB 1600DATA"The (0, 20) ; red$; "The 6845 CRTC" -' correct answer was; 1610DATA"The D7002C ADC" t040PRINTred$; answer $ (correct an-wer) 1620DATA"The 74LS00 gate" lO'oOENDPRDC 1630DATA"The 6522 VTA" 1 060 1640DATA"The Video Ul A" 1 I070DEFPRDC cont 1650: 10gOPRINTTAB(5,23),"Pen here to qo on 1660.DATA"Which Area of Momory is 1"; " targratit; L' " ; assigned to Contrail l090RePEAt: PRQC quopPn 1 ng I/Qt^" 1670DATA"Fr(=d"., " rr," " " " Ji , John , nOOUNTrL p<-2n>;-24 AND "Ethel peny-2-^ 1 630DATA " 1 3h el a " , .11. .1.0V0IJ7 1690: li20ENDPR0C 1700DATA"rf we were controning t 130: an e>;tra VIA from 11.40DEFPRDC score the BBC Micro. i"J h i c h s D c f; e t vi o u 1 d ilSOCLSsPRINT— yellDwd we connect to?" 1710DATA"Di5C i nterf ace" , "User port" 1720DATA"Printer 1 1 BOENDPROC port",lM H-r- R,,s" 1730DATA"The .1,190: Tube", 1 740 1200DEFFNagaift(Tti) 1750DATA"Using the R3432 1210PR:1'NTTAB(5, Port,' 1.0) ;qreen*"AnDther qn'>" what is the 1220PRINTTAB<5,12)":i'",tarqet*I"r ?fs- fastest transmission ].230PRINTTAB(S, " " 14) :i ; t flrqr^tf. - '' "f' NO" speed available?" 1240REPEAT:PR0!: quopen ' 1760DATA"1200 Baud", .1.250UF4TIL pen>.-6 AMD "39200 Band" 177pDATA"9600 " =- Baud", "IN H:.-","-^N H^ (peny i2 OR peny = ]4) 1730DATA2 1 260VDU7 1790: 1270 IF peny ^12 THEN =:^"yES' ELSE -"NO" 1300DATA"Which of 1 2BU : the foliowinq EPROMS cannot be used in 1 290DEFPR0C quopen the BBCNicro''" 1310DATA"2732 4k:" 1 300L0CAL , "2764_ INTEL 3K" off Bet , w 1 d t h , - r a ] 1320DATA"2764_HITACHI 1310off.5et^-1024S:w:Ldth=40:scale-l 8K" 1320REPEAT 1330DATA"27i2a 16K","2716 2K",5 1330: 1 340 1350DATA"What is the current level of 1340?S100 ^e) 1900DATA"Which Software Pack Is not 1410ENDPRDC available on the BBC Nicro"^'" 1910DATA"LISP", 1 420 "PILOT", "FORTH" 1430REI1 1920DATA"WaRDPR0CES3ING", "BASIC" ry Y-locations of answer lines 1930: ' 1940DATA"Who is Education 1450DATA4,a, 10, 12, 14 16 hanager 1460;; for ACORN'^" 1950DATA"Tony Ouinn" 1470REN Each question 1480: 1960DATA"Herman Hollerith" 1970DATA"Shj.rley William-." 1490DATA"What is the type of main 1980DATA"John Coll " processor fitted to the BBC micro?" 1990DATA"Jane Fransella",4 ISOODACA'-The 6800", "The 3030" 2000: 2010DATA"END"

40 ACORN USER MARCH BBC ASSEMBLER

INDIRECT Al I I RESSING

W^hen dealing with large tables or Tony Shaw and John Ferguson show lists of data it is useful to have instructions that allow you to read how to work with a variable or com- from or write to a variable or computed address. Indexed ad- puted address in memory dressing, where the position of the data is calculated by adding the 113 lODET contents of the X or Y register to a 20 REM JLMP INDIRECT :NSTRUCTiar^ base address, is helpful, but is 30 OSflSCI=&-FFE,T; restricted to a range of 256 40 VECTOR=&2i50 50 P%=&2000 locations about the base address. S0r For example, LDA &2000, X would 70. START LDft only allow access to locations nm \_(jw By DF 'y^HT -J0 between &2000 and &20FF. STP VECTOR 30 LDfl #g.2i?! \ KIGH The technique of indirect 3VTE OF "STRpr- 100 STft VECTDR+1 addressing solves this, and allows 110 \ftSCII "ft" you to work with a 'variable 120 JBR DSfiSCl \ PPilVT "P" address anywhere within memory. 130 JMP (VECTDP) \BRCr\ TO SIT-^RT The simplest instruction that 140J uses the technique is the indirect 150 E>4D

JMP. Although not involved with > RUN

reading or writing data to memory it 2000

serves as a useful introduction. 2000 P9 . m START LDP #00 .i.LGW BYTE OF "STfiR Like the normal absolute JMP 2002 BD 50 21 STfl VECTOR instruction, the indirect JMP 20 LDP) #&20 J-HIGH BYTE OF 2007 "STPRT" transfers program control to a new 3D 51 STfi VECTQR+1 212)00 41 position in memory. However, the LDO ttASCC'Pl") -iHSCII "fi" ::00C 20 address that follows the indirect E3 FF JSR DSflSCr -J-PRINT "fl" 200F 50 21 JMP JMP is not the address Ihe (VECTOR) -J-BfiCK TO STfiRT program jumps to. Instead it acts b 70. START LDh #ST(hR1 MOD 2^6 \ LOW BYTE OF as part of a pointer or vector to the SCI STFi VECTOR final location. Confused? The 90 LDft #STfiRT DIV 256 \ H I GH BYTE OF example of J M P(&1 800) should help. 100 STfl VECTDR+1 Note how the brackets are used in Program 1 (a) assembly language to distinguish the . Example using indirect jump (b) Using JMP indirect from the JMP absolute MODandDIVtofInd ADH and ADL of label instruction, MOD function to obtain the remainder when START (&2000) is

I he address program control divided by 256. In a similar manner passes to is stored in two memory line 90 finds the high byte of locations - &1800 and &1801. START using DIV to give the whole

Figure 1 shows how the first number part of the division. location contains the low byte of But why bother with complicated the address (ADL) and the second indirect jumps when an absolute the high byte(ADH). jump wouid perform the same job? Program la shows a simple In the simple example above there routine that uses the JMP indirect is no advantage. However, one instruction as part of a program application where indirect jumps

loop to fill the screen with the letter do prove useful is in maintaining a A. Memory locations &2150 and' fixed entry point to a subroutine &2151 act as vectors pointing to that can be 'redirected' to perform the start of the program at &2000. different tasks. For example, the Program lb shows a small but operating system routine OSWRCH. useful refinement used to load the (&FFEE) is used by the BBC micro ADL and the ADH bytes of the label to write characters on the screen.

START into the indirection pointers The first instruction in this routine is vector and vector +1. The low byte JMP {&020E) with an indirect jump is obtained in line 70 using the through WRite CHaracter Vectors

ACORN USER MARCH 41 ^ ,

BBC ASSEMBLER

&020E (WRCHV). Whenever the operating system wishes to alter the effect of OSWRCH, eg to direct output to a printer or modem, all it has to do is lo change the contents of the vectors in RAM to point to a different output handling routine. The entry point to the subroutine OSWRCH remains fixed. Program 2 uses this technique to convert all upper case characters sent to the screen to lower case. It starts by altering WRCHV and WRCHV+1 to point to a new output handler routine starting at OUT. The Indirect indexed is really three but this time the X register is used, A new routine intercepts all characters modes in one combining indirect second difference lies in the order in from the operating system and addressing together with zero page which the modes are applied. In the with > converts those ASCII codes and indexed - Y. It sounds horrific, previous case the indirect address &40 lo lower case. (A close look at but let's examine a typical was evaluated before the index was the ASCII code table shows this is instruction. Like the indirect jump, added on. With this mode the indexing bit five in the easily done by forcing brackets are used in assembly is performed on the zero page vectors ASCII code to a one). After the language io define indirect before the indirect address is eval- change, characters are then addressing. Hence: uated. allowed to pass down the normal The exampleof LDA(&80,X) should IDA (&80) output channel to the screen. help. If the X register contains four Upon executing the routine all would mean 'load the accumulator then locations &0084 and &0085 future operations with the screen with the contents of the memory would be used as the ADL and ADH will produce lower case characters. location pointed to by the contents vectorstothefinal location containing

The sample Basic program shows of zero page locations &0080 and the data (figure 3). a typical display with Basic &008r. Just as with the indirect keywords in lower case. To return jump instruction &80 contains the to normality, press the BREAK key ADL and &81 contains the ADH. applications the and the operating system initialisation nor many added of using the or program will restore the original Kegreltably this simple instruction complexity X Y is not required. With both values to WRCHV and WRCHV+1 does not exist. The real instruction registers takes the form; indirect indexed and indexed indirect the programmer can read LDA(&80), Y Unfortunately, 'straightforward' or write data to any location within indirect addressing is not available with the contents of the Y register memory by merely attering the for IDA, STA and CfVlP instructions. added to the address found in the contents of the zero page pointers. Instead the microprocessor uses a vectors (figure 2). The vectors must Program 3 illustrates the technique more complex form of indirect lie in zero page. using zero page pointers POINT addressing that involves either the Indexed indirect is again a com- and POINT+1 to store characters X or Y index register. bination of three addressing modes. entered from the keyboard in an

10 REt^ CHRNGING UPPER TQ \c>»^r Cfl.SE REM ^0 BY ALTERING "WRITE CHfiRfiCTER VEPTDR- > I ist 10 +or n=l to 10 40 WRCHV=S.02BE:REM WRITE CHfiRfiCTER VECTORS ^^'um^ 20 pr i 50 FOR nt "f i do" PflS5=Cl TO 3 STEP 3 30 60 Py.=&.0D0t next n > run 70CQPT PASS f ido S0. RTORT LDP #OUT MOD 25E \ POINT TO + 30 tm BYTE ido f i dr. 100 LDR #OUT DIV .:'5b \ POINT TO f i 110 HIGH BYTE do Slfl WRCHV+1 \DF NEW 120 OUTPUT ROUTINE f ido ^' \ BfiCK TO BR3IC f ido 130. OUT CMP #&40 \ CONVERT CODES > 8.40 f ido 140 BCC MIBS f i do 150 ORA #&.20 \SET BIT 5 ,e CHANGE TO f i do 160. MISS JMP LOWER CASE a-E03S \DDWN NORMAL CHANNEL f ido 170:] TO SCREEN 1E0 NEXT PASS Sample screen output 130 COLL STftRT

Program 2. Redirecting OSWRCH to produce lower case characters

42 ACORN USER MARCH B

BBC ASSEMBLER

' ' > L rsT — ASCII text file starting at &2000. 10 REM PROGRfiM PROVIDES The program begins by initialising fl SIMPIF pnTTno 20 REH TO STORE TEXT PRdS ilmfu? ™ X to zero and setting the vectors to 30 REM KEYl. .ENTER TEXT FILE 40 *KEYi"CflLLA0DS0l|M" point to the first location in the file 50 OSRDCH=g.FFE0 (&2000). The operating system B0 OSflSC:=«-FF£-^ routine OSRDCH is used to obtain 70 POINT=S,.S0:REM ZERO PAGE POTNTprs^^'^^-^3 S0 FOP PfiSS -0 a character from the keyboard TO 7: STEP^ 30 P%=&-0D50 "" which is then sent via OSASCI to i00COPT PfiSS

the screen before line 160 stores it '''''"" '='^ 120 LDPLDfl ;t-JTJTo°ir^"^^ ^^^ ™INT #8-^0:510 POINT+l v in the file. Although indexed 130 rn «.-'|7i00 indirect addressing was used, 140. sg a, JSR °^ "^^'^^^'^ DSRDCH \ GET KEY ^ indirect indexed .addressing with 150 -JSR OSflSCI \ONTO IB0 SCREEN Y ^ would perform the job. ^'^ TEXT same 170 CMPSSirS^'^'''):'™^^#g.5- FILE \ IS IT END "_"? An underline character (ASCII iS0 BEQ fin, t90 IMC &5F) marks the end of the file POINT \ UPDATE POINTERS 200 8WE again \BftCK FOR MORE returning control to Basic. Lines 210 INC PDIMT+l 190 to 220 increment the storing 220 JMP <3ga,r. \ BACK 2-".0. FOR MORE 1 , RTS BACK pointers to point to the next 240] \ TO BfiSIC available location in the file and 250 NEXT PPiSS 2G0 END ensure POINT+1 is only incremented whenever the low order vector reaches zero. (Note - no limitation

is made on the maximum size of )LIST Program 3. 'Editor' program to generals text file text file.) 10 REM (use mode 7 on model A to avoid the DISPLAY TEXT Rrj.JTI,-.p- ^0 MODe7:N = corruption by screen) assembled the routine sits «.2000 When -E REPEAT Program 4. Basic listing to in page D out of the way of Basic. 40 9%='' N: CALL aFFE3 -4 display text file Line 40 configures function key 5i2 ."y^N+l D0 UNTIL AX=--Gsrii' •!> one to the program. execute Program 5. 'Execute' program enables text Program 4 shows a short Basic V rile to act as command file program that can be used to display the text file. Finally, the routine given in "^^ 30 *KEy2"CflLLS0Dai KM" program 5 enables the BBC micro to execute a series of commands entered using the simple editor of 3EIC0PT the previous program. After PB3H iiei executing program 5, the machine wiil obey each instruction wiUiin the IZB "15 \BflCK TO 15B. BfiSIC file if it IM srx jisrasE text as came directly from \ store x 1B0 LDX «0 the keyboard, following 17a ^gg-r x^a each ^yrE lea r^„^ ll^'^^-H'l"^' FROM FILE command until the end of file 190 200 I^NO (&5F) \ STORE on STHrii character is read. 23 I.C POINT 220 ^UP^TEPaf^irTRS Figure 4 shows a typical 2-3B INC POINT+1 2'4H. HERE ^'-'^ command tile entered using the 250 \RECLOIM "[,< LOX tSruRE ^RECLflln . editor and figure 5 follows the 2E0 ;-7H '"'^^" CHflPflCTER RTS 1 'If^rn''^^ machine's activity while executing 280. Flwi 290 the file. 300 LDX XSTDRE \RECLflIM 31 » JMP , RDCHV, 3203 \BflCK TO KEYBOARD 370 WEXT POBS program 5 begins by altering the ReaD CHaracter Vectors (RDCHV) to point to the new input routine 'IN', After returning to Basic the HMEW !PRINT"WOTHING THEBF" machine operating system is +NEW NOrnTNG THERE directed to IN' instead of the PRINT")\10THrfyG THERE" keyboard to obtain commandi >::0 afiii^T'TRETD" Subroutine 'IN' begins by savm\ 20 PRIIMT"FRED" ' "» Elvi: 30 END ;PBrNT"l WILL NOW X register in location RUN PRuG^M'- the &82.1 PRINT" ^Wri-L raw RUN I WILL MOW RUN PRDGRflM" PROGRAM Indirect addressing is then used to' LIST FRED obtain a character from thua >^IST PRINT"THflTS THE LOT" WEW 10 MODE? command file whicli is passeci to :iB PRINT"FRED" uIST 30 EMD the operating .system. When th( -) >PHINT"THfiTS THE Ot" TKPTS file character is the THE LOT end of '^ad >NEW contents of the input vectorsysr^ /LICT Figures. returned to their original values Machine activity Figure While 4. Exampre command file executing command the keyboard re-enabled.W' file in figure 4 ACORN USER MARCH s^ 43 6

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44 ACORN USER MARCH .

Primaty maths and micros

In January's Acorn User, Heather than merely enliven work, we must Ruth Townsend and Paul Govier wrote of using micros to hunt down or create software that McGee advise on the enrich and extend the primary will promote other activities on the choice, and use of, school curriculum. Teachers with list. The relative scarcity of the an interest in maths will also want micro as a resource makes the software for teaching to examine the micro's role in need for good software imperative. mathematics to primary relation to the Cockcroft Report, Drill programs have to be used pupils. Good programs and in particular to paragraph 243 individually and it is unlikely there which issues the following challenge. will be enough machines in a are the only way to

Maths teaching, it states, should primary school to make this develop the potential of provide opportunity for: feasible. the micro - but some There is no doubt drill on the topics are best left to • exposition by the teacher; micro is more popular than drill • discussion between teacher and from many current textbooks; and other tools, such as pupils and between pupils informal research shows children Bigtrack or Simon. themselves; can complete up to four times as We list some good • appropriate practical work; much work using the micro as they of software • consolidation and practice of can with pencil and paper. This sources and fundamental skills and routines; gives more time for the other advice on page 48, • problem-solving, including the activities advocated by Cockcroft, while three educational application of maths to everyday but the general theme of both the programs are reviewed situations; Cockcroft Report and Mathematics • investigational work. 5-11 is that such skills could be on page 51 better developed, with better Most people in maths education pacing of pupils and faster recall of today would agree that the first and facts, if more work were done fourth activities predominate in orally. junior and secondary schools, Many activities, such as testing although less so in infant schools tables or performing routine where practical work is much more calculations, are catered for by common. If the micro is to do more such toys as Little Professor or

ACORN USER MARCH 45 MICROS IN SCHOOLS

Dataman. These are much cheaper than a computer and can be purchased in sufficient quantity to allow a large number of pupils to use them at the same time. Both can be programmed to give various activities at different levels of difficulty. They provide valuable protection against practising errors and give the instant feedback pupils enjoy from a computer, If the school is following Cockcroft's advice and developing work with calculators then simple consolidation exercises can be made enjoyable and instructive at no extra cost.

I here are many programs which aim to help pupils with their maths by helping them to develop a longer attention span and the ability to concentrate on details. These activities can easily and Small groups and discussion more cheaply be carried out using a simple game called Simon which G

'arithmetic training' and that is all it is, but it has the features I he most discussed mathematical demanded of a drill program: programs at present rate are Jane rewards for success, a timing and Logo, both of which will be feature and flexibility of levels. It used most profitably in small can neither teach nor diagnose - groups. Jane is available, with reassuring to those who make their extensive notes, from Longmans money by these skills!

46 ACORN USER MARCH MICROS IN SCHOOLS

Micro Software. It is the 'function game' used for years in progressive maths lessons based Problems and investigations on the format of input/operation/ output. Functions are given boys' and girls' names, where I he MEP Micro-primer pack will tear that equipment will return the default conditions are that contains two mathematical programs to the dust ol the stock cupboard. boys add and girls multiply, which at first glance seem to The other MEP mathematical although the precise operations demonstrate the micro's capacity to offehng is Farmer where the user is can be set differently. It has stimulate practical work and invited to solve the farmer/dog/chil- potential which a brief review investigations. dren/grain crossing-the-river problem. cannot do justice to, and is well First there is Shopping which It makes good use of the micro worth viewing at your local takes pupils (or significantly, one because pupils are invited to teachers' centre. pupil!) on a shopping trip, There are participate, but is not nearly as rich The same is true of any representations of a shopping list in potential as the similar Boat version of Logo whose application and some coins, and it is hard to {from SMILE). This program is also goes beyond maths. The way It see how this activity is better than about crossing rivers but leads to a helps to develop the concept of handling either real money or worthwhile investigation. angle measure, the nature of a plastic money. This is typical of program and variables, and a programs which are written to structured approach to problem- satisfy some craving which the n good investigational program solving make it a must for maths programmer had, presumably the for small groups must generate lessons. The most easily desire to prove that coins could be plenty of work away from the micro available version, suitable for all drawn on the screen. No doubt and exploit its ability to support the Dol approved machines, there will soon be programs which conjectural work in maths. There comes in the Logo Challenge simulate structural apparatus, meas- are few such programs available at package from Addison-Wesley. uring equipment, atthbute blocks primary level as yet, but other It's beneficial to use Bigtrak and the like. The optimist will see examples are Frogs (from SMILE) before using Logo and a recent this as motivating practical work and Jugs (from Davidson Centre, MEP publication is helpful. away from the micro, but pessimists Croydon). HOME STUDY COURSES Bourne Educational Software BE5 makes learning fun uJ [DB You've the best micro, chosen WORDHANG (Code P20) Superb version of 'Hangman' word guessing game where vou have now choose the best courses ! to guess the letters of a word with a limited allowance of mistakes. Watch your children improve their spelling and word knowledge

by trying to stay alive! It keeps check on their scores too! 30 Hour BASIC Utilises full colour high resolution graphics facility of BBC micro -watch his face as the final mistake is made! A beginner's BASIC programming course. Incorporates internal list of words divided into groups to suit age range of 5 to 13 years (no responsibility accepted for disconsolate children when Mum and Dad get addicted too!). Structured Programming in BASIC Features facility to guess full word at any time — but beware of the penalties for getting it wrong! A second stage BASIC programming course. Includes easily loaded lists totalling 260 words — and your own lists easily saved too! Suitable for Model B. Shows you how to get the best out of ANIMAL/VEGETABLE/MINERALICode P21) BASIC. Think of an object and see if the computer can guess it correctly! BBC Program asks you to xWmk of an object and then asks a series of

questions as it tries to guess the answer. Ultimately the program either guesses the object correctly or asks for a question to Beyond BASIC on the Beeb: distinguish the item from the computer's incorrect guess! Assembly Language Programming Stimulates fascinating (and educational) discussions as to the 6502 difference between an alligator and a crocodile, steel and iron, etc, An easy introduction to assembly language and encourages use of reference books. Programmed questions and objects entered can be saved at any programming on the BBC Micro. point, so extending interest. Suitable for Model A and B. TO: BES, Bedfield Lane, Headbourne Worthy, Nr Winchester. Hants S023 7SQ. Tel: 0962 882474 All 3 courses available now as QlV Code Item Price Total NEC correspondence courses. Write for free P20 Wordhang f7.95 leaflet/enrolment form. P21 Animal/ Vegetable/ Mineral E4.95 P20 + P21 Wordhang + Animal /Vegetable/ Minerat Elfl.DB

(30 hour BASIC text only is available, I enclose cheque/ P.O. payable lo BES value: E Name price £5.95 post free.) Address NATIONAL EXTENSION COLLEGE Dept. 45, 18 Brooklands Avenue, BES POLICY is for ample supplies of software to be available before advertising and normally to despatch items within 24 hours Cambridge CB2 2HN of receipt.

ACORN USER MARCH 47 MICROS IN SCHOOLS

Setting up lessons

for the whole class

It is likely that many teachers will cogs being used, the position of want to use the micro for lessons the pen within the cogs, and the with the whole class. If this is not to nodes and revolutions of the be in the style of poor pre-micro resulting pattern. Pupils initially use

class lessons, software should the micro to check it is a good satisfy some or all of the following model of Spirograph, ie the patterns criteha: made by the micro match those made by the pupil using the plastic • stimulate class discussion; wheels. When this has been • reach all pupils, irrespective of established, the pupil can use the ability; program to test hypotheses which • engage the class in 'what if?' would be too tedious or impossible activity; to test with the apparatus. The • lead to plenty of work away from strength of this approach is that the micro. when pupils think they have a

theory it can be tested speedily. Takehalf (from SMILE) is one This is the essence of satisfying

such program. It runs for about 12 conjectural work. minutes and operates In film-mode, ie the only interaction possible causes the program to pause or f upils are also encouraged to continue. A square is disected in a design new spirographs which can host of ways so that black and create patterns which are impossible white areas are always the same. with the material version. Spiro has also been used to develop spatial awareness and a broader range of problem-solving skills in pupils who

Wfhether it Is shown as an initial are poor in these areas although stimulus or after the same activity good at numerical work. The has been done with paper and program is now being developed scissors is a rrtatter of judgement. more fully as part of an fylEP- The author, Ronnie Goldstein, gives funded project on developing Addresses an interesting account of work thinking skills in the primary based on the program in Some school, but early unsophisticated lessons in mathematics using a versions are available from the SMILE, Middle Row School, microcomputer shortly to be Davidson Centre, together with Kensal Road, London W10 published by the Association of some notes prepared for pupils on Shell Centre for Mathematical Education, University of Teachers of Mathematics (ATfvl). a primary gifted children course, Nottingham One look at the program will Eureka also allows the immediate School of Education, University Park, impress the primary teacher with testing of hypotheses. Again from Nottingham NG7 2RD. Addison Wesley Publishing, 53 the wealth of potential for language Shell Centre, this shows, in both Square, work in maths. graphical and pictorial form, the Bedford London WC1 B 3DZ A second strong program for water level In a bath as taps are Ruth Townsend, Maths Advisory class use Is Spiro (Davidson turned on and off and plugs are put Service, Davidson Centre, Davidson Centre, Croydon) which is designed in and pulled out. The teacher can to follow up practical work with a opt to show only one representation Road, Croydon CRO 6DD. Tel: 01-656 0913. real Spirograph. It has been used so there can be discussion about Software, 33-35 to investigate the connection what must have happened to Longmans Micro between the number of teeth on the produce a particular graph. Tanner Row, York, Y01 UP. NECOPS, Newman College. Gen- ners Lane. Bartley Green, 'One look at the program will Birmingham 32. ATM, King's Chambers, Queen impress primary teachers with the Street, Derby DEI 3DA Bigtrak plus. MEP Case Study 3. wealth of potential language work in Contact nearest Regional Infor- Centre maths' mation for details.

48 ACORN USER MARCH MICROS IN SCHOOLS ^5r

PracHcal considerations

I here is great potential in maths caused by a badly aligned teaching, particularly in work television (easily cured by a involving drawing or movement, to technician) or by faults in the use the micro as an electronic software which have to be cured by blackboard. If a micro is used in incorporating scale factors into the

this way for class display the drawing routines. The problem is

screen must be clearly visible to all compounded if the printer, which

pupils and it is unlikely that the might be used to copy the diagram monitors supplied with the Dol from the screen to paper, uses package will be large enough. One different proportions to those on possible approach is to use the the screen. Most printers can be school's colour television, but the set from within the program to give difference in quality between an a variety of horizontal or vertical RGB monitor and a domestic spacings, but teachers need to be

television is quite startling. It may prepared to answer pupils who be worth enquiring whether your measure lengths or angles and LEA has arrangements for converting discover that the computer is ordinary colour televisions to RGB wrong. for computer use. Some schools may still have \Jne neglected use of the black and white video monitors computer is computer managed which are useful for programs such learning (CML). This could be as Jane. Jugs or Subgame but valuable in a subject like many others loose much of their mathematics where the order of

impact without colour. It Is also acquiring skills is important. It frustrating for a pupil to be asked entails diagnostic testing for those to choose between, say. a red dot having difficulties, and good record and a green dot when they both keeping. There are programs appear grey. Graphics which have designed to free the teacher from been created using subtle blends these clerical tasks so more time of colour often virtually disappear can be devoted to curing the on black and white screens and problems. All such systems need blue lines often appear very faint. some means of accessing data Programs which use lengths or quickly, such as floppy discs or angles can become confusing if a cartridge disc microdrives, and horizontal unit of length does not using cassette storage is not equal a vertical unit. This may be sensible.

M.lathematics in the primary favours decomposition for subtraction, school must be carefully planned would have to consider carefully

and co-ordinated if pupils are to using a program which depended have a satisfactory range of upon equal additions. experiences, develop the necessary skills a positive attitude to The integration of the micros into Trj) for mathematics as an interesting and the teaching of maths means enjoyable activity. Most schools teachers cannot opt out of using have a of work (often Coaf>ut*r'B bOArd scheme the micro once it has been decided based on a major scheme such as by the school that it is the only r Nuffield, Scottish or Fletcher) and a sensible way of developing teacher with responsibility for particular skills. This places

mathematical development. It is pressure on the single micro in a

crucial that careful planning school, particularly when it will be precedes the use of micros in the used for other activities, and teaching of mathematics to ensure highlights the points made in consistency with the scheme used. Charles Bake's article about where A school using the Scottish the computer is sited (February mathematics scheme, which strongly Acorn User).

ACORN USER MARCH 49 .

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SPACE FIGHTER (32K) £6.30 (on cassette) / £9.90 (on disc) INVADERS (32K) £i.50 Ion cassette) / £9.90 (or disc) Atcade-stylf game based upon (ealuios Irom DEFENDER and SCRAMBLE Superior version ol the old classic arcade game ir>cluaing a lew extras -18 5 lypes of menacing alien luo al you and may airempi lo ram you Separata marching invaders drop bombs Ihat erode your delences, and 2 lypes ol atlack phases, fuel dumps, asteroids, lepoaling laser cannon, smark bombs, spaceship I'y over releasing large bombs thai penetrate through your hi-score, rankings, 6 skill levels, bonuses delences Hi-score, increasing difficulty, superb sound el'ecls and graphics

£6.50 (OD Cassette) / £9.90 FRUIT MACHINE (32K) £6.50 (on cdssettel / £9.90 (on disci ALIEN DROPOUT (32K) (on disc) Probably the besi Iruil machine implemeniaiion on Ihe market. This program Based upon the arcade game of ZYGON, but our version improves upon the original arcade game ilsclf You havetoshooi the aliens out ollheir "boxes" has it all HOLD, NUDGE, GAMBLE, moving reels, featistic fruits and before Ihe "boies ' till up full, the aliens fly down relentlessly, sound elfecls. multiple winning lines This is JVi^ (run machine program to Once buy exploding as ihey nit Ihe ground Suitable (or use with keyboard or joyslick

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To: Liz Digby Firlti, Globe Book Services, Houndmills. BASINGSTOKE. Hants- RG21 2X8 Please send tne Prices inclusive P8-P, detailed of VAT and with Assembly Language Programming for ttie BBC Microcomputer teaching notes. For full details of these and other (£8,95) Double cassette pack (C16,00) subjects, write (stating main interest) to: Cheque enclosed for C (plus 50p for p & p) GARLAND COMPUTING Name Address 35 Dean Hill, Plymouth PL9 9AF

50 ACORN USER MARCH MICROS IN SCHOOLS

Three useful educational programs

MAZE is a program which sets up Maze: Origin unknown but many program, reinforcing the process mazes and displays them in plan maze programs are available. being developed. Although the view. Pupils are required to Tower: Available from SMILE, points and processes could have navigate a cursor around the maze Middle Row School, Kensal Road, been achieved without a computer, from a given starting point to home London W10 in terms of productive use of by typing the instructions 'left', Snap: Available from Newman curriculum time results clearly 'right', 'up' or 'down' at each College, Genners Lane, Bartley justified the use of such a resource. Intersection. Each run of the Green, Birmingham 32. (This Tower was used in conjunction program sets up a different maze, will be in Microprimer pack 3.) with Snap, where equivalent although the starting point is fractions appear on the screen as always the same. fractions by building a progressively shaded portions of cards. The idea The game was played with the larger tower of colour. This may be is that when a pair of equivalent whole class volunteering instructions. possible with other equipment but fractions appear the child touches Three pupils sal in front of the the program offers a clear, simple, the keyboard space-bar to signal

computer, with a screen to separate efficient method of demonstrating 'snap'. A sensible amount of time is

them from the class, and were the principle. It supplements the allowed as the fractions change to shown how to use the return key. teacher when used individually or allow the pupil to think, They had a card to remind them of by small groups, Listening and observing individ- the instruction keys and how to uals at the keyboard, and later obtain a new maze. rupil ability ranged from remedial during more concentrated question- After about ten minutes, two to gifted, but all achieved a high ing, showed everyone had quickly pupils left the computer, and two measure of success. The groups achieved a high level of proficiency others replaced them on the were balanced and discussion in recognising equivalent fractions. keyboard, leaving one to instruct before each new fraction was the newcomers. In this way, every entered led to a good deal of oral Tony Pierce pupil had a turn at the game, and language work. Barabara Tarranto they needed very little teacher help. There was a satisfying degree of South Norwood Primary School, This program is useful as an enjoyment present in using this London introduction to the computer -every child achieved success, and their Ten points to note concepts of 'left', 'right", 'up' and 'down' were greatly improved. Pupils showed great co- • Plan the use of each • Integrate the use of the operation and teamwork in program for individual, group micro into normal maths deciding on an instruction and or class use. Some programs activities while exploiting Its learnt quickly from each other. can be used in more than capabilities. Tower and Snap are not names one way. • Do not restrict the use of one would readily associate with • Use the appropriate equipment micros in maths teaching to the teaching of fractions. However, for particular programs, eg the least or most able. Make both are examples of the type of colour monitor, printer or them available to all pupils. computer programs which offer the discs, and consider the • Do not use computers to teacher avenues of practice effect on the pupil of their replace practical work which normally only possible through absence. is essential for concept lengthy, conventional, mechanical • Remember Cockcroft's advice formation. methods, at which pupils of low about mental and oral work; • Consider whether programs ability or short attention span often using computers is a poor should use standard units for fail. substitute for either. lengths, particularly as it is programs arrived of The as part • Exploit the computer's possible to copy diagrams a package delivered for use with power to motivate, particularly on the screen onto a printer our first school computer, They through graphics, but do not which alters the screen were used In the context of the triviallse maths or insult your proportions. school's normal schemes of work pupils' intelligence. • Do not use expensive and supplemented conventional • Work through programs computers to perform activi- teaching methods. computer The yourself before using them ties which could be done was thus being used as a tool with pupils, just as you equally well on small devices rather than as a teaching machine. would with any other new like Little Professor, Dataman, Tower was presented to show material. Simon or Bigtrak. visually the size and notation of

Next month: teaching programming to primar/ pupils

ACOHN USEH MARCH 51 NOW AVAILABLE As featured in December's Acorn User Crovdon LOCO Project LOCO CHALLENGE Heather Govier and Malcolm Neave Project Adviser: Paul McGee

^ Availability

LOGO CHALLENGE is available in four different Teaching Packs, one for each machine. Each Teaching Pack contains one copy of the Pupil Book, one copy of the Teacher's Guide, and

two copies of the appropriate cassette or disc, one of which is a

back-up copy. The Pupil Book is also available separately in packs of five.

Teaching Pack for BBC Model B (cassette) £29.95 Teaching Pack for ZX Spectrum (cassette) £29.95 Teaching Pack for RML 480Z (cassette) £29.95 Teaching Pack for RML 380Z (disc) £37,95

Pupil Pack (5 copies of Pupil Book) £ 1 4,95

iiniaiitum*|iQK^i^n'i"'^*'i'|>"^^i'-"^'^">^"'

Features the "turtle graphics" of the LOGO language

Suitable for children aged 9 to 1 3 years All drawings can be stored for later re-use or incorporation into more complex patterns Teaches programming procedures, problem-solving, and turtle geometry Ideal for groups of 4 to 5 children Software available for BBC Acorn Model B, Sinclair ZX Spectrum, Research Machines 380Z, Research and Please r'eturn the coupon ior further details or to place your Machines 480Z order.

Addison -Wesley Publishers

53, Bedford Square, London WC I B 3D

Gradual introduction of commands Please send me: Each step clearly illustrated n 201 18401 X Teaching Pack for BBC Model B £29.95 Contains 1 Lessons and over 30 Challenges 20 M 8404 4 Teaching Pack for ZX Spectrum £29.95 Challenges follow each Lesson to encourage further D 201 18402 8 Teaching Pack for RML 480Z £29.95 exploration and experimentation with the commands D 201 18403 6 Teaching Pack for RML 380Z £3795

D 201 18400 I Pupil Pack £14.95 liyk D Primary/Middle School Catalogue 1 983 eacher s Guic Secondary Computing Catalogue 1983 D Complete Addison-Wesley Computing Catalogue 983 Adopts a "teach -yourself approach to the program Introduces more complex procedures Name _ Gives suggestions for classroom organisation Position Includes suggested solutions to many of the Pupil Book

Challenges School -

Address

Telephone No. Side one contains the LOGO CHALLENGE program Side two contains the Answer File TEACH, which gives Addison -Wesley Publishers

all Pupil solutions to the Book Challenges 53 Bedford Square, London WC I B 3DZ

52 ACORN USEn MARCH .

^^ REVIEW

ss

vm "^mmi

fcr typ:

by Heather Govier r'ui

''" "'iiKi "Vim,-, «M,. nir, 1. ,. „

Every micro supplied to a primary uses of micros In schools; give school through the Department of teachers confidence in using the ~"""'4^:s';^ "iin Industry scheme will arrive micro throughout the curriculum; ^"-"l:-^!'%: accompanied by a distance introduce some concepts of learning package called Micro information technology; Introduce primer produced by the Micro- social and education implications electronics Education Programme. of technology.

The Micro primer consists of a There is little to quarrel with in number of distinct elements; text, this and the package meets the audio cassettes and computer objectives drawn up well, although software. It is envisaged that the there is perhaps undue emphasis package will provide about 30 on social issues. Teachers will Fo '"'inter hours of study for teachers either primarily be looking to the working alone or preferably with Microprimer for practical support in colleagues. This individual study introducing the microcomputer into *"M/ should followed be by two day the school and classroom. "««*, courses to be run by LEAs. Indeed, Discussion of broader issues might it is a requirement of the Dol have been better left to articles in ''•'^ scheme that schools receiving the journals and magazines. On the

half price subsidy undertake to other hand, perhaps it is sound

'' "-iMi send two teachers for such training. policy to punctuate a 30 hour curse r ij'""'°l'hv *t So LEA courses cover similar with more thought-provoking items. %^ "hk ground, a 'tutor guide' is in "•"-B^,, preparation. A figure of 30 hours is probably '".rii, The Micro Primer consists of: a rather low for most novice teachers. wallet containing an Overview. There is a large practical com- Study Text. Header, audio case- ponent to the course, true study studies and regional information time may well be twice the quoted "'.'^""« leaflet; an Easel containing the figure. ^''^^:^-.X System Guide and an Activity The suggested routeway through 5-'---:::^ Guide; two software packs - Micro- Microprimer has 22 work units

*''" primer Pacl< 1 and Factfile. which vary from text based to ';«"!"/""' Unlike the materials in the wallet, practical, many units having an the easel and the software are element of both. The route is machine specific, certainly a winding road, but makes an interesting and varied progression I he Overview is intended to through the material. Symbols are guide the student through the pack, used to indicate the type of structunng the material into a activities involved in each unit, a coherent course, which should be format which is useful in planning a

read before anything else. It course of study. contains a statement of the aims The Study Text was written in Cover of the software book, and objectives of the package only eight weeks by David with some sample pages which are to: introduce teachers to Chandler and forms an excellent explaining programs page 56

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ACORN USER MARCH 55 REVIEW ^^

Overview - outlines course structure with case studies page 53 core to the package. The text aims 25-minute case studies. These deschbed with examples and the to introduce the new technology in allow primary teachers who are meaning of screen prompts and a straight-forward manner avoiding using micros in their classrooms to error messages is explained. In jargon and this it does admirably. A explain in their own words what practice, however, the System glossary explains most technical they are using them for and why. Guide lacks clarity and is terms. The Case Studies consider ambiguous for novices to use The book is divided into seven structured reinforcement data without help. Occasional errors units, each concluded by review handling, simulations, Logo and cause further confusion. activities and references tor further management of the micro, with the The Activity Guide on the reverse reading. It is well indexed and debate over what constitutes a of the Easel is an insructional attractively presented, A number of 'valid' educational use of micro- exercise designed to introduce articles referred to in the text have computers running throughout. teacher to programming. Although been grouped together by Derek While much of the content of these of less use to the average teacher,

Daines, and presented as the tapes is duplicated in other parts of it is clearly presented and makes a second component of the Micro- the package, the use of this good introduction to programming. primer - The Reader They have alternative medium adds variety to In addition to writing programs, the been chosen primarily' for their study of the Microprimer. The fact guide covers the adaption of capacity to provoke thought and that they can be listened to by a existing programs by changing discussion. number of people at once means data statements and print statements. The largest part of the book is they could be used as a focus for The remaining component of the

Section 2 - 'Computers in the staffroom discussion and debate. It Microprimer package is the

Classroom', bracketted by shorter is difficult to see how the textual software - perhaps the least sections on social implications and materials could be studied by more satisfactory element. One cause for implications for primary education. than one person at a time however disappointment is the fact that only Most of the articles have been and so group use is likely to be one of the four promised software written by practising teachers and limited. packs is being supplied with the the approach is pragmatic. The package, as much is not yet ready. writers describe computers in use Thus instead of receiving 30 in a way that has worked well in following the format adapted in software items with their machines, their schools. This transmission of the Input package produced by schools will get only 12, Of these, first hand experience is an excellent MEP for the secondary sector, the two are short programs designed to way for teachers to learn about the practical guides in the Microprimer help in the setting up of the sysem, educational possibilities of micro- are presented in the form of a one is simply a datafile used by computers. handy Easel. This can be stood another program and the pair Whilst some of the articles in The next to the computer for easy use called Mquiz and Quiz are really Reader have been specifically and contains a System Guide and two stages of the same activity, so commissioned, many have been an Activity Guide, both machine there are really only eight discrete drawn from previous publications. specific. items of software. For schools in They are linked by editorial The System Guide is a series of areas with good LEA software comments and although very vaned instructions for setting up the micro support this may not be too serious, in style and quality make and loading, running and saving but where such support is not interesting reading. programs. Good use is made of forthcoming eight programs is Neatly stored in the flap of the pictures and all keyboard characters shamefully few. A detailed review of Microprimer wallet are two audio to be typed are written in blue. The these programs will be included in cassette tapes which contain four use of most of the specialist keys is the next issue of Acorn User.

56 ACORN USER MARCH ^^ SOFTWARE REVIEWS

Five offerings for the BBC micro from two houses.

Billiards, H & H Software, Model B, £8.50 Chain this Model B game and you're looking down on a lime-

green billiards table. Your ball is blue, your opponent's is green (you can't play the computer). Instead of a cue, there's a cross on the screen - blue when it's your turn, green when its your opponent's. You use the arrow keys to move your cue. But try to avoid moving the cross over the balls, they get rubbed out. Also the table is not quite flat - just to make the game more interesting! Backspin or 'stop' is keyed in using to 9; speed or 'weight' is any

letter a to z. If you manage to hit another ball, there's a satisfying 'crash'. The computer keeps the score for pockets, In-offs and cannons - just like the real thing. Atan Pipes

Eldorado Gold, Program Power, given area of memory with labels rotated or mirrored repeats, and an Model B, £6.95 tor each instruction, and its format even coarser 'hammer and chisel' This is a whacky adventure-style is such that it can be amended as or area filler would be useful. game set in the Wild West. required and then re~assembled. Alan Pipes Eldorado though holds the interest ASCII symbols can also be output, with amusing comments (some and the whole lot can be dumped Reversi by Program Power, mis-spelt!) and sound effects. It is to a printer. £4.95 mainly conversational, but with the This is a small, straightforward Reversi is the Victohan predecessor little graphics odd window giving disassembler with none of the of the popular Othello game. Play is the setting. Commonly used debugging features seen in more between black and white only, with take, commands; drop north, south, sophisticated (and larger) programs, black going first. When a counter is etc can be accessed via the user such as breakpoints and memory placed, any of the opposition's definable keys. When you're really moving. It does its job accurately counters trapped in a straight line stuck, a help button gives and well, and will be a welcome between it and others of the same (sometimes) helpful hints. You can't and useful addition to the machine colour are reversed. Play proceeds save games, so you'll have to get code programmer. in this way, with counters on adept at taking and dropping - a Philip Garritt mdividual squares changing colour score Is available though (by going many times in the course of a hotel!) back to the at any time. Tess, H & H Software, Model B, game, until the board is full of Alan Pipes £8.50 black and white counters and a No this isn't an Adventure game final tally is taken. Disassembler by Program Power, based on the novels of Thomas The program offers the player £5.95 Hardy - tfs a graphic design choice of colour, and will not allow The popularity of machine-code package for producing repeating any illegal moves. The large eight programming is reflected by the patterns. You start with a white by eight board is displayed on the fact that BBC machines have a square which you can add to or cut screen along with the current score. built-in assembler, so it is not away using fine or coarse 'pencils' Despite the fact that the computer surprising that a disassembler is controlled by the arrow keys. It's only takes two or three seconds to available. Requiring now only 4k to like sculpting in two dimensions. make a move, it thrashed me every run, the program is suitable tor both But watch out - every time you add time. A and B models, and can be something to the right-hand side of Surprisingly for a game of this located at any position in RAM. the square, the computer is eating type only one level of play is When run, the program prompts for away at the left. It's making sure the allowed, and no instructions are start finish and addresses and an shape will tesselate. So get out included. I don't think this program address for assembler code to be your book of Escher prints and would encourage me to take up the placed. This last optional feature have a go! Two points though - it game more seriously. stores disassembled code in the will only do straight repeats, not Philip Garritt

ACORN USER MARCH 57 REVIEWS SOFTWARE '^^

Three more offerings, some more disappointing than others

Painting, Drawing, BBC Soft, if you are trying to position the in the air, rebounds off the sides Model A, £10 each cursor near the edge of the screen and slows to a hall in a realistic

These two programs, by the same and go slightly too far, it does not way. There is an option which author, have many similarities, fold over to the other side of the allows dribbling the ball, in which therefore after a brief description of screen, but puts you back in the case the player in possession can

the facilities which each offers, I centre of the screen, to start again! be tackled.

shall make general comments Also there seems to be a bug in I found this game great fun to

about both. Painting in that as often as not play, and it will be even better if Painting is concerned with different when you press a key, the cursor Program Power produce a version

ways of putting colour onto the does not appear at all, although it for joysticks. The only crowd

screen in mode 5. By using the usually appears if you try a second invasion I had to worry about was function keys you can get the time. the gang who were kicking me off following effects; clear the screen; Setting up the effects Is also the machine so thai they could select logical colour; change the awkward. Most effects require two play! palette; GCOL parameter - OR, or three parameters to be typed in Philip Garritt

XOR or normal; blocks of random every time you use that effect. It

dots; blocks of solid colour; blocks does not even allow you to default Programs 1 , Programs 2, by BBC of cross-hatched colour; polygons to the last known parameters for a Publications

of solid colour (many-sided being a given effect. On the whole Programs 1 is a

circle}, superimpose text; give up! If these programs had been motley collection - some programs The program cassette also produced by a back-room pro- appear to have been added simply

contains Trees. This is a ready- grammer and sold at £5 for the two, to fill up the tape.

made painting program which I don't think you would have any The advertising suggests that the draws modern art-type trees and cause for complaint, but when they 'programs have been carefully produces 'music' at the same time. come out at £10 each under the designed to let you understand

There is also a fully annotated name BBC which we tend to how they work,' This reviewer found version of the main program, associate with quality educational understanding difficult! A few of

presumably so that you can use the products, then I must feel them are interesting from the point

ideas for your own l^rograms - a disappointed. I don't know whether of view of giving useful algorithms commendable idea. these represent good 'art', but they which could be used in other Drawing produces various line- certainly do not represent good programs. In particular, the rotating drawn effects in model's, again programming. cube of Cube and Plotter which selected' from the function keys; Paul Beverley drew three dimensional graphs. clear the screen; set actual colours The accompanying booklet of foreground and background; Footer by Program Power, £6.95 suggests some ideas for midfying draw a line of specified thickness; Footer is a two-player football game programs to explore other features

draw a polygon; draw a sphere; for the model B. There is only one of the micro, but it proved very draw a cone; draw a squared grid; footballer per side, drawn as difficult to implement these. The draw a 'horizon', ie a series of stlckmen with proper running reason being that none of the parallel lines giving a feeling of movements of their arms and legs programs is well documented nor depth to the piGture;,i£M|fe text; give as you shift them round the green listed.ini the. apeompanying booklet.

up! Jk and white screen. Each player has It is very difficult to read and work

Thistiftssetle also contains a a group of five keys on his or her ']6B' a screenful of incomplete demons,^ration remarkably similar to side of the keyboard - four for ilstings! Trees, ''called Sculpture, and manoeuvring and one to kick. Much of the same criticism can annofatid versions ofttl^j.programs. The footballers can be made to be levelled at Programs 2 without

' If you were to buy these run diagonally by holding down two the redeeming feature of a few programs hoping to use them with keys at the same time, and things useful programs. The only useful

primary school aged children, get a t>it confusing when they come algorithm here is a spinning glo&^i.' while except perhaps the very oldest, I into close quarters, as they look LU-riar Lander, a good game think you would be disappointed. identical. In its own right, does not iustify the In my view they would be difficult The top of the screen displays cost ,of the tape and would be for anyone to use who is not the score and time (games last 300 better included in a series of already confident with micro- seconds), and also a moving games programs. computers, as not enough has direction indicator whose position It is difficult to see the value of been done to make these programs determines the angle of the ball these tapes. If they aim to instruct

user-friendly. when it is kicked. there is not enough support

Cursor handling in both programs It is quite easy to learn the material - if they aim to entertain,

is cumbersome as it is invisible knack of making accurate goal there is not enough interaction, unless you are pressing a key. Also, shots. When kicked, the ball curls CM.

58 ACORN USEP MARCH .

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ACORN USER MARCH 59 MAIL ORDER AND RETAIL SHOP. TRADE AMD EXPORT INQUIRIES WELCOME. GOVERMMENT AND EDUCATIONAL ESTABLISHMENTS OFFICIAL ORDERS ACCEPTED WATFORD ELECTRONICS Carriage: unless stated otherwise, please add min. 50|) to all cash ardorsl. ' APPLICABLE TO UK CUSTOMERS ONLY ALL PRICES EXCLLISIVE OF VAT. VATpPLEASE ADD 15% VAT TO THE TOTAL COST INCLUDIMG POSTAGE. SHOP 33 35 CARDIFF ROAD. WATFORD.HERTS. Telephone 40588 HOURS: S.OOam TO 5.00|)m MONDAY TO SATURDAY, AMPLE FREE CAR PARKIMG. ACCESS ORDERS: Simply telephone through your order on Watford S0234/40589 IX'S /VLL ll\l XHE GAIVIE!

CHESS (32K) £9.95 Wordwise contains all the usual word SPACE GAMES processing features. The more complex An excellent machine code program with facilities such as search and replace or file ALIEN DESTROYERS {32K) £7.95 superb Mode 1, colour graphics, 6 levels, handling commands are menu driven so Sensational, high speed 'INVADERS' pro- piay black or white, illegal moves rejected, that even a beginner can understand how gram with an abundance of features. This 'en passant' castling, take-back of moves and to operate them. program lias manv unique extras e,g-; 'Battle display of player's cumulative move-time. Wordwise will work with whatever filing Analysis' showing the number of each alien COWBOY SHOOTOUT (32K) system is currently implemented. Supplied type shot down, £6.50 with full instruction and manual. 11 .0 operating system only). ASTRO NAVIGATOR {32K) £6.95 Full feature, 2 Player, cowboy shooting game. Hide behind the cactus plants and Navigate your way through a variety of moving chuck wagons until they are shot treacherous caverns, inhabited by killer away. Shoot your opponent and avoid rockmites. There are 5 skill levels and the lop getting hit yourself. EDUCATION 5 scores are ranked at the end. Excellent JUNIOR MATHS PACK (32K) colour graphics and sound. ELDORADO GOLD <32K) £6.50 E5.95 ASTEROID BELT (16K/32K) Legend has it that old Bill McCusky, who met a sudden death, had built up a vast treasure Makes learning fun for 5-1 1 year olds. This £7.80 somewhere in the nearby territory. Can you package consists of 3 programs (menu A great new space game practically identical end up rich where many have failed? driven) that increase in difficulty as your to arcade original. child becomes competent. A very good the An inspired piece of FOOTER (32K} £6.95 machine code programming producing one supplement to standard educational meth- of the most exciting games around. Another high resolution graphics game from ods. the author of our Galactic Commander. A 2 GALACTIC COMMANDER (32K) player game in which each player has to use WHERE? £6.95 his football skills to try to out-run, out-dribble Do you know 'WHERE?' you are? This well £7.95 and finally score against his opponent. A written program, using high resolution Nine phase aptitude test for aspiring space serious contender to 'MATCH OF THE DAY'. graphics offers timed tests on the geo- vehicle commanders. The program presents MUNCHYMAN (16K/32K) £6.95 graphy of Great Britain, a real challenge and the use of machine code and hires graphics makes for beautifully Colourful and highly entertaining version of smooth action. Great sound effects. the popular arcade game. Munch your way to WORLD GEOGRAPHY (32K) high score before the 'MUNCHERS' devour £6.95 LASER COMMAND (32K) £7.50 you. Beautifully drawn Hi-Res colour map of the Classic of 6 Cities against attack Defence REVERSI <16K/32K) £7.80 world illustrates and aids this graded series from Alien planets plus random bombing A sophisticated multi-option game. Play of tests on capital cities and populations of raids from alien spacecraft. Super fast against the computer or another player or the world. machine code arcade game with superb even watch the computer play itself. 5 skill sound and graphics. P.S. levels allows any player to enjoy the game All prices quoted in t/^ese lists are exclusive without continually winning (or losing). MARTIANS £6.95 of VAT. Please add 15% to the total cost Very popular. Defend your planet against the ROULETTE (16K/32K) £5.95 including VA T. descending Martians with your Force-Field All the fun of the Casino in your own home. Carriage: Please add 60p pBp insured to all but beware of the Destroyers who can This is a beautifully presented game for up to orders. annihilate you. 6 players. The odds are calculated according All ex-stock items are despatched by return to the official rules. of post. SPACEMAZE (32K) £6.95 All our software is copyrighted. SNAKE (32K) £7.80 There is no VA T on Books. You have crash landed in the legendary labyrinth of Titan, inhabited by monsters An arcade type game. Gives hours of fun. known as 'FROOGS'. Find your way through One of the best games available for this machine. Try it for yourself. to the 'TRANSMAT' before being cornered BOOKS and eaten. The game has 8 levels of skill and 3D colour graphics. 30 Programs-BBC Micro C 4,95 APPLICATIONS 30 Hour BASIC (BBC Micro) E 6.00 6502 Application Book £10.25 TIMETREK (32K) £7.50 CONSTELLATION (32K) £6.50 6502 Assembly Lang. Programming The ultimate 'real-time' Startrek, where The great Bear! The Southern Cross! The £12,50 indecision in the battle zone is your major Horned Goat! See the night sky gloriously 6502 Assembly Lang. Subroutines £1 1 .80 enemy, 20 skill levels. Special features: depicted in hires graphics. Constellation has 6502 Software Design £10.50 PANIC BUTTON for once only space leap. been adapted and enhanced from our ACORN ATOM Magic Book £ 5.50 New Klingon fleet after 30 Stardates and successful ATOM program. Advanced 6502 Interfacing £10.95 Torpedo sight control. DISASSEMBLER (16K/32K) ALP for the BBC Micro £ 8.95 BASIC Programming on BBC Micro £6.96 £ 6.90 OTHER GAMES Relocatable disassembler program. Lists BBC Micro Revealed £ 7.95 object code and Assembler mnemonics from - ADVENTURE (16K/32K} £7.50 Discover FORTH Osborne £1 1 ,25 and to any specified addresses. The listing FORTH Programming (Sams) £12,50 All the excitement, intrigue and frustration of can be stopped and restarted. Page mode Getting Acquainted/Acorn ATOM £ 7,95 a mainframe adventure. Explore the tortuous option and output to a printer are available. Intro to Micro Beginners Book (3 EdI forests, dark caverns and castle dungeons. ASCII symbols may be output if required. £ 9.90 Great skill and imagination are required to The Assembler code may be stored and Let your BBC teach you to program play this game. modified and the program re-assembled. £ 6.45 ZOMBIES' ISLAND (32K) £7.95 FILER £8.95 Micros in the Classroom £ 4,90 Practical Prog, for BBC & ATOM £ 5,95 Fight for survival on an island inhabited by A powerful file handling program for BBC, Programming the 6502 £1 1 ,20 hungry, dangerous cannibals. An excellent FILER allows the user to build up, man- Mastering VISICALC (Sybex) £1 1 ,95 BASIC and MACHINE CODE program, ipulate, store and retrieve data on the BBC, A very powerful package indeed. CHARACTERS (16K/32K) £5.80 WORDWISE {32K) (8K EPROM} Makes redefining of Invaders, Foreign Characters, Technical symbols, etc's £39.00 character shapes simpler. Clumsy binary and Without doubt the most sophisticated piece pi hexadecimal notations are not req, anymore. of Software yet written for BBC Micro. eo ACORN USER MARCH BBC BBC Computer Software

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ACORN USER MARCH 61 ERSOFT zPERIPHERALS AND SOFTWARED HOME ACCOUNTS FRENZY

An accounts program specifically The object of ihis game is lo

designed for the home user. It destroy as many obstacles as contains many features which possible. You are in coniro! of a

make it the best accounts package land speeder in an alien ciiy. currently available for the BBC 'Running over' various objects Microcomputer. such as dogs, fire hydranis and

Home Accounts is a compre- people. Your speeder has no hensive program allowing total brakes and you musi dodge anti- control ofall data. Full documen- matter blocks. Fast reactions and

lation is supplied making it easy skill are required as your vehicle to learn and simple to use. gets faster and faster. Available for the Model 'B' Micro For Model 'A' or 'B' Micro. only. PRICE: £5.75 PRICE: £12.50

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Whefher your equipment is worth £50 or £5,000 you • Early Learning Home Finance will find the cost of insurance is very acceptable. Fun Games • Games of Strategy Full details will be sent on receipt of a note of your Painting • Drawing • Music name and address together with the value, age and use Programme Programs Vol. 1 The Computer of your equipment. (No stamp required). The Computer Programme Programs Vol. 2

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62 ACORN USER MARCH (SROOfS

are encouraged to bring along as much hardware as possible. For further details contact John Harris There is now a Swedish Acorn The Bottisham Acorn User Group at 1 Rowan Close, Bottisham, user group (address below) and as first met last March and now holds Cambridge CBS 9BN. Tel: (0223) you will gather from the name, it regular sessions at the address 811487, deals with both the Atom and the below - although a new venue is Eastv/Qod arrives Beeb. They thank us for a 'very nice being sought as Mr Harris's house £, magazine' - we thank them for becomes more overrun. A letter has arrived at our office letting us know they are around. Each monthly meeting is from Eastwood Town Micro- devoted to a special topic. In computing Club announcing their

December it was graphics, with presence. They have two meetings members providing constructive a week and can be contacted Please use the latest list when criticism of each other's programs. through: Ted Ryan on Langley Mill trying to contact groups, as January will be devoted to 65011, Roger Hellings on Langley these are updated each issue. educational software. Mill 69281 or Robert Clifford on Most groups also appreciate a The group is considering setting Ripley 81 2459. Their next fund self addressed envelope for up a software library, and members raising event is in March. reply.

m CLUB CONTAQS

• Ruperl Steele • Mr J, Ashurst • Paul Barbour Amateur Computer Club Acorn Computer Users Group Laserbug SlJohn's College Abraham Moss Centre 4 Station Bridge Oxford 0X1 3JP Crescent Road Woodgrange Road • Mr B.Carroll Manchester 8 London E7 0NE The Collage, 42 Manor Road • Mr D.L Evans • Brian Pam AldershotGUIl 30G 23 Hitchin Road Colour Micro Users Group • West Midlands Computer Group Henlow Camp 40a High Street 12 Apsley Road Bedtordshire Stony Stratford Oldbury Milton Keynes • N.P. (Bazyle) Butcher West Midlands B68 OQZ Harrow Computer Group Tel: (0908) 564271

1 St Peter's • Muse (for teachers) • Mr J- Price 6 Close Bedford House Bushey Heath Freepost Broms grove 27-28 81 George's Road Watford WD2 3LG Worcs Brighlon 862 7BR • Mr P. Frost Sussex Atom Users Group • Mr D. Coulter Preston BBC User Group • Mr P. Beverley 18 Frani

ACORN USER MARCH 63 ATOK^'?vy"VV,^ a^

Bruce Smith gives his verdict on the Ross utility EPROIVI as a toolkit

I he Ross Software utility EPROM Calculated jumps such as GOTO buffer may be printed using plugs into the utility socket, IC24, (20 + N) are ignored and must be *BSTRG whilst *CHAR will print a and occupies 4k of memory from located and altered separately. single ASCII character. *BLOCK AOOO hex onwards. Once installed, Blocks of lines may be removed fills an area of screen memory at it adds a further 33 commands to using *DELETE. co-ordinates X,Y and of size A,B- N the Atom's own Basic vocabulary. *VAR phnts the decimal values defines whether the block is set, These appear as cassette OS of Basic's integer variables, which inverted or cleared, and is used commands and must therefore be may all be set to zero with *ZERO thus: *BLOCK N X,Y,A,B prefixed with an asterisk. The toolkit {useful for debugging). *PACK "POINT X,Y P tests the screen at '0' provides a cassette interface, removes all those byte-eating position X,Y returning a '1' or a flashing cursor and a variety of aids spaces from programs, whilst in any variable 'P' if the point is set to make life easier. preserving the so-called significant or clear.

The Atom must be made aware spaces. It does not remove REM The *SHAPE and *TABLE of the utility EPROM's presence by statements, but these can be found commands are difficult to under- executing LINK 44992 in direct and listed using *FIND. stand, but once mastered allow any mode, which should result in the The inclusion of *READ and number of shapes to be defined normally inert Atom cursor beginning *DATA gives the Atom a more and stored in a memory table. to blink on and off. The floating standard Microsoft Basic feel and Plotting any one of the shapes is point ROM does not need to be makes manipulation of numerical simple: *SHAPE 9, 20, 30 would present for the toolkit to work, and and string data a breeze compared draw shape 9 at screen co- the entry address must be re- with the somewhat cumbersome ordinates 20,30. LINKed after BREAK. method outlined in Afom Theory and Practice. The data pointer is set I he utility ROM arrived embedded to a specified line number with the in foil-covered polystyrene foam, V/nce initialised the Atom's 300 use of ^RESTORE, protecting it from static electricity. baud COS is replaced with a much *KEY $ N and *KEY N provide The accompanying 12 page faster, though less reliable, 1200 true keyboard scanning, passing manual provides adequate informa- baud version. * TAPE controls the any detected values to a specified tion on the new commands, baud rate, being switched between string or variable, 'N', respectively. although the general layout is

300, 600 and 1 200 baud with either *WAIT provides programmable somewhat haphazard. Included is a *TAPE1. *TAPE2 or *TAPE3 delays in increments of 1/60s. useful section on the 12 new error respectively, *BSAVE allows Basic codes used by the toolkit to they programs be saved so may NI otes may be 'played' with Only nine bytes of precious be *RUN in a similar manner to *TONE D,P where 'D' is the block zero RAM are accessed by machine code programs. duration of the note and 'P' it's the utility EPROM, namely AA hex ^APPEND and ^VERIFY are pitch. *KBEP outputs PRINT $7 to AF hex in zero page and 023D to particularly useful. The former chain until a key is depressed. 023F hex. However, *RENUMBER loads Basic programs onto the end *STOP has the same effect as uses screen memory from 8200 hex of one another, whilst the latter LINK # FFE3 but prints the line as its scratchpad - not much good command checks saved programs. number where the halt has with a minimal Atom.

During all cassette input and occurred *POP allows subroutines I have only two criticisms. First, output, visual indication of loading to be 'jumped' out of without a utility commands such as 'RE- and saving is provided by a display RETURN -not good style. NUMBER and "AUTO have no of each byte transferred at the top Some good graphics facilities default values and if one or both of the screen. are included, the best of which are parameters are omitted an error The three most frequently used several excellent 'soft' VDU occurs. Second, the use of utility commands will undoubtedly commands enabling strings of delimiting commas between vari- be *AUTO, *REN UMBER and characters to be printed in any ables after commands is not

*DELETE. The first *AUTO provides graphics mode. As an example, this standard. Thus I found myself automatic line numbehng, the start program wilt print 'ATOM' in each continually reaching for the manual and step values of which must be mode at co-ordinates X,Y: to distinguish between, for example, specified, such as *AUTO 10,10. A *POINT X, Y P and *SHAPE N X , Y 5 X=4 ; Y= 28 - short bleep is emitted if the line 10 FOR N =0TO4 minor points but annoying. number generated already exists. 15 CLEAR N At £15.95, the Ross Software Similarly programs may be 20 *STRG X,Y "ATOM" utility EPROM is good value and 25 'WAIT 120 ^RENUMBERED with GOTOs, worthy of consideration. Details 30 NEXT; END GOSUBs and *RESTOREs altered from: Ross Software, 44 Premier to match their new destinations, The current contents of the input Avenue, Grays, Essex RM16 2SD.

64 ACORN USER MARCH ELECTRONEQUIP (Authorised BBC Dealer and Service Centre) SPECIAL OPENING OFFER DUE TO MOVE TO NEW PREMISES ALL ORDERS RECEIVED DURING NEXT MONTH QUOTING REF ACOU/C WILL BE ENTERED INTO A WEEKL Y DRAW AND 2 CUSTOMERS IN EVERY 100 WILL RECEIVE THEIR GOODS FREE OF CHARGE THIS MONTHS SPECIAL OFFERS BBC High quality 14" RGB Colour Monitor/ BBC1 BBC Micro Model A 299.00 TV. Colour monitor suitable for 80 BBC2 BBC Micro Model B 399.00 BBC36 columns with ability to receive TV 244.95 BBC3 BBC Model A Micro with 32K 333,50 BBC4 BBC Model A Micro 32K & VIA 339.50 New improved cassette recorder for BBC21 Upgrade Model A to B 99.82 BBC, Has monitor facility, counter, BBC27 Disc Upgrade for BBC B BBC45 remote 35.88 109.25 BBC30 14" Colour Monitor for BBC 286,25 Dual BOOK disc drives for BBC micro BBC33 BMC12A 12" Black/Green Monitor 90.85 BBC48 with free Z80 second processor card 897,00 BBC34 12" Black/Green Monitor for BBC 113.85 BBC35 12" Black/Amber Monitor for BBC 129,95 Large stocks of Software for many BBC36 14" Monitor/TV, 80 columns 244,95 machines as well as BBC. Acornsofl, BBC40 Cassette Recorder for Bug-Byte, CP/M, Program/Micro BBC 29.90 BBC41 Single 5,25" Disc Drive 100K 265.00 Power, Computer Concepts etc. BBC42 Dual 5.25" Disc Drive for BBC 447.00 Business systems enquiries welcome. BBC48 Dual 800K low profile disc drives 897.00 Systems and Software available from BBC49 5.25" Discs for BBC 40/80 tracks 2.20 500 to 100,000 BBC50 Epson MX80T type 3 for BBC 373.75 BBC54 Daisy Wheel printer for BBC 558.90 Torch Colour Machine 800K floppies ex. VAT 2795.00 BBC70 Plinth/Stowage for BBC 29.90 Torch Colour Machine Hard Disc ex. VAT 4995.00 BBC80 Cassette lead for BBC 4.60 BBC54 Daisy Wheel printer for BBC 12cps 558.90 BBC95 Printer lead for BBC 17.25

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ROM £46.00 ASTEROIDS , , £ 8.95 F/T3 - ^'^ EPSON MX80 The printer recommended for the J GLAXIAN E B.95 BBC Microcomputer 1U;J1J BILLIARDS . . , £ 8,50 FROGGER £10.00 * Dot Matrix Prinler^^^ * Hi-Hesolution Graphics GOLF £ 8.00 * 80 Cps ^^^ e * Bi-direclional Printing

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ACORN USER MARCH 65 , .

Oakleaf Computers LTD V\^ORDSCAN Education Hobbyist S Small Business Computers FOR ALL BCC MICRO OWNERS- PROCESSOR CASSETTE. ITS NOT JUST A WORD ON ACORNS THAT' Even for those owners who do NOT -i^*7e^2^^5 LOOK BETTER own a printer ONANOAKTREEI WORKSTATION THE UNIT SUITS BBC VIC 20 So far, you have used your machine to play games. Now TRS 80 ZX SPECTRUM ETC With a ^uilt- in accessory drawer you can get some REAL benefit, using it for WORD this smart unit lurnsyourselupinio PROCESSING. a prolessional and business like system. Tne drawer holds up to 50 diskelles or your tape collection and leads elc to use program, professionally An extremely fast and easy TWIN USER JOYSTICK INTERFACE ATOM/BBC £1 3.95 written to cater for any amount of TEXT from a simple letter Prolecl the keyboard ol your computer by inlertacing "Alan" on the Model A to an extensive essay on the Model B. loyslicks to It. The loyslicks plug into Ihe interface which in lurn simply plugs into either the Atom 64 way bus or the BBC 20 way user

port, (Atom bus units available ai C3,99 it ordered with ine inlerfdce) Designed to interface with the EPSON MX80 FT3, but will Now two people can successfully play games or one person can^ operate on any 'machine compatible' printer. A Bureau have more control over Ihe computer Full software supplied

Service is available tor PRINTING if you need it. 'Edit' your

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stock ii Disk drives off the memories, printers of disk show you the program and documentation in operation. | shell. Hardware, books interfaces etc All available ' printers Phone now Prices Prices dropping Phonel Otherwise write to "Dial Software", 72 Downend Road, always competitive tor quolalion Alll Downend, Bristol BS16 5UE, for full details of the Package current BBCl peripherals stocked and the Bureau Service. [ ALL PRICES INCL. VAT AND P&P Please send your remittance to:

1 21 The Price of the Package is £18 + VAT DUDLEY ROAD GRANTHAM, ^J/VUIU LINCS. NG31 9AD The Print Service is charged at min £2 per 1000 words ^(aJRN speoausts TELEPHONE: (0476) 76994

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66 ACORN USER MARCH scisis^. ATOM

Paul Beverley give the circuitry for a high resolution digital to analogue converter using a single output from the Atom

If you need a high resolution digilal to analogue converter and are not too worried about how quickly it responds then you may be loathe to spend £30 for a commercial 1 2-bit digital to -50 f- Averago voltage analogue coverter chip, ~-4- « Vma" This article describes a versatile method of using an Atom to produce an analogue voltage. It Average has the added advantage over the vollage conventional digital to analogue converter of using only a single

Figure 1 . output line from the computer. Variable mark-space ratio pulses producing different average voltages There is also a trade-off between the level of resolution and the speed of response which can be adjusted to suit any particular PBT oulpul application. In addition, this (bl17ol «BSOOI ^— ii_t. method depends on generating a square wave with selectable time period and mari<-space ratio - a r Timer 2 '' facility for 1- useful certain applications. inlerrupl llao (t"l5 ot • BBOOl

1

1 I he idea is to use the two timers within the 6522 versatile interface (' 1 1 adaptor (VIA), working under interrupt, to produce square a wave Figure 2. Timing diagram for versatile interface adaptor pulse pulse of variable mark-space ratio. generator. Tl is set by timer 1 and T2 Is set by timer 2 Figure 1 shows that as the mark- space ratio is increased, the average level of the signal for the equivalent of a 12-bit digital part in 4096, even though at a increases. Therefore, if the square to analogue converter you need a given setting the actual voltage wave is put through an averaging filter with a response time of 10 or may vary more than this, either side circuit, we get a voltage output 20 milliseconds. This time depends of the average. It depends entirely which is proportional to the ratio of on how much ripple you can on the application as to whether 'mark' time to periodic time. tolerate in the output. The higher you can get away with this, Because the timing of the pulses the resolution you try to get, the is done by the versatile interface longer the periodic time has to be I he actual pulse is generated by adaptor, which runs at 1 (VlHz, we and the more critical the amount of the timers on the versatile interface are limited to using timings in npple becomes. For example, one- adaptor. Timer one, which can be whole microseconds. Therefore, to bit variation in an eight-bit digital to made to produce an output on get the same resolution as an analogue converter represents the PB7, is used to set the 'mark' time digital eight-bit to analogue equivalent of 0.4 per cent hpple, of the pulse. Timer two is used to converter you have to set the whereas one-bit variation in a 1 2-bit give the overall time of the pulse. periodic time of the pulses to 256 system is 0.025 per cent ripple. The timing sequence is shown in microseconds. For 1 0bits it would Although it depends on the figure 2, At 'A', timer two has just have to be 1024 microseconds, application, you may not necessarily timed out and generated an and for 1 2 bits, 4096 microseconds. have to keep the ripple down to the interrupt. The interrupt routine It takes a few cycles of the equivalent of a single-bit variation. shown in figure 3 does the job of incoming pulse waveform for the It may be sufficient to be able to reloading and hence restarting circuit averaging to respond to raise and lower the average both the timers. At 'B', the high byte changes in mark-space ratio. Thus voltage, with a resolution of one of timer one is loaded, so PB7 goes

ACORN USER MARCH 67 .

hether your interests lie in 'business, educational, scientific, 'Wi' control or games applications, this system provides a possibility for

expansion which is unparalleled in any other machine available at present; com- ments Paul Beverley in the July 1982 edition of Peisona! Computer World.

The BBC Microcomputer can genuinely claim to satisfy the needs of novice and

expert alike. It is a fast, powerful system generating high resolution colour graphics and which can synthesise music and speech The keyboard uses a conventional layout and electnc typewntei 'feel'

You can connect directly* to cassette re- corder, domestic television, video monitor, disc dnves, printers (dot matrix and daisy wheel) and paddies. Interfaces include RS423, inter-operable mti\ RS232C equip- ment, and Centronics. There is an 8-bit user port and IMHz buffered extension bus for a direct link to Prestei and Ifeletext adaptors and many other expansion units. The system allows numerous machines to share the use of expensive disc drives and printers.

BASIC is used, but plug-in ROM options will allow instant access to other high level languages (Including Pascal. FORTH and LISP) and to word processing software.

A feature of the BBC Microcomputer which has attracted widespread interest is the Tube, a design registered by Acom Com-

puters The Tube is unique to the BBC Microcomputer and greatly enhances the expandability of the system by providing, via a high speed data channel for the addi- tion of a second processor. A 3MHz 6502 with 64K of RAM wall double processing

speed; a Z80 extension will make it fully CP/M'* compatible.

The BBC Microcomputer is also at the heart of a massive computer education programme The government has recommended U for use in both primary and secondary schools. The BBC Computer Literacy Projea includes two series of television programmes on the use and applications of computers.

There are two versions of the computer. Model A, at £299, offers IGK of RAM and Model B at £399 has 32K of RAM,

For technical specification and order form, send stamped addressed envelope to RO,

Box 7, London W3 6XJ and for details of your nearest stockist ring 01-200 0200 r n Broader horizons BBC Model B Microcomputers are Please send me by courier _BBC available for immediate despatch Model B Microcomputer's ) at £399 by courier to your door. Including VAT and delivery. Cheque If you would like to take advantage enclosed for £ payable to BBC Microcomputer System of our special delivery offer just fill in readers a /cor charge this coupon, but remember this only ACCESS 13 barclaycardS applies to the Model B , and only in the UK. Any other items have to be ordered on the standard order form Signed or from a BBC Computer Stockist. Name BBC Microcomputer System Offer Address- c/o Vector Marketing Dennington Estate Wellingborough Postal Code Northamptonshire NN8 2RL Co Reg No M03810 VAT No. 215400320 J BBC Microcomputer System Oder, c/a Vecloi Model A has a limited range of inieiiaces but can be The BBC Microcomputer System Marketing, Dennington Estate. Wellingborough, upgraded to meet Model B specification Northamptonsluie NN8 2RL. "CP/M IS a registered trade mark of Digital Reaeaich The BBC Microcomputer is designed, produced and dis- tributed in the UK by Acom Computers Limited .

ATOM

Bullerworth tiller I 470k \/ Any silicon diode [^=n

+v ^^ 100k lOOK

'O'-'"', lOOK c: 4- -V Buffer circull

22nF 1

Figure 3. Buffer circuit and four-pole Butterworth filter

low. Then at 'C\ timer two high byte Line 70. This shows how to set is loaded which restarts the timing the high and low bytes of the 'mark' and clears the interrupt. When timer time (in this case #800 = 2048), one times out ('D'), PB7 goes high Line 80. Set the value of the 40 tLDfl mSTfl Bt5 again. When tinner two limes out overall time of the pulse (in this again ('A'), another interrupt is case #1000 = 4096). generated and the whole process Line 90. To get the pulses 4'"' PLA;Pri: ] starts again. started in the first place, you have ?> The advantage of using interrupts to load the high byte of timer two ''M=)(MBiE-'4=«00 is that the puises will continue to using byte indirection so that when

be generated, once started, it times out, the interrupts start. whatever else the processor is After that the parameters of the !':' END doing, unless the interrupt mask is pulse can be changed as in lines set, in which case the pulses will 70 and 80. stop until the mask is cleared To stop the pulses, simply again. disable the interrupts by using would for B?14 = 32. To restart it again, use need a 12-bit equivalent B?14 - 128 + 32 which re-enables that gives approximately a one-bit r rogram 1 is the interrupt routine the interrupts and B?9 = to get ripple. If you want a faster response plus the setting-up of the pulse timer two going again. either because you are prepared to generator with one particular accept a larger amount of ripple or timing. because you are using a lower Line 10;P is where the routine is I he circuit diagram in figure 3 resolution, reduce the value of to be assembled; I is the interrupt gives a single transistor switch to these four capacitors accordingly. vector; B is the base address of the invert the pulses from PB7 so the The buffer needs a -1-5 volt VIA; M is some free space in zero time set by timer one gives the on supply which can come directly page for storing high-byte values time rather than the off time. The from the computer, but Ihe for the timers. bigger this value, the larger ihe operational amplifiers need a Line 20 sets the interrupt vector output voltage will be. Because of bipolar suppiy, ie a positive supply to point to our interrupt routine. the nature of the circuit there tends and a negative supply. However, Line 30. B?14 is the interrupt to be a problem with offset currents since very little current is needed, enable register of the VIA. It in the operational amplifiers. This you don't need to use expensive enables interrupts on the time out means that a zero input does not mains-powered supplies; a couple of timer (bit two five of the lER), produce zero output voltage and of nine volt dry cells will do. It B?1 1 is the auxilliary control this cannot be adjusted by adding would be a good idea, in that case. register of the VIA. It sets up the a normal offset zero adjustment to put a 100 nP decoupling in two timers the 'single shot' mode potentiometer. This may not matter capacitor between each supply rail and enables BP7 to be an output for a particular application, but if it and the zero volts line on the circuit for timer 1. does, replace the 741s with FET board, as near to the operational Line 40. This is the start of the operation amplifiers such as 3140s amplifiers as possible. actual routine. Gel the high byte which are pin compatible with the The other point to note is that the from zero page for timer 1 741s. interrupt line on the 6522 VIA is not Line 50. Get the high byte from The response time of the filter is connected to the IRQ line on the zero 2. page for timer set by the four 22nF capacitors. computer. If you trace the track on Line 60. Restore the accumulator Using this particular value gives a the printed circuit board from pin from the stack and return from the response time in the region of 20 21 of Ihe 6522, you should be able interrupt. milliseconds is which what you to find the link to join it up. f

ACORN USER MARCH 69 C BBC CI Specialists A J SOFTWARE ^ ^J^ L^ for BBC micracDniputers

VAT Included where applicable Ihe Record Changer' 32K £19.95 Cats. £24.95 Dbc. for Indexing, membership lists, (directories, inven- Quality Disk Drives tories, budgeting, ete., etc.

sided 1 •. 100k O1D.00 Single drive 40 track single don't buy a database In ttte daric — Dual drive 40 track single sided 2 x 100k £350-00 check tt>e spec! Dual drive 40 track double sided 2 200k £546.25 Dual drive 80 track double sided 2 « 400k 099.^ * Visible File — Scroll around ttie file UP/DOWN/ own PSU for reliability, and include connecting All drives are cased wiih SIDEWAYS by function keys cables and utilities disk. Delivery £4.00 * FULL SCRON UPDATE — Use cursor to overtype: Software for the BBC Micro character INSERT/DELETE ^/ilhln field: ERASE rest of litsi implementation on the MISSILE CONTROL the field: TAB from field to field, etc. BBC Micro ot the popular arcade game. (32KI E9.00 MAZE MAN an authentic version of the popular * Sort — on character and numeric fields arcade game. (32K) £6.00 * Search — tor a match on field contest BALLOONS a highly original game that soon becomes compulsive playing. I32KI £6.00 * Select — select records satisfying conditions on tfie memory dump routine includes DISSASSEMBLER one or nx)re fields; or manually a scrolling back in memory facility, (15K) £5.00 * — total numeric fields of SELECTED records MISSILE CONTROL, MAZE MAN and BALLOONS Total use ihe Keyboard or Joysticks for control * Artttwnetic — combine or>e or more fields of your 30 + Programs for the BBC Microcomputer SELECTED records with any arithmetic expression: field This Book contains program listings, with explanations and tips put t^ie result In any numeric BBC Micro on using the * Print — print your SELECTED records with pagi- GAMES UTILITIES GRAPHICS and MUSIC nation Most programs will run on Model's A and B various Authors. Edited by C. J. Evans, •^ Up to a 1000 records, (typically 330 at length 40) A pair of cassettes with all the programs is available. * Up to 20 fields, number of decimal places con be BOOK £5.00 specified for numeric fields BOOK and CASSETTE SET £9.00 * UHllty — to ADD/CHANGE/DELETE fields LEADS The BBC Micro comes without a cassette lead 7PinDinto2 "S.Smmandl x 2.5mm minijacks £4.00 Itie Wordsmtth* 32K for Centronics 737/739 7Pin Dm lo 5Pin Din and 2,5mm minijack £4.00 7Pin Din to7Pin Din £4.00 £19.95 Cass. £24.95 Disc. 7Pin Din PLUGS Two for £0.65 For Reports. Essays. Ttiesls. efc . etc 6Pin Dm PLUGS (for RGB socket) Two for £0.65 (360' for Two for £0.65 5Pin Din PLUGS RS232I Forget control codes — let 'WordsmNh' RS423 TO RS423 (BBC Micro to BBC Micro) realise your printer's potential Two metre cable £4.00 Four metre cable C5. 00

TELEVISION/MONITOR LEADS lull range available • Full Screen text edifor with wordspill Phono plug to Co-ax with high quality cable 3 Metres £3.00 * Unlimited document size BNC Plug "to BNC Plug £3.10 BNC Plug to Phone plug * Page numbering, headings, footings, margins, lo Rediffusion TVRM) £2.20 (i.e. BBC Micro indentatton RGB 6PIN DIN to 6PIN DIN 1 metre £4.00 2 metre £5.00 • Full Support tor proportional, mono, condensed, PRINTER CABLES elongated and underlined printing BBC to 36 way Centronics Type connector £17.50 - justification maintained even when mixing BBC to 25 way D Type (For use with RS232I £ 9.50 Right line BBC to 40 way edge connector (Centronics 7391 £20.00 proportional, condensed, elongated on same TORCH to 36 way Centronics Type connector £20.00

Blank C30 Computer Cassettes

Ten lor £4.50 Simple Word Processor 32K 15 Way D Type Plug with Cover £2.75 £9.f5 Cass. £14.95 Disc. Computer graphics design pads 1 00 sheets £4.00 Simple to use; allows you to set margins, justify text, insert and delete lines of text, set page length or BBC Upgrade Kits force a page, variable TAB, Multiple copies Save RAM UPGRADE (lOOnsl £23.00 text on cassette or disc. View text formotred before A Printet and I/O Port £ 9.50 KIT printer KIT B Analogue Port £ 8,00 printing. Works with any KIT C Serial I/O and RGB £10.00 Options Timetable 32K KIT D Expansion Bus/Tube £ 8.00 £M.95 Coss. £19.95 Disc. Full Upgrade kit £60.00 A must for every secondary school. This programme All components full specification h»elps with tt)e tlnnetabllng of pupils 3rd year optton your STAR DP8480 PRINTER From £250.00 Inc VAT ct>olces. Try tfie effect of any changes to Options Timetable and let tt>e micro do all ttie 80 CPS : 80/96/132 COLS BIDIRECTIONAL LOGIC SEEKING donkey work. Has been In use tor the last three years TRACTOR WITH FRICTION FEED in a 6 form entry comprehensive using a CBM 3032 — CENTRONICS £217.39 f £32.61 VAT - £250.00 rx>w runs even faster on the BBC Model B. RS232 E235.00 ^ £ffi.25 VAT = £270.25 Not only ttw cheapest, but ttie best High Res Graphics option to allow BBC Screen dumps £15.00/£20.00 14" RGB Monitor/Colour TV (24HR SECURICOR DELIVERY FOR PRINTERS £8,00) Swltchdble £250 Inc. VAT and cable. £8.00 carr VAT Included where applicable Royalties for quality software Send SAE for lull Price List of our large range of accessories. All prices VAT inclusive C.J.E. POSTAGE Add 50p per order or as stated Depi \m. li HENflY AVE, RUSTINGTON Vision Service Ltd W SUSSEX BN16 2PA (D906ZI 6647 AJ 61 Jeddo Road nikcmcaniputers London W12 9ED

70 ACORN USER MARCH ATOM

/Vs has been said, the BBC board Last month Barry Pickles reviewed manual is pretty abysmal and contains some errors. The pseudo- Acornsoffs BBC Basic board for variable FALSE has a value of 0, - the Atom. Here, he gives some not 1 . It also says you cannot use this board with the Atom DOS. In ideas on using it fact you can, but it's tricky! If you have a BBC Basic program starting al &0900, when you switnh back to Atom mode that program will still be there, but it will now be at HINTS USiS £2900. You won't be able to read it ON

properly, but it's still there and you

can save it as if it were an Atom pro-

if THE BBC gram, using disc, or, have a BO you toolbox ROM, on tape in fast COS.

Similarly. if you have a

disassembler, you could use it on Program 1 BBC programs or, indeed, on the iMftEH-BLOCK HOVE BBC ROMs. To do the latter, you will need to copy the ROM into INPOr-ST^RT 2^ ADDRESS OF RAM, and program 1 is a simple BLOCt" A$:STflRT^EyAUfi$) block move to accomplish this, The 3e INPUT-END program should be RUN in BBC MESS OF BLOCK" {^ummi^mim mode and. on completion, it will give you the base address of the

block, as it will appear in Atom then switch over, load mode. You 5^' IF SIZEK >mb PRIHJ'HQ} ENOUGH SPflCE":RUN your disassembler into a convenient

block and away you go! 69 FOR mPl=SJmi 70 FINISH^ BBC Basic 'tokenises' all its keywords into two bytes. This has a ?S ?0EST?;=-?LDOPX:DEST»STM number of consequences. First, you have no lower case letters. Second, BO mi abbreviating keywords is pointless

since they will be printed out in full, when listing, and there is no saving. n ?mvnm mpizm - s^tch to mmmc" The final consequence is that, in Atom mode, a program is BBC '^i^mrm^jHE SLOCK Program BEGINS AT rmr unreadable, as it displays hordes of 2. graphics characters!

|he idea of having a standard graphics screen is a neat one, but

it can cause unexpected slowness.

What happens is that, if you plot a series of points from, lets say, 0,500 to 1280,500, the system will attempt to plot at every location inbetween. Of course, many of these points do not exist in reality, so a lot of time is spent waiting lor the next plottable

point to appear, If you want fast graphics plotting in loops, insert a suitable step size. The Sound command does not work exactly like the BBC micro and the points that concern us here are the values for pitch and duration. The BBC uses values from to 255 for each, whereas, in this implementation, values between to 65535 are used, so, again,

ACORN USER MARCH 71 — ATOM

scaling will be required. Note that Table 1 . Operating system vectors each single value is approximately one eighth of a note, on a musical Location Type 'vector scale. Further, the BBC micro has a buffer, which allows successive nm Reserved FFFF notes to be 'queued'. There is no m2 m: B42D buffer here and you must make $294 IRS Bi\m sure that note is one completed

on the Atom PCB, there are three All addresses are shown m He;-; for fiat. unused address lines in the 'text — I _

RAM' area, and it is possible to Program 3.

piggyback extra RAM to fill memory REM-ALl STRINGS MUST BE DIMENSIONED from e2000 to £27FF and from 2020 BYTE%-E(4000 + X% 20 DIM AS|7|, ALIFNSI7), BLAfJKS[71, If the R0W%|7| £3C00 to eSFFF. you have 2030 FOR LOOP%=0 TO 23 REM-DEMONSTRATIOM 7 latter, there is possibility that any a 2040 ?BYT£%=ASC(MIDS|AS, 30 MODE " sent, in mode, to 0./\LIENS-=" ":BLANKS=' data BBC 2050 BYT£%=BYTE%+32 locations between &1 COO and 40 PROCVDU23(ALIENS,0,24,126J 83,255 36 90129) 2060 NEXT LDDP% &1 FFF, will be corrupted. This is 50 PRDCVDU23|BWNKS.O,0,0,0,0,0,0,0) 2070 ENDPROC really this 60 FDR because Acorn intended C% = 1 TO 10

area to use ICs 51 & 52 (normally 70 PR0CPAT|/;LIENS,C%,4|

block-zero on the Atom) but, with a FOR N =^ 1 TO 100D:NEXT ^i piggyback, the system can end up PR0CPAT|BLANKS.C%,4] trying to send data to both sets of NEXT C%:FND RAM, with unforseen consequences! 999 REM-OEFINE CHARACTER PLUS STORE IN There is, however, a simple 'fix', This STRING D£FPR0CVDU23(AS, RDVI%[0), is to remove IC12 (on the BBC R0W%|1) R0W%(2] mm.{2l R0W%(4|, R0m|5), board), carefully bend outwards R0W%(6I, RDW%|7'll 1010 FOR LOOP%=0 pin six and replace the IC in its TO 7 1020 ^S AS socket. Now, solder a wire from (the = + CHRS (ROW% (LO0P%)| disconnected) pin 6 to any +5v line 1030 NEXT L0OP% - there's one on the VIA. The effect 1040 ENDPROC

is to completely disable ICs 51 & 199B REM- PUT CHARACTER ON SCREEN AT COLUMN X% ROW y% 52, when in BBC mode - of course, 1999 RFM-32 COLS BY 24 ROWS IN MODES TO 3 they normally in work Atom mode. 2000 DEFPRDCPAT[AS,X%,>%) This should only be done if you 2010 - n=\n II A 256 have RAM al £3CO0. Any piggybacking for addresses below £2800 should be removed 'missing' completely, since this is already at &2000. Note that only the first 8k provide two of the - provided on the BBC board. will be addressed. functions - PLOT 85 and VDU 23 Finally, there are two areas of so that you may implement block-zero RAM available for the published games programs. Program user. These are from &70 to &8F 2 is easy to follow, but you should is for 'proper' memory expansion, (32 bytes) and &021 E to &02FF remember that in normal BBC Acorn have provided for an 8k (225 bytes). All OS calls are programs, the co-ordinates repre- expansion, from &2000 to &4000 in indirected through vectors at sented by XMOVE% to YDRAW%

BBC mode. I assume (since i don't &0200 to &021 D. In this way, you have already been defined before know anyone who has one), their can add your own routines, by the call to PLOT 85, These own 8k card will work but, as for altering these vectors to point to programs could be more elegantly larger boards (eg Timedata, Audio the address of your own routine. written, but they will give an idea of

Computers, Watford etc), these will Table 1 gives the available OS how to overcome some of the only work by altering the vectors. challenges presented by routines addressing links, so that they begin To round off, programs 2 and 3 not implemented on this board, #

72 ACORN USER MARCH HOME & BUSINESS TECHNOLDGY

Probably the widest selection^'—>of software available by mail order. All ihe lop manufacturers including Acorn Soft. UK (Sinclair), Superior Software, Bug Byte, Program Power, Hessel, Procyon.

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SCREEN SHOTS FROM PROGRAMS April Issue: 3D Noughts and Crosses, Moon Lander, Ellipse and 3D Surface, Plus articles on Upgrading to Model B, Making Sounds, and IN BEEBUG MAGAZINE Operating System Calls. May Issue; Careers. Bomber, Chords, Spiral and more. Plus articles on Graphics, Writing Games Programs, and Using the Assembler. June Issue: Mazetrap, Mini Texl Editor. Polygon; plus articles on upgrading, The User Port, TV set and Monitor review, Graphics part II, More Assembler Hints. Structuring in BBC Basic, plus BBC Bugs. RACER July Issue BEEB INVADERS and other programs— plus articles on NOVEMBER using the Teletext mode. BBC cassette bugs fix. Software Review, using user defined keys. More on structuring in Basic. Using the User Port, and many 1982 hints and lips. September Issue: High/Low Card Game, and Hangman Programs. Articles on Logic on the Beeb, Debugging, Moving multicoioured characters, creating new colours, Operating system 1.1. Plus Postbag, Hints and Tips, and Procedure Library. October Issue: Program Features: Alien Attack; Calendar Generator; Union Jack; Memory Display utility. Plus articles on Beebugging; Improving Key Detection; Acorn Press Release on O.S.H,2; and Issue II Basic; The Tube and Second Processor Options; or New Series for less experienced users; and ENVELOPE Software Reviews. EDITOR November Issue: Program Features: Racer (excellent 16K racing car gamel, Minr Texl Editor (Mk2l, Transparent Loader, Music with Memory, NOVEMBER 1982 Harmonograph Emulator, New Character set for Modes 2 Et 5; and cassette block-zero — bug retrieve. Plus articles on sound and envelope design- includes indispensable envelope editor program; Debugging Part 3, BBC — Memory Maps and addressing explained; Serial Printer Port fRS423) and RGB upgrade. Plus a large number of Hints & Tips, and a guide to our past issues and their contents. Dec/Jan Issue: Program Features: Space City linvader-type game). Breakout, Artist (Joystick painting program); Rescue (miraculously retrieves Program' message); and Pack — SPACE programs after bad loading or 'Bad program to compact Basic programs. PLUS Disc System Review, Software CITY reviews -including Wordwise, Book reviews, Adding Joystick interface to DECEMBER model A; How to access the video controller chip; and ideas for the newcomer; plus a new crop of Hints and Tips. 1982

BEEBUGSOFT: BEEBUG SOFTWARE LIBRARY offers members a growing range of software from £3.50 per cassette.

1. Starfire I32K)- 2, Moonlander (16K). 3D Noughts and Crosses I32K). 3, 3D SHAPE Shape Match (16K), Mindbender (16K). 4. Magic Eel (32K). 5. Cylon Attack (32K). 6, Astro-Tracker I32K). DECEMBER Utilities: 1. Disassembler (16K). Redefine (16K). Mini Text Ed (32K)- 1982 Applications: 1. Superplot (32K). 2. Masterfile (3K).

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Send £1.00 & SAE for Sample Membership: UK 5.40 for six months, 9.90 for one year. Overseas one year only: purope £16.00, Middle East £19,00, Americas & Africa £21.00, Other Countries £23.00 Make cheque to BEEBUG and send to: BEEBUG Dept 13, 374 Wandsworth Rd, London SW8 4TE Send editorial material to: The Editor, BEEBUG, PO BOX 50. St. Albans, Herts AL1 2AR

74 ACORN USER MARCH COMPETITION

ON THE TRAIL OF INTELLIGENCE Simon Dally introduces this month's competition with the tale of the Turkish de:ight which fried

Long before computers were canbe made to behave more thought - in fact he hooked into invented people were fascinated cleverly than ourselves - has Eliza) and the following conversation by 'intelligent' machines which provoked considerable and ensued: appeared to have a will acrimonious debate, both theoret- Student: Can I borrow your of their maker. independent Even ical and practical. computer terminal tonight? today can mesmerised by of the pioneers of we be One Eliza: Why should you wish to dumb machinery such as toyshop computer theory was Alan Turing, borrow the computer tonight? 'robots' doing tasks which would who devised a test for Al. In Student: Because I want to do excite no interest if carried out by essence this laid down that if you some work. beings. put someone into a with human room no Eliza: Is your work important to In 1 769 an engineer named indication of who or what he was you? von Kempelen astounded the communicating with (eg a teletype Student: Yes Viennese Court with a machine machine), would he be able to Eliza: I see. called The Turk. It consisted of a recognise what was at the other Student. VJe\\7?? lile-size figure dressed in a human end? Eliza: What do you mean, 'Well'? turban and seated in front of a In the 196Qs, another pioneer Student: Can I use your computer box, the top of which was a in the Al field, Joseph Weizenbaum time? chessboard. of MIT, developed a program Eliza: Let's discuss further why the of the called Eliza, To amazement versions of which are your work is important to you. spectators, not only did the available on several micros. After ten minutes in this vein, machine talk, it also appeared to 'Talking' to Eliza Is both getting nowhere, the enraged be voice-activated. It had a intriguing and frustrating. Eliza Dr vocabulary of around 30 words acts the part of a sympathetic student telephoned Bobrow at rousing and, via a complicated system of psychoanalyst, probing away and home, him from sleep, levers, grabs and pulleys, could making sympathetic noises - but and the sublime descended to the ridiculous: move both its own and its never offering solutions. opponent's pieces. Even more In 1968 at MIT an incident Student: What the hell do you

intriguing, it beat virtually occurred which has since passed think you're playing al?

everyone who challenged it. into folklore. One version goes as Dr Bobrow: What do you mean,

Over the next few decades the follows. A student came Into a what the hell do I think I'm playing

machine went on tour. It played computer room one night seeking at?

against Napoleon, and in Berlin to use a terminal. The only It is arguable that the machine attracted 100,000 paying spectators unoccupied one had a note passed the Turing Test with flying

in three months. attached to it saying, 'This colours, though a purist might Numerous accounts appeared terminal is reserved for Dr object on the grounds that the speculating about The Turk, one Bobrow'. Knowing Bobrow often human being had not been told by Edgar Allan Poe claiming there worked from his home terminal, his task was to distinguish

must be a human chess-player the student dialled it up (so he between man and machine.

concealed inside it. A sceptical American reporter, in tradition, There were the best Lou Grant an equal number of grey and yellow noted that wherever The Turk tickets and all licitets were sold. Funnily enough appeared, the local chessmaster only one booklet consisted was not to be found. More entirely of tickets all of the same colour pertinently, a cry of 'Fire!' would and by an odd coincidence Ihe winning make the machine rock violently! (,cket was exactly the middle ticket of this We shall never know how this booklet The second prize was A RAFFLE was conducted won by the contraption worked (it perished al the person who had bought Christmas Computer Convention the during a fire in Philadelphia in highest numbered The lickets, numbered ticket. from one What likely upwards were the respective 1854), but the explanation is consecutively, were sold from wmning numbers? Answers that a dwarf or small adult was booklets, each of which on a postcard please conlamed the same number to f^arch concealed within the machine, of Competition, Acorn tickets. All tickets which User, 53 had one Bedford while a strong player would be or more digits Square. London the same in iheir WCJ B 3DZ, to arrive part of the audience, passing on number were printed nol later than on grey Tuesday, paper. Tickets whose April 5. Two Acornsoft coded signals. numbers packages consisted of go !o Ihe lucky winners totally different digits (please state which were printed on yellow machine vou In the computer age of artificial paper have.) intelligence - whether machines

ACORN USER MARCH 75 For the best hardware, the best software.

The BBC Microcomputer system is either a proverb, nursery rhyme title or a generally regarded to be the best micro in its sensible sentence. price range you can lay your hands on.So,il Learn more languages. voure lliinlung of buying one or already own LISP (price £24.35) is the fundamental one, you II want to know about the software thats language of artificial intelligence research. been specially designed for it. Acornsoft, Not surprisingly, its made by 4C0RNSftFT UI^GUAGES I .4C0RNS*FT LANGUAGES the software division of Acorn Computers Ltd., ' who designed and built the BBC Microcomputer. USP FORTH naturally you can expect the highest quality Modal B So hKlhtBBCMtoooooButwModdsAaxJB I| Iwfhe BBC Mtoocomputw software with the built-in ingenuity to fully exploit the BBC Micro's potential.

(PFtlND LPAR) for everyone. (SPRINT (CAR I) H Further education ISBTO H iri-U& H (IpOOP Creative Graphics,which includes the book 'Creative Graphics on the BBC Microcomputer" (price £17.45), provides 36 programs on cassette producing a spectacular range of pictures and

patterns in full colour, including animated it consists of 5.5K of machine code interpreter, pictures, recursively-defined curves and three plus 3K of initialised LISP work-space dimensional shapes. containing utilities and constants. It comes Word Sequencing (price £11.90) contains complete with a book that introduces you to three word sequencing programs on cassette. programming in LISR as well as some Each program presents a series of jumbled fascinating applications. words which must be arranged on screen to form FORTH (price £24.35) is a complete implementation of the FORTH language to the 1979 standard specification for the BBC Microcomputer Model B. This much acclaimed programming mnm language is also accompanied by a specially written book explaining all you need to know.

Mind-boggling games. Philosophers Quest (price £9.95) is an advanced adventure in which you tell the computer what you want to do and it

76 ACORN USER MARCH —

more by sending for our free catalogue.

How to set ———I— f-i Acornsolt programs. If you re a credit card holder and would like to buy cassettes of the programs shown in this advertisement, or if you would like to know the address of describes back in plain English your progress your nearest stockist,just phone 01-200 0200. through a fascinating world of fiendish puzzles Alternatively, you can buv the cassettes to be solved. directly by sending off Snapper (price £9.95) is a colourful game the order form below to: where you guide your ^snapper' through the Acornsoft c/o Vector maze, tsating dots and fruit and avoiding the Marketing, Denington creatures that chase you. Complete with full Estate,Welli ngborough, sound effects, score and a ladder of high scores. Northants NN8 2RL. Rocket Raid (pri<'e £9.95) sends you on a Also use this form if you mission to raid a heavily guarded Martian fuel would like to receive depot. You must fly your rocket over mountains the current free and through caverns, avoiding enemy missiles Acornsoft catalogue. and dodging convoys of deadly fizzers. Please allow 28 days for delivery. Increase your business acumen. ® CreditCard Holders. Ring 01-200 0200. Desk Diary (price £9.95) is an indispens- able program that can hold a file of several 'lb: Acornsoft, <'/o Vector Markrtino;. Denin^on Estate, hundred names, addresses and telephone Wellingborough Northants NN8 2KL. numbers. Please send me the following:- ((;„d Ai'Dnisofl And View, a program that enables your pr()(;h\m PHICi: O UANTin ro'iAi. usr (inly) ( in-ativf (iraphiti? £I7.4:i (Sl(\OI/SBIHIi; machine, together with a printer, to operate as a Vtord Sequeiifinfi itll.90 {.SBKOfi) fully operational word processor.(The program is LlSf £24.H5 (SB!,()2/SB!KH) lOirrH £24.35 siiLi)i/.s[trK);{) in ROM, but can easily be fitted to most BBC I'liilosphtTsQuewl £9.'J5 (SB(;oi) Micros by your local dealer.) You can ftnd out Snapper £<).'>5 (SHi'AH) Ruckf t Raid £'>.*>.S {SB(;05) Desk Diarv £^.95 (SBBOI)

TOTAL

1 enclose PO/cheque payable to Acornsoft Ltd. Or charge my credit card.

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ACORN USER MARCH 77 1 .

BBC SOFTWARE Sofware OOCB Research & model B EDUCATIONAL-1 A or B £8.05 SUM Marketing Hours of fun and learning for children aged 5 to 9 years. Animated graphics will encourage children to enjoy maths, spelling and telling the time. The tape includes MATHl, 1V1ATH2, CUBECOUNT, • P+P INCLUDED •Delivery in 8days SHAPES, MEMORY (Model B only), SPELL and CLOCK. • We test software not you ! EDUCATIONAL-2 A or B £8.05 — is more advanced Although similar to Educational 1 this tape •ALL ONLY £6-50 EACH and aimed at 7 to 12 year olds. The tape includes MATHl, MATH 2, AREA, MEMORY (Model B only), CUBECOUNT and SPELL. 3uporb vuraion o1 th« Id classic arc«da gaasi A/B £9.20 GAMES OF LOGIC AND CUNNING ^A/U 4S M*rchlno Invaders drop For children and adults alike. The tape includes AUCTION, FLIP, bcMbs Incraaslno difficulty. REVERSE, TELEPATHY and ROTATE. "^Oers hl-scora, aiiparb graphics SUPERLIFE B £9.20 and Bounif. Fast (machine code) version of a popular 'Game of Life' in a large universe. Can you produce 'Blinkers', 'Spinners', 'Gliders' and 'Spaceships' or have you only wondered what they look like? All this in Superlife and more as this tape includes 'Competitive Life' Fast action vBTsloo of with the Reds and the Blues competing for space; perhaps you can ttia popular arcad* gaan. '\ t, skill rwala, rankings, alter their evolution. bonus lasar basas and Incraaalng difficulty. KATAKOMBS B £9.20 ^^MA/; Supvrb sound Are you cunning enough to discover and seize the treasure in the •ffacts and graphics. Kaiakombs AND return alive? What and where are your enemies? Can you outwit them? Yes? Then your adventure will take you through unending forests, beside tumbling streams, over lonely plains to desolate ruins and finally underground to the tortuous Incredlbls arcdda typu ganw Katakombs. f aaturlng oiushroams, snal 1 s,

f 1 1 vs, spldars and cant ipBds« UTILITIES A/B £8.05 b skill lavals, Incra^slng Behind the mundane title lies an assortment of useful procedures dl'f Icul tv bDnLis«s, and Eiicellant graphics and functions which can save you hours/days of programming rankinc-i. and sound effort: date conversion, input and validation routines, graphic routines (cube, rectangle, etc), sorts, search and many more. *«* SPECIAL OFFER *** Any 3 cassettes for £20.70 Cheques & Add 50p pip per order. SRM Please state your Model and quote ref. AC PO.s to 542, Manchester Rd. Cheque/PO to: GOLEM LTD SRM" 77 Qualitas, Bracknell, Berks RG12 4QG. Telephone: (0344( 50720 Bury,Lancs.BL99PA

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MARCH 78 ACORN USER REVIEWS

ASSEMBLY WITH THE BEEB

Assembly language programming listings produced on a dot matrix areas that the BBC machine allows for the BBC micro by Ian Birnbaum, printer. Nowhere to be seen is there the assembly language programmer Macmillan, 305pp. £8.95 a copy of any output produced by to get a lot out of the machine with the assembler. Comments follow little effort. THE cover material proclaims this the listings in the style - 'lines 20- Also marketed, but not available book will appeal to three types of 50' and a description of the with the review copy of the book, reader. First owners of BBC section. This has resulted in are two software cassettes (£9 machines who wish to delve into comment appearing several pages each). As well as programs from the assembly language programming; adrift of the listing in some cases. text the tapes contain four second, the student ci teacher of How comments appear is perhaps additional utility programs including computer science requiring a just down to personal preference, a disassembler. structured course, and third, the but the right hand side of an The race to produce the first book person with a knowledge of Basic assembly language listing is on assembly language for the BBC who is thinking of buying a BBC usually empty so why not use it? micro has been won. The author has machine. Tho book does contain The programs are, nevertheless, done his bit by supplying plenty of material appropriate for each useful, including a high resolution useful material, but more care and category, but the attempt to be all screen copy, a monitor program control atthepublishing stagewould things to all men results in a book and several sort routines. One undoubtedly have improved the end not ideally suited to any. However, chapter consists entirely of such product

Ian Birnbaum has pieced together utility programs. It contains much useful information a considerable amount of material One omission is a full treatment (without an index) which may appeal maki-ng it a useful source of of the Beeb's powerful CALL most to the enthusiast, but it does not information. statement The ability to pass provide the gentle introduction In common with other recent numerous parameters to a machine necessary to woo the novice into the books, the author relies heavily on code routine from Basic is a delights of assembly language pro- relating assembly language pro- valuable feature of the BBC gramming on a very special machine. gramming to imitating the state- machine. Even the standard ments and structures of Basic. The operating system calls receive John Ferguson limitations of this approach in its limited attention yet it is in these Tony Shaw assumption that most people quickly pick up elementary Basic are unimportant if those that don't are not going to be interested in assembly language programming. IT'S AS CLEAR AS This assembly language comparison MUDD to Basic works well in places. In particular one chapter gives a clear introduction to loop structures by

contrasting the FOR . . . NEXT and D Pascal from Basic by Peter nobody understands, Bill Mudd,

REPEAT . . . UNTIL structures of Brown, Addison Wesley, 183pp, a stubborn devotee of Basic, Basic with their assembly language £6.95 whose programs never quite counterparts. work and Mr Perkins the security The BBC assembler Is almost FROM its title, you might think man, keen on reliability. unique in terms of its friendliness, this book is Intended solely for of with ease of use and the accessibility of those learning Pascal as a Users Basic BBC machines may consider some of operating system routines. It Is second computer language. This criticisms of their these features that one might is emphatically not the case: the the language unfair. This is Professor expect the book to make use of book is more a treatise on because Brown has unfortunately chosen early on, but. disappointingly, this is general programming style. to use the rather old ANSI not the case. It opts instead to stay Professor Brown is an minimal Basic for his standard. with a conventional 'computer experienced teacher and skilled BBC Basic has learned from the science' start - block diagrams of author. He has produced a book computer systems and an ample which is a fine amalgam of block-structured languages. helping of binary arithmetic. lucid, witty writing and clear, This book is however far from Throughout the book are numerous detailed information. His expla- being an attack on Basic. Where exercises for the reader to try, nation of the world of Pascal is praise for the language is solutions for which are provided. ably assisted by such characters deserved such as in string Many programs are included, as Professor Pimple, an academic manipulation, it is given. The although most are poorly laid out devotee of Pascal, whom page 80^-

ACORN USER MARCH 79 REVIEWS

^- from page 79

author is quick to point out THE PLOTS THICKEN areas where Basic would be the better language to use. Occa- sionally this endeavour for fairness is taken to extremes. n Graphs and charts on the BBC betting as a mathematical to For example, it is true that the microcomputer by Robert Harding, plotting transformation and setting speed of Basic as compared to Acornsoft. 104pp, £7.50 (cassette v-iewpolnts so more than one graph Pascal depends on the imple- £9.95) can be displayed on the screen. mentation, and that Pascal can In both level two and level three be slower than Basic. However, complete example programs are given as far as micro users are THIS is a set of mathematically- showing how the procedures should concerned most Basics are oriented, graph-plotting utilities be driven. Incidentally, one practice interpreted or at best partly written as Basic procedures. These the author adopts is to start the names compiled, whereas Pascal is are 'compiled' into complete of all global variables with ""which is invariably fully compiled at least programs using the "EXEC a good way of preventing logical as far as P-code and runs much command to extract programs from errors due to the programmer select- faster. For many micro users this the cassette. The material covered ing variable names identical to those is the main criterion for includes histograms, pie-charts, intended for global variables. switching to Pascal. plotting functions of one and two The book is clearly written and Professor Brown has also variables and stereo views of nicely produced with a spiral given a brief overview of functions of two variables. The binder. Because of their generality, operating systems, a subject book consists of procedure listings, the procedures are lengthy and generally unfamiliar to users of a deschption of each procedure unless you are desperate to save Basic. What most micros and how to use it, and a liberal or only to one or £9.95 want use describe as an operating system number of illustrations of the two utilities, I would not is in reality just an operating utilities in use. recommend purchasing the book system kernel, providing primitive The material is ordered into three without the cassette, facilities, such as reading and levels to enable high or low level writing characters, opening files access, depending on the user's and so on. Basic then provides requirements. Level three, the Hlowever, 1 have three quibbles. the operating system command highest, includes complete programs First the book is rather expensive program, with high-level instruc- ready to run, that are loaded using for 104 pages, but I suppose you CHAIN. These are then supplied are purchasing a software package tions The micro and Acorn with data from the keyboard, or a rather than a text book. Second the BBC Atom are unusual in having function is selected to generate the Basic is written in traditional style operating systems that also data points. For example, when (although it's an improvement on provide high-level commands ustng the level three histogram some of the stuff you see around). (for instance, *LOAD, *FX), but program, points are supplied, one Little use is made of mnemonic even these are rudimentary at a time from the keyboard, variable names, spacing and with a fully-blown together with a seiection of options indentation to highlight program compared operating system, such as Unix. such as colour, bar base, width and structure. I find this somewhat Pascal is not interactive like title. disappointing given that BBC Basic, and so requires an In level two, a procedure, rather Basic programs can be made environment (provided by the than a complete program, is used much more readable with the operating system) to work in. and this has to be supplied with the facilities available in the dialect. This book gives readers an data set up in global arrays, Contrary to popular opinion, writing into environments. together with option selection as readable programs only has a Insight such procedure parameters. marginal effect on interpreter run By far the most impressive time. Readability is important with a features are the comments programming product such as this if a reader, for throughout on example, wanted to muse through the style. It is here that this book I his is an excellent approach procedures to familiarise himself will benefit all programmers, fromi an educational viewpoint, a with graph drawing techniques. whether schooled in Basic, user being taken through the Finally, the surface plotting Pascal or other languages. The facilities available in each utility, procedures suffer from the lack of author emphasises readability before moving on to tailor the utility hidden line removal. This is not and there is a marvellous for his own purpose. Indeed, the particularly arduous either in run section on the evils of GOTO. value of the package is likely to be time overheads or algorithmic Lastly, there is great detail on as an adjunct to the teaching of complexity for this special case. writing large programs which are school mathematics. secondary Without hidden line removal some easily maintained. If you wish to Level one the lowest level, is of the illustrated functions look like improve your programming ability similar to level two as far as crushed balls of chicken wire. this is an enjoyable way to do it. 'compiling' is concerned, but allows access to more detailed facilities, Alan Watt Jeremy Bennett

80 ACORN USER MARCH ;

Draw with the BBC micro and show the true potential of your machine

Fill complex shapes in any one of 20 colours 356 496 • D "5 Draw points, lines, rectangles, ellipses and circles Smooth curves Draw wire frame diagrams Draw in 3rd dimension Measures distances which are displayed Displays actual foreground colour Store up to 10 ehipses or circles in memory Re-draw any one of these at cursor position Change any one colour for another Ekla sketch lines. Half tone facility Clear screen, load screen, save screen IMnt characters or numbers at any pixel point Error messages for incorrect input Fully comprehensive manual

Listed above are some of the functions available for the BBC "B" Micro, however, there is an edited version for the BBC "A" machine. This programme has been purpose designed for simplicity and ease of use. There is no need to input any numerical data, as all judgements are made visually. ^designs The BBC Micro is the finest drawing machine in its price range. Find out what it can do.

The A.B. Designs Drawing Programme costs only E35 for the model B (over 70 functions) and C25tor the model A . When ordering includeSOpfor p&p. Please send telephone no. with all correspondence. For further Information send S.A E& phone no to A.B. Designs, 81 Sutton Common Road, Sutton, Surrey.

rq FORTH OOBtoZTkIt f q FORTH" runs on 16K or 32K Level Computing BBC MICRO 9 rire pleaseri !3bC micros and costs £15. It: to announce a new taoJkit for » follows the FORTH-79 STANDARD ••r FORTH" O •clsnt;if Ic Si aducstlanal applicatfonB q on 32K BEIC micros. O and nas fig-FORTH facilities; It costs only EIU and adds the * provides 260 FORTH words; following facilities to FORTH: COMPLETE HARDWARE S SOFTWARE PACKAGES * la infinitely estensible; * a 6502 assembler, providing FOR MODEL B' DOC MICRDCDMRUTER SYSTEM * has a full-screen editor; machine-code within FORTH; * allows full use of the M.O.S; * turtle graphics, giving you * permits use of all qrap^iic easy-to-use colour graphics; modes, even 0-2 (just!); * decompiled routines, allowing Professional Joystick as -SO * provides recursion easily; the versatile enamination of * runs faster- than QBC BASIC; your compiled FORTH programs; EnvJronmantal Monitoring Packages * needs no added hard«ar-e * the full double-numher set; - T(7rTi[.of?rrk''.i.Ji"'n, IKi.irT^iriEir.inn, hfi.jr"niciii.y tr^z^ 18-00 « includes a 70 page technical * an esample FORTH programiand manual and a summarj card; demonstrations of graphics; lOOyear Clock -Calendar Unit 35-30 * has hundreds of users. * other useful routines. Asteroids m/c,g E/.90 no/com Galany Invaders . m/c,g £5.90 tutensiori Basic £1b/£30 ROM ALL aOFTWAFlE PnoviDED OtM CASBETTE Missile Defence , m/c,g E7.90 AUds 30 new keywords to HASld Super Gulp eb.y £4.90

Compression Assembler 2 . £12 5-games cassette Lsc £5. go manuailB only avallabls at 79p e»L-.h high speed (FULL RANGE IN CATALOGUE) -(funrl.-^tjlR ijyainFii. ftK.-kage ^lurcha3e ALL PRICES INCLUDE p-t-p snd VAT Spectrum HjojCB no/com 1) ADVF-NTURi^ COLOSSAL : The classic mainrrarne game "Adventure" far datalls of chaaa and othar producta with all the original treasures S creatures + 70 entra rooms. plaaaa aand a. a. a. to :- ADVENTURE 2) QUEST : Through forest, desert, mountains, caves, Chris Hall Softuwara Engineering water, fire, modrland and swamp on an epic uiiest vs Tyranny. DUNGEON DaparCrnant B ADVENTURE : The vast dungeons of the Demon Lord have 47Buah Lana survived His fall. Can you get to their treasures first? FraaklaCon Every Level 9 adventure has over 200 individually Oescribed PRBSTON PR4 1SB locations and is pacl^ed with puzzles - a game can easily take months to complete. Only sophisticated compression techniques can squee:;e so much in! Each game needs 32K and costs £9.90 ALL PRICES INCLURE PAP AND VAT - THERE ARE NO EiXTRAS. Please send order BBC MICRO or SAE for catalogue, describing ynur micro, to:

Ccjat-ef fective InsLrutriPntaLian ton Home or School LEVEL 9 COMPUTING Dept A, 229 Hughenden Road, High Wycombe, Bucks. HP-r3 SPG

ACORN USER MARCH 81 ,

IP YOU WANT: * The Latest News on tHe BBC Micro * Top Quality Programs *Useful Hints and Tips *Honest Beviews * Independent Opinions * Local User Group Information "Members Special Offers THEN YOU NEED:

The Newsletter of the Independent National BBC Microcomputer User Group MEMBEBSHIP: £12 for 1 year (£15 overseas) or send &l and an A4 size SAE for a sample copy

WBITE TO: LASERBUG, 10 Dawley Ride, Colnbrook, Slough, Berks., SL3 OQH. MEMBERS IN 14 GOTTMTBIES WORLDWIDE

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ORDER FORM Please use BLOCK CAPITALS Please send me D Printer with parallel lead for: Name: BBC n Acorn Atom D Dragon D @ £101.15 inc. VAT (+£2.95 p+p) Address:

I enclose cheque/money order (delete where necessary) made payable to AMBER CONTROLS LTD. for £ OR debit my Access/American Express/Diners Club Card where necessary) Postcode: (delete | l | | | | | | | | | | | | |~r~l Signature:, f allow 38 days for delivery) Telephone (0264) 54524 Post to: AMBER CONTROLS LTD., DEPT. JG2, CENTRAL WAY, ANDOVER, HAMPSHIRE.

ACORN USER MARCH 82 PRINTERS PRINTERS FOR BEGINNERS. George Hill introduces I you to the ins and outs

/\fter buying of 'hard' copy. He starts your computer and The basic difference is in the playing pre-packaged games for a off with a description mechanism by which the data is few weeks, the need for a printer transferred to the paper. They are: of the types available. will gradually grow. Money spent in daisy-wheel; dot-matrix; electro- acquiring a printer is well spent, which home users, small businesses, sensitive; ink-jet; graph-plotter. and you ougfit to or start saving up educational establishments The simplest to understand, and now if you don't already own onr. could reasonably afford. Teletype the one producing the highest

Printers are vital to develop good machines will not be considered, quality output (but no graphics), is programming technique, and cut nor line- or page-printers used in the daisy-wheel printer. The paper down the length of time spent conjunction with mainframe com- is fed, as in a typewriter, across a puters. staring at a flickering television They are far too large and rubber roller. The character font is a expensive, screen. If you copy programs from and their only advantage plastic wheel with spokes (figure 1) is enormous magazines you will inevitably make speed. and the characters are embossed typing errors, A printout can be laid on the ends of the spokes. An side by side with the original, and I he computer has a limited electro-magnetic hammer strikes control over the you can check it much more the appearance of the character head which strikes readily. characters printed. Characters are the ribbon, transferring its images Also, as your own programming letters, numbers and punctuation to the paper. The daisy-wheel is develops you are much more likely marks making up a 'character sef. rotated until the correct character is to write legible and well-structured The computer merely generates a in front of the hammer, the hammer is fired, programs if you can construct them series of ASCII numbers which it and the whole printing with a printout available at each sends along the wire(s) to the mechanism moves across the stage. Relationships between the printer. The printer decodes the paper, printing one character at a parts are much clearer and the numbers, and prints its own version time. The speed and sophistication need for sections and explanatory of the character. Thus a change of of this process varies considerably REMs is more obvious on the mode from 2 to on the BBC with price! printed page. computer will change the appear- The second type, the dot-matnx Finally, you can refer to a ance of the characters on the printer, is probably the type most previous program while typing in a screen completely, but will not likely to recommend itself to the new one, without having to perform affect the printed ones at ail. The home user. The printhead consists any complex manoeuvres. type of character printed is of a series of very fine, strong wires, which are fired Apart from program listings, generated from a source in the individually by printer solenoids there are also the advantages of known as its 'character font'. (figure 2). The wires print The font varies, is through ribbon having printouts of the results of but usually a a and the paper is pretty fed over in your programs. Once you own a permanent feature of the a roller as the typewriter. printer, and the The printhead phnter you will design your appearance of the moves across the characters is only subject to minor paper and can print a band of dots. programs to use it automatically at appropriate moments, and sequences variation duhng a run. There five like: are types of printer I ypically an 80 character line available within our parameters. PRINT Results on 1) VDU only, would have more than 400 dots per 2) Printer and VDU?" 2" INPUT'Typel or N Electromechanical IF N=2 THEN PROCPRINTERON print head hammer will start to appear in your Character head programs. With some printers you can also copy the graphics screen. Daisy wheel

You may later wish to invest in or write some form of word-processing system. Word processing is the wheel rotates greatest development since the Ribbon typewriter and to take advantage of its flexibility wonderful and Ribbon cartridge capabilities, a printer, and preferably a good one, is an absolute Head carnage movement necessity. Guide rails

Now we know the advantages, Figure 1. Daisy-wheel printer let's look at the types of printer

ACORN USER MARCH PRINTERS ^^

line, and the band would be six to nine dots high. Thus each } character is printed on a matrix

(figure 3). The character font is in

ROM in the printer (ie it is stored in a chip on the printer's circuit

board). If an 'A' is sent to the printer the appropriate dot pattern is extracted from the ROM, and the wires are fired in the correct order as the printhead scans the paper. The electro-sensitive system uses special paper which is a sandwich of paper, ink and aluminium foil (figure 4}, Printing is Front view carried out by wires in contact with the foil. When the wire is raised I Print needles " Solenoid instantaneously to a high voltage, a current flows, melting the foil and exposing the ink underneath, which Figure 2. Dot matrix printing appears as a black dot on a silvery background. The character font is again in ROM. The latest printers in our price- 1 % range are the ink-jet and graph- The ink-jet phnciple I 1 plotter types. operation is illustrated In figure 5. A jet of electrically charged ink droplets is fired at the paper, and • • • i deflected by electric fields in much the same way as the electron beam Atumintum foil • • • in a television set. The character — • font is again in ROM, but controls • • • « the direction of the deflections. The graph-plotter type uses fibre Head movement direct ion Figure 4. Electro-sensitive paper tipped pens and draws its image by programmed movements.

ink-jet ^ Figure 3. Letter E on 9 b / 5 matr X Until more is known of the

'•••••••••••f and graph-plotter types I shall not '^1 be able to give accurate

comparisons, so for the present I { shall not consider them. The only

is electro-sensitive I know of the Horizontal deflection plates Sinclair. An article appeared in the

Vertical Shield November issue on Interfacing it to Charge Paper the Atom, but the problems make it Nozzle electrode / a non-starter for beginners. / / A list of points to consider when choosing a printer follows. At the B--E:- cheaper end of the market one desirable feature is traded off Deflected ini

Charge Paper width. Some cheaper control printers will only operate on their own size of paper (normally in roils). ^| data Q Character Usually this is very narrow, resuitifl^^ Pump in long thin listings which are not easy to read. In the middle price

Ink supply range, paper width is up to A4 size (about 8,5 inches wide). Only in the larger, more expensive machines

can full width computer paper be Figure 5. Ink-Jet mechanism used. This is unlikely to be a disadvantage to the home user, but

84 ACORN USER MARCH Cumana drives BBC Mkro best!

CUMANA DRIVES + OWN POWER SUPPLY = BIG PLUS FOR BBC MICRO USERS

. . . JUST FOR STARTERS SJS^ ':S?i2£S2 12 WO

I

The 'ice on the cake' is that, because the Cumana Drive has its own power supply, it can be used with many other Micros when connected via the appropriate cable. Cumana supply a Drive connecting cable which has a st^idard 34 way edge connector plus 34 way BBC connector in the same cable length. This allows the Cumana Drive to be connected to numerous makes of micro without the need to change connecting cable. And the Japanese manufactured disk drives are quiet and utterly dependable. CS50A Single sided 40 track TEAC drive in a cabinet with own power supply 1 0OK El 99 CDSOA 2 single sided 40 track TEAC drives in a cabinet with own power supply 200K £369 CS50E Single sided 80 Track TEAC Drive with cabinet and own power supply 200K £265 CD50E 2 single sided 80 Track TEAC Drives in cabinet with own power supply 400K £495 CS50F Double sided 80 Track TEAC Drive with cabinet and own power supply 400K £345 C050F 2 double sided 80 Track TEAC Drives with cabinet and own power supply BOOK £619 2 drive Cable for BBC Micro £15 2 drive Cable for BBC Micro plus TRS80, Video, Genie etc. £18 UPGRADE KITS B £90 Cumana Ltd Unit 1 , The Pines Trading Estate, Broad Street, SS«S^^"»-=^' GUILDFORD, Surrey. GU3 3BH. Tel: (0483) 503121. "i^^oliSSb*"*' Telex: 859380 CUMANA.

ACORN USER MARCH 85 PRINTERS

business users might need the wider paper facility.

Sorcickel holes Paper-feed mechanism. This can be by two methods. First is the

traditional typewriter mechanism, Fan-lold paper where the paper is squeezed between two rollers, one of which is Paper Paper guide rotated by a motor. This is the Roller ."i\ fnction-feed mechanism. Second is by a tractor-feed mechanism, where 'i- % ! 1 the paper has holes down its

gives more accurate control, and is preferable for graphics. Paper for friction-feed normally So, unless the characters you wan! Graphics capability. There are two comes in rolls and often needs a are all on the same wheel, you forms of graphics printing available. special roll-holder, which is not won't be able to use them in the The first is the 'chunky graphics' always supplied as standard, same printout. character set, based on a three by Tractor-feed paper comes in packs Dot matrix printers normally have two matrix, and controlled typically of perforated sheets, folded tike a only a single basic appearance for by ASCII values 128 to 192. fan, hence fan-fold paper. Any type each character in the font, but a of printer might have either variety of printing methods ^ mechanism, so you need to be produces a wide apparent variation. fffpeclUc in your enquiries. It is For example, the letter 'A' is always "ds^sirable to be able to use single the same dot pattern, but the dots sheets of ordinary paper. This will may be printed closer together, only be possible in a printer with doubled up. further apart, producing

the tnctloii-feed option and you will different appearances (figure 7). have to feed the sheets in by hand, Some of these features are under unless you have a very expensive software control (ie you can change special attachment - beware of them by sending the appropriate paper end deteqtprs which switch control characters or escape ofl the printer in rriiej-page. sequences to the printer from the keyboard. or from within a Manufacturers tend to refer to this program). Some need changes in 'full capability', it Printing speed. This is often as graphics but switch settings or link placements quoted in advertisements in c/s requires some mathematical ability, within the printer. 'Control characters' (characters per second), and must good programming and much are those with low ASCII values, no! be confused with baud rate, experimentation to use, and even generated by using the control key, then it disadvantages. which Is the rate at which electrical has which subtracts 64 from the ASCII signals can be transferred to the The second is never available on value of any key pressed printer from the computer. The latter daisy-wheel printers. It involves the siiTiultaneously (eg CTRL A sends will be discussed in the next article ability to control each individual dot 65-64, ie 1). 'Escape sequences' in this series. Printing speeds vary wire in the phnthead, and hence are generated by sending ESCape any dot pattern under the widely from 1 2 c/s to 300 c/s. produce (ASCII .27) followed by a variety of Beware of quotations of lines per control of the programmer. Here the letters or numbers. Each printer has second unless you are sure of the number of dots per line and the its own function assigned to each, characters per line. For long degree of control are chtical to and there is little agreement programs and lists you will find a performance, and the ability to between manufacturers. printing speed of less than 40 c/s a produce a 16 colour dump with disadvantage. different patterns for each colour would require a minimum of 480 10 REM 1 REM dots per line, and 640 or 960 would normal double Printing styles. Major changes be more desirable. Satisfactory, width may be made relatively easily on a though much more limited, pictures daisy-wheel printer by changing the 9 REM 10 REM can be printed with as few as 256 wheel. Thus italics, joined script, double double width dots per line, but any fewer than and greek alphabets may be height and height that involves splitting the picture up

available, but you cannot change and printing it in parts, at least for Figure 7. Dot-matrix print styles the wheel in the middle of a run. the BBC computer.

ACORN USER MARCH PRINTERS

Line spacing and wraparound. Although you may think the last What should influence you in Linefeeds can be tricky things on is the only sensible option, there your choice of printer, if it is to be *Jf printers. First you able to may be are occasions when it is desirable between daisy-wheel and dotr vary the amount of space between to have this feature under your matrix? Unless the primary purpose lines, and indeed this may be control. It is known as wraparound. of your printer is the production of crucial in graphics printing. This top quality printed matter in the ability Interfacing. This will be dealt with may be under software form of letters and circulars, or you as a separate topic in a future control, may need changes in neecj tp produce multiple carbon article. The two forms are called internal switching, or there may be copies, or you are really buying a no ^serial' and 'parallel', and the BBC control possible. Second, the typewriter, and its use as a printer printer micro may interpret a carriage can cope with either. Some is a bonus, you should probably return printers character (ASCII 13) either can be switched from one opt for the dot-matrix printer. The form literally (ie it returns the printhead to the other,, but this usually quality produced by middle priced but continues printing involves setting on the same switches located in dot-matrix printers will satisfy all but line) or it may perform 'auto- the bowels of the machine. the most fussy (particularly if you fit linefeed'. That means the paper is a new ribbon regularly). The added Reliability. In my experience advanced every time a return is ability to reproduce graphics is modern printers are reliable, and encountered. Again control may be probably the deciding factor. are unlikely to give trouble in the under software, or switched, or not should you course of normal moderate use. How much be available. Third, If a line is Like other delicate mechanisms prepared to pay? Prices vary overlength. the printer may inierpret in the range to they do not like major abuse. enormously £60 a carriage return as an instruction £2000, and on the whole you get to do one of three things: truncate what you pay for, It is however the line at the maximum width set, Noise. If you are noise-sensitive, unlikely that the home user should ignoring all characters above the as I am, the clatter and whirr of pay more than £400. pre-set linelength; overprint the noisy parts can be annoying, Daisy- Some of the latest printers will excess characters on top of the first wheels are generally more noisy be reviewed in these pages to help characters on the line; perform a than dot-matrix, and cheap printers you choose. But remember, you're linefeed and print the excess are more noisy than expensive buying, so take a good look and, if characters on the next line. ones. possible, use it firsL f

At Microage you can now get the very best miCRDAGE value in microcomputer printers. We've selected ELECTRDniCS only the best printers available so you can choose confidently, knowing you're getting the best value BIG value in small printers for money.

The Amazing Seikosha APlOO Big brother to the AP80 the APlOO is a Accessories wider more sophisticated version of the APSO Seikosha GP-80 Ink Ribbon £4.76 {75p p + p) with a full graphics capability and the ability Seikosha GP-lOO Ink Ribbon £5.75 (75p p+p) to take standard width computer stationery, Dust and sound Cover £3.95 (75p p + p) the APlOO is an ideal choice for anyone with Friction feeds for 80/100 £25.00 {£1.50 p + p) a microcomputer. Its features include: Please Rush me details of all Printers. 80 cols 30 cps • Dot Matrix Unihammer The Incredible Seikosha AP80 action • 116 ASCII standard characters The is tfie AP80 probably world's • Full graphics capability* Up to 10" paper LOWEST COST compact 80-column graphic width • Upper and lower case • Double Name_ dot-matrix printer available. width printing • Centronics interface; It can produce single and double width characters and has the ability to produce any Address. pattern through its dot-matrix capability The APSO's robust construction and its

unique "unihammer" make it an extremely cost effective and efficient printer. Its features include The computer I shall be using it with is: 80 Cols 30 cps • Dot Matrix Unihammer

action #96 ASCI I standard characters* Up to 8" paper width • Upper and lower case • Double width printing • Standard AU3 interface: Centronics Official Orders Accepted miCRDflGE ELECTROniCS dealeYnq^ieswelcome 135 HALE LANE EDGWARE MIDDLESEX HAS 9QP TELOl 959 7119 TELEX 881 3241 l/HLL Ul~99:i illV Open Mon ~ Sat 9.15 am - 6.00pm. Thurs 9.15 am - 1.00pm.

ACORN USER MARCH 87 COMPUTER COMPANY LIMITED

choice for microcomputer components

QUALITY &VALUE DELIVERY & SERVICE Every product in our catalogue is carefully selected as We guarantee to despatch by 1st class post or Securicor being of the fiighesl quality and is backed by our every order received by us up to 3,30pm that day, for 12 month "no-quibble" guarantee. Most of our range is goods available from stock. That means that, due to purchased from leading manufacturers such as Texas our commitmeni to massive in depth stocks, better than Instruments, Motorola, National Semiconductor, Intel 95% of our product range is available lo you within 24 etc. Our bulk buying power and low overheads ensure hours. Every product we sell is supported by our that these products are sold at the lowest possible, technical enquiries department and datasheets are often unbeatable prices. available on most products. BBC MICROCOMPUTERS AND ACCESSORIES

BBC COMPUTERS BBC35 Discl'O Cable 34W IDC to ACORNSOFT BOOKS FOR THE 2 X 34 way Card Edge £12.00 Model B £346.95 BBC MICRO BBC 36 Disc Power Cable £ 6.00 Model B + Disc Interface £441.95 BBC 44 Analogue Input Plug SBD01 Creative Graphics £ 7.50 & Lever £ 2.25 SBD02 Graphs -Charts £ 7.50 SBD04 Lisp £ 7.50 BBC MICRO DISC DRIVES BBC 66 1 M BusConnector + 36" Cable £ 3.50 SBD03 Forth £ 7.50 BBC31 Single TOOK Drive " Please ring for current delivery on Expandable to 2 xlOOK £229.00 BBC ACCESSORIES Acornsofl products before ordering. BBC 32 Dual 1 0OK Drives £340.00 BBC33 lOOKUpgradefor BBC45 Joysticks (per pair) £11.30 BBC 67 Eprom Programmer £57.95 BBC 31 £122,00 (assembled) BBC 34 Dual 400K Drives £649.00

All disc drives [except BBC 33) complete with Manual. Utilities Disc, and BBC MICRO COMPONENTS Connecting Cables. 4516 lOONS 2.25 ACORNSOFT 6522 BBC UPGRADE KITS 3-19 FOR THE BBC 74LS244 0.59 BBCA2B CompleteAtoBUpgrade £44.75 74LS245 0.69 Business BBC 1 16K Memory £18.00 SBE03 Games 74LS163 0,34 BBC2 Printer/User V'OKK £ 7.50 SBE04 Tree of Knowledge DS3691N 4-50 BBC3 Disc Interface Kit £95,00 SBE02 Peeko Computer Inc DS88LS120N 4.50 £ 8.65 BBC4 Analogue Input Kit £ 6.70 Manual UPD7002 4.50 SBEOl Algebrail Manipulation BBC5 SeriatVORabKit £ 7.30 8271 £36,00 BBC6 Bus. Expansion Kit £ 6.45 PK £ 8.65 20 Way Header £ 1-46 SBX01 Creative Graphics All kits are supplied with lull fitting 26 Way Header 1.76 Cassette £ 8.65 instructions. 34 Way Header 2.06 SBX02 Graphs&Charts 40 Way Header 2.32 Cassette £ 8-65 1 5 Way D Ski 2.15 Desk Diary Inc Manual £ 8.65 SBBOl 6Way DinSkt 0-90 Lisp Cassene £14-65 SBL02 5 Way Din Skt 0.90 SBLOl Forth Cassette £14.65 SBGOl Philosophers Quest £ 8.65 BBC SOFTWARE IN ROM. BBC CONNECTORS SBG07 Sphinx Adventure £ 8.65 Wordprocessor "View" BBC 21 Printer Cable and Amphenol SBG03 Monsters £ 8.65 T.OMOS Plug (not assembled) £13.00 SBG04 Snapper £ 8.65 BBC 22 User Port Connector and SBG15 Planetoid £ 8.65 Cable 36" £ 2.46 SBG06 Arcade Action £10.35 BBC 23 Cassette Lead £ 3.50 SBG05 Rocket Raid £ 8.65 BBC 24 7 Pin Din Plug £ 0,60 SBG13 Meteors £ 8.65 BBC 25 6 Pin Din Plug £ 0.60 SBG14 Arcadians £ 8.65 BBC 26 5 Pin Din Plug £ 0.60 SBG10 Chess £ 8.65

THE ABOVE LIST SHOWS JUST A FEW OF THE ITEMS IN STOCK. PLEASE TELEPHONE YOUR REQUIREMENTS - OR BETTER STILL SEND FOR OUR FREE CATALOGUE

Carriage Orders up to E199are sent bv Isl class post. and E200 + bv Securicor. Of 100 0.50 EiaO-ft99 1.25 C200 + 5.00 Ijv Securicor.

Prices quoled I + carnage chargesl are exclusive of VAT and are subject to change without notice, Quentitv Discounts are available on nianv products, please ring lot details. Official Orders are welcome from Education Establish nienis. Government Bodies and Public Companies, Credit Accounts are available to others subject id status. Pavment is due strictly nett by the 15[h ot tlie month. Credit Cards are accepted (Access and Visa) for leleptione and postal order and NO SURCHARGE is made. Out of stock Items will follow aulomaticaliy. at our

discretion, or a refund will be given if requested. MIDWICHCOMPUTERCOMPANY LIMITED niCKINQHALL HOUSE, RICKINGHALL, SUFFOLK IP22 1 HH TELEPHONE (0379) DISS 898751

ACORN USER MARCH BACK ISSUES

BACK ISSUES of Acorn User are available at a telephone. Their number is: (0732) 351216. cost of £1.25 each including postage and We are running short of some of the early packing, Please make cheques or postal orders issues of Acorn User as a result of heavy payable to Addison-Wesley and send with your demand, but we can offer a photocopy service

order to BKT (address If below}. you have any for articles which appeared in these early queries on subscriptions or back issues, issues. The cost per page is 16p. Write to: contact BKT. The company will also accept Acorn User Reprints, Addison-Wesley Publishing, credit card payment for subscriptions by 53 Bedford Square, London WC1 B 3D2. To ensure regular delivery of Acorn User, send this form (or copy) to: Acorn user, Freepost, B.K.T. (Subscription Services) Ltd, Douglas Road, Tonbridge, Kent TN9 2TS. England SUBSCRIPTIONS

Preferred Method of Payment Acorn User Please complete the appropriate section and delete where necessary C). Direct Subscriptions Please open one year's subscription to Acorn User UK Subscribers

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Send this form, with your remillance, to the address Post Code above.

AU8

ACORN USER MARCH 89 Software for the BBC Micro

Beeb-calc A ROM based spread sheet program.

Debugging Program

2 machine code debugging programs— one in ROM, one on tape. Essential for the machine code programmer. An ideal complement to the assembler built into the BBC machine.

The word processor for the BBC machine. This ROM based word processor has Disk Doctor received superb reviews. A ROM containing usefu Supplied with full spiral bound manual and disk utility programs. cassette containing an example Enables the recovery of typing document and free tutor program. any data off the disk Now available from stock. Quantity including deleted files etc, Discounts. esaoo + £1.50 p&p + vat.

Mode 2 graphics a machine code High speed and high resolution game much like the Galaxians' graphics are combined in this game found in the arcades— very fast and to produce an exciting game — also works with joysticks almost identical to the original arcade version. £7.80 +VAT £7.80 +VAT We give very generous trade discounts

Cash or royallies — we pay the best rales around )fu any good BBC micro software Our tapes are guaranteed to work on all Operating Systems. High resolution graphics with Another game that has received skill — thousands of levels more very favourable reviews- Fast and COMPUTER features than any other chess game addictive. £10.00 + VAT. £7.80 +VAT

Dept AC6 16 Wayside, Chipperfidd,

Bu\' il with AfCrs.' Herts, WD49JJ.tel(09277)69727

90 ACORN USER MARCH LETTERS

Letters Acorn User 53 Bedford Square London WClB 3DZ

issues, of interfacing this? They can be obtained Back for £125 for a drive and £50 for slaves. hardware and I note facilities are advertised for A lost micro user teachers through Ihe auspices of your groups magazine. Do you know if individuals Sir, In October 1982 1 took delivery of Sir, outside the teaching profession can Last September I purchased a a model B BBC micro which BBC model B and have thoroughly obtain these? They would be useful to developed some problems. I sent the our small local user group enjoyed the machine. Sometime before at ICI in machine back to Wellingborough, I purchased Huddersfield. my machine I read an omitting to insure it, and I have been

article in which it was that stated B.D.Gott told on the phone that they have no owners of the BBC micro would Huddersfield record that it arrived. receive two complimentary copies Could you please circulate the of Acorn User. However. I have not number of my micro [119843, and on received any complimentary first copies, so The two issues of Acorn User the keyboard 11172] to make it more I assume this practice has now been (July/August and September) were difficult to dispose of? slopped, no doubt for sound reasons. mailed out free. Unfortunately, these B. Ross I was pleased therefore to see your have now been distributed, and the West Sussex first nationally circulated November dwindling supplies have to be issue and immediately purchased it. reserved for subscribers, unless you My compliments on the presentation are prepared to pay for them (see Sadly, we have heard of several and contents of the magazine. This back issues and subscriptions machines disappearing in the post. It has been reinforced by your December information, page 73]. would obviously be wise to take out and January issues and I have now The point you make about duff some form of insurance with the placed a regular order with my local soldering is an important one - Post Office when you send your newsagent. There is however one many problems with TVs, and micro off for repair. problem; I do not possess copies of cassettes, can be put down to bad

your first three issues, Would it be connections. possible to obtain these? Your idea about the joystick/ 'B' software There are several other queries I numeric pad has been noted, and we would like to raise with you which hope to carry an article on this in on upgraded 'A' you may consider worth looking into. Ihe future. Joe Telford's article on First, computer my functioned the lightpen may be of interest - and Sir, Recently I sent off a coupon to perfectly [excluding ROM bugs) for George Hill on printers. Acornsoft and was pleased to receive several months, However, recently I It would be nice to cover every a colourful brochure describing their have experienced problems with disc under the sun, but space programs for the BBC micro. My one flashing across the TV screen and doesn't allow this. The article on problem is that the programs are picture distortions. On investigation I discs you mention in January's issue described as either 'model B' or "model found the lead to the TV had a fault - should, however give pointers to A' compatible. As I possess a model A the earthing wire to the input using any of - brand disc and your with the memory upgrade to 32k, I connector on the lead was not dealer may be able to help. would be pleased if you could tell me soldered, merely wrapped around. The facilities which user groups which model B programs will run on After soldering this on the problem negotiate depend on how hard you such a machine. disappeared. try. The teaching user groups rely on Peter Waymont What articles about on hardware self-help and information exchange. Essex peripherals? I would like to make a Your local dealer may give you combined joystick/numeric pad which discounts and your bargaining You will be able to run all model B would give greater flexibility in power would undoubtedly increase games on your micro so long as you program applications than a simple if you teamed up with other user have a 6522 VIA [versatile interface joystick/fire button. Take for instance groups in ICI, or locally. adaptor) chip. A few games do not Planetoids, this requires seven inputs, Many other aids for the teaching require this chip, but you will have A joystick/numeric pad would profession come from the MEP - a to ask your dealer which these are. accomodate this easily. Government sponsored body. Their The chip plugs into the IC69 socket On the same lines, I was impressed products may be put on sale - but on the board inside the computer. with your article on interfacing discs remember that the software was You can get these chips from to the Beeb. particularly those used originally written in individual dealers, who will fit them in a couple for the TRS80. What about the schools. The MEP just tidies it up, of minutes. The cost will be around Aculab floppy tape- is there any chance collates it and distributes it. £11 including VAT. ACORN USER MARCH 91 LEHERS

advice. We also reviewed the £70 dark with no screen reflections and Amber printer last month. This obviously you don't use a flash. Error puzzle printer can also be used with the Frame the picture so only the screen Atom. is in view. Use 64ASA film for still Sir, Out of curiosity and not need, I Point two: yes, this service is now displays, 200ASA for moving wish to make a query about our BBC available and you should be able to displays and shutter speed l/25th model B computer. change your EPROMs for a series second. The best aperture setting When we switch it on and one chip through your dealer. must be discovered, by trial and immediately type OLD we get Ihe It's not directly possible to error - use your light meter to error message 'Bad program", Then, if squeeze out more memory. The determine an initial setting and we type RUN, 'Syntax error in line second processor will allow more bracket each way. 255, Bad program' is returned. Type program and variable space but it's This advice will produce the best

RUN once more and two lines of not possible without it due to the 64k pictures. For results which are quite rubbish are shown. Typing RUN once memory limitation of the 6502 acceptable, hut not as professional, again and either we are told: 'Mistake' microprocessor. the most important points are a dark or 'No room'. Or the top lew lines of room and a steady camera. the display 'fizzle' up and off the screen - in both cases all keys except BREAK are disabled. 'Guide' errors Until we decided to always type Graphics program NEW before entering a new program, Sir, page 453 of the BBC User Guide we got the error message 'No room' contains an error. In the third line of won't work very quickly, almost as if our micro's the page, it is stated that OSFIND chips are full of nonsense. returns the channel number in the Y Sir, Is this normal? register. The channel number is On running graphics program 2 [page Helga Zunde actually returned in the accumulator, 54 of the December issue] on my A. Assembler programmers will be model B. despite scrupulous checking interested to learn this. and re-checking 1 could get nothing No, this is not normal! We feel that Washington Jordan other than Ihe message: 'Not local at your micro has RAM problems - you London 10220.' can get these changed by your Who or what is at fault? I would dealer. welcome any suggestions, Here are two other errors: Page 179, Keith Leadhitter line 10120 should read: Hampshire Printer choice MOVE X%,Y% not MOVE %X,Y% We tried this procedure many and EPROIMs and page 518 (index) the entry for different ways, and the only way to PRINT in hex should read '^ PRINT reproduce the error message you Sir, I am considering buying a printer in hex 18.410. were getting occured when the for my 32k model A. I have added a program executed the procedure printer port and two chips - IC70 and without calling it. IC69. Is there any more hardware to be All procedures should be put added before a printer can be used? I Advice on beyond the END statement of a have up to £200 to spend. Are there program so they cannot be executed, any printers that are recommended for screen photos unless called by name from within the BBC? the program. For example, consider I have been having problems Sir, I wish to take transparencies of the following lines: loading files to and from cassette and text from my TV screen. As you use 100 DEF FROCprint I believe it is my OS o.l EPROM. such pictures, can you help me with 110 LOCAL N Promises were made that this would any information? 120 PRINT "Hello" be replaced free of charge - is this Eric Jones 130 ENDFROC service now available? Clwyd

it the Is it possible to squeeze about 6k If this is run will produce more of variable storage above my 32k error message 'Not local at line 110', using either extra hardware or re- Most photos used in this magazine whereas the same procedure called allocating memory? showing screen displays (see in a program will execute with no Jonathan Brenchley February issue page 57 'Rocket errors. For example: Sussex Raid') are taken from a monitor 10 FROCprint which provides a much sharper, 20 END To answer your first question, you steadier picture than a domestic 100 DEF FROCprint now have everything needed to drive television. 110 LOCAL N the printer. There are no printers rec- Our photographer offers this 120 PRINT "Hello" 130 ENDFROC ommended by Acorn for the Beeb in advice: mount the camera on a your price range - and for under tripod; use a single lens reflex We hope your program runs, as the £200 your choice will he limited. See camera with a long focus lens teletext mode is such a nice one to George Hill's article (p67) for some (135mm is ideal). The room must he use.

92 ACORN USER MARCH PRESENTS

GRAPHICS PACKAGE

Salamander Software has recently obtained sole U.K. marketing rights to a sophisticated graphics package for use with the BBC Model B microcomputer. The pack- age was developed by a firm of consultants and design engineers to the oil and utility industries for in-housc use, and has now been assembled in commercial form for appli- cations in the home, business and schools.

The package consists of an advanced picture drawing system controlled entirely by normal keyboard input and using cassette tapes for software and picture storage, so that no additional hardware is required.

THE MAIN SYSTEM FEATURES ARE:

* Picture drawing in mode 0, 1 or 2 * Actual and Logical colour changes at any time * Drawing functions include lines, boxes, circles, arcs, text and shape repetition * Drawing aids include grid, elastic band, save and home cursor (5 positions) Colourflll Text window showing X, Y cursor position, length, angle, colour menu and current colour Saving and loading of pictures using cassette tapes Multifile picture Flashing crosshairs cursor User instructions/prompts Spiral bound manual

PRICE £24.95 inc VAT

Available rruin: Satinlander Software 27 Ditchling Rise Brighton East Sussex BNI4QL

or ask at vour lucal Acorn dealer Trade enquiries: Tel: B'lon (0273) 771942

Send stamped s.a.e. for full catalogue oocBmicvO'Kid

SOrTW»HE--Piogr3nis lha\ aie guaranteed lo run' Save houi and woriv with these utililies and piaclicdl proqiams c . casselte. NEW SOFTWARE FOR YOUR BBC MICRO 2 CBihbook 8 Double enliy Cashbook with accounts. E 4.9S A.'B 4 Hailing B Database roailmg systeni with 6 options incladmg E 4.95 A tuli database program offering unlimited array power 2 satis, labels, search and updalirq as like with its own heading a PayroU Two pari piogiam lo handle weekly wageD loi £11.90 As many columns you each 100 employees FuUy suppoited. around Adjusted number of rows each with its own key field Enter 101 Cnrdi Beal Bruce Foxsylh at his own game. £ 2.95 A/B 102 8aHl« Fast moving simulation oi Falkiands minelield. £ 2.95 B numbers or strings as required to fill the array Alter, sort, 501 Bannst Print oul large tenl and graphic chaiactets. £ 2.95 A/B 502 Distances Graphic maps ol U.K. EUROPE and WORLD E 2.95 search, list and evaluate data using cursor Mathematical Calculales dislances belwaen any two points on calculations on individual data, rows or columns. Enter Earth. 2,95 50:i riaga Full colour Hags oi Ihp world. Eduodlional. your own equations or formulae and watch the results. 504 Stalpacli SlalisLics offering over 18 options. 7.95 B 801 SssTchbaa PROG to search a BASIC program and allei il. 1.95 A/B 602 Pmcvar PROC to list all vaiiablBB used m a program 1.95 A/B B03 PTOctlush PfiOC lo clean out memory including rntegers. 1.00 A/B 804 Ptocald A combination oi 801, 802 and 803. 2.95 A'B BOS Dalchr ' Design graphic chaiaclers, display and store 2.95 A/B 806 Sortm/c Machine Code Bubble sort for up lo 255 integers. t.OO A/B 807 SoHbai A very fast BASIC sort. 1000 ilems in 42 sees. 1.00 A/B tHemo-Cale 808 Dltlity Jt A combination oi 801-807. Super value 4.95 A/B Coming shortly; Fiench Verbs & Trigonometry Order as 505 MEMO-CALC Total price just £7.95 Hardwara An aluminium stand lo fit ovei the BBC Micro lo E 17.50 support your VDU OI T.V, Saves space on your desk Plus p'p II 50 inclusive. and prolectb your micro from damage. Anodised super quality. (manual £2.00 extra)

Holldayi Waekands In Paris for computer enthusiasts by coach E 39.50 and including three star hotel. Have fun and make friends NEW FOR EMPLOYERS Eaitai al Falmoulh In Cornwall lot a computer £ 10.00 jamboree Apartments lor up to 6 people at a per per day An addition to our PAYROLL suite for MONTHLY staff. apartmenl price cjl luly and AuguEil prices 1110 and £120 per week. VbM SUIcon Vallay in Calllornia ioi Iwo weeks, flying £699.00 £5.95 with Pan-Am. See San Francisco, Los Angefes and MONTHLY PAYROLL 3 Vegas. Apartments available on Cosla Brava Irom £39 per week For users of our PAYROLL 1 & PAYROLL 2 for Weekly Download our software Irom Prestel on Micronet 800 staff just order PAYROLL 3 for the monthly pay Holiday Details on Prestel '80091722 » calculations. Other purchasers will need PAYROLLl (database) £5.95. If you want further inlorntation before parting with your hard cash drop a line to: earned Micro-Aid (AU) Micro-Aid (AU), 25 Fore Street, Praze, Camborne, Cornwall TRW OJX. 25 Fore Street, Praze, Camborne, Cornwall TR140JX Tel: 0209 831274 Tel: 0209 831274

**- "^ NEW 100 PAGE ACORN PLUS CATALOGUE ^^,

Control Universal stock Acorn, Rockwell, Cubit and fine peripherals. Send for our catalogue.

all Acorn ACORN ^^ '^''^9 Control Universal on four telephone lines for technical advice and last deliveries on eT/\/^ V ^5 P''octucts - Eurocards, systems, Atoms, all software, networks components, connectors, spares STOCK ^^ - everything you need,

MORE; gf Control Universal also stock Rockwell Computers, EPSON and TEC pnnters, BMC and MlCROVITEC CTQQir ^p vdu displays, G.P.I. EPROM programmers and erasers, disks, stationery, memorv and TTL chips,

The CUBIT range is made by Control Universal and includes single board computers with 4K RAM and ^kL VIA I/O chip for 6502, 6802 and 6809 processors; CU-MEf\/ memory card for eight 24 or 28 pin memory CUBIT ^5 chips, with on board battery back up for CMOS RAM; CUBIO 64/80 channel digital i/o card: output and 20 digital i/o channels, ^^ CUBAN eight bit analogue interface with 1 6 analog inputs, one analog CU-KEY ascii keyboard.

'ATOM PLUS 17K RAM — £69 'CU-DRAM' 64K bytes DRAM — £129 why 17k? For all Acorn and Control Universal systems. Each block of 4k can be enabled or disabled to match the system. - to fill in the gap from hex 3000 to 3FFF with 1 K of Carries also a 4k/8k 28 pin socket for ROM or EPROM. static RAM, and provide 1 6k of dynamic RAM from and can be software selected at board level to allow up lo 3000 to to 7FFF. Uses 5v only devices, and fits in the 1 6 boards in one system and hence a maximum of standard Atom case. 1 Mbyte of RAM. Standard Eurocard size and bus connector Standard Eurocard size and bus connector

CONTROL UNIVERSAL LTD. VISIT OUR Unit 2, Andersons Court, Newnham Road, Cambridge (0223) 358757 NEW SHOWROOM

94 ACORN USER MARCH 7

^^ DEALER LIST SPECTRUM

Official Acorn Dealers Acorn dealers stock and service the BBC micro, Atom Computer, Acorn systems and Acornsoft software. The Acorn dealer not only sells computers and peripherals but provides vital customer support. Most have recently attendedtechnlcal seminars in Cambridge to ensure that they deal effectively with customers' enquiries. In addition. Acorn supply dealers with specific test and diagnostic equipment to speed fault finding. LONDON DprerE Qsla Mflik^lmg Oavcn ConiDuiers NSC Compulins Wicrocenlre L13SW1 Pjiignton Snppa Lid Bog nor Rflgrs Dl-asa 501fi/5Q9B 0803-S26303 Manchester 0243 827779 QiauprOEIS J KD. Inlesralnd on 1-63 2 2269 01 -SOB 7724 SarvH^S TVNE AND WEAR Make the most of your Spectrum, with these Pl/mourh LEICESTERSHIRE M CCS Micfoelecltorncs Lta E2 07G2SZeie C A Cortiputeis Ga loghead acclaimed books from the experts! 01-739 3232/729 1BB1 Lelcealer 0o32-a21924 Mult< Dala Services oonser 0533 849407 NswcaatlB Com puts LtdSWI Landsovrne CrynuLjleT Seryii^as 01-B28 7487/9 CeriirB UNCDLNSHIRE MBWcaalle-uporv-Tyne moiIUnoraaSVII SournarnouEh FbI"; ComputGrs 0632-761168 0I-SJ3 7730 020f zoieft Bostort REW Wast End UJD5 651100 PROGRAMMING YOUR ViObo CHnlra WC2 WEST MIDLANDS 0t-S4O 33BB/7 UVERPOOU Techno malic LEd MERSErSIDE Lid NWIO Oatd E'charbQB Lid ZX SPECTRUM Hdrli^w 01-452 1 STO 051-647 9135 0?7B '12639 03843-7061 1 /2/3 Tecinomsiic liJ W3 Cam Dili e rs trK All 01-723 0?3a MIDDLESEX RomTord YORKSHIRE Tim Hartnell and Dilwyn Jones The Vidsq Palate Wfl 0708-60725 MicToage Blecfrunics 01937 8S87 Erjgware M Dlisct ObIb MBrkeiing 01-9S9 Ltd 711B AVON Twichenltarr 0532-792332 DalaiinK Comauter Cer>irs More than 100 routines and programs, 230 pages, and value MicrocOrri purer SyElema T«icker>r>am & Bupplias for every BrialDl ShellieldSIO Spectrum user. 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Just £4.95. 061-449 9933 Compuler FflcHitiHB 0473 GlaHgow Norfhein rfrmpuiars Scunlhofpe 691B1 Warfinfllon 0724-63167 Midwich Computer 041-221 0310 Lorn Computer 0928-35110 Holderness Computer Co Lid Services Servrcas Rickinghall 0379 89S751 OI»n Interface, CLEWEUtND Huir Cualornieisd 0964 30225 0631 85S35 Dept., EreclronrCG Ltd SURREY Personal Corr pule rt AA Vixon Compular Croyupn Computer MrddleBhrough Syslems Wflsi Coast Centre Ayr 44-46 Earls Court 0B4S-24777? Cleelhofpan Road, London, W8 6EJ 01-689 1280 0292 265062 0472 58561 CORNWALL JS Simnslt Silicon Centre Please send me: Brewdr h Qunnay Computers Ltd Edir^burgli Camborne KENT Kingston upon Tharnes 031 657 4546 Kent Micro 02U9 712681 01-546 3793 Gate Microsystems CampuEerri PJ Erjuipmsnls Ltd Duhdaa UlcraleslLId I ) PROGRAMMING YOUR ZX SPECTRUM-£6.95 Baamin MaFdarons Guitd'orO 0332 28194 0622 52784 0483-504601 02U8 317I 3D Coniputers UNCASHIHE SorBilDn THE DERBTSMIHE NORTHERN IRELAND ( ) SPECTRUM SOFTWARE LIBRARY-£4.95 Ine Bifle Snop 01-337 4317 C E M Miaocompuler rl^ancliester) Lid 3D Computer Centre Serviceg 061-236 4737 Sutton BeltasL sample Maril CDTr^putera Ltd 01-642 253ii ( ) A issue of INTERFACE, the monthly magazine Wgan 0232-441 1 1143564 DEVOM 0942-496021 SUSSEX published by the National ZX Users' Club-£1.00 Cun>pur?is A t D Ltd CaatiB Eleclrcnics Ban I nam Hastings 0391 55665 046B 62180 0424-437B75 ISLE OF MAN I enclose SttB A Byres Modern Elect £ rr Typeslyle Ltd il1rar:ombe St Annas Dnchan 0271-83801 0253 711876 0824-25890/24650 Name

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ACORN USER MARCH 95 BA+F SOFTWARE A + F

" ^^^p—r-i'i^'T ^ ' ^

v^^

1370

-.^^»>;

_ BBC MODEL A 12K ATOM '"' " '"" '''*''^' "'°°"*"' """ """ Tower of Alos' Starburst £5 75 f6.90 (above also runs Torpedo Ruri £6^90 on Model B) Hours of erijoyment for all the family £6.90 BBC MODEL B featuring fast moving graphics, sound SmTp'pani? £6 90 Lunar Lande"r £6.90 effects and high score tables where Early Warning £6.90 Pgi'J,jgr £6.90 appropriate. Road Runner £6.90 2Q(j|ac' £6 90 Frogger (Machine £8.00 Death Satellite* £6.90 Code) * Hours of Purgatory with these adventure games — can you get out alive? »*»***»**««»*»*»***«#*»#*«#**##******#***»«**«*»•****»»*»»*#*#*»*# BBC 'B' BRAND NEW INTERACTIVE ADVENTURE GAME WITH SUPERB GRAPHICS. 'PHAROAH'S TOMB' WILL BE THE BEST £8.00 YOU HAVE EVER SPENT ON AN ADVENTURE GAME. •**»******»**#**********************«*******•*******************************

ATOM 'TOOLKIT EPROM ADD 4 or 6 EPROMS 22 Extra Commands and Five features including TO YOUR ATOM WITH OUR 'ADDA' BOARDS 1200 Band Cass, operating System. £18.50 4-Way 'Adda' board £20.75 6-Wav 'Adda' board £28.75 PLEASE NOTE: NO EXTRAS, ALL PRICES INCLUDE VAT AND POSTAGE CARD NUMBER TO ORDER BY MAIL' SEND CHEQUE, POSTAL ORDER OR CREDIT OR^^^J^p^^I^e'^'hone (24 HOUR ANSWERING) CREDIT CARD NUMBER

VISIT OUR SHOWROOM FOR A DEMONSTRATION OR MAIL ORDER 061-223 6206 TELEX: 667461 (Attn, A + F) 830 HYDE ROAD GORTON MANCHESTER M18 7JD ^s woiv Noovna Daa wnuiD3ds snims yivio

ACORN USER MARCH 96