Acorn User May Reader Service Contents Acorn User

BBC micro, Electron and Atom magazine M°y 1983 £1

GRAPHICS: mixing colours SCHOOLS: language work PRINTERS: the easy way BBC: new OS details ATOM: sound board A BBC: new Basic

blues on c BBC micro *BBC & ACORNSOFT SOFTWARE * BBC BUGGY * DISC DRIVES * PRINTERS * JOYSTICKS * MONITORS * BOOKS AND MANUALS * GAMES AND PUZZLES * SERVICE * ADVICE BEST FOR USERS BEST FOR DEALERS Acorn and BBC users will find everything they want As Acorn's only official distributors we can supply -and we mean everything-at our Nottingham retail store. anything you want, as soon as you want it. For instance we have just been appointed distributors of Ordering Acorn and BBC products through us the BBC Buggy, the clever little mobile featured in the means quick and efficient service. We are prompt, reliable television series "Making the Most of Your Micro" and and offer excellent service back-up.

BBC software. Don't worry if you can't get to Nottingham. You will like our credit terms as well. Just send us a SAE and we will send you a list of dealers, We can get you any Acorn or BBC product without and details of our mail order stock. fuss and by using the official distribution channel you can be sure of a completely safe delivery service.

NEW! 200K DISK DRIVES If you are thinking about Upgrade your BBC Micro with our new 200K dual becoming an Acorn/BBC .ESP*** been anrv,- * disk drive. Designed to fill the gap between the Acorn dealer talk to us now. ***"£ for UK WiSfiS""are 100K and 800K disc drives, our 200K unit has already and won rave reviews a nd it's ready now. It costs £389. 00 pi us COMING SOON -'E' DAY! £110.25 for the operating system. To order fill in the Yes it's almost here, the Acorn Electron, the coupon below. microcomputer the whole industry's talking about.

If you are an Acorn/BBC dealerthen you will want to I To: Leasalink Viewdata Ltd Scientific House, Bridge Street, Sandiacre, Nottingham NG10 5BA be the first when the Electron is launched. I Please send me I Through us you will guarantee enough Electrons to | 200K Dual Disc Drive(s) @ £389.00 (inc VAT) keep your customers fully satisfied from day one -and

| Operating System(s) @ £110.25 (inc VAT) Current Price List Only* I I FREE keep you one step ahead of your competitors.

I I enclose a Cheque For: £ Please Debit My Access/Barclaycard/Amex Leasalink Viewdata Software are the sole distributors for

No , | , , j i i i i_ the Logical program shown on BBC TV as well as Spreadsheet. r\ r- Name: Address: LEAMUNKWEWIHIt I m m limited m m Post Code: Day time Tel No: I Scientific House, Bridge Street, Sandiacre, Nottingham "Please enclose s.a.e. Allow 28 days for delivery. NG10 5BA Tel: 0602 394000 .

Cumana drives BBC Micro best!

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

. . . JUST FOR STARTERS

HASSLE

12SS^^

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 standard 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 00K £1 99 CD50A 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 CD50F 2 double sided 80 Track TEAC Drives with cabinet and own power supply 800K £619 2 drive Cable for BBC Micro £15 2 drive Cable for BBC Micro plus TRS80, Video. Genie etc. £18 UPGRADE KITS A^ £90 to an I ^fclJU* Cumana Ltd , Unit 1 , The Pines Trading Estate, Broad Street, 6' GUILDFORD, Surrey. GU3 3BH. Tel: (0483) 503121 0^£&«*»° Telex: 859380 CUMANA.

ACORN USER MAY READER SERVICE CONTENTS ACORN USER

MAY 1 983 Special offer NUMBER TEN Hints and tips A selection from Joe Telford to readers covering procedures, discs and functions - and more.

on binders • ::~. EXCLUSIVE: Electron revealed Musical synthesis Jim McGregor and Alan Watt Others claim to have shown one, analyse jazz, blues, nursery now see the real thing. rhymes and folk. News that effects YOU BBC anger at logo misuse, Acorn ••••• • attack business market, fast tape : :.... system, competition results, Beeb Forum live BBC TV micro show Retrieving the lost program, beating a dreaded error message THESE quality binders have in Ian Birnbaum's expert corner. been specially commissioned for readers from a major British Basic II manufacturer. They are available Some deny its existence. exclusively through Acorn User We give you the low down, Schools: 8 page pull-out atan introductory price of £3. 95 • ••• Heather Govier examines some includes •••' which postage and : packing. exciting developments in language work So, to keep a year's worth of Graphics listings on micros. your favourite magazine in Tim Fish shows how to generate primecondition, sendforoneof Lissajou's figures. these maroon, simulated leather finish binders. Acorn DIY Beeb interface box User is printed in gold on the Down to practice with Paul front and spine of each. New *FX calls Beverley with a major project. Make your cheque payable to Details of commands in

Addison-Wesley Publishers newOS1.2 chip. •: Ltd, and send it to BKT .: .— !( (Subscriptions), Douglas • •••• f • • Atom sound board Rd, Tonbridge, KentTN9 .u •...• 2TS. Lightpen revisited Rival the Beeb's noises with David Tilston. Include your name and Joe Telford adds to his address or use the form in March article. page 92. Allow four weeks for delivery. This offer applies to • ••• •i • • s : ««4 the UK only. • • Reviews ••• ••• Also turn to page 92 for Olivetti's ink-jet printer details of other reader services- More colours Starship command game subscriptions, back issues, Peter Voke explains mixing Horserace forecast program photocopies and reprints. on a model A and B. Basic with Holmes book

How to submit articles: You are welcome to articles send to the Editor of Subscription Information: Send Acorn User for publication. Acorn User cannot undertake to return them unless a your cheque or postal order made stamped addressed envelope is enclosed. Articles should be typed or computer payable lo Addison- Wesley Publishers written with double line spacing. Black and white photographs or trans- Acorn User, BKT (Subscription parencies are also appreciated. If submitting programs a cassette or disc is vital. Services) Ltd, Douglas Road, Tonbridge, Payment is £50 per page or pro rata Please indicate if you have submitted your Kent TN9 2TS, England. Tel: (0732) article elsewhere. Send articles, reviews and information to: The Editor, Acorn 351 21 6 Telex: 9 <> User, 53 Bedford Square. London WC1 B 3DZ.

ACORN USER MAY MAY CONTENTS EXHIBITION

Competition ACORN Simon Dally offers software, and speaks out on piracy. USER : J ' * A to Z of printing EXHIBITION George Hill takes a step-by-step BBC MICRO-ATOM- ELECTRON look at how to get going. Cunard Hotel London W6 - Cover design 25 28 August by Phil Kanssen Readers' letters Photo by Malcolm Aird

Teletext, sound, EPROMs, Editor As you'll have read in last TV problems - we provide Tony Quinn month's Acorn User, this year the answers. Editorial Assistant sees the first Acorn User Kitty Milne Exhibition to be held at the Managing Editor International Hotel, Jane Fransella Cunard Hammersmith, London W6, Reader services Production

Peter Ansel I August 25-28. Subscriptions, back issues, Tina Teare You'll find everything you binders, photocopies, reprints: Marketing Manager need to make the most of Paul Thompson all the facts are here. your micro at the Acorn User Promotion Manager Exhibition: Pat Bitton Publisher • Hardware y. i Stanley Malcolm • Software User groups Designers and Typesetters • Add-ons GMGraphics, Harrow Hill Plenty of news this month Graphic Designer • Books for clubs Phil Kanssen Printed in Great Britain And, of course, Acorn User by E.T.Heron & Co. Ltd magazine. Advertising Agents Admission will be £2 for Coming soon in Acorn User: Computer Marketplace Ltd 20 Orange Street adults and £1 for children. If New series: Introduction to London WC2H 7ED you're a subscriber to the 01-930 1612 programming techniques magazine, look out for half- Distributed to the News Trade price entry vouchers nearer Schools: Information technology by Magnum Distribution Ltd. and syllabus 72-8 Fleet Street, the time of the show. London EC4Y 1 HY. Reduced price admission Atom: Programming forum Tel: 01-583 0961 will also be available for Telex: 893340 Magnum G, BBC: Interrupt handling parties. For further Published by school Addison-Wesley Publishers Ltd. details, write to: Printers: Learn to write your 53 Bedford Square, own graphics dump London WC1B3DZ John Jones or Susan Phipps Telephone: 01-631 1636 Interfacing: Using this month's Acorn User Exhibition Telex: 8811948 Street DIY project ISSN: 201-17002 7 20 Orange London WC2H 7ED Electron: We're going to get one! ©Addison-Wesley Publishers Ltd 1983 Tel: 01-930 1612

Annual subscription rates All rights reserved. No part of this publication may be reproduced without UK £15 prior written permission of the publisher. The publisher cannot accept any Europe £18 responsibility for claims or errors in articles, programs or advertisements Middle East £20 published. The opinions expressed on the pages of this magazine are The Americas and Africa £22 those of the authors and do not necessarily represent those of the Rest of the World £24 publisher, Acorn Computers Ltd, or Acornsoft Ltd. Acorn, Acornsoft, and These prices are inclusive of post and the Acorn symbol are the registered trademarks of Acorn Computers Ltd packing (air mail overseas) for 12 issues and Acornsoft Ltd.

ACORN USER MAY Official BBC Dealer BBC DISC SYSTEM BBC Disc Interface inc. 1 .2 operating Model B £399 System £95 Installation £20 BBC Single Drive (price includes VA T. Carr. extra £81 (100K) £230 + £6 Carr. Complete Upgrade Kit £50 BBC Dual Drive (800K) Installation £15 £699 + £6 Carr. Individual Components also available. All mating connectors with cables in stock. WIDE RANGE OF 'VIEW BBC Word Processor ROM SOFTWARE HELD IN STOCK Teletext Adaptor 2nd Processor (6502) + 64K RAM BOOKS Basic Programming 2nd Processor (Z80) + 64K RAM on BBC £5.95 30 HP, Basic (NEC) £5.95 Please Phone to Check Delivery Details on New Add-ons Let your BBC teach you to Program £6.95 BBC Micro Revealed £7.95 Assy. Lang. Program on BBC £8.95 Program the 6502 £10.75 6502 Games £10.75 SEND or PHONE FOR OUR BBC LEAFLET 6502 Software Design £10.50 (No VAT on Books - f 1 p&p/book)

BBC COMPATIBLE 5H" 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: 100K £190 200KE255 400KC345 Double Sided 80 tracks £32 DUALDRIVE: 200KE360 400KE480 800K£610 p&p£2/pack Carr. £6/ Single drive £8/ Dual drive. Disc Cable: Single £8 Dual £12 PRINTERS EPSON RX80 & FX80 NEC PC8023 BEC RX80 100 CPS 80 COL Tractor Feed SEIKOSHAGP100A • 80 Cols. 100 CPS • Proportional FX80 160 CPS 80 COL F& T Feed • 80 Cols. 30 CPS • Self Testing • Hi- Res Spacing • Hi-Res & Block Graphics • Hi-Res Graphics • Bi Directional Logic Graphics • Standard & Double width • Bi-directional • Logic Seeking Forward Seeking • International Characters characters only Reverse Line • & Feed International & • 32 Print FONTS • Auto underline £185 + £6 Carr. Greek Alphabet • Auto underline • Super 8- Sub Scripts • Super & Sub Scripts • 2K Built-in MX80 F/T3 £325 + £8 Carr. buffer MX100 F/T £425 + £10 Carr. £345 + £8 Carr RX80 F/T3 £298 + £8 Carr. FX80 F/T3 £420 + £8 Carr.

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

MONITORS Kaga 12" Colour Monitor RGB Sanyo Cassette Recorder £250 + £8 Carr. £26.50 + £1.50 Carr. 14" Microvitec 1431 Colour Monitor Kaga 12" Antiglare Green Monitor Cassette Leads Carr. £249 + £8 £107 + £6 Carr. 7 pin DIN 3 jacks £3.50 Microvitec 20" 2031 Colour Monitor Hi- Res 12" Green Screen Antiglare 7 pin DIN pin DIN + jack £4.00 £319 + £8 Carr. Monitor £99 + £6 Carr.

carry We 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 & l5°7o VAT Technomatic Ltd (Export: no VAT, p&p at Cost) MAIL ORDERS TO: 17 BURNLEY ROAD, LONDON NW10 IED Orders from Government Depts. & Colleges etc. welcome. SHOPS AT: 17 BURNLEY ROAD, LONDON NW10 Detailed Price List on request. (Tel: 01-452 1500, 01-450 6597. Telex: 922800) jj 305 EDGWARE ROAD, LONDON W2 J Stock items are normally by return of post. [*

ACORN USER MAY -

NEWS

Summer launch (or Electron JUNE is the date set for full- scale production of Acorn's new £150 home computer - the Electron. A major feature of the machine is that its language

is BBC Basic, which means

it will run most software written for the BBC micro. Memory provided is the same as the model B - 32k ROM and 32k RAM. The Basic interpreter also includes the BBC machine's powerful 6502 assembler. As revealed in last October's Acorn User, all the Electron's keys will be programmable. Ten are set - aside as function keys, while Acorn's Electron the first p icture to be printed 29 provide single key entry clock is included. The major for Basic commands such as speed difference will be CHAIN, LIST, etc. The caps excuusNE seen in the high resolution BBC to get lock key doubles as a graphics modes (0 to 3). In function shift to control the baud, and outputs are other display modes the tough over programmable keys. provided for colour tele- Electron will run at about The Electron is really a vision through the standard two-thirds the speed of a 'chopped down' BBC micro aerial socket, composite BBC micro. logo misuse and this is reflected in the video, and PAL or RGB An American TV standard fact that its processing monitors. version will undoubtedly be THE BBC has hit out at speed is slower, it does not Power to the Electron produced. However, Acorn is companies which misuse its support the mode 7 screen, comes through a separate waiting to see how the BBC logo and is prepared to take has only one sound channel transformer which is pro- micro goes down across the legal action to stop the and few interfaces. The vided with the machine. Atlantic first. The Beeb has worst offenders. changes to BBC Basic are to The Electron's casing been modified and is In letters to computing allow for these hardware measures 330x160x50mm, already being tested in the magazines and advertisers differences. which is about the same US to meet their safety the Corporation warns that However, a range of add- width and height as the BBC standards. So far it has been use of its logo (the letters on modules are planned to micro, but less deep. It is, well received in their BBC inside their distinctive provide disc and printer however, a lot stronger than computer press (see for rhomboids) is infringement interfaces (Centronics and the Beeb's and the same example Computing and of copyright and that 'the RS232), the Econet net- colour. The grid strip on the Electronics, March issue). BBC is not prepared to allow working system, the Tube casing is brown, with cream The Electron will be built such use'. - for running second pro- lettering and green acorn in Singapore, unlike the BBC solicitor Tom Rivers cessors, the 1 MHz bus very Habitat! BBC micro which is mainly told Acorn User companies interface, teletext, Prestel, The 6502 microprocessor from Britain with overseas had so far been co-operative and speech synthesis. runs at 2MHz (same as the sales provided from the Far although he had received no Cassette input is at 1200 BBC micro) and a real-time East. reply from one major culprit. But Mr Rivers was adamant about the BBC's intent to

stamp out abuse. 'I am going Entry discount to subscribers to stop if, he declared. This action has been SUBSCRIBERS to Acorn The Exhibition is set to prompted by concern within User will receive a special provide the first major the BBC that use of its logo £1 discount on entrance appearance of the new implies products have been to the Acorn User Exhib- Acorn Electron, Second IAC0RN licensed by the Corporation. ition in August. Processors and Teletext However, in most cases this Vouchers to be inserted adaptors. USER is not so, the letters point in a future copy of the Bulk discounts on tic- out. The BBC feels 'the magazine will give £1 off kets are available to quality of the products is not the entry fee (adults £2, schools for the Exhibition EXHIBITION acceptable' and is 'keen to children which runs from Thursday impose some form of quality £1). BBC MICRO ATOM ELECTRON Only one voucher will August 25 to Sunday 28. control on the market'. be issued per subscription, Details from Acorn User Cunard Hotel London W6 Application for permission and these will be collected Exhibition, 20 Orange St, 25 -28 August to use the logo should be at the door. London WC2H 7ED. made to BBC Enterprises.

ACORN USER MAY Acorn means business with '£2000 system'

ACORN is planning to go into Hauser says, business in a big way this year. ABM is only Help with Quest Hermann Hauser, joint months away as Z80- program managing director, tolcMcorn pack is finalised GOOD news for anyone User the company will 'launch who keeps getting trampled a business machine this year issue. sort of integrated systems on by elephants in Phil- for under £2000.' The software is aimed at needed. osopher's - Acorn- Quest 'The Acorn Business the small business and gives Reliability checks are being soft has released a book Machine will be based on a great value for money,' said stepped up on the BBC micro of jumbled hints and BBC micro with Z80 a spokesman. now Acorn has two years' ex- answers. Second Processor' said 'It is pitched at the right perience on the machine. A The eight page leaflet Hauser. 'It will include two level for an introduction to redesign is also being made covers the most popular disc drives, integral TV business computing, but to reduce the number of com- questions and replaces screen and communication expands to give entry to ponents which will in turn re- the old postcard for clues. - facilities Econet as well as more sophisticated tech- duce the possibility of things It is sent to anyone who links to the telephone niques.' going wrong. needs help. system.' The package covers Recent checks were made Acornsoft are due to The expertise and tech- accounting, productivity and on the machine's packaging release seven new packs nology to build the ABM has programming. Acorn claims and involved throwing it down this month - three on long been available within to have 'scoured the world the stairs at the company's chemistry, a programming Acorn, says Hauser. 'It is for good software', and to be HQ! package called Microtext, merely a matter of packaging.' dealing with market leaders The customer service Draughts and Reversi, Meanwhile, Acorn is final- in each sector. department has been expand- Starship Command (see ising the CP/M software Buying British was one of ed and Acorn now plan to vir- reviews) and another package for release with the the original aims, but, says tually double their office space adventure - Countdown to £295 Z80 Second Processor Acorn, software houses to meet expansion in this and Doom. - as revealed in last month's were unable to provide the other departments.

Cassette microdrive for Beeb Small IF YOU CAN'T afford a disc similar to those used by drive and interface, but dictating machines, each cassettes drive you insane, with a capacity of 60k per the Hobbit could be the side (disc capacity is 100k Employers answer. for single-sided, single- The Hobbit is an automatic density). Like discs, cassettes digital cassette recorder are formatted for easy (rather than acoustic) which information retrieval. plugs into the user port of An EPROM operating the BBC micro and is ready system is supplied which is

to go for £135 plus VAT. It is plugged into a sideways claimed to be almost as ROM socket alongside the good as a disc system - at BBC operating system and half the price. It is up to Basic - the manual gives full

seven times faster than a instructions. If the thought normal cassette. of fitting the EPROM is too Hobbit uses tiny cassettes, much, the makers, Ikon

Computer Products, will fit

it. Hi- res telly Existing files or programs can be copied from normal ELECTRONEQUIP have cassettes onto the Hobbit announced a new 14" TV/ either for back-up or to load monitor which, they say, your favourite games that has better resolution than much faster.

most other receiver/ Ikon claim the Hobbit is Payroll,TaxandN.I. package-BBC32K monitors. It is not a modified compatible with all versions TV but a purpose-built unit of the Beeb operating

which can accept RGB or system and it comes with its ONLY Pentland Software Ltd normal TV input. There is own leads and cables. 39 Scol Ion Avenue also a separate sound input. Further details are avail- It costs £21 + VAT. able Bonnyrigg Details from Ikon Computer £9-95 from Electronequip, 36-38 Products, Kiln Lake, Incl p&p. Midlothian EH19 3QB West Street, Fareham, Laugharne, Carmarthen, Hants. Tel: 0329 230670. Dyfed. Tel: (099 421) 515.

ACORN USER MAY .

_J!l_ MYSTERIOUS _^_ = =Sf ADVENTURES '^ FOR BBC MICROCOMPUTER MODELS A & B*

Join the growing band WRITTEN IN of Adventurers who ULTRA-FAST are enjoying these MACHINE CODE. absorbing and stimulating programs. Step into another world of SAVE GAME Fantasy, Magic, Mys- FEATURE. tery and Sorcery. Only your wits and cunning SPLIT SCREEN can ensure success in DISPLAY. these scenarios!

THE GOLDEN BATON — Venture into a strange province of CIRCUS — Your Car has run out of Petrol on a lonely road Sorcery and Evil Magic to recover the Golden Baton, a miles from habitation. As you trudge relunctantly down the priceless artifact whose powers are said to bring great Health road in search of help you are suddenly confronted by an

and Prosperity to the Land. amazing sight. . in a nearby field is a Huge Circus tent! But THE TIME MACHINE — As a Newspaper reporter you are this is no ordinary Circus as you will soon discover sent to investigate the eccentric professor who lives in the old FEASIBILITY EXPERIMENT — Far across the gulfs of time house on the Moors. What is his secret and why is his house and space, a dying race of super-intelligent beings search the now deserted? Universe for a Hero to save their existence At length their ARROW OF DEATH (Pt. 1) — A blight has fallen on your thoughts turn to planet Earth. You are chosen to be their homelands, the Baton has become tarnished and now radi- saviour in a bizarre scenario where death is a mere thought

ates a malevolent aura of Evil. Your mission is clear — trace away . . in the source of this Evil and destroy . or be destroyed. This is THE WIZARD OF AKYRZ — You are the Royal Palace. '8 the first part of an Epic Adventure although each part can be The King beseeches you to rescue his daughter from the evil

played as a stand alone scenario. wizard. If you succeed your reward will be priceless failure ARROW OF DEATH (Pt. 2) — You now have the means to will bring certain death. this — Travel into the realms of destroy your enemy . . but you are far from home and PERSEUS- AND ANDROMEDA land is strange to you. Can you cope with the deadly perils 9. ancient mythology Battle with grotesque monsters and super- which approach you and have you the strength to see your natural powers as you search for the hidden secrets of myth mission through to the final conflict? and legend. ESCAPE FROM PULSAR 7 — Alone on a gigantic Space- TEN LITTLE INDIANS — This mystery begins with a train horribly the into country. secrets are held by the Freighter. . . The rest of your crew have died at 'lO. journey a strange What hands of a mutated Zoo-Specimen. Your only chance of strange country mansion? What meaning is attached to the escape is to reach the Frail Shuttlecraft. But the lurking strange idols? Maybe you will find out if you live long

Monster is hungry and you are the only food it has left enough "Adventures 5 10 require 32K RAM

Each adventure comes attractively packaged for just £10.29 inc. Dealer enquiries welcome

Available soon for ZX SPECTRUM, ZX81 (16K), APPLE II

III SEND CHEQUE OR P.O. TO: DIGITAL hOe FANTASIA deptacu. 24 NORBRECK ROAD, NORBRECK, BLACKPOOL, LANCASHIRE. III Tel: (0253) 56279

ACORN USER MAY )

NEWS

BBC programme Concern in Commons over goes live Computer Education

Following the success of Education Secretary Sir their latest series 'Making Keith Joseph's proposals the Most of the Micro' the unveiled in a government BBC are planning to put on White Paper, 'Teaching a live computer programme. Quality' have one gaping The BBC are inviting hole . . . there is no comments and queries in mention of computers. the series from viewers with The failure to include any and without machines. reference to computer The live show will go out studies or the proper use on BBC1 on Sunday of computers in teaching October 2nd from 11am to came despite growing 12.55pm with a studio March competition Commons criticism that audience. The show will be winners teachers are too often headed by Ian inade- McNaught- Ourwinning caption came from Mr P.L. Callan of Oldham, handicapped by Davis with a panel of training or lack of Lanes. Runners up were Mr T. Tugwell of Northampton, quate experts, including Acorn's suitable software. Thomas Perry of Barking, J. Olive of Basingstoke and John Coll, to answer Matthew Healy of Walsall. The White Paper looks queries. at teacher training We had over 400 entries to our other March com petition ways could be improved and the If you would like to join to find the hidden message. The first correct entry received for practical ex- the studio audience or put was from Mr R.B. Hargreaves of Stockport who receives a need your comments, ideas or free subscription. A runners-up prize goes to Ian D. Fildes perience. But nowhere, the questions, write to Micro of Vancouver who sent in his reply by telegram as well as throughout 35-page document, is attention Special, P.O. Box 7, London post card! For those still guessing, the message was in W3 6XJ giving your name morse code on pages 12 and 13 and read 'Checkmate focused on equipping and daytime phone number. checkmate ha ha'. teachers to use micros, either for computer studies or as a teaching aids. Liberal education Dol recommends spokesman Alan Beith HEXADECIMAL PRESS MP describes the White Acorn Econet Paper's omission as "very Spring surprising." It was a view Software Sale The Department of Industry echoed by Labour's inform- Cassettes: and the Manpower Services ation technology spokes- Commission have rec- WORDPLAY (BBC Models A & B) £5.75 man John Garrett MP. Text formatter with: Justification, pagina- ommended the Acorn Econet Down at the Department tion, 'soft' tabs, centering, word for their two hundred of Education and Science counting, string search, margin control, Information Technology it was being pointed out etc, etc. Centres. PLUS: Subprogram embedding within how part of the package to text, video screen dump, FREE Turtle Acorn say that nearly a put a micro into every graphics on demo tape. quarter of the 12,000 BBC school involves sending WORDPLAY (Acorn Atom, mm. 12K RAM) £5.50 micros they sell each month two teachers from each As above, without Turtle graphic routines. are equipped with Econet secondary school on a Requires Micro-Power 'Toolbox'. interfaces. Most of these go special course, BBC 6502 (UTILITIES) £4.95 to the education market but special course. How far Disassembly, Memory Dump, Trace, etc. other customers include this will take the total The Rolls-Royce of disassemblers. For British models A or B. Telecom, the DHSS, novice though might be National Physical Labor- debatable - for the course SPECTRUM Z80 DISASSEMBLER £4.95 atories and Boards. As four Disassembly, tracing, debugging facili- Gas lasts just days. ties, mnemonics for ROM locations, etc. typical networks have around Meanwhile many primary SOCCER SIX' £4.95 10 machines, this means schoolteachers are finding Fast-paced interactive video football that around 250 networking themselves with a "Do-lt- game. For BEC model B. systems are being set up Yourself" course and a ASTRO-NAVIGATOR £4.95 each month. step-by-step manual. Solar navigation calculations for BBC Models A & B.

These special introductory prices (which include postage, etc. Software Sales Overseas can only be held till 1st July '83. British software, as well as British micros, is growing in Cheque or P0 with orders to: popularity overseas. One education software house, HEXADECIMAL PRESS Chalksoft of Somerset has just announced distributorship 23 Torrington Gardens, Bounds Green for its home and school software for the BBC micro in London N11 2AB Australia and Africa. Deals are also pending for several N.B. Logarithmic discount scale for multiple orders. Write for details. countries in Europe. This is justone more in the increasing number of software companies joining the export drive.

ACORN USER MAY Kolomanoeri OfttUttTC 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 package was developed by a firm of consultants and design engineers to the oil and utility industries for in-house use, and has now been assembled in commercial form for applications 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) * Colour fill * 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 from: Salamander Software 27 Ditchling Rise Brighton East Sussex BNI4QL

or ask at your local Acorn dealer Trade enquiries: Tel: B'ton (0273) 77l«42

Send stamped s.a.e. for full catalogue

ACORN USER MAY HOME & BUSINESS TECHNOLOGY

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

PeekoCompuier 9.95 BBC models A & B in stock: Junior Maihs Pack 6.84 Philosopher 's Quest 9.95 A- £299 B-£399 Planetoid 9.95 Meteors 9.95 Arcadians 9.95 BBCI00KSingledrive(Requiresdiscs(a)) 265.00 Swoop 7.99 TORCH Z80 800K Disc pack includes Z80 proc'r Chess Model B 7.99 + 64K(b) 897.00 Space Invaders Model B The best 6.95 BBC/LVL200KTwinDrive(a) 397.00 Atlantis — Superb fast Action 32K 6.95 TEAC200K Single Drive (a) 304.75 Hyperdrive32K 5.95 TEAC400K Twin Drive (a) 569.25 Stratobomber 6.95 TEAC400K Single Drive (b) 396.75 Send for full list. SAE TEAC800K Twin Drive (b) 711.85 Connecting cable for TEAC drives 17.25 (a) SCOTCH Single sided discs Box of 10 28.75 Sound pick-off module (simple to fit) 6.95 (b) SCOTCH Double sided discs Box of 10 39.80 Amplifier and loudspeaker suitable for above 37.50 Light pen 34.50 Full upgrade kit (fitting £3 1 .00) 69.00 X-Y digit iser 80.00 Discinierfaee(fitiing£l5.00) 109.25

The above price art VA1 Inclusive, Add i UK) pip i»r orders bdw* £100.00 and mum Cover Polyester Cotton 3.97 (Secttficor delivery) for order', above 1100 00 Access .ind Baielaycard accepted on all icerm except BBl computers, Cover Soft PVC 4.45 Carrying Case for Computer, Cables, Cassette/ ELTEC COMPUTERS au Disc Drive 55.20 Carrying Case a soft supported nylon version 217 Manningham Lane, Bradford, BD8 7HH. of above 23.00 Tel (0274) 722512.

Microage of Edgware -Acorn's largest dealer- now bring you the most powerful range of disk drives for your BBC Microsystem B* A BBC Compatible Single drive(lOOK) £235 B BBCSingledrive(lOOK) £269 C BBC compatible Dual drives (200K) - £389 All drives are fully compatible with the BBC D BBC compatible slimline Single Micro and are complete with full manual, utility drive (400K) £399 disk and connecting cables. Remember these E BBC compatible slimline Dual are top quality products manufactured by TEAC drive (800K) - £799 and Mitsubishi. All prices include VAT. F BBC Disk Interface (inc 1.2 ROM & Open Mon-Sat 9.15-6.00 Thurs 9.15-1.00 Send this coupon in fitting 24 hrs) - r-^ £95 to obtain a 5% discount on all products (excluding B & F).

To M it. mage Electronics, Hale Lane, AU5~\ I 135 Edgware Middlesex KA8 9QP

i Please send me qty. A i , B i , C i j,Dl ,E i.Fi

total of at cost £ I enclose cheque nn ks*vtfc

. i i Or debit Access. Barclaycard No i_ i i i i i i i i we my i eac*>* rt

Signature

Name , Address miCRDflGE ELECTRDF11CS 135 HALE LANE EDGWARE MIDDLESEX HA8 9QP TEL: 01-959 7119 TELEX 881 3241 Postcode Telephone.

ACORN USER MAY BBC BASIC II LOW-DOWN IN, the new version of Basic, specify where the code should be Acorn's programmers have put right stored. For example, suppose you a number of rather obscure errors ON NEW want to assemble code for use in a they discovered in Basic I, and sideways ROM at &8000 and you have also added some features. want to put the code temporarily at Most of the errors are fairly memory location &3000 upwards obscure, and will not even have BASIC from where it can be transferred been noticed. Despite doubts aired into the EPROM. You will need to Apart from the errors which have set 0% = &3000, but P% should be about its existence in been corrected, the LN and LOG set as &8000 - the actual execution magazines, Acorn functions have been recoded to some address of the code. make them more accurate. has released a second To make this compatible with the The new functions include BBC Basic. original arrangement (where P% OSCLI, which stands for operating The differences are, was used for both the program system command line interpreter. however, minor. Here, counter and the origin at which the The idea is that from Basic it is code was to be stored), OPT is Paul Beverley covers the impossible to use a command line used. The first two bits of the OPT that contains a Basic variable. For major changes. command (ie OPT 0-3) determine example, you cannot say *FX5,X% whether a listing is produced

where X% has some particular closed, before it could again be and/or errors are reported. The third value. This is because as soon as opened using OPENOUT to write to bit is now used to determine * Basic meets the it passes the it. To read more data, the file had to whether 0% and P% are separate (if whole of the rest of the line to the be closed and re-opened again the bit is set to 1) or linked (if the command line interpreter, and the using OPENIN. This made random bit is cleared to 0). Thus OPTs 0-3 command line interpreter does not access filing tedious and slow. work as before with P% acting as

understand X% since it is a Basic OPENUP allows users to read program counter and origin, while variable. You cannot even say: and write to the same file without OPTs 4-7 should be used when the

having to close it and re-open it code is to be stored at a place

*FX5,2 : REM Serial printer every time. Program 1 creates a file other than where it is to be as the colon is specific to Basic. using OPENOUT and allows you to executed. What OSCLI does then is to say look at individual items of data and Program 2 illustrates this. Using pass the string which follows (in change them. OPTs '4 TO 7 STEP 3' gives the two brackets) to the command line However, OPENUP cannot extend pass assembly with listing and interpreter. The examples below a file. The way to do that is to errors reported only on the second shows how to use OSCLI with a OPENIN the file, OPENOUT pass. As the program is assembled,

variable by turning the variable into another filename, and copy it all the addresses used are in the

a string, concatenating it with the across the old file to new and add &8000 range, but if you examine rest of the command, and then the extra data. memory locations &3000 onwards, passing them to the command line The third feature is handy for you will find the assembled codes. interpreter. putting machine code programs in • The new Basic ROM is already The second useful new feature is EPROM in the sideways ROM going out in machines and will be the keyword OPENUP, for up- sockets. The idea is that when available from dealers. To discover dating disc files. Previously, the file assembling a machine code which you have, type REPORT. A

had to be opened using OPENIN program you continue to use P% as copyright line will result. BBC Basic II

to read data from it, and then the program counter but use 0% to is dated 1982.

= 10 X OPENOUT ("DATA") INPUT "Serial or Parallel Printer", A$ 20 FOR NX = 1 TO 100 IF ASC(A*> = 80 THEN XX = = ' 30 PRINT* X, NX 1 ELSE XX 40 NEXT OSCLI ("FX 5," + STR*(XX)> 50 CLOSE* X 60 70 X = OPENUP ("DATA") 80 REPEAT 10 DIM CODE 100 >RUN 90 INPUT "Number of 20 FOR NX = 4 TO 7 data item to be changed", NX STEP 8000 OPT NX 100 IF N7. = 30 OX = GOTO 170 CODE 8000 .start 110 PTR# X = (NX - 1) 40 PX = &8000 * 5 : 8000 A9 21 LDA* 33 REM Set 50 [ OPT pointer to data item NX 8002 20 EE FF JSR &FFEE 1 20 INPUT* X, RX : 60 .start 8005 4C 00 80 JMP start REN Pointer moves on by five 70 LDA* 33 bvtes 8008 \ etc 130 PTR# X = - 80 JSR 5/FFEE PTR* X 5 : REM So move pointer 90 JMP start back by five bytes >P. ^ 140 100 \ etc &3000 PR I NT "The current value "; is R7. A9 150 INPUT 110 ] "New value", DX \D *V &3000 160 PRINT* X, DX 120 NEXT NX 170 UNTIL NX = 21 >P. 180 CLOSE* X &3000 190 END 20 Program Program 1 2. Uses temporary memory . Creates file using OPENOUT location

ACORN USER MAY 11 '

GRAPHICS

LOOPY GRAPHICS

THIS short program by Tim Fish for 1 80.2 are most attractive.

the BBC micro produces the well- As listed it will run on a BBC known Lissajou figures in mode 2. model B. For model A change Type in the listing, type RUN and mode 2 to mode 5 at the start of

press return. The program then line 1 30 and change line 250 to: asks you to input a phase number. c=c+1:IFc=4THEN c=1 Numbers which are simple divisors

of 360, eg 45, 90, 180, 270, will Pressing any key will stop the produce simple patterns. Values display, except R which will restart slightly higher than these, eg 271, the pattern.

10 REM :*::*: Lissajou t%

REM :*::*: :; ;;. £0 c yj rn Fish %% ft MODES IPC5C— lTHEN40ELSEPROCr.PYR7 rv«

: 4fe3 c» i : i CL8 (>0 COL 01 iR i 28 58 PR INT "Enter P'm&e < 0-3*0 >»,

: UTDY J FDV< 80RDy :; < ??- ^f >360THENPR I NT 0^368 uu i ubw

78 B~RNi.X 6 ) 80 Or -"-Dr."360

,oq 5-1 **V?aY119* "° Mode 5 next Un*** S~ **" ***'' »ou have a model h*J ' -SB MODE2 M0 VE640 , 512. VDu i . . 9 , B fl « . n 14W GCOL0,c

erfS : l-W•i )i\ VUUd'd, .; : 1 , ; 0j 160 VDU29* 640 j 512 J 170 F0RRPT*1T0C

1 80 ' F0RCX*8TQ368S FEP8 CV«C r+0Y$8 190 X*SIN< RftDc; CX > >*639 « Y»SIN< RRD< CY > )*51 :i.

200 DRAW ;=;:;, V 210 I F NKEY< >•- i: I X j. THEN I FGET** " R

220 NEXT : NEXT 230 REM **Ch*»9* -next Uiw fen- WOd*l R**

5':;: c»c+l : If-c»7THENo»l 260 IFc»B THEN250 270 GCOL0,c 2&® GOTO 170 290 IFGETO ITHEN48 300 OEFPROCGPYRT Photos: Pam Fish i PR I :i 3 NTTflB< , 24 > ,; Press any k <*y , , *« """ •"' GFT 420 END P ROC ' -

12 ACORN USER MAY GRAPHICS

ACORN USER MAY 13 ,

NEW *FX CALLS BBC C. J. E. Specialists microcomputers THIS list of *FX/OSBYTE calls reached Acorn User from Acorn. Most are undocumented in the BBC VAT Included where applicable micro User Guide (page 501) and are all implemented in the Series One operating system. Quality Disk Drives

Single drive 40 track single sided 1 * 1 00k £210.00 Dual drive 40 track single sided 2 x 1 00k £350.00 Dual drive 40 track double sided 2 x 200k £546.25 Decimal Hex(&) Function Dual drive 80 track double sided 2 X 400k £799.25 All drives are cased with own PSU for reliability, and include connecting 'FX 13 OD Two parameters may be supplied in X to cables and utilities disk. Delivery £4.00 disable events {User Guide p465): Software for the BBC Micro X = 7 disable RS423 receive error event X = 8 disable service/network error event MISSILE CONTROL the first implementation on the •FX 14 OE As above, but parameters enable events BBC Micro of the popular arcade game. (32K) £9.00 MAZE MAN an authentic version of the popular 'FX 1 1 7 75 Returns the VDU status byte (which contains arcade game. (32K) various status flags in the X register. £6.00 BALLOONS a highly original game that soon becomes Bit - set if VDU2 sent, cleared by VDU3 - compulsive playing. (32K) £6.00 Bit 2 set if paged mode on, cleared if off - DISASSEMBLER the memory dump routine includes Bit 3 set if software scrolling, cleared if a scrolling back in memory facility. (16K) £5.00 hardware scrolling MISSILE CONTROL, MAZE MAN and BALLOONS Software scrolling is used when text windows use the Keyboard or Joysticks for control have been defined whereas hardware scrolls are used when 'he whole screen scrolls 30 + Programs for the BBC Microcomputer Bit 5 - set when cursors joined by VDU5 This Book contains program listings, with explanations and tips Bit 7- set if VDU disabled on using the BBC Micro

"FX118 76 Returns with the carry bit set if the CTRL key is GAMES UTILITIES GRAPHICS and MUSIC will pressed, and with the negative bit set if the Most programs run on Model's A and B SH IFT key is pressed. Machine code routines Edited by C. J. Evans, various Authors. may branch on these conditions. A pair of cassettes with all the programs is available. 'FX123 7B This call is used by the user print routine to BOOK £5.00 indicate to the MOS it has finished its task BOOK and CASSETTE SET £9.00 (cf*FX 5,3 command). •FX138 8A This call has been expanded to allow a char- LEADS acter to be inserted into any buffer. X must The BBC Micro comes without a cassette lead contain the buffer number, and Y the char- 7PinDinto2 x 3.5mm and 1 x 2.5mm minijacks £4.00 acter to be inserted. A list of buffer numbers 7Pin Din to 5Pin Din and 2.5mm minijack £4.00 appears with *FX 21 {User Guide p428). 7Pin Dinto7Pin Din £4.00 'FX 141 8D Exactly equivalent to "ROM 7Pin Din PLUGS Two for £0.65 •FX152 98 This call examines a buffer, The buffer number 6Pin Din PLUGS (for RGB socket) Two for £0.65 must be in X, and the call returns as follows: 5Pin Din PLUGS (360' for RS232) Two for £0.65 Carry bit set if buffer empty RS423 TO RS423 (BBC Micro to BBC Micro) Carry bit clear indicates character! present s) Two metre cable £4.00 Four metre cable £5.00 in buffer TELEVISION/MONITOR LEADS full range available Y contains the next character which will be Phono plug to Co-ax with high quality cable 3 Metres £3.00 returned if the buffer is read. Character BNC Plug to BNC Plug £3.10 in Y has not actually been removed BNC Plug to Phone plug from the buffer). (i.e. BBC Micro to Rediffusion TVRM) £2.20 'FX153 99 Inserts a character into an input buffer handling RGB 6PIN DIN to 6PIN DIN 1 metre £4.00 2 metre £5.00 the interrupt character, generating an escape condition if necessary. Valid only for X = or 1 PRINTER CABLES Y must contain character to inserted. be BBC to 36 way Centronics Type connector £17.50 'FX 156 9C Change control register. 6850 The 6850 is BBC to 25 way D Type (For use with RS232) £ 9.50 altered to: (Old value AND Y) EOR X (User BBC to 40 way edge connector (Centronics 739) £20.00 Guide p438). Refer to 6850 data sheet. TORCH to 36 way Centronics Type connector £20.00 'FX 158 9E Respectively read and write to the speech 'FX 159 9F processor chip. Blank C30 Computer Cassettes •FX233 for E9 As &E7 (User Guide p441 ) but affects the Ten for £4.50 system 6522. The system 6522 is used exten- 15 Way D Type Plug with Cover £2.75 sively in the normal operation of the micro. Computer graphics design pads 100 sheets £4.00 This call should be used with extreme care. •FX235 EB Return presence of speech processor: BBC Upgrade Kits

X =&FF if present, &00 if not. RAM UPGRADE (100ns) £23.00 'FX241 F1 Read/Write *FX 1 value (User Guide p438) KIT A Printer and I/O Port £ 9.50 •FX 245 F5 Read/Write "FX 5 value (User Guide p438) KIT B Analogue Port £ 8.00 'FX 246 F6 Read/Write *FX 6 value (User Guide p438) KIT C Serial I/O and RGB £10.00 'FX252 FC Reads identity of current language (a number KIT D Expansion Bus/Tube £ 8.00 Full from to 1 5). This indicates which socket the Upgrade kit £60.00 presently selected language ROM is in. The All components full specification sockets are numbered from right to left starting

at 1 5. On board sockets are 1 5, 1 4, 1 3 and 1 2: STAR DP8480 PRINTER From £250.00 Inc VAT the remainder can be installed offboard. 80 CPS : 80/96/132 COLS 'FX253 FD Returns a number indicating what sort of BIDIRECTIONAL LOGIC SEEKING reset last occurred: = soft break; 1 = power- TRACTOR WITH FRICTION FEED on break; 2 = CTRL break CENTRONICS £217.39 + £32.61 VAT - £250.00 "FX254 FE Read/Write RAM: 1 28 = 32k, 64 = 16k RS232 £235.00 + £35.25 VAT - £270.25 'FX255 FF Read/Write start-up option byte. This allows High Res Graphics option to allow BBC Screen dumps £15.00/£20.00 the keyboard link value to be read. It may be (24HR SECURICOR DELIVERY FOR PRINTERS £8.00) written to, but the value will be reset to the actual wired value on any reset other than a VAT Included where applicable soft-reseet. The links are configured as follows: Send SAE for full Price List of our large range of accessories. 12 3 4 5 6 7 8 X D 2 Di B Ma M* Mi Di POSTAGE Add 50p per order or as stated D2, : disc configuation bits (see Disc Manual) C.J.E Dept (AU). B : auto-boot select (auto-boot when fitted) 25 HENRY AVE, RUSTINGTOh t * W.SUSSEX. 8NBNI6 2PA I09062I 6647 M3, M2, Mi : screen mode on hard reset (0-7) li X : unused microcomputers

14 ACORN USER MAY Available now

Full instructions supplied MICROVOC - the Sound System for the BBC Micro

Yes it's here. A com- voc can literally fill the average sized room with plete sound system a quality of sound you may not have believed for the BBC Micro, possible. realistically priced at Supplied with robust, ultra modern, spheri- £21 (inc VAT) plus cal speakers which can be free standing, to £1.50 post and complement the BBC machine, or fixed to the packaging. wall, or indeed out of sight on the underside of

Microvoc is a complete sound system your desk, Microvoc brings out the true quality designed specifically for the BBC Micro, of the BBC Micro's sound facilities. capable of use with either speech synthesis or The external speakers can be disconnected computer produced music. at will leaving Microvoc's volume control to Using the BBC Micro's own power, Micro- operate the internal speaker of the BBC Micro. OUR GUARANTEE None of the original components of the BBC Micro, including the cabinet need to be modified in any way to install Microvoc

Our prime concern whilst designing Micro- 'Reset' and 'Econet' apertures at the rear of the voc was to ensure that your BBC Micro machine. warranty would remain unaffected. If your BBC Micro suffers from the Microvoc can easily be fitted in five minutes infuriating 'Buzz' then you will also need and requires no drilling, soldering, or any 'Buzzgo'. Buzzgo simply plugs into the 1Mhz technical expertise whatsoever. It can just as Bus to eliminate the infernal buzz. If purchased easily be removed, leaving your BBC Micro in with Microvoc, Buzzgo costs an additional £2 its original condition. (inc VAT). For separate purchases Buzzgo Microvoc simply plugs into the existing costs £3.50 (inclusive). fittings on the BBC Micro and makes use of the

MICRO-ADVENT (A subsidiary of Advent) Ashlyn House, 113 Writtle Road, Chelmsford, Essex Opening hours: 9.30 a.m. -3.30 p.m. Monday-Friday. Telephone 0245 59708

ACORN USER MAY 15 . .

LIGHTPEN «r

Joe Telford corrects his developed across R2, a resistance normally tying LPSTB on the CRTC in design March's to +5V. This effectively means that Acorn User, and the LPSTB input is pulled to explains how to use the when the diode isn't illuminated. Once the diode is illuminated by a pin photodiode and TV screen, it will begin conducting, Schmitt receiver and hence Tr1 will turn on. This places zero potential on the

collector of Tr1 , which effectively switches off Tr2. The LPSTB input is LIGHTPEN then pulled back to 5V. This change of state can be THE lightpen article in the March detected by the CRTC and the CHANGES issue of Acorn User caused a good software provided in the March deal of comment. The final circuit issue will calculate the position of photodiode J / shown incorporated a pin photo- the pen on the screen, although the symbol diode which does not operate in offset values may vary because of the circuit - 1 [N 2 given although a few the components used, and readers At\ode y^ cathode minor alterations allow it to do so. may find a little experimentation Adventures with the lightpen necessary, though Mr Lee has began back in September, and the found that three such pens have Pin initial circuit relied on the worked perfectly. The normal photodiode photodiode. However, to improve approach to adding extra compon- case view on development time, and cut down ents would be to include them in the component count, the later an interfacing box, but they are Figure 1 circuit used a different device - the small enough to /be mounted Schmitt receiver, RS part number directly onto the D connector. 303 270. Unfortunately, the final Readers wishing to do this may text was written five months later, find figures 3 and 4 useful, but and unwittingly referred to the should remember that too much incorrect device. heat will destroy the transistors. In For readers who have not addition, the leads may need to be invested in the lightpen yet and protected against shorting, especially

wish to do so, the simplest if the connector cover is metallic. approach is to use the Schmitt Figure 4 is the pinout of the BC108 receiver, in the March circuit as the transistor Mr Lee has used. pin numbers are exactly compatible. The final connection to the pin For readers having difficulty photodiode is shown in figure 3 Figure 2. Circuit diagram ordering from RS, most High Street and readers must remember to

TV repair/hi-fi shops can order it. connect pin 2 of the diode to +5V

If you have bought a pin and pin 1 to the base of Tr1

photodiode, there is no need to Assuming the photodiode is worry, because for an extra 50p or already available the extra com-

so, it will work. ponents needed are: R1, 4k7

Figure 1 shows the pin resistor Vsth watt 10%, about 5p: photodiode as an electronic Tr1, Tr2 BC108 transistors, 20p symbol and from the viewpoint of each.

the casing connections. If we The circuit will react to the connect pin 2 to -F5V, the diode will brightness of the TV screen which

conduct when illuminated. It has an may need adjusting. Mr. Lee has Figure 3. Component construction extremely fast response time, but found the accuracy of his circuit to the TV screen is not bright enough be approximately plus or minus one to give a pulse the CRTC can pixel, and so amending program 3 detect. We need to amplify the in the March issue by changing

pulse from the pin photodiode. line 40 to:

Probably the easiest approach is to 40 x=20:y=15 use a couple of transistors to provide the necessary signal, will help set the accuracy of the

Figure 2 is such a circuit pen, which is partly dependant on suggested by Mr M. Lee of brightness. Cheshire. Tr2 is normally conducting Our thanks to dealers and RS because its base is held at +5V by Components for handling enquiries Figure 4. BC108 pinout

resistor 1 . This means the full 5V is about the March article.

16 ACORN USER MAY ^STlkCRDflGE ELECTRDniCS

ACORNSOFT FOR BBC 'Snapper.'Planetoid.'Monsters.'RocketRaic 'Meteor 'Super Invaders, Philosophers Quest, Sphinx Adventure, Arcadians, Lisp c Cassette, Peeko Computer, Creative tt** Graphics Tape, Graphs and Charts Tape, so Desk Diary, Arcade Action, View (on ROM) and Printer Drive Cassette. Available on Disk. All Acornsoft at £9.95 each, except Arcade Action (£11.90), Lisp (£16.85), Drawn to scale. View and Printer Drive (£69.90), Wordwise word Processing ROM (£46.00) + £2.00 p+p. Only a selection of Acornsoft available.

BBC MACHINES Model A, 32K RAM & 6522 BBC compact.slimline Disk Drive. Chip £329.00 BOOKS Model B £399.00 Practical Programs for BBC & Atom £5.95 Model B + Disk Interface £494.00 BASIC Programming on the BBC BBC Dust Covers £3.95 Micro £5.95 BBC Compatible Single Disk Drive* Assembly language programming for £235.00 (100K) BBC £8.95 BBC Compatible Dual Disk Drive* BBC Micro Revealed £7.95 (200K) £389.00 Creative Graphics, Graphs & Charts, BBC Dual Slimline Disk Drive* LISP all at £7. 50 each (DoubleSided& Density 800K) £799.00 30hr. BASIC £5.95 Verbatim Single Sided Diskettes Let your BBC Micro teach you to program lOfor £22.50 Verbatim Double Sided Diskettes £6.45 lOfor £39.95 Let usfit a disk interface in 24hrs £95.00 RH Electronicscolour light pen £37.00 BBC MONITORS 14" RGB Microvitec Colour Monitor (as used in the BBC Computer Caweb. - • Printer Prog.) Including lead £284.00 B GP100 Microvitec High Res. inen Colour Monitor £575.00 paper. sheetsof atomy £2i5 12" Zenith High Res. Green screen GP100A Printer price ever. JREE Monitor £95.00 The lowest £R BNC Cable forabove £4.95 BBC Compatible Cassette Player price on application POSTAGE RATES Blank Data Cassettes 10 for £3.50 + £1.30p&p Small items such as Ribbon, books & software:- item DIN to Jack Lead £2.00 1 £1.00, 2 items or more + 75pp&p All Dust Covers £1.00 p&p 50p per unit Official Joysticks per pair £13.00 BY COURIER TO YOUR DOOR + £1.30p&p Large items such as Computers, Disk *AII Drives include manual and utility Disk. Drives & Monitors:- 1 item £7 2 items £10 All items subject to availability. 3 or more £13 PRINTERS All the products are the official versions, Acorn AP-80A now down to £189.00 ATTENTION!! beware of imitations, they will invalidate Acorn AP-100A now down to £215.00 All Lynx, One, BBC, Commodore 64 your guarantee. AP-80A Ribbons £4.95 owners, we pay top royalties for quality software programs. Please write or We accept official orders from educational AP-100A Ribbons £5.95 establishments. Brand new Epson FX 80 phone for details. Contact us for details Credit card holders can phone in for All printers include cable paper express despatch. & Epson Dust Cover £3.95 Barclaycard and Access E3 Send large S. A. E. for lists and info pack. Parallel printer cable £15.00 welcomed All prices include VAT ALL PRICES INCLUDE VAT. FOR FURTHER fTlirRnfiRF R FPTRnnir^ DETAILS AND MAIL ORDER LIST SEND LARGE S.A£. ^^^^^^ Open Mon-Sat 9.15am -6.00pm. Thurs 9.15am -1.00pm. TEL: 01 959 7119 TELEX 881 3241

ACORN USER MAY 17 At Microage you can now get the very best miCRDflGE value In microcomputer printers. We've selected ELECTROniCS 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 AP100 Big brother to the AP80 the AP100 is a Accessories

wider more sophisticated version of the AP80 Seikosha GP-80 Ink Ribbon £4.75 (75p p • p) with a full graphics capability and the ability Seikosha GP-100 Ink Ribbon £5.75 (75p p + p) to take standard width computer stationery, Dust and sound Cover £3.95 (75p p + p) the AP100 is an ideal choice for anyone with a microcomputer. Its features include: Please Rush me details of all Printers. 80 cols 30 cps • Dot Matrix Unihammer The Incredible "I Seikosha AP80 action #116 ASCII standard characters The AP80 is probably the world's • Full graphics capability • Up to 10" paper LOWEST COST, compact 80-column graphic width • Upper and lowercase • Double dot-matrix printer Name. available. width printing • Centronics interface: It can produce single and double width Or characters and has the ability to produce any Address. pattern through its dot-matrix capability.

The AP80'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 AU5 interface: Centronics Official Orders Accepted 'U llli(iWiW«Mi|i-Ji|iniis [SrlSJTC WSWiVJ: 135 HALE LANE EDGWARE MIDDLESEX HA8 9QP TEL: 01 959 7119 TELEX 881 3241 CALL 01-959 7119 Open Mon Sat 9.15 am 6.00pm. Thurs 9.15am -1.00pm. WltUfcmfrUHtt

micro-Kid HTicro~ftid expand SOFTWARE Programs lhai are guaranteed to runl Save hours of work and worry with these utilities and practical programs on cassette or disc

102 CASHBOOK Double entry 4 columns with accounts f 5 95 B to serve you 1113 LEDGER Complements CASHBOOK with ageing 8. analysis f 5 95 B 104 MAILING Holds 218 addresses System with 6 options. 2 Sorts. Labels, 2 Searches & Update f 5 95 B NEW TEAC SLIMLINE DISC DRIVES NEW 105 PAYROLL In two parts to handle weekly or monthly PAYE & Nl (WorM| (or lOOemployees Supported £13 90 B 105a Manual Extra (No VAT) £ 2 50 (Cased with their own Power Supply, 10b MEMO CALC Database Calcsheet with up to 255 columns, string or numeric data, sorts, searches, calculations with Manual & Format Disc) lull print facility 9 95 106a Manual Extra (No VAT) 2 00 - 201 CARDS Beat Bruce Forsyth at his own game 2 95 A 8 100k £199.00 200k £265.00 202 BATTLE Fast moving game simulation of a minefield 2 95 B 203 HANGMAN Word game French, German. Italian. Spanish 795 B 400k £345.00 - 800k £619.00 301 BANNER Paper printout of large text & graphics 2 95 A B 302 DISTANCES Graphic maps of U K „ EUROPE & WORLD Calculate distance between any two places 395 303 FLAGS Full colour flags of the world & questions 3 95 NEW EPSON FX-80 PRINTER NEW 304 STATPAK Statistics offering over 30 results 895 501 SEARCHBAS PROC to search a BASIC program & alter it 1 95 A B 502 PROCVAR list variables 160cps, 40, 80 or 137 columns. PROC to used in a program 1 95 A B 503 PROCFLUSH PROC to clear Resident Integer Variables 1.00 A B 504 PROCAID A combination of programs 501, 502 5 503 3 45 A B Elite, pica, italic, proportional and bOb DEFCHR Design, display & store graphic characters 2 95 A/B 506 Machine sort for SORTM/C code up to 255 integers 1 00 A B emphasised text in three sizes and 50/ SORTBAS A very fast BASIC sort 1 000 items in 42s 1 00 A B 508 UTILITY A A Comination of 501 to 507 Superb value 595 A B nine languages. Tractor, roll or 600 FORTH Second language ROM for either OS £34 74 601 WOROWISE fast ROM Superb & easy Wordprocessor OS 1 £34 74 B sheet paper feeds. 701 BOOKS Various titles for the BBC Micro from (No VAT) £ 6 95

801 CASSETTES CI 2 Computer quality boxed in 10s £4 50 RRP £379.00 810 DISCS MEMOREX Soft Sectored 40 track 5 25 £1995

901 NEW EPSON FX-80F T 160CPS. 3 FOUNTS, Graphics £379 00

HOb SEIKOSHA GP- 1 Printer 00a 50cps. 80 columns, tractor f 1 95 00 SEIKOSHA GP100A Printer 910 NEWTEAC Slimline Disc drives suitable for BBC Micro with Powei supply. Formal disc & Manual 100K Single Sided 40 Track OTHERS AVAILABLE £199 00 50 cps, 80 columns. Tractor paper feed.

920 VDU STAND Stainless steel support protects your micro f 1 9 95 £195.00 ADD VAT TO ALL PRICES. FOR COPY ON DISC ADD £ 1 00 NO PACKING CHARGE.

If you want further information before parting with your hard MEMOREX 5.25" discs - £19.95 for 10 earned cash send for our new brochure to:- C12 cassettes - £4.50 for Micro-Aid (AU) 10 25 Fore Street, Praze. Camborne, Cornwall TR14 OJX. Add VAT to all prices. Packaging included Tel: 0209-831274

18 ACORN USER MAY 1 1 , " , .

GRAPHICS

|l you think the model A BBC micro can only display eight Peter Voke explains how to get more different colours, with a maximum colours out of your BBC micro. . - of four at one time, read on. Forty distinct shades would be nearer the mark, with more than a dozen displayed simultaneously. Mode 2 all SHADE on these MORE a model B can put A hues on the screen at once.

But how is it done? The usual technique is to put bytes directly into that part of memory storing the COLOURFUL picture. However, it is not the best (number of distinct horizontal lines red and yellow lines at Y= 0,1,2,3, way, for these reasons: on the screen) is 256 'pixels' in all and so on; use Y = 0,4,8,12,16

graphics modes (0. 1 . 2. 4 and 5) hitting a new set of pixels each • putting bytes one by one into even though the Y coordinates run time. One colour goes at Y = 0,8,16 memory ('poking') is slow and

. from to 1023. This means that . . . and the other at 4,1 2,20. inefficient, plotting a point at coordinates To construct a particular colour • screen memory locations vary 100.100 (PLOT69,100,100) followed generated in program 1 or 2, you between modes and are different by another at 100,101 is a waste of need to know which underlying in models A and B. time, since both points lie inside colours it is made from. In both • the. numbers put into memory are the same pixel, which has a vertical programs the underlying pure related to the colours in a spread of V coordinates from 100 colours occur on the diagonal complex way (more about these to 103. So PLOT69,100,Y commands running from bottom left to top right below), with Y = 100, 101, 102, or 103, all of the rectangle. Each mixture is • people using television sets may affect the same pixel, the 25th from obtained by alternating the find annoying stripes running the bottom, since 100/4=25. underlying colour in the same row diagonally across colours, similar Don't attempt to fill the screen with the one in the same column as to radio interference, with orange by plotting alternate the mixture. For example, check programs using direct • memory page 22 addressing will run into big trouble with expanded systems. >l_.

A different method to poking is demonstrated by the photo 30REM "COLOUR:-; 4" program on the Welcome cassette, ftTE8 C:0L0UR MIXTURES 58REM ?uTS?IN although it does not hint at how S 4-COLOUR MODES 60REM PETER VOKE 19ft? many colours could be present, For "" 78 large areas, the principle is simple: generate a new shade by mixing existing colours (black, red, green, 180*TV8, yellow, blue, magenta, cyan, white) H0*f:«:ii,0 on alternate horizontal lines. For 120MODE 7 instance, alternating lines of red l >*£?«»THENMQWE J2252! 1 EL9EM0DE5 1 40VP%» S1 i HPV.*0 , will give 00 VDU23 , and yellow a convincing 858? . j Jn 150 orange, while red and magenta 160FOR C55«0 TO give bright pink. Type in and run 3'GCOt 0,r?> 170FOR V5S-VP5J TO VP5S+ i 88 "sTEP * program 1 to see the range. Model 180MOVE 0, VX PLOT! - „ 1280, 0. NEXT B owners can use program 2 which 190VP!i-VP3s+ 192. NEXT puts all the shades on the screen 200 simultaneously. This is by far the 210FOR C":=0 TO a»GC0UB*C5s best method of getting mixed 220FORV5s«184 TO 668 STEP 8 colours on a TV display. 2301WE HP*,V3S«PLOTi,3l9,0.NEXT 240HP5j»HPfc+320 NEXT There are a number of points 250 about these programs. *TV 0,1 in 260FR NT TREK > ' I , i " PRESS " PFTI IRN' line 100 resets the vertical position " 270PRINT "FOR NEW COLOURS" of the display and turns off the 288F0R I%»0 T04«F0R . i.v=iv+j Tn * interlace. This makes the new 290F0R Kr<*J5i+l TO S'FOR L*«K5S+i' TG ^ colours steadier (at least on my TV), 300R=C;ET:VDU19,0,i-;. ' ;0 .il9 , 1 , £,£, 3 1 VDU 9 , 2 , i K": > , and gives a wider range of 8 19, 3 IX , @

320NEXT : NEXT . NEXT . mixtures. To reset the position and NEXT : R=GFT 330 interlace, use *TV X.O (with X= or 340CL.S i PR I NT " TREK 6 , 4 > F I N I SHED 1 or 255 (User Guide pages 23, 350R=GET i CLS . VDU20 . *FX 12.0 435). 360END STEP 8 in lines 170 and 220 is Pr ogram 1. Colours for model A crucial. The vertical resolution

ACORN USER MAY 19 MAIL ORDER AND RETAIL SHOP. TRADE AND EXPORT INQUIRIES WELCOME GOVERNMENT AND EDUCATIONAL ESTABLISHMENTS OFFICIAL ORDERS WATFORD ACCEPTED. Carriage: unless staled otherwise, please add min. 50p to all cash orders. ELECTRONICS \/ A XAPPLICABLE TO UK CUSTOMERS ONLY. ALL PRICES EXCLUSIVE OF VAT V AA I PLEASE ADD 15% VAT TO THE TOTAL COST INCLUDING POSTAGE. DEPT ACORN, CARDIFF ROAD, WATFORD, Herts, England SHOP HOURS: 9.00am TO 5.00pm MONDAY TO SATURDAY AMPLE FREE CAR PARKING. ACCESS ORDERS: Simply Tel Watford (0923) 40588. Telex: telephone through your order on Watford 8956095 50234/40589.

BBC MICROCOMPUTER NEC PC8023BE-C Printer RIBBON CABLE LEADS 36" long (Female Plug at one end, other end free) Model A £299 Model B £399 100 CPS, Bi-directional, logic seeking, 80 SK9 Printer Cable (26 way Female) £2.75 incl. VAT (can £7) columns, Tractor/ Friction, 2K Buffer, propor- SK10 I/O cable (20 way Female) £2.00 tional spacing, attractively finished SK1 1 1 MHz Bus Cable (34 way Female) UPGRADE KITS. Upgrade your Model A to £320 (£7 carr) Mod. B with our Upgrade Kits and save £3.20 SK 12 Tube Cable (40 way Female) £3.70 yourself C s s s EPSON NEWFX80 • BBC1 16K Memory (8 -4816AP3 100nS) £16.00 36" 10" PRINTER LEAD Ready made £11 • BBC2 Printer User I/O Port £6.98 Tractor/ Friction feed, 160 CPS, 11x9 matrix, • BBC3 Disk Interface Kit £75.00 137 columns max.. Bidirectional, MISCELLANEOUS CONNECTORS • BBC4 Analogue I/O Kit £6.40 Logic seeking, proportional spacing, Hi-res bit Plugs Sockets • BBC5 Serial I/O Kit £6.70 image, Italics & Elite Char, Subscript & Super- RGB (6 pin DIN) 30p 45p • BBC6 Expansion Bus Kit £6.10 script. £399 (£7 carr) RS423 (5 pin Domino) 30p 40p • Printer Cable Ready made 36" £11.95 Cassette (7 pin DIN) • Complete Upgrade Kit Mod. A to Mod. B £43.00 25p 65p MX100FT/3 ECONET(5pinDIN) 15p 25p Paddles 15" Carriage, 136 columns, plus all the facili- (15 pin 'D') £1.10 £2.15 ties of MX80FT/3 Only £425 (£7 carr) READY MADE LEADS for BBC DISC DRIVES 'TEAC BBC Compatible CASSETTE LEADS: 7 pin DIN Plug LISTING PAPER to 5 pin DIN Plug + Uack Plug £2.00

85" or9|" Fanfold paper plain or ruled to 3 pin DIN Plug + 1 Jack Plug £2.00 (1000 sheets) £7(150pcarr) to 7 pin DIN Plug £2.50 5" to 3 Jack Plugs £2.00 1 fanfold paper (1 000 sheets)

£9(150pcarr) 6 pin DIN to 6 pin DIN Plug (RGB) £2.50

Teleprinter Roll (econo paper) £3 (1 50p carr) Official JOYSTICKS £11.50/pr

MONITORS LIGHT PEN All parts available for the Acorn User's "SHINE A LIGHT" Light Pen article for £8.50 US50A — Uncased, Single sided, for BBC. Written 40 track. 5J", 100K £125 BUSINESS SOFTWARE professional CS50A - Cased with own Power Supply, by Chartered Accountants and coded by competent Programmers. Ideal for small Et S/S 40 track, 5J". 100K £180 medium size companies. CD50A-Twin Cased with own PSU, • CASH BOOK ACCOUNTS PACKAGE £82 Single sided, 40 track, 53", 200K £350 • SPREAD SHEET ANALYSIS. BEEBCALC CS50E - Single case with own PSU, MICROVITEC 1431. 14" Colour Monitor, £17.35 Single Sided, 80 track, 5i",200K £250 • INVOICES & STATEMENTS CD50E - Twin cased with own PSU, RGB Input, (as used in BBC programmes.) Has customer file to produce Invoices & 53", Interface (carr Double sided, 80 track. 400K £475 FREE Lead £249.95 £7) monthly statements. Calculations include CD50F-Twin cased with own PSU, SANY03125 14" Colour. RGB & V.H. Sync. automatic VAT. Saves hours of tedious work. Double sided, 80 track. 53". 800K £599 17.35 Attractive screened metal Cabinet. Value for Mitsubishi Slim Line - Uncased, Double density, • COMMERCIAL ACCOUNTS money. Double track. 53", One Megabytes, track density £199 (carr £7) The features include: Daily Journal, Credit 96TPI, track to track access time 3mSec only £249 Interface lead for Sanyo £8 Sales, Cash Sales, Credit Purchases, others, Single Mitsubishi Slimline cased with Sales Ledger, Purchase Ledger. Bank Account. ZENITH 12" Green Monitor. Year to date summary. fully interactive own PSU. 1 Megabytes £299 A suitable for all businesses. Files Twin Mitsubishi Slimline cased with PSU. Hi-resolution £75 (carr £7) program can be saved and loaded. Useful for Cashflow control 2 Megabytes £575 with an immediate accessibility to Debtors Et Single Drive Cable for BBC Micro £8 on Creditors totals. Bank totally supported incl. Twin Drive Cable for BBC Micro £12 BBC FORTH Cassette running balance. 17.35 10 Verbatim Diskettes, S/sided £18 5J", Follows FORTH-79 standard and has fig • MAILING LIST 10 Verbatim Diskettes, 53", D/Sided £30 FORTH facilities - Provides 260 FORTH A dedicted database to allow manipulation of words — infinitely extensible— Full screen Names, Addresses Et other information. The unique 'searchkey' system gives further 10 user editor — Allows full use of MOS — Permits use definable parameters for own selections. Facility of all graphic modes, even 0-2 (just) — Easy to find name or detail when only part of the recurtion faster than — Runs BBC BASIC detail is known. Prints labels in variety of user BBC PRINTER GP100A Only £13 specified formats. £17.35 FREE 70 page manual Et a Summary card. • DATABASE The program that everybody needs. Facility

includes: Sort Search, List print if req., Ideal for BBC FORTH TOOLKIT Card Index application. You can write your own Database to suit your req. with limitless number Adds following facilities to FORTH. 6502 of entries on separate cassettes. £17.35 Assembler, providing machine-code within • STOCK CONTROL FORTH — Turtle graphics enables easy to use Takes tedium out of stock control Et saves time and money. Routines include stock setup, user Trac- colour graphics— Decompiler routines ena- reference numbers, minimum stock level, bles versatile examination of your compiled Feed,. 80 financial summary, line print records, quick FORTH programs — Full 30 double number set— stock summary, add/delete stock, etc. £17.35 CPS normal & An example FORTH program & graphics • HOME ACCOUNTS Runs a complete home finance package for double width demonstration — other useful routines — 64 you with every facility necessary for keeping track of Characters. Dot res graphics. Parallel Interface page Manual. Only £10 all expenses like, H.P., Bank, Mortgage, etc. Standard. Our price includes FREE 500 £17.35 SHEETS of PAPER. CASSETTE RECORDER & ACC. Only£175(£7carr) • SPECIAL OFFER • Top quality Slim-line, portable Cassette Recor- 2764 EROM 1 + 425p 25 + 395p • SEIKOSHAGP250XlO"TractorFeed, der. Ideal for Computer use. Mains/ Battery 80 col. 50 CPS, normal Et double width & operated with counter. £28 EPROM COPYING SERVICE height characters, RS232 & Centronics C12 Computer Grade Cassettes in library Now available while-u-wait Interfaces standard. £235 (£7 carr) cases 40p £2 per chip

20 ACORN USER MAY SPACE GAMES CHESS (32K) £9.95 WORDWISE An excellent machine code program with superb ALIEN DESTROYERS (32K) £7.95 Special offer only £35.00 Mode 1 , colour graphics. 6 levels, play black or Sensational, high speed 'INVADERS' program with Without doubt the most sophisticated piece of white, illegal moves rejected, 'en passant', castling, an abundance of features. This program has many Software yet written for BBC Micro. Wordwise take-back of moves and display of player's unique extras e.g.; 'Battle Analysis' showing the contains all the usual word processing features. The cumulative move-time. number of each alien type shot down. more complex facilities such as search and replace COWBOY SHOOTOUT (32K) £6.50 or file handling commands are menu driven so that even a beginner can understand how to operate ASTRO NAVIGATOR (32K) £6.95 Full feature, 2 Player, cowboy shooting game. Hide them. Navigate your way through a variety of treacherous behind the cactus plants and moving chuck wagons Wordwise will work with whatever filing system is caverns, inhabited by killer rockmites. There are 5 until they are shot away. Shoot your opponent and currently implemented. Supplied with full instruc- skill levels and the top 5 scores are ranked at the end. avoid getting hit yourself, Excellent colour graphics and sound. tions and manual. ELDORADO GOLD (32K) £6.50 ASTEROID BELT (16K/32K) £7.80 Legend has it that old Bill McCusky, who met a EDUCATION sudden death, had built up a vast treasure A great new space game practically identical to the JUNIOR MATHS PACK (32K) £6.95 arcade original. An inspired piece of machine code somewhere in the nearby territory. Can you end up Makes learning fun for 5-11 year olds. This package programming producing one of the most exciting rich where many have failed? consists of 3 programs (menu driven) that increase games around. in difficulty child becomes competent. A FOOTER (32K) £6.95 as your very good supplement to standard educational Another high resolution graphics game from the CROAKER (32K) £6.95 methods. author of our Galactic Commander. A 2 player game People HUH I Pity us poor Frogs! Trying to hop in which each player has to use his football skills to WHERE? £6.95 the logs over the rivers was difficult but now the try to out-run, out-dribble and finally score against Do you know 'WHERE?' you are? This well written motorways. Then come the Crocodiles and diving his opponent. A serious contender to 'MATCH OF program, using high resolution graphics offers timed turtles. Survival becomes just impossible. Arcade THE DAY'. tests on the geography of Great Britain. type, machine code, excellent sound and graphics. WORLD GEOGRAPHY (32K) £7.00 LOGO II £9.95 (32K) £7.95 Beautifully drawn Hi-Res colour map of the world GALACTIC COMMANDER This language is now very popular in American illustrates and aids this graded series of tests on Nine aptitude test for aspiring space vehicle phase schools as it is an ideal educational program. It can capital cities and populations of the world. commanders. The program presents a real challenge graphically demonstrate the ideas of defined and the use of machine code and hi-res graphics procedures, sub-routines, loops and even recursive PROGRAMMING MADE EASY only E8.00 makes for beautifully smooth action. Great sound programming. Gives excellent intro to LOGO A new concept for schools - A set of workcards to effects. language for young and old alike. introduce programming to primary school pupils. An invaluable asset to Teachers and Parents alike. The HITCH-HICKER (32K) £5.95 MUNCHYMAN (16K/32K) £6.95 language has been carefully chosen to provide a balance between 'Computer Technology' and A great adventure game. Tests your skill and wits Colourful and highly entertaining version of the standard language. Bulky and often despised text Whilst trying to collect 5 objects scattered round the popular arcade game. Munch your way to high score have replaced by the set of Workcards. universe. Directions can be found in the clues. before the 'MUNCHERS' devour you. books been Each card can be handled easily at the Computer REVERSI (16K/32K) £7.80 Keyboard. Also included are a SUPPORT PRO- LASER COMMAND (32K) £7.50 A sophisticated multi-option game. Play against the GRAM specially produced to reinforce the work Classic Defence of 6 Cities against attack from Alien computer or another player or even watch the covered by the cards and a CHECK LIST for children planets plus random bombing raids from alien computer play itself. 5 skill levels allows any player and teachers to monitor progress. A must for spacecraft. Super fast machine code arcade game to enjoy the game without continually winning (or primary schools undertaking computer learning. with superb sound and graphics. losing).

MARTIANS £6.95 ROULETTE (16K/32K) £5.95 Defend your planet against the Acorn ATOM Very popular. All the fun of the Casino in your own home. This is your Force-Field but descending Martians with a beautifully presented game for up to 6 players. The UTILITY ROM beware of the Destroyers who can annihilate you. odds are calculated according to the official rules. WEROM is Watford Electronic's own most sophis- SPACEMAZE (32K) £6.95 SNAKE (32K) £7.80 ticated but easy to use 4K ROM based on BASIC extension for Acorn ATOM. Plugs straight into the You have crash landed in the legendary labyrinth of An arcade type game. Gives hours of fun. One of the utility socket in an ATOM with floating point. The Titan, inhabited by monsters known as 'FROOGS'. best games available for this machine. Try it for special features are: Find your way through to the 'TRANSMAT' before yourself. High Speed Tape Interface -Memory Dump, being cornered and eaten. The game has 8 levels of Modify Machine code breakpoints— BASIC Error skill and 3D colour graphics. Trapping READ, DATA and RESTORE Full BASIC Keyboard Scanner (BBC like) -FULL NEW. . . NEW. . . NEW SWOOP (32K) £6.95 Disassembler AUTO Line Numbering— PLUS: The new GALAXIANS IT'S HERE AT LAST! 3 New Adventure games. May be the best yet CHAIN, Cursor Movement, Loop Aborting — Easily written. strongly recommend them. All have Extendible further. Supplied complete with instruc Galaxian style machine code arcade game. 30 We tions. E9.95 screaming, homing, bomb-dropping, explosive egg- over 200 individual locations and packed with puzzles. take easily to finish. laying BIRDMEN, swooping down in ones and twos A game can months Only sophisticated compression techniques can to destroy your laser bases. The explosive eggs BOOKS much in. feature makes a normally difficult game into a squeeze so 30 Programs - BBC Micro £ 4.95 challenge 'par excellence'. ADVENTURE QUEST (32K) £8.60 30 Hour BASIC (BBC Micro) £ 6.00 6502 Application Book £10.25 ADVENTURE (32K) £8.60 TIMETREK (32K) £7.50 COLOSSAL 6502 Assembly Lang. Programming £12.50

The ultimate 'real-time' Startrek. where indecision in DUNGEON ADVENTURE (32K) f8.60 6502 Assembly Lang. Subroutines £1 1 .80 the battle zone is your major enemy. 20 skill levels. 6502 Software Design £10.50 Special features: PANIC BUTTON for once only ACORN ATOM Magic Book £ 5.50 space leap, New Klingon fleet after 30 Stardates and APPLICATIONS Advanced 6502 Interfacing £10.95 Torpedo sight control. ALP for the BBC Micro £ 8.95 CONSTELLATION (32K) £6.50 BASIC Programming on BBC Micro f 6.90 OTHER GAMES The great Bear! The Southern Cross! The Horned BBC Micro Revealed £ 7.95 Goat! See the night sky gloriously depicted in hi res BBC Micro Instant Machine Code ADVENTURE (16K/32K) £7.50 graphics. Constellation has been adapted and including Software Cassette £34.00 enhanced from our successful ATOM program. Creative Graphics on Micro £ 7.50 All the excitement, intrigue and frustration of a BBC £1 1 mainframe adventure. Explore the tortuous forests, Discover FORTH Osborne .25 DISASSEMBLER (16K/32K) £6.95 Easy Prog, for £ dark caverns and castle dungeons. Great skill and BBC Micro 6.50 Relocatable disassembler program. Lists object code Further imagination are required to play this game. Prog, for BBC Micro £ 6.90 and Assembler mnemonics from and to any FORTH Programming (Sams) £12.50 specified addresses. The listing can be stopped and Getting Acquainted/Acorn ATOM £ 7.95 ZOMBIES' ISLAND (32K) £7.95 restarted. Page mode option and output to a printer Graphs and Charts on BBC Micro £ 7.50 Fight for survival on an island inhabited by hungry, are available. ASCII symbols may be output if Intro to Micro Beginners Book (3 Ed) dangerous cannibals. An excellent BASIC and required. The Assembler code may be stored and £ 9.90 MACHINE CODE program. modified and the program re-assembled. Let yout BBC teach you to program £ 6.45 Micros in the Classroom £ 4.90 CHARACTERS (16K/32K) £5.80 FILER £8.95 Practical Prog, for BBC & ATOM £ 5.95

Makes redefining of Invaders, Foreign Characters, A powerful file handling program for BBC. FILER Programming the 6502 £1 1 .20 Technical symbols, etc.'s character shapes simpler. allows the user to build up, manipulate, store and Mastering VISICALC (Sybex) £11.95 Clumsy binary and hexadecimal notations are not retrieve data on the BBC. A very powerful package Structured Prog, with BBC BASIC £ 9.50 req. anymore. indeed. The BBC Micro An expert Guide £ 7.90

ACORN USER MAY 21 T

GRAPHICS

+ page 19 that orange is made up of red and yellow. With a mixture of yellow and black, or blue and white, the strips 30REM "COLOURS 16" 40REM 01 the two colours running DEMONSTRATES COLOUR MIXTURES 50REM IN 16 COLOUR horizontally can be clearly seen. To MODE <:' MfiDF 2> S0REM PETER VOKE 1 9*2 get a particular range of shades, 70 first select the appropriate palette of pure underlying colours using

VDU19 commands (Acorn User, 1O0:*: TVS, 1 July/August, page 7, User Guide ii0*p>ai,e 1 20MQDE page 382); then use those colours, 2 VP5$-200 HPJc- \ S0 '" 1 30VDU23 i .; 3202 j , , , in pairs on alternate lines, to RgM CURSOR OFF" 1 40 produce the mixtures. Model B 150FOR C5i"i TO 7-GCOL . rv owners using mode 2 will not need 160FOR V5S-VP5J TO VP5S+S8 STEP 8 VDU 19 since all eight pure colours :l 70MOVE O , V5S > PLOT 1 , 1 280 , NEXT are available anyway. i80VPWP3c+S« « NEXT This brings out an important 190 point. On some TV displays there is 20OFOR CX=;[ TO 7:GCOL0,C^ 2i0FORv:-;=ioo a distinct difference between to 8SR STEP "ft

22BM0VE HPJi VJi - , PLOT 1 , 1 . shades produced by programs 1 or 59 , NEXT

230HP"'5wHP":+160 : NEXT 2 that are opposite each other (top 240 left to bottom right) and hence are 250PRINT TflB<0,n "PRESS RETURN" made of the up same underlying 268PRINT "FOR FLASHING COLOURS"

F0VDU23 i i 2 ,• 8202 > 1 .; REM ! CURSOR'"" ' UNFF 280FOR i.v=i TO 7<*FX15,:l

290R=GET ' VDU 19,. I5J, l.v;+8.: pixel , NEXT ls+ cviaxwctcf 2wd OAafActer 300

3 1 : ©COLOUR 4 « RwGET *FX 1 . MINIM 1 17 320PRINT TAB<6,1> "FINISHED" 2 \o IV .fl-CET 330CLS ' VDU20 i *FX 1 , 50 1 11 340*FX12,0 * 12 S 13 Program 2. Colours for model B b 14 7 IS

8 It

10******««**3|B|c***#«*«*****##* . :, ,, S K ; 20 30REM "NEW VOI

£ i 4 R ij ] T i\ w l I ., LOuFE D P H Ich w - 50REM PETER VOKE 1982 60 Figure 1 . Order of strips of screen

8 u colours. (This does not work on a 90MODE 5 'DIM ...!::•„•:: 3 > monitor or with off.) interlace For 1 •:].' $0VDUES . i : i ; rv.-ts B£&£ , instance when red and green are 110 the underlying colours, the two 120FOR I>= TO 3 I30J5J< mixtures can look utterly different, I"-;; >=RND':; 8 :-~i KH»I3 t40K55«K5S-l i IF !<::•;;< one being bluish, the other khaki, GOTO LSi 150IFJ5SC I>S>ssJ?j GOTO130 with interlace off. The reason is that 160VDU19, ;,;;,,,:••:; ].,;>. o : the of « NEXT appearance an underlying 1 70 colour depends on precisely where 180CLS : T=10+RND< 70 > REPEAT T«T-1 the lines are plotted on the screen, iSSS^i^RNWSlO.LOS^RNDCSl: which in turn on 200R i depends when the 4»&40+RND< 639 > LTJs-RNDC 639 j program starts relative to the TV's 2i0GCOL3,RND(3) 220F0R V5s*L05fi TO HISs vertical synchronisation. If program STEP 8

2 30MOVE v:> . LTX , DRfiW RTX . « 1 or 2 is run several times, the two YX NEXT 240UNTIL T<0 OR INKFYC-691 different mixtures of red and green 230 (say) change places in random a 260 IF INKEV<-69> GOTO 120 way from one run to the next. 270$FX15,1 In one sense this is a bonus 280PRINT TABU . 30 >" NEW COLOURS? (Y/N)" y y '• " - » since it gives still more subtle hues, 4 **GE r* . IF Y»» V OR y*. „ y G0T0 j ; J00IF but it is important to remember that Y*0"N" AND V*<>"-n" GOTO 270 3 i the precise appearance of these

320VDU20 • MODE 7 colours cannot be predicted. In 330CLS : END many situations this may be an Program 3. Random pattern generator advantage. Program 3 is another

22 ACORN USER MAY i

GRAPHICS

random generator for model A, but uses colour mixtures. 20 A simple way of obtaining these 30REM "GCi shades reliably and predictably is EM DEMONSTRATES THE EFFErj OF ,; to use program 4. The user ' TEM VALUES OF GCOL 1ST PfifWMETO and 60REM PETER VGKE 1982 definable characters 224 225 70 have been set up to fill in alternate lines. 224 filling in one set, 225 the

other. Lines 1 1 and 1 20 set up the 1 ? 00MODE i B5fi»8 : I F H I MEM >&680& R>=~ characters. 110IF BSi THEN MODE 2 'ELSE MODE * In this program model A owners 120PRINT TAB* 0,31 )*\fl>U5 should use MODE 5 in line 100. i30®3C*&.0303 #FX9 • 140 The VDU5 in line 100 is important character to 'MOVE 0,9@0 as it allows the second I INPUT be printed on top of the first without 6® R NUMBER : LESS THAN 25* G •„ 170IF C5s>255 THEN G**G>. destroying it, and prevents GOTO" 170 :l.o0H^=0 ' " scrolling. If VDU5 is left out, '•-< 190PRINT """ -Trsss SHIFT for everything becomes faster, but only '

more • »o^ DELETE fco sfinp " one character of the two can be 200 IF B's, GOTO 2: printed in any position, mixing its 210VOU19 J 3,3.i 0.il9,0,4.i0.i 19.2j2.0j 220 colour with the background. JREPEAT Without the VDU5, use COLOUR instead of GCOL O.C. When speed

•for C5fi«i ro 9 is everything, user defined characters

260MGVE579, : 96 MQVE579 , 32 and no VDU5 is the way to do it. 270FOR KJs-i TO 7'GCcLk,Wi Let now look at byte-poking 280PLOTS5, us 579+100*X* , 9g and related methods. If you have 290PLOT8S, 579+i«0*X5« 3 300NEXT never seen it, try this in mode 5: 3101 F Cfc*»9 THEN 400 FOR X% = HIMEM + 1 TO HIMEM

320GCOL0 , 7 MOVE , ; 80 PR J NTG* . H +10240: ?X%= 15: NEXT 330GCOUG5S.H3! 340MOVE 479/ 96 'MOVE 479,32 The screen fills with red. Changing 3S0PLOTSS, 1279, £6 PL0T85 ,' l£?9 V the 15 to 240, produces yellow. 360VDU4 ,10, i , 5 Now change 240 to 90. Orange 370H&»H%+1 results, made up of red and yellow 3S0IFH^>7 THEN HJ$*0 « G%«G^+j stripes, but the stripes are vertical 390 IF G":>255 G*»G%-256 400MEXT instead of horizontal.

4 i To understand this, we have to 420 IF know how the computer codes the NOT.::iNKEVX-l> OR INKEYO90>) GOTO 420 430UNTIL INKEY<-90> colours in its memory. In modes 0, 440 3, 4 and 6 it is simple with only two 450VDU4,20H1OOE 7 logical colours, and 1 . The first 460END byte of the so-called screen Program 4. More reliable than program 3 memory (beyond HIMEM) contains j. * * * * * * 1 * # * * * % % % % % # % g % % % % % % % % % t % * SO the information for the first eight 30REM "STRIPi pixels across the top of the screen 40REM DEMONSTRATES COLOUR in all cases, though the pixels are

E E M v i-i in 4 5 B U S E R C ft R ft C T E R 8 „ twice as wide modes and 6 as

60REM PE rER VOKE I 982 in mode or 3, The next byte 70 codes for the eight pixels 8 * * * * * % * * * % % % % % % % % % % % % % % % % % % % % x % % underneath the first eight, and so 90 on to the eighth byte, making an 1 2 O0MODE i MOVE , 1 023 VDU5 eight by eight matrix of pixels - the 1. 1 0VOU23 2515 224 , , , , , 255 , 255 , , 255 . first character on the screen. The 120VDU23j 225, 8, 255, . 233 , , ;'55 , @ . 3 «ifi ninth byte codes for the eight pixels 130A**STRING*< 18, CHR*< 224 ) > 1 40B**STR I NG*( 1 S , CHR*< 225 > : at the top of the next character 1 50 along (figure 1). This continues all 1 EOF OF 01 :>;=a TO 7 'FOR C2r<*0 Tn ? the way along the line, and onto the 170FOR T5i*l TO 4 next, to the bottom of the screen. ISOGCOLO, Civ i PRINT 0$ what has this to with i But do 1 90VDU 1 i 1 GCOLO , C23S PR J NT TflB B$ 200VDU11 'NEXT colour modes? Simply that the 2i0NEXT»fl*GET-NEKT same sequence of bytes in memory

220VDU4 i END is assigned to the same sequence

Program 5. Displays of small strips on the screen (as in all possible colour mixes (A and B) figure 1) in all modes. In modes 4

ACORN USER MAY 23 .

GRAPHICS

to 6 the strips are twice as wide as in modes to 3, while modes 3 and 4- 6 just put some space between Pixel Pixel 1 lines. However, in a colour mode Strip; co (ours Black Red Wh'rtc Yellow individual pixels within a strip are bigger. For instance, in mode 5 the i i i i pixels are twice as wide as in mode logical colour 4, so there are only four in the strip

instead ot eight. There are still eight bits in the byte memory, so each byte pixel has two bits - just enough to O O 1 1 O 1 1 ° code for four colours. The two bits ^54 for a pixel represent the colours in lO just the way you would expect: 00

for logical colour 0, 01 for logical Figure 2. Bit pair arrangement in byte colour 1, 10 for 2, and 11 for 3 (if you know your binary). The tricky part is the way these four pairs of bits are arranged in the byte. The

bits for pixel 1 are in positions 1 VvJW'ite. Ma^en-fa and 5, those for pixel 2 are in slrip; colours positions 2 and 6, 3 in 3 and 7, 4 in 4 and 8. Figure 2 may make it 1 T clearer. Pixel 1 is at the right end of om „ OlOl the strip, pixel 4 at the left. \oa\UK\ colour The orange effect was produced > by alternating red and yellow, )C1\

colours 1 and 2, within the strip. bN/+< > O 1 l 1 Merging 1, 2, 1, 2 as in figure 1 O oil S9 gives 90. Another way would be to - lo alternate 2.1,2.1, which gives 1 65. Figure 3. in 2 A less stripey. more checkerboard Merging m ode effect can be obtained by putting

90 in the first byte, 165 in the special effect; but making G bigger GCOL G.H is called (line 330) and second, 90 in the third, and so on. than 4, its normal maximum, PLOT85 is used to plot a strip of Model B owners will find the produces mixed colours which are mixture across the other colours.

above method works in mode 1, the same as the ones created by The 'underneath' colours show at although the resolution is finer as poking the screen memory directly the bottom of the screen. Since so

the strips are half the width. In - but does it much more quickly. In many of the mixtures are flashing,

mode 2 things are a little different mode 2 the mixtures are usually this is turned off using *FX9,0 in since each pixel has the possibility flashing. line 130. of being any one of 16 colours, and The parameter G can be given To get a particular mixture, note

needs four bits to code it. There are any value up to 255 before it starts the pure colour at the bottom of the only two pixels per strip, and the to repeat its actions. Values to 4 same column, and the figures G merging of binary numbers is are the usual ones {User Guide and H printed on the left. In the shown in figure 3. page 262), while 5 to 255 produce program where you want the By now you may have noticed mixtures. The effect not only mixture, first ensure the same pure the diagonal stripes mentioned depends on the values of G and H, colour is plotted in the area earlier moving across the mixed but on the colour plotted on top, concerned, using GCOL0,N and colours, rather like radio interference and the specific assignments of PLOT. Then do GCOL G.H using on a TV picture. This is due to actual to logical colours made by the values of G and H given by drifting of the horizontal sync, VDU19 commands. The best way of program 5, and replot over the causing the colours to wash across making use of this method is to same area with PLOT85 or 81 each other. have a program on hand that Model A owners should work in A faster method of producing shows all possible mixtures, and mode 5, and line 210 selects the these mixtures is provided by the gives the numbers G and H needed palette. Change this line for a Basic commands GCOL and PLOT. to produce them, hence program 5. different set of colours, but always GCOL is followed by two numbers, The program works in mode 2 use the same palette in any G and H. the first of which specifies for model B, or mode 5 for model A. program. the action' and the second the First the colours available in the Ten minutes spent playing with logical number of the colour to be mode are plotted in columns program 5 will convince anyone the plotted. Making H bigger than the across the screen. Then the values BBC micro has a cauldron of number of logical colours has no ol G and H are written on the left, colour effects hidden inside.

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26 ACORN USER MAY . !

HINTS & TIPS A POT POURRI OF ROUTINES Reader response has galvanised Beeb Guru

I his month we look at a number Joe Telford into I first assumed that the DFS was of hints which cover some library producing this month's hunting for a program on disk, but routines and FX calls. First, though, on noticing no drive lights, I a word of thanks to readers who wealth of ideas. realised that this couldn't be the have written in appreciation of my Procedures, discs, case. The speed of access between column. Acorn User readers are 'Searching ' and 'File not found' always willing to share their know- functions and recursion indicates that the micro is

ledge and expertise, so this month I are all dealt with in searching memory. As OS 1.0

number of their useful onward have the *ROM command, I include a simple terms giving ideas. They are all expanded upon, presume that the delete-shift-break so complaints to me please, not to some elegant results combination is trying to autoboot a

our helpful readers. program in ROM. I have View and Sergeant T M Murphy of Wordwise in my machine and delete too, but because it is an Blandford Camp, Dorset, suggests neither of these were run, so the invisible character and it cannot that disc system users who wish to *ROM filing system seems to deal delete past the beginning of the enter the cassette filing system on with Basic applications programs. line the screen display is left break need simply press delete- Who will produce the first uncluttered. Pressing delete-shift- break. In fact holding down any key applications chip? break produces the message:

while tapping break will let you Concluding, I notice that in all

enter the CFS from DFS. However, BBC Computer these cases page is not altered ie it that character is displayed after the Searching remains at &1900 for disc based break message, and because of File not found systems. Further information on the auto repeat the character is soon BASIC OS will be given in a future Hints multiplied. This happens with > and Tips. page 30

RELOCATING PROGRAMS WITH DISCS

Regular readers will be and so I offer program 1 and so the program proper is aware of different techniques This routine can be executed. This routine takes used by myself and that master spooled then added to any about three or four seconds to of machine code, Ian (Buzz- existing program. Running the relocate a program of 10k, bomb) Birnbaum, over the complete program on machines which seems reasonable. It problem of relocating large with page set at &E00 will was produced by the Micro- programs. If you have a result in no relocation. Page electronics Education Pro- machine with a DFS chip then set to any other value, ie for gramme when it was discovered the memory from &EOO to DFS or Econet, will result in a that some of the programs &ig

The solution is to relocate Line 32015 resets top and the chip. I am grateful to Bob them beginning at &EOO (&EOO program is then re-run. This Coates for permission to is page for V 0.1 OS). time, however, page is &E00 reproduce the coding. How we do this is the

problem. In January, I suggested i IF PR GE < > & £ 8 8 G0T03288S an approach in Basic using a 2 CLEhR: ?S£3-4 = 244 user defined key. I felt this was simple and being in Basic (is there a better language?) easy 3 .: Q S * T APE P = S T P 4 to understand. Ian followed up 3 2 8© 5 P I \ Q TO TOP -PAGE E PAGE:NE> T with a high-powered machine ^2Q:S 1% : &E08*I% code routine to go one better, 32815 ?&13=?&13-tPflGE-SE80 DIV 2b± that was that. However, and 32828 P ft G E = & E 8 8 : RUN driven by a couple of letters

from readers, I felt that the honour of Basic was at stake, Program 1. Relocation

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HINTS & TIPS

page 27

RECURSION, OR HOW TO GET A 10 X = 6

•-• 29 p p rj i j _ e c u r T @ PROCEDURE TO CALL ITSELF 49 DEFPR OC.recur BACK to procedures and of times the procedure can call 5 y s X + functions. Can a procedure or itself). There is a short delay when "0 p C T kj T X function call itself? The answer is the condition of line 65 is true, 1 I P R Q C _ r e c u r 'yes' and the process is called because the program has to B2 E N D P R C recursion. It is useful to know how •ENDPROC down 1930 levels of many times a function or procedure recursion to conclude the procedure. Program 2. Procedure recursion can call itself in a recursive loop. We can try the same technique Running program 2 shows how with a defined function. Look at

many times a procedure can call program 3 and run it to check on 10 X = ® itself. The maximum number of the number of times a function can 2 3 PRINTFN-^ecur times this can happen depends on call itself. As with procedures the 3 3 END how many procedures in maximum of recursive calls DEFFN_reeur are number 43 memory, each one reduces the depends on how many other 5 = number of times any particular functions coexist in the program.

•• £ o P R I N T procedure can call itself. Now add Adding line 65: --,. pRINTFN-recuT line 65: 65 IF X=930THEN =X o ra = ' 65 IF X=1930 THEN ENDPROC demonstrates visually the 'domino' This stops the recursion when X is effect of returning from the 930th Program 3. Function recursion 1930 (almost the maximum number recursive call. L Why use recursion? Well, let's consider the problem of finding the

factorial of a number. Figure 1 shows the calculations required for factorials. How can this be coded 10 F = i:^=-< T p in Basic for the BBC micro? The ' -i 20 FOR i = r TO 1 9 E problem is that the sequence = * 3 3 F F cannot easily be expressed as a + NEXT i formula and, therefore, the solution T 59 PRIN F to the problem may be more easily found by a repetitive algorithm. Program 4. Factorials from loops Program 4 is one possible solution. This is probably acceptable to most

users, though it requires variables and would need fitting into a 10 F=l c procedure for regular use. Some 2 P R I N T N ..factorial ( 5 would consider program 5 an 3 END improvement. It is about the same " - -• ar i al< n - D EFF _ - length as program 4 but includes r i a 1 ec r F = £ > n : = F - f a c t o t F H the function, already defined. It should be easy to follow, as the only complicated line is line 50 Factorials from recursion Program 5. which simply says:

'While the number you are at (n)

is more than 0, multiply F by it, an= calling the answer F, and reduce FoctoriQl Q ] CUlatriom the number by 1 then repeat this line with the new number you have reached.' * # 1 2 Perhaps not so simple? Anyway, the best way to become used to

recursion is to do it again and

again and . . Now that the number of disk users are increasing, we need to - - library r, ^ p-; n n £ » n ^ .. produce some routines, which will run as self-contained calculations Figure 1 . Factorial units in any program. I now offer some possibilities to start libraries

30 ACORN USER MAY HINTS & TIPS

8300 DEFPPOC_bocking'**> 3310 LOCAL i% 1,a ******* 8 3 2 C l 5 3100 DEFPROC-<** 1 3330 FOP j".= TO 2- 8110 LOCAL 2 '• J ' '**' CHR*15 ' t x m e K 1 .' 832 8 3 6 " D U 3 Q 314S ENDPROC 3 370 ENDPPOC Program 8. Delay procedure Program 6. Mode 7 background

8200 DEFPROC-SPOce 3210 PRINTTAB<7.2- I continue i 8220 PRINT'Press SPACE to ' <% . > , J ) P000 DEFPPOC_dblH<: 3230 *FX15> 1 - i BS10 FPINT T AB^ <-i,y) iCHR*l 1*1 REPEAT UNTIL GET=32 * 8240 ' + sCHR*C141 ' 3020 PRINTTAB* <-l,y D 32 50 ENDPPOC D g 330 E N P P C procedure Program g. Space bar move characters Program 7. Double-height

off. They need *SPOOLing to disc P."Hello Cheeky" Number = 12*8 so that they can be EXECed at a PROC dblht(STR$(Number),1 0,2) will destroy the background effect, later date. while will print 96 in double-height It a routine is to provide a value numbers at TAB(10,2). One value of needed in the main body of a P.TAB(2,0);"Hello Cheeky" such simple procedures as that program then that routine should would be invisible. Success is there is a saving on space within be defined as a function. If the the program. If users need double- routine is doing something which P.TAB(0,2);CHR$1 29"Hello Cheeky" height lines more than three times doesn't need a value returned, then which shows up as red lettering, in a program then the double- the routine may be defined as a unless you have selected a red height routine can save memory. In procedure. Generally speaking, a background. Note that this clumsy a long program, such a simple function can do anything which a CHR$129 can be avoided by routine could save hundreds of procedure can, though the reverse shifted function keys. For example, bytes. is not necessarily the case. in Program 8 is another short Look at program 6, which is a routine which does nothing for a procedure intended to clear a P.TAB(0,2);"rHello Cheeky" specified time. Calling the procedure: mode 7 screen to a required where the first 'r' indicates a background colour. The effect PROC delay(.5) character formed by pressing appears almost instantaneously, SHIFT-fl. will cause the program to hesitate and is very effective. Program 7 is a very simple during its execution by a half The procedure is called by a line procedure which prints double- second. Any time from 0.01 such as height characters at any point on seconds to millions of seconds PROC backing(CHR$130) the mode 7 screen. The information could be passed as a parameter, is passed in three parameters: though at 0.01 seconds the The CHR$130 can be reduced to procedure is inaccurate, because x$ - the string to print (which the key sequence (quotes SHIFT-f2 of the time taken in calling the might be prefixed by a quotes> on machines with OS 1.00 routine. As the delay required colour code); or later. The shifted function keys increases, so the accuracy x - the column position of the and related colours are given in the improves, and is acceptable for start of the string; User Guide on page 439. The basic normal delays, say 0.25 seconds y - the row position of the idea of the routine is to print the upwards. string. colour character transmitted as a Delays in a program are useful,

parameter (x$) down the left-hand A possible calling line might be: but it is often better to let a side of the screen. This is followed program progress at the rate of its PROC dblhf Hello Cheeky',1 4,1 2) by the teletext control character user, (this is particularly true with 157, which turns the background which would print a double-height children using programs, as they for that line to the colour preset by message centrally on the screen. need to think and re-read text).

x$. Remember that if you print on Looking at the routine, the x-1's Look at Program 9 which is any line after calling this procedure of lines 8010 and 8020 are there so called by the line: first positions in each that the x value transmitted is that the two PROC space row must not be overwritten or the actually the start of the string. This background for that line will vanish. is because the double-height on and prints the message "Press Note also that any text will need to character, CHR$141, is issued just SPACE to continue" in the centre of

be preceeded by a colour before the string. It is also possible the bottom line of the mode 7 character. For example, following to print double-height numbers by screen. The current buffer is the procedure call with converting them to strings: flushed by line 8230 but

ACORN USER MAY 31 i , " 1 5

HINTS & TIPS

experiment with *FX1 5,0 or *FX21 ,0.

Altering the program to run in any r © 5 U 1 t V a l u e mode is simply a matter of r jSj Q Sf sct 7 in changing the numbers and 24 "• - e line 8120 to centre text on the last - - -. - : r e r : : _ w e line of the screen. " £ : ~ of r o t * -j s r . e 1 1 Remembering the comments Capitalises i parameter about functions being used to Figure 2. Results of 'effect' return a value to the program, one useful library routine which could A possible calling line would be: are accepted, though it is be coded as a function is the possible to delete back through general purpose input routine month=FN gpi(2,2,"01 23456789") the string. (GPIR) of program 10. The MEP which says get a two-digit number • Problems associated with the project maintains that a GPIR is a from the digits available in quotes input command are automatically concept rather than a particular and place it into the variable overcome. routine, and so the version 'month'. • End of text entry field is presented is only one realisation. The benefits of the routine are: signalled by sound, as are Users should provide their own unacceptable characters. versions. • It operates at any point on the • The range of valid characters Rather than explore this function screen (you must tab to the can be set on entry to the line by line, I will describe how to required position first). routine. use it, and what features are • Only the number of characters • Special effects are featured to available. set by the first parameter (len) control input, using the effect parameter. Let's examine each parameter in turn. First len'. This value tells the ON ERROR GOTO 90 10 function how many characters are 20 MODE* allowed in the text entry field. Each 30 rem mm I r; PROGRAM possible character is marked by a *£> REPEAT 58 dot, over which characters may be S* 60 INPUT LINE'Procedure i typed. The dots re-appear on + 0$ 70 UNTIL NOT E'JAl < "FN._ deleting. Any attempt to enter more 30: than the number of characters set -, 29 THEN MODE g ip £ p R by len is ignored, though there is a "

-• at ";ERL:ENE REPORT PRINT short beep. Exit from the GPIR is 10 0- only after pressing return. g PR I NT M So rr procedure i The next parameter is 'effect'. ; " doesn' fc » j q $ This may be a value from to 3

inclusive. It alters each character 130 IF FM.re a a ., THEN 3D 1-0 END as it is typed at the keyboard using 15 figure 2. - He b i From 160 p E M define P r o C The last parameter is 'valid$', a DEFFN-SQUARE page 72* 196 MOVE 2 2-200

200 i id* 200 DRAW 4®@. 9Q00 DEFFN.gPi len, effect vol 210 DRA W 400 9 1 9 L :• 2 A L o * - b "> ? i7; " DRAW 200 '' - Q 2 oi = : " !• 200 " ' A « P ' 230 D W 9030 PPINT3TPI NC*

• DRAW 300-300 ; : GOTO9040 PRINTCHRtbi " ; CHR* C8) DRAW 200.200 300 9 7 IF effect=0 THEN9103 3 1 = F N _ r e a d y r b = b A N D ELSE 9083 : effect*! 33 DEFFN-0BL0NG b = b F: 3 2 = 3^0 MOVE 200 • 2O0 - = $ ( * ' 9090 IF e f f e c 3 A N D ( R I GH T o 1 300- 2 00 " 3 50 DRAW " P :< i = b=b AND 223 360 DRAW 800: 50 r OR 9100 : l.EN«.o*)=ler DRAW 200 500 GOT'! 9040 370 I =0 V0U7: IN^TP ' VOl id* CHR$b DRAW 200 200 380 9U0 PRINTCHR*b; : o*=a*+CHR*b: GGTO9040 +00 DEFFN.'-eodv GPIR 410 PRINT"5PACE continues Possible any other exits" 420 =GET=32

PROC calls . Elegant Program 1 1 1 32 ACORN USER MAY BBCBBCBBCBBCBBCBBCBBCBBCBBCBBCBBCBBCBBCBBCBBCBBC

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Newnes Book of Personal Computing Edited by Philip Chapman Written by a team of well known specialists A non-technical introduction for the layman * Well illustrated

Whether you are interested in personal computing for education, business or hobby- or whether you simply want to know what all the fuss is about!— Newnes Book of Personal Computing will lead you gently through the micro minefield. The book has been specially written for those with no previous technical knowledge and aims to introduce you to the fascinating world of personal computing in a readable and friendly way. Contents: Personal computer hardware, programming, The World of Personal Computing . Henry Budgett

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ACORN USER MAY 33 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* and the guarantee will start from that date.

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34 ACORN USER MAY i

MUSIC THE BEEB COMPOSES Jim McGregor and Alan Watt explain Mlusic has been called a computer generate a rhythmic compromise between chaos and how to compose any structure that is similar to that of a monotony. Program 1 provides an simple folk tune. style of music using example of chaos and program 2 In music, rhythm is concerned three examples of well-organised a BBC micro. with the grouping of notes into monotony. For a computer to beats, of beats into bars, bars into compose interesting music, there Their programs phrases and so on. In the Oxford must be some degree of each analyse style and Companion to Music, the entry involved, and it must satisfy certain under 'phrase' states that any rules that make it recognisable. generate rhythm simple four line hymn or folk tune Random is not music necessarily structures and pitch falls clearly into two halves or unpleasant, particularly if the 'sentences'. Each sentence falls texture of the music is controlled. values from the into two phrases and each phrase Program 3 illustrates this point and results normally consists of four bars plays music selecting two random (although this is sometimes varied). numbers to drive the pitch and single envelope statement. In this We shall use this simple model for duration in a sound statement. case, we could have used two our first attempts at automatic Superimposed on this basic envelope statements with different composition. method are three effects: parameters and selected, but the To a computer scientist or setting and resetting of envelope linguist, the above description • an echo (two sound statements parameters (PROCpitchset and suggests the use of a 'generative referencing separate envelopes); PROCpitchreset) is the structure grammar' to describe the structure • a glissando or slide (de rigueur required for dynamically changing of a piece of music. Such grammars in arcade games) at pseudo- envelope parameters and back are used extensively by computer random instants; again in a playing loop. scientists to describe the structure • pitch distortion at pseudo- Rhythm is a very important of programming languages. In this random instants. component of all music. Indeed in case we might start with the rule: The net effect is not uninteresting. some primitive cultures, music TUNE ::= SENTENCE SENTENCE The pitch distortion is inserted by consists of rhythm and very little

changing the parameters in a else. We examine ways of making a which we read as 'a tune consists

10 ENVELOPE 1,1, 0,0,0,0,0,0, ENVELOPE 1,1, 0,0,0,0,0,0, '26,-4,0,-63,126'l00 20 ENVELOPE 1 ?6, -4, 0,0, 126, 100 2,1, 0,0,0,0,0,0, ENVELOPE 63,10,0,-63,63,110 2,1, 0,0,0,0,0,0, 30 ENVELOPE 3,1, 65,-4,0,0,63,50 0,0,0,0,0,0, 30 prevnote = 1 *6, -8, 0,-10, 126^50 40 FOR = 40 FOR note=1 I 1 TO 100 TO RN0C100) 50 50 channel note = RNDC255) = RND(3) 60 60 envelope = RNDC3) 70 70 Pitch = RN0(256)-1 80 SOUND 80 durat ion=RND(32) 1,1, note, RNDC8) 90 SOUND 90 SOUND channel, 1,2, note, RNDC8) envelope^ itch,dur at 100 prevnote 100 NEXT note = note 110 PROCpitchreset 120 NEXT Program 1. Chaos 130 END

DEFPR0Cslide(old,new) ENVELOPE 1,1, 0,0,0,0,0,0, IF old>neu THEN step = -1 - 126,-4,0,-63,126'lOu ELSE stenP 1 20 SOUND 81001,0,0,0 ~ ENVELOPE 2,1, 0,0,0,0,0,0, = old TO new ",10,0,-63, 63,110 STEP step 30 SOUND 81001,0,0,0 ENVELOPE 3,1, 0,0,0,0,0,0, SOUND 811,1, i, 126 '" 8 '°'" 10 12 2 40 FOR ' 6/50 PROCpitchreset note = 1 TO 20 NEXT 50 SOUND 1,1,53,8 60 NEXT note ENDPROC 70 key=GET 230 DEFPROCpitchset 80 FOR pitch=53 TO 101 STEP 4 240 = 90 pil , 6:Di2 = _ 16: a SOUND 1,1, pitch, 8 ^ "0 pnl = 2: = . 100 NEXT pitch pn2 4 Dn3 . 2 110 key=GET ENVELOPE 1,1, Pn,pi2,pi3,pn1,pn2,pn3, 120 FOR phrase = 1 1 TO „„„,,, 2°,-4,0,0,126,100 130 SOUND 1,1,53,8 140 SOUND 1,1,69,8 280 DEF 150 SOUND 1,1,81,8 PROCpitchreset 2°0 160 SOUND 1,1,101,8 ENVELOPE 1,1, 0,0,0,0,0,0, 170 NEXT phrase 126,-4,0,0,126,100

Program 2. Monotony Program 3. Random stroll

ACORN USER MAY 35 e g I

MUSIC

10 ENVELOPE 1,1, 0,0,0,0,0,0, 400 IF beatsleft=0 126,-8,0,-63,126,50 THEN PROCsubdi vi degrcup Cminf i ni sh) 20 ENVELOPE 2,1, 0,0,0,0,0,0, PROCsubdi v ideg roup (mi 410 FOR nnt B -1 rn nnot e) 100,-8,0,-80,100,50 T ° next 9roup DIV duration 420 PROCplaynoteLar f 100 INPUT "Beats per bar",t imes i 430 110 INPUT "Minimum NEXT note note",m i nnot 120 PROCtune 440 UNTIL beatsleft=0 450 130 END ENDPROC 460 200 DEF PROCtune DEF PROCselectgroup 470 210 PROCsentence LOCAL g,timeleft 480 220 PROCsentence timeleft=beatsleft*8 490 IF 230 ENDPROC beatsleft=1 OR t ime lef t=mi nf i ni sh THEN 500 eatsleft=o:ENDpRoc 240 DEF PROCsentence REPEi;:^: D e::;ri;o 510 250 PROCphrase 520 260 PROCphrase 530 270 ENDPROC beat s lef t=beats lef t-q 540 ENDPROC 280 DEF PROCphrase 550 DEF 290 LOCAL bar PROCsubdividegroup(mindur) 560 300 FOR bar=1 TO IF nextgroup=mindur OR 3 nextgroup MOD mindurOO THEN 310 PROCbar(minnote) duration=nextgroup:ENDPROC 570 320 NEXT bar REPEAT 330 PR0CbarC16) 580 duration=2RND(5) 590 340 ENDPROC UNTIL nextgroup MOD duration=0 600 ENDPROC AND duration>=mindur 350 DEF PROCbar(minf inish) 610 DEF PROCplaynote 360 620 envelope = 1 pitch=53 370 beatslef 630 SOUND t=timesig 1, envelope, pitch, duration 380 REPEAT 640 envelope=2 390 PROCselectgroup 650 ENDPROC Program 4. Syntax generated hythi

of a sentence followed by another piece of music from the grammar. PROCbar(16) sentence'. We could then go on to In program 4, the rule defining a ENDPROC define tune has been transcribed directly Corresponds to rule into a procedure that generates a SENTENCE ::= PHRASE PHRASE PHRASE ::= BAR1 BAR1 BAR1 tune. PHRASE ::= BAR BAR BAR BAR BAR2 DEF PROCtune or we might decide that the last bar The PROCsentence parameter indicates the of a phrase should have a different minimum duration for PROCsentence permitted the structure from the other bars. Thus ENDPROC final note of the bar and we have PHRASE. := BAR1 BAR1 BAR1 BAR2 created the last bar of a phrase (a Corresponds to rule BAR2) by supplying a different where will a BAR2 have a different parameter. 16. This indicates that definition from a BAR1. Rules like TUNE ::=SENTENCE SENTENCE the bar generated by this call these are usually referred to as should have a final note of duration 'rewrite rules'. PROCsentence is similarly. defined at least 16 time units, ie a minim. (A A more These complicated example of two procedures could have semibrieve has duration 32, a musical a grammar might start off been combined into one, a tune minim 16, a crotchet 8 and so on - with defined being as four phrases, but it see April's Acorn User). Forcing a is always advisable to maintain a phrase to end with a longish note PIECE :: = SONATA RONDO procedure structure that reflects the FUGUE gives an impression of rounding off structuer of the process being the phrase. The first three bars of a The sign is T read as 'or'. The modelled. We may decide later that phrase are allowed to terminate rewrite rule states that a piece is the first sentence in a tune should with the shortest permitted note either have a sonata or a rondo or a a slightly different structure than available for the tune being fugue. The definition the second. Defining a tune in terms might composed. This value is called continue with of sentences and a sentence in 'minnote' and is input to program 4 terms of phrases will make it easier SONATA ::= EXPOSITION as a parameter. The value input to incorporate changes like this. DEVELOPMENT determines the overall 'tempo' of RECAPITULATION PROCphrase is defined in a the piece. similar way. It makes three identical The 'grammar' of a bar will Simple rewrite rules provide a calls of PROCbar and then a fourth depend on the number of beats in concise notation for describing the call of PROCbar to generate the a bar (another input parameter). For structure of language or music, but last bar of the phrase. The type of example, in 2/4 time, we could have they have many limitations and the bar to be generated has been BAR1 system has to be 'augmented' for indicated by a parameter. ::=CROTCHETGROUP more advanced applications. CROTCHETGROUP MINIMGROUP Returning to our simple folk-tune DEF PROCphrase example, the structure of the rules LOCAL bar A bar can be a group of notes constituting trYe grammar can be FOR bar=1 TO 3 equivalent to a crotchet followed by directly reflected in the structure of PROCbar(minnote) another crotchet group, or a bar a Basic program that generates a NEXT bar can consist of a group of notes

36 ACORN USER MAY MUSIC

equivalent 10 a minim, we snan noi allow note groupings to cut across TUNE ::= SENTENCE SENTENCE the 'beat' structure of the bar. We SENTENCE ::= PHRASE PHRASE could define PHRASE ::= BAR1 8AR1 BAR1 BAR2

BAR1 ::= CROTCHETGROUP CROTCHETGROUP | MINIMGROUP CROTCHETGROUP ::=

I CROTCHETGROUP ::= I JlJJlfi73 J J~J J J J J assuming a semiquaver as the mini MG roup ..'-jijjinn^mi rm minimum permitted note (duration BAR2 ::= J = 2). For convenience, we insist that notes in a group all have the phrase same duration. We do not permit

CROTCHETGROUP ::= J73

A minim group is defined as MINIMGROUP::= BA«- 1 BAK- 1 6AK 2.

Recall that we require a phrase to M|rVlM*0Up MlrVIMO^OUP terminate with at least a minim. With two beats to the bar, this means BAR2 ::= J nn n rm jj j The complete grammar for 2/4 time

is listed in figure 1. The whole process of generating a sequence Figure 1 . Grammar for 2/4 rhythm and part of sample once generated of symbols (in this case notes of a certain duration) using rewrite rules can be viewed as a tree structure.

Using choice where choice is ma j or 53, 61, 69, 73, 81, 89, 97, 101 available we could generate the diminished 53, 57, 65, 69, 77, 81, 89, 93, 101 tree shown in figure 1. This blues 53, 65, 73, 77, 81, 93, 101

particular tree is just one of a large M i ndu 53, 61, 69, 73, 81, 85, 93, 101 number that could be generated whole tone 53, 61, 69, 77, 85, 93, 101 from the rewrite rules. BAR1 and dorian minor 53, 61, 65, 73, 81, 89, 93, 101

BAR2 would be defined slightly aeo I i an minor 53, 61, 65, 73, 81, 85, 93, 101 differently if we had three or four (or harmoni c mi nor 53, 61, 65, 73, 81, 85, 97, 101 more) beats to the bar. The pentatoni c 53, 61, 69, 81, 89, 101 definitions of BAR1 and BAR2 are major arpeggio 53, 69, 81, 101 implemented in a fairly ad hoc fashion in PROCbar in program 4. Table 1. Sea es with sample pitch codes The procedure repeatedly chooses a group consisting of a structure is usually fairly evident. in this case a major arpeggio. random number of whole notes less We now turn our attention to the One further addition has been than or equal to the number of pitch of the notes played in the made to this program. A new beats left to be played, subject to tune. parameter is passed to each of the constraint imposed by the A particular piece of music (or at PROCsentence, PROCphrase and

'minimum last note' parameter. least a section of a piece of music) PROCbar to indicate whether it is Each group chosen is then split is usually confined to notes taken the final example of that con- into an equal number of notes from a set of notes that are closely struction in the tune. This enables whose duration divides into the related to each other in some way. the program to recognise the last group chosen and whose duration The set of notes, or 'scale', used note and constrain it to fall on the is less than or equal to the contributes in a large way to the keynote of the scale. minimum permitted duration. The character of the music. Table 1 Try running the program with notes of the group are then played gives some scales and arpeggios notes taken from the major (all on middle C). together with sample sequences of arpeggio and you will obtain a

One further enhancement that pitch codes based on middle C. We moderately pleasing if rather assists the listeners' perception of can easily alter our rhythm on monotonous effect. Then try some rhythm is to use a slightly louder middle C program so that it selects of the other scales listed above. envelope for the first note of a bar random notes from a particular We shall now use notes taken than that used for the remaining scale. Program 5 indicates the from the scale of C major extended notes of the bar. modifications needed to do this. downwards by three notes to lower Listen to some of the output from The data statement at line 80 G and up one note to upper D. program 4 and you will find that the defines the number of notes and Once the set of notes (the key) 'sentence', phrase, bar and beat the pitch values for the scale used, on which a tune will be played has

ACORN USER MAY 37 )

MUSIC

JL -O- O 3Dl ^ xy ^ Q XT ^- Extended 5c^j(e of C rr\

10 ENVELOPE 1,1, 0,0,0,0,0,0, 290 LOCAL bar 126,-4,0,-63,126,100 300 FOR bar=1 20 ENVELOPE 2,1, TO 3 0,0,0,0,0,0, 310 PROCbarCmin 100,-4,0,-80,100,80 note, FALSE) 320 NEXT bar 330 30 READ scalelength PR0Cbar(16,f inalph) 340 40 DIM scalenote(scalelength) EN0PR0C 50 FOR n=1 TO scalelength 350 DEF 60 READ scalenote(n) PROCbarCminf inish,f inalbar) 360 70 NEXT envelope = 1 370 80 DATA 4, 52,69,81,101 beatsleft=timesig 380 REPEAT 390 90 keynote=scalenote(1) PROCselectgroup 400 100 INPUT "Beats per IF beatsleft=0 THEN PROCsubdi bar",timesig videgroup(minf in i sh 110 INPUT "Minimum ELSE PR0Csubd1vi note",minnote 410 FOR „„.-i ™ degroup(minnote) 120 PROCtune note-1 TO nextgroup DIV duration 130 END 420 PROCplaynoteCnote=nextgroup DIV duration AND beatsleft=0 AND finalbar) 200 DEF PROCtune 430 NEXT note 210 PROCsentence(FALSE) 440 UNTIL beatsleft=0 450 220 PROCsentence(TRUE) ENDPROC 230 ENDPR0C

240 DEF PROCsent-nce(finalsent) 610 250 PROCphrase(FALSE) DEF PROCplaynote(finalnote) 620 IF finalnote 260 PR0Cphrase(f inalsent) THEN pi t ch=keynote P ' tCh = S 270 ENDPR0C :alen0te) 630 ^m,L 1 ! SOUND 1, envelope, pitch, duration 640 280 DEF PROCphraseCfinalph) envelope=2 650 ENDPROC Program 5. Rhythm with random notes from a scale

been determined, there are a well-known tunes taken from a random note from the scale, but the

number of further constraints that child's recorder tutor (Baa Black basic technique used is easily

can be applied to make a tune Sheep, Bobby Shaftoe, etc). If we extended. mimic a particular style as certain imagine all these tunes being First set up an array containing notes and combinations of notes played in C major, on the 12 notes the percentages in table 2. In order will be more common than others. from lower G to upper D, then the to select a note, we generate a One way of making our program figures in table 2 give, as per- random number in the range to select pitch values more system- centages, the relative frequency of 100 and add up values from the atically is to make it use probability occurrence of each note over the array until the total exceeds the distributions when selecting the nine tunes analysed. (These were random number generated (see

pitch of a note to be played. The produced by program 9.) figure 2). The number of per- simplest (and least satisfactory) We now generate a note so that centages added determines the

type of distribution that can be the probability of getting a note from the scale that is selected.

used is the first order probability particular note matches its entry in This approach is implemented in distribution. table 2. The tunes generated by program 6. Table 2 shows the result of a doing this will not be much better Note sequences are much more 'first order analysis' of nine simple than those obtained by choosing a important in composing melodies,

and if we want to constrain the note gabcdEFG c D sequences that are chosen by our 3.4 0.7 3.4 15.0 12.6 13.8 8.5 14.3 i.O 11.1 6.3 2.9 program, then consider higher order probabilities. Table 2. First order note probabilities The use of second order probability distributions makes the

a b c d E F g G A B C D . choice of a note dependent on the preceding note. 9 42.9 0.0 0.0 28.6 14.3 7.1 0.0 7.1 0.0 0.0 0.0 0.0 a 0.0 0.0 66.7 0.0 33.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Table 3 shows second order b 21.4 0.0 7.1 50.0 21.4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 distributions resulting from analysis c 0.0 0.0 12.7 40.0 14.5 18.2 10.9 3.6 0.0 0.0 0.0 0.0 d 7.7 0.0 7.7 26.9 28.8 13.5 9.6 5.8 0.0 0.0 0.0 0.0 of our nine simple tunes. One row E 0.0 3.5 0.0 17.5 26.3 21.1 14.0 17.5 0.0 0.0 0.0 0.0 in this table corresponds to one of F 0.0 2.9 0.0 0.0 20.0 45.7 8.6 22.9 0.0 0.0 0.0 0.0 G 0.0 0.0 0.0 3.5 1.8 15.8 21.1 22.8 31.6 0.0 1.8 1.8 our notes and the entries in a row A 0.0 0.0 0.0 0.0 0.0 0.0 3.0 24.2 18.2 48.5 0.0 6.1 give the percentage of occasions 8 0.0 0.0 0.0 0.0 0.0 0.0 0.0 13.0 13.0 43.5 23.9 6.5 C 0.0 0.0 0.0 0.0 0.0 3.8 0.0 3.8 3.8 30.8 42.3 15.4 on which each of the other notes D 0.0 0.0 0.0 0.0 0.0 0.0 0.0 33.3 16.7 8.3 25.0 16.7 followed the note to which the row corresponds. For example, row one Table 3. Second orde r prot abilit es indicates that lower G is followed

38 ACORN USER MAY t e

MUSIC

10 ENVELOPE 1,1, 0,0,0,0,0,0, 630 SOUND 1, envelope, pitch, duration 126,-4,0,-63,126,100 640 20 ENVELOPE notesplayed=notesplayed+1 2,1, 0,0,0,0,0,0, 650 envelope=2 100,-4,0,-80,100,80 660 ENDPROC 30 READ scalelengtli 670 DEF 40 DIM PROCsetupf reqtablel scalenote(scalelength) 680 LOCAL 50 FOR n=1 TO scalelength lb1,l,n,fileno 690 DIM 60 READ scalenote(n) freq1(12) 700 70 NEXT FOR n=1 TO 12 710 80 DATA READ freqICn) 12, 33,41,49,53,61,69,73,81,89,97,101,109 720 90 keynote=scalenote(4) NEXT n 730 ENDPROC 100 PROCsetupf reqtablel 740 DEF PROCselectpitchl 110 INPUT "Beats per bar",timesig 120 750 LOCAL rand, n, sum INPUT "Minimum no t e",m i nnot 760 rand=RND(1)*100 130 notespl ayed=0 770 140 PROCtune n=0 : sum=0 150 END 780 REPEAT 790 n = n+1 :sum=sum+f reql (n) 800 UNTIL sum>=rand 810 pi tch=scalenote(n) 820 610 DEF PROCplaynoteCfinalnote) lastnoteplayed=n 830 620 IF ENDPROC finalnote THEN pi ch=keynot e ELSE PROCselectpitchl 10010 DATA 3.4,0.7,3.4,15.0,12.6,13.8,8.5,14.3,8.0,11.1,6.5,2.9 Program 6. First order tunes by another lower G on 42.9 per cent of occasions by middle C on (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) 28.6 per cent of occasions by D freq 1 3.4 0.7 3.4 15.0 126 13.8 8.5 14.3 8.0 next to middle C on 14.3 per cent 11.1 6.3 2.9 of occasions, by E on 7.1 per cent of occasions and by upper G on rand=RND(1)*100 Say, for example, rand=43.5.Then the first six values in freql 7.1 per cent of occasions. added before we obtain a total that exceeds 43.5. This means that play the sixth note in the scale. The modifications to the we previous program needed to scalenole(6) generate notes according to the Figure 2. Selecting a note by probability distribution second order probability distributions are presented in program 7. The Sheep). The string at the start of the from two jazz blues scales (Bb and first note of the tune is generated data for a tune establishes the Eb, data statement 670). It uses a using the previous one, and from range of notes for the tune starting rhythmic chordal accompaniment then on, a note is generated three notes below the keynote. and the three voices are according to the probabilities in the There then follow the names of the synchronised using the technique row of table 3 that corresponds to notes in the tune in the order in in April's Acorn User, where we the previous note played. Using which they appear. The program described how PROCinitialise, this method eliminates the occasional prints the tables in the form of data PROCharmonise and PROCsound violent leaps in pitch that occurred statements numbered from 10000 work. Voices two and three are with the previous version of the upwards that can be absorbed into loaded up into rows two and three of program. The entries in table 3 another program. To do this, type the three row pitch and duration arrays, and a simple blues chord associated with such violent leaps *SPOOL"freqtables" progression is are mostly 0. RUN taken from data statements 560 to 590. PROCjazz The use of second order *SPOOL probability thus encourages the initialises row one of this array by program to use commonly accept- and the data statements for the randomly selecting starting notes able pitch intervals between tables will be stored on cassette. for a phrase from the appropriate consecutive notes. These can be added to any scale. The rhythm for a phrase is typing randomly selected from data If we want the program to use program by *EXEC "freqtables". commonly-used sequences of If you want to analyse music that statements (1 091 onwards). notes, we can move on to third includes accidentals, then you will The creative part of the program order distributions where the have to invent your own could be significantly improved: probability of choosing a note will nomenclature for the notes involved depend on the two previous notes and extend the program accordingly • The intervals used in the phrases played. This makes a marked You can make music more like the are all major or minor seconds improvement to the sequences original by using higher probability and could be varied. generated. We leave you to think orders, but as it becomes more like • Rests or gaps of silence should about the details. the target style it becomes less be introduced as space is very original. important in music. In case you want to analyse your Finally we return to letting the • Fast note phrases used con- own favourite type of music, we computer do its own thing and get secutively should b e followed present program 8 which was used it to play some 12 bar blues. by a long note. to generate the distributions of Program 9 plays or improvises on • Repetition of a phrase should be tables 2 and 3 together with the 12 bar blues. It does not use occasionally introduced. data for one tune (Baa Baa Black probability tables but selects notes

ACORN USER MAY 39 MUSIC

100 PROCsetupfrcqtablel 910 101 PR0Csetupfreqtable2 ENDPROC 920 DEF PR0Cselectpitch2 950 LOCAL rand, n, sum 940 610 DEF PROCplaynoteCfinalnote) rand=RND(1)»10Q 950 n=0 620 IF Hnatnote THEN : s„m = pi tch=keynote 960 REPEAT EL5E IF notesplayed=0 THEN PROCsel ectpi t chl 970 n=n + 1 : sum=sum*f req2< ELSE las tnoteplayed.nl PR0CselectpitcH2 980 UNTIL sum>=rand 990 pitch=scalenote

DIM freq1<12), freq2<12,12> freq3<12.12 12) 440 DEF INPUT "Number of tunes", PR0Cstandardisetable2 noof tunes 450 FOR tune=1 TO nooftunes LOCAL l,n PROCanalysetunc 460 FOR 1=1 TO 12 NEXT tune 470 total=0 480 FOR n=1 TO 12 490 60 PROCstandardisetablel total=total+f req2(l, n ) 70 PR0Cstandardisetable2 500 NEXT n 510 IF total>0 THEN

90 PROCoutputtablel FOR n = 1 TO 12:freq2(l, n ) = f reQ 2U,n)»10n/total: 100 PR0Coutputtabte2 NEXT n

520 NEXT I 530 ENDPROC

660 130 DEF PROCanalysetune DEF PROCoutputtablel 670 LOCAL 140 LOCAL scaleS,lastbut1S,lastS,n n ; IF n<12 THEN PRINT 720 NEXT n 190 'req1Uastbut1) freq1 = Clastbut1)*1 750 PRINT 200 freql(last)=freq1 (I ast)»1 210 740 ENDPROC freq2(lastbut1,last) = freq2(lastl.ut1,last)* 220 REPEAT 750 DEF 250 next=INSTftCsealeS,next$l PR0Coutputtable2 760 LOCAL 240 IF n»Xt=0 THEN l,n,lineno PRINT "Error in DATA "-tui ';scaleS; 770 250 freql (next)=freq1 lineno=20010 (next)-H 780 FOR 260 freq2( last, 1=1 TO 12 next>=freq2< last, next >»1 790 270 freqS; :IF n<12 THEN 840 NEXT n 850 PRINT 550 DEF PROCstandardisetablel 860 540 LOCAL n, total I ineno=l ineno»10 870 550 total=0 NEXT I 880 ENDPROC 560 FOR n»1 TO 12 total=total*freq1 Cn) 580 NEXT n 1120 DATA gabcdEFGABC, »,c,8,G,*,8,C,A,S,F,F,E,e,d,d,c / 6,G e, 390 FOR n=1 F, F, # TO 12 F, E, E, - .' E, d, G, G, G,F,G, A, F,E,d, d , . 400 freql

10 ENVELOPE 1,1,0,0,0,0,0,0,65,10,0,-65 65 126 EL ° PE ^'O'O'O^O ° 1",-4,6,-l6o ,26 100 770 ,0 CT DEF PROCplaybars(n, keyS) 780 FOR bar = 1 TO 40 Ch<3 200) n "" D '! ' ' dura t>onC3,200),noofnotes(5),r 790 50 «tnote(5),clock<3) FOR phrase = 1 TO 2 800 60 PROCinit PROCselectstartnote ialise<2) 810 70 PR0Cinitialise(5) PROCselectupdown 820 80 PROCjazz PROCselectphrase 830 90 PR0Charmonise(5) PROCplayphrasetkeyS) 100 END 840 NEXT phrase 850 NEXT bar 860 ENDPROC 110 DEF PROCinitialise(voice) *** Defined last month **•* 870 300 ENDPROC DEF PROCselectstartnote 880 startnote = RNDC15) 890 ENDPROC 310 DEF PROCharmoniseCnoofvoict ** Defined last «»* month 900 460 ENDPROC DEF PROCselectphrase 910 sphrase=RNDC6> 470 DEF 920 restoreto = 1090 tsphrase PROCsound(yoice,sync> 930 *• Defined RESTORE restoreto last month *** 940 550 ENDPROC ENDPROC 950 560 DATA DEF PROCplayphraseCkevS) 24, A«,h,Atf ,dq,A*,e,R,w A# e A« e B n «« a Q >« '/R,w 960 READ noofnotes 570 DATA C-»,h,C^,dq,c'«,e,R,; 5.:- ^ h a2 dq ; J ^,k,w,ue 2; a, 970 note = A*,h,A»,dq,A#,e,A#,w i,C*»,w, startnote 980 FOR i = 1 TO 580 DATA D ' ' • noofnotes 24, ,h,D ,dq,D ' • • ,e,R.w e D e R n n h *. 990 READ 590 0ATA k "» e,R,w length ;, '*£&£*"£*%£*' 1000 ii ?tf*?''£"> ,h,D',dq, 11 = ii 1: durationC1,ii) = length 1010 IF keyS = "Eb" THEN P 1tqhC1,H) = EbCnote) 600 DEF PROCjazz ELSE pitch(1,ii) = 1020 Bb(note) 620 DIM Bb(15), note=note* updown Eb(15) 1030 IFnote > 13 OR note < 1 630 i i = THEN note=7 1040 NEXT i 640 FOR note=1 TO 15 1050 ENDPROC 650 READ Bb(note) 660 NEXT note 670 1060 DEF PROCselectupdown 45 ' 5 65 ' 69 7? "" !' ' ' 85 ' 9, ' 105 11 680 ' ^117,121,155,141 1070 IF RND(2) = 2 THEN uodown= -1

690 Eb(note) ELSE updown= 1 = BbCnote) 20 1080 700 NEXT note ENDPROC 7in PROCplaytheblues 1091 DATA 3,2,2,2,2,2,2,?,? 715 noofnotes(1)=i i 1092 720 ENDPROC DATA 4,4,4,4,4 1095 DATA 2,8,8 1094 DATA 1,16 750 DEF PROCplaytheblues 1095 DATA 740 PR0Cplaybars(4,"8b") 4,2,6,2,6 1096 DATA 745 PR0Cplaybars(2,"Eb") 11,1,2,1,2,1,2,1,3,1,?,, 750 PR0Cplaybars(6,"Bb") 760 ENDPROC Program g. Micro Blues

40 ACORN USER MAY q

Windsor Computer

wcc COntrG BULKREED LTD.

BERKSHIRE'S LEADING BBC DEALER

PHONE WINDSOR 58077

FOR ALL YOUR BBC

REQUIREMENTS

1 THAMES AVENUE, WINDSOR, BERKS

ACORN USER MAY 41 1 1

BEEB FORUM

IAN BIRNBAUM sets out to improve your programming techniques on the BBC BUG STUMPS CASSETTE micro. He will answer reader's questions in this column and Paul Knight writes from Devon: In There is clearly data on tape but develop their ideas - as well the time I have owned a BBC I cannot extract it. This must be a as giving some of his own. model B, writing programs and common beginner's problem. Can But the real aim is for readers recording them on cassette has you help? to provide the questions and the answers. produced no difficulties. However, having developed one particular From the description, I suspect At least £5 will be paid for the program is not loading at all! any tip published, with £10 program over 100 hours, I fear it is Let me explain. for those which merit a one- lost. a star award and £20 for real Having loaded the program from When you load program humdingers! cassette, and made some amend- from tape, the operating system The idea must be original will search for block zero of the ments I tried to save the new and be described clearly file with and program over the top of the old - a the appropriate name. fully. It should not have been Thus, if the program is called mistake I shall not repeat. The new published before. program, longer than the previous, PROG, you should get on the Your contribution should screen: be typed or printed, with any appeared to save correctly and as substantial listings on a check the tape was rewound. Searching cassette, but only included to *CAT indicated all was well, and the Loading make a point. numbers following the file-name PROG 00 etc Send your hints or were 29 2973. and the program will load. questions to Forum, BBC When it next load came to the However, if block zero is Acorn User, 53 Bedford program, everything seemed to go missing, Square, London WC1 B 3DZ. you will get: well, but although the block Please include a self- Searching numbers 29 2973 appeared, the addressed if envelope your PROG 01 etc tape was not turned off, The noise contribution is to be returned. We cannot answer from the earpiece during loading and the program will not load! letters individually, but a sounds normal, but LIST produces The clue is the omission of the cross-section of common and nothing after Escape, Other frantic word 'loading' (as well as there interesting points will be attempts yield at best 'bad being no block 00). covered. program'. This is a common problem

*0PT'.

Listing 1 . >*0PT1, 1 > CL0I OPENING") i REP. U. BB£T#l«13i ?PA0E-13i ISfOi REP. : sU.E0F#(l) sCI DBE#ls *0PT2. I7.=r/.+ l 1 7.?P ABE=B6ET#1

10F0RI7.=0 TO 3 step; 20P7.=&C00 310.L00P2

30 1 OPT 1 7. 320J SR INCRE 40LDA &1D 330 INC &74 \ INCREMENT COUNTER 50STA &71 340LDA (&70),Y 60LDA #0 350CMP #&0D \ START ADDRESS IS PAGE 70STA &70 360BEQ N2 BOTAY 370CMP #S<20 90 380BCS L00P2 100LDA 390LDA #&40 #&OD \PUT 3 IN PLACE OF CONTROL CHARACTERS HOST 400STA (&70),Y A <&7r>) \ CARRIAGE RETURN 120 AT THE BEGINNING 410JMP L00P2 130. LOOP 420 140JSR INCRE 430. N2 150LDY #0 440LDA &74

1 450LDY #2 60LDA (8,70) , Y 460CMP <8,72),Y 170CMP #?

BEEB FORUM

LOADING M. Cozens of Kent earns £5 for this tip on loading machine with OS 0.1, where occasionally code and saving memory block zero is not correctly recorded (April and September's Acorn User contain a fix to prevent this bug). *CAT will not THE January Acorn User (page followed by the machine code pick this up, and is not the best 25) indicated ways of reducing saved as: way to verify. *LOAD ""8000 is program length and loading CFF better - and it gives an almost •SAVE "MC" COO machine code routines. The complete check whilst leaving following is an alternative To use the program in future your program intact. which has been used success- CHAIN"" the Basic program. This is all very well, but what fully. The machine code This will automatically test the about Mr Knight's program? program to be located in say memory and if the machine Fortunately, there is a way to &C00 to &CFF is first loaded code is not present LOAD it recover most of it. The key is to and run in OPT3, the contents and then carry on. If the code treat the program as a file, and of &C00 being noted, eg if the is present, for example after an read it byte by byte. first code instruction is LDY #0 escape during program use, Type in listing 1 below, wind then &C00 would contain 160. then the *LOAD command is your tape to the program start The Basic program is then ignored. In addition the and press PLAY. Most of it will loaded and line numbering original machine code program load in. Ignore any 'Block?' adjusted to allow a new first can contain key and character errors (*OPT2,0 ensures the line of: definitions, to be used later in computer will ignore them). IF ?C00O160THEN*L0AD "MC" the Basic program. These Once loaded, the program The Basic program is then would be stored in &B00 should list, with just the last few resaved once on a clean tape, onwards, of course. lines missing. If by chance you get 'Bad program' use Mr Denis's machine code routine on it, and you should recover most TWO WARNINGS ON VDU DRIVERS of what you want.

A number of letters have pointed Compare out that VDU22 will change mode FOR I%=1 TO 100:VDU14:PRINT inside a procedure, but it is not l%:NEXT Way round quite as simple as that. with the dreaded For example, listing 3 will work

only when the value of HIMEM for VDU14:F0R l%=1 TO 100: PR I NT bad program mode B% is at least as high as for l%:NEXT

mode A%. That is, the following Running them will produce different applies: results. This is because each LISTING 2 gives a machine VDU14 resets the count for paging f A%=7, B% must be 7 code routine from Mr E Denis and so repeated use has no effect. f A%=6, B% must be 6 or 7

of Brussells to retrieve any f A%=4 or 5, B% must be at least 4 program when the dreaded f A%=3, B% must be at least 3 'Bad program' occurs. Save the f A%=0, 1 or 2, B% can be anything CLEAR RESETS LOMEM assembly code as backup, and also save the machine code by This said, it seems that in most One more point about CLEAR running the listing and using instances you can just as easily which does not seem to be widely *SAVE "BADPMC" 0C00 OCFF. change mode outside the procedure, known (see last month's column)

Now *RUN "BADPMC" will and you should do so unless there Like RUN, it resets LOMEM to retrieve your masterpiece lost is a good reason to execute the the value of TOP. This is actually in memory. change inside. quite logical, and is used to good It will retrieve as much as effect in my self-erasure routine possible, replacing any errant Here's a warning about VDU14. (January's Acorn User). control codes by @. It is fairly straightforward to go through 10MODE locate A7.:A*=»0ut of Procedure" and the whereabouts of ( 20PR0CTEST " Insi de Procedure" ) PRINTA»- one of these. Alternatively, a 30DEF PROCTEST END (A*) : VDU22, B7.: PRINTA*: ENDPROC short program could be written to do the search for you. Listing 3.

ACORN USER MAY 43 Atwo-minute operation

turns your BBC Micro into tl heart of aword processor.

V I KW is a software program from Acornsoft (the software division of Acorn Computers Ltd., who designed and built the BBC Micro) that enables you to use your BBC Micro, together with a printer, as a fully operational word processor. View is supplied as a Rom chip that can easily be fitted to your BBC Micro by your local dealer, in a painless two-minute operation. Then, once installed, you only have to switch on and View is operating immediately. (You can easily switch back to normal computing with a single command.) Also included in the View package are two special books: into View," that takes many ways in which View can help you, and you by easy stages through all the word the 'View Guide' which provides a quick processing commands and explains the reference to all View facilities.

Youll find that View is, by any standards, a thoroughly professional system,

yet still surprisingly simple for the beginner to master. The 'Spark-Jet Printer* shown

in the photograph is the ideal choice of printer for your word processing

application. Extremely quiet, it offers high resolution graphics from

monitor orTV. screen and is available now from dealers.

I f you'd 1 i ke more information, write to Acornsoft, 4a Market Hill, Cambridge CB2 3NJ. Or, for details of your local Acornsoft dealer, phone 01-200 0200. yfCORNSSFT

44 ACORN USER MAY .

MICROS IN SCHOOLSw

LYNDA PRIMARY < Ebt s/our KNOvVlFD(^£ 1. WHAT po V00 call, a LANGUAGE bPltsKTF'R WIDOW DEVELOPMENT MINISTER Heather Govier outlines some exciting work WINNOV^ on language programs for primary schoolchildren in the fifth part of our education series 2. WHAT po n/oucALL w/v+e~r. vv he:n \-r talking, listening, reading and luch software strengthens the IS L-LJKEWARrvi. M recording. Adventure games (such view that microcomputers have no as that reviewed by Charles Bake contribution to make to language in April's Acorn User) are a good development. However, programs MUMID source of stimulation for creative or are now appearing which offer far descriptive writing, or for creating To£Pn> more than just 'barking at video'. situations beyond pupils' experience. UumuS Since many computer aided Ideally, the teacher or pupil should learning programs are written by be able to alter the hazards and 3. AnorHER NAf^g with people a mathematical or rewards to make them relevant to programming background, it is not por a GMO

for a fixed period of time and then If a game has a series of

asking the pupil to type it on the rewards and punishments, the

GrUD&iiLE screen, or by drawing pictures and effect is lost if the punishment, eg, asking for the appropriate word. being eaten by the technicolour The first technique merely tests monster which growls and belches, short-term memory, while the is far more attractive than the S. WHICH IS A PAH- second presupposes that a picture reward of 'Well done, Sally. ^ THE Body demands a noun rather than an Games can have the advantage adjective, phrase or sentence. One of encouraging group discussion.

early version of picture is AiRtERY naming Hangman much more valuable if gave two screens full of detailed a group works together and must instructions to pupils who were reach unanimous decisions before

ACORN USER MAY 45 MICROS IN SCHOOLS

important with poor readers with a record of failure and a low self- image. Communicating with a computer may seem a surprising route to improving communication between people, but the computer's demand for precision can be used to good effect. Pupils who use information retrieval systems find that they learn

to be less precise if their enquiries produce too few possible responses,

and more specific if too many responses are found. Similarly, they

have to consider synonyms if the particular information they want does not seem to be present in the database.

One pupil using a quiz program, very similar to the one provided in the Microprimer package, produced Figures 2-4 show an example of the quiz which is illustrated in Tray in action taken from a

figure 1 . The Croydon version of screen display. Quiz also allows pupils to enter a A session starts off with just range of comments which appear punctuation, and the text slowly when users obtain particular builds up as pupils take a guess on the letter or word. The scores. They realise that an sequence continues overleaf expression may seem humorous when used once but can become

irritating when used frequently, and usually performed. It is difficult to The program Tray combines all this is made clear to them by their provide a situation in which reading these factors to create a new fellow pupils rather than the can be slowed down to such a dynamic approach to the teaching teacher. degree that pupils are able to take of reading. Tray is a sort of

Teachers are sometimes reluctant the process in steps or stages. Hangman activity, but to describe it

to correct all the grammatical It is not surprising that schools thus, fails to do justice to its use errors, spelling mistakes and poor have frequently abandoned the and potential. A piece of text is choice of words for fear of effort and once the basic skills stored in the computer but remains disheartening their pupils. Similarly, have been mastered have left hidden from the readers as though

pupils dislike rewriting work and so pupils to develop their reading. The it were an undeveloped photo- rarely see a well-finished piece of traditional comprehension exercise graphic print. The pupils are able to

work. Word processing systems and cloze procedure test rather bring up the text a little at a time in

can provide the environment in than teach, although with discussion the developing tray. As it is slowly which pupils are willing to they may help to extend vocabulary. revealed the readers are called continually improve a particular The appearance of computers in upon to hypothesise about the

piece of text until it is satisfactory. schools provides a medium for meaning, initially with inadequate This assumes that schools have language work which proceeds information. Thus their comprehension discs and printers. A further use for step by step in the right grows slowly through a series of these peripherals is in cloze testing, atmosphere. Pupils need a sense false starts and blind alleys until a

where the disc is used to record all that it is alright to play and safe to final consensus is reached. of the pupil's responses and this experiment. They need a social While the ideal size of group is uses the teacher's time more climate sufficiently relaxed to be about half a dozen the program has effectively. capable of exorcising the spectre been used satisfactorily with a full Problem solving is generally of the 'right answer', an environment class, and once children have considered to be a mathematical capable of giving house-room to all become familiar with the activity activity, but a fluent reader is a sorts of shy little insights most of there is no need for the teacher's problem solver par excellence. In which will turn out to be wrong but constant presence. The program tackling a complex piece of text, many of which will have a useful, was developed for remedial readers the reader is constantly formulating indirect part to play. Pupils also in secondary schools but can also hypotheses, testing them against must have some equally 'green' be used with primary pupils, the text and revising, accepting or colleagues to compare notes with. although the abilities of pupils in rejecting as appropriate. Others may see alternative the group should not be too Such a reading strategy is possibilities and in discussion all disparate for maximum collaboration. difficult to teach because of the participants are called upon to The program has a scoring complexity of the task and the defend and explain their preferred system which uses a jackpot. speed at which such thinking is interpretations. Initially the jackpot is 26 and falls

46 ACORN USER MAY MICROS IN SCHOOLS

T T E T Rl T E R

1 : E T E R E 1 THE IR T E E E E E THE E E R HERE E E ET RE E ET T T E T E T T THR H THEIR TR RE T RT

EE THEIR T . EET E T . T E EET THEIR EET R E T E E Rl T E ,

R ITH HITE 1 E . T TE E . T E E E THE HE REE

TTHE RE RE ) (T ET E E )• (THET

ETI E El E E , ET E E E E ,

TEE HI 1 TH E E HI THE THER T E T E T E : THE T E T E E T IT'S E R THE RE E T HI .

TTH E T H E , T HOSE T E , IE ET E E H 1 1 E THEIR H R RE THE THEIR T ET T . . .

T E ? R THEIR R 1 . . .?

24, the team had by one each time a letter is bought. class distractions in the school jackpot was now text looked like When the pupils reach the stage of library. The pupils were introduced 30 points and the being able to predict letters, they to the text as a blank screen except figure 3. pupils began to spot win a number of points calculated for punctuation marks (see figure Now some in the seventh against the current jackpot level. 2). The workings of the cursor, words. Was that 'feet' they Thus early predictons are rewarded which can be used as a pointer, line down? Where could several possible more highly than late ones. were explained to them and the predict 'h'? After out the best For predicting a single letter the task introduced as a game of the's had been pointed group can win only one point. For Hangman. At the outset the team bet was fell to be the one which predicting a word or phrase they were given a budget of 50 points began a phrase at the beginning of can win as many points as there and told that they might buy a letter line three. correctly and are letters in the word, plus a for 10 points, in considering which 'The' was predicted instructed to reveal quarter of the jackpot for each would be the best letter to buy the computer discussion all further instances of the same letter. Thus they are encouraged to there was much about of letters (this can be done at be bold and predict larger chunks vowels and about which was the triplet resulting further cost). Fifteen instances of of text. Penalties for failure are most usual vowel, in a no although they arranged so as to promote the communal decision to buy the 'the' were counted parts of words such as same strategy. letter 'e'. could be letter 'there', they' or 'either'. Someone When the jackpot falls to 1 6, and In discussion over which apostrophe in line again after every two jackpot points should be bought next 'a'/r' and 's' spotted the 'it's' predicted have been lost, the pupils are were suggested. When one child fifteen and was of invited to write a brief telegram on said, 'Who votes for "a"?' the followed by 'here' in the third line 'r's 'i's were now what they think the message is teacher introduced the group to the text. All the and looked about. This requirement forges a consensus politics of the game. If a taken giving a text which 4. Focus was link between reading and writing. vote were taken some pupils would like figure 'their' with The process of phrasing a telegram be disappointed and thus it was immediately turned to forces the pupils to question their agreed that a letter would be much discussion as to its meaning. feet' a likely current understanding. The program chosen only if all pupils agreed. 'Their seemed think was successfully is able to store all telegrams and Pupils were encouraged to combination and after taking 's' a present them at the end of the now in terms of words rather than predicted and spotted. session to allow the pupils to just letters and to ask themselves combination 'Th se' was or review the emergence of their which words are common. 'The' What could it be: 'These' understanding. was felt to be the most common 'Those'? 'Yes, but we've had all the The pupils were a group of six word and after discussing the "e"s' said one girl, 'so it must be third year junior children who were relative merits of buying 'h' or 't' the "those"!' thinking working with a teacher away from letter t was finally chosen. The This type of good and

ACORN USER MAY 47 MICROS IN SCHOOLS

checking is seen throughout a session with Tray and is just as apparent with groups of pupils as it is with adult groups such as teachers. Teachers, as with all TOURIST A E RO ======, A TOURIST CAr aspects of computer use, exercise A

: 1 AIR A SAI PAR E INTH more caution and are more inclined AR E THE THE EO E AROU HERE THE PEOPLE A to be reticent when asked to ETA A ASS. ARE A E theorise. The scoring system ARE A E O THEIR TRA S ARE T ARTS THROUGH T/^ encourages the more adventurous THROU H UTS. CAN SEE approach. OU A SEE THEIR YOU THEIR FEET RO THEIR FEET R" Successful prediction of 'a EASURI TA ES, ON ON IV EA tourist' in the first line added a new AR ITH HITE 1 ES. AR WITH Wr dynamism. Now it was possible to THE HA E OUR E ES THEY HA E speculate about the general (THET OAT THE A ARE RE ). (THET OATT meaning of the passage. 'Perhaps it SO ETI ES A S E IA O E ASSES, SO ETI ES A is about visitors to America or HIS 1 TH E E ASHI HIS 1 TH E E Hollywood?' THE THE OTHERS SO : THEN THEOTF There was much discussion IT'S EAR THE RES E T HI . ITS EARTHI about the word hidden by the stars.

It was explained that this word had UT THOSE SO TSHA ES, UT THOSE SC been deleted from the passage and SHA 1 SI E THEIR HAR IES SHA INS would not appear even at the end ARE THE THEIR UTS... ARE THEY THE of the exercise. Perhaps this hidden OR THEIR RAI S. . . ? OR THEIR RA word indicated where the tourist had come from. It clearly had a lot of letters and so the children tried to think of long place names. Could it be Switzerland or Australia? Figure 5. From this pupils were Figure 6. Telegram ti Suddenly it became possible to encouraged to explain the story Is the tourist from Au spot words and phrases. 'Are these in a telegram. Are the people musei their boots' was suggested for the penultimate line but after careful counting 'boots' was seen to be too long. Was that 'around here' in line Figure 7. ET-inspired theory of Figure 8. The correcl three? Perhaps line five read 'you a visitor from space? One child felt conne< can see their huts'? This led to much discussion about whose 'huts' they were until a bit of good checking was exhibited when some one said 'No we've had A TOURIST CAME FROM ======, A TOURIST CA SAID: PARKED INTH all the aitches it can't be "huts".' PARKED IN THE AIR AND

THE PEOPLE / Perhaps it was 'nuts'! All agreed on THE PEOPLE AROUND HERE you can see' and a successful ARE ADE OF ETAL AND LASS. ARE MADE OF prediction was made. The score THROUGH THEIR TRANSPARENT PARTS THROUGH TH now stood at 123 but not many of YOU CAN SEE THEIR UTS. YOU CAN SEE THEIR FEET R the pupils were still interested in it. THEIR FEET ROLL The task had become so ON LON MEASURING TAPES, ON LONG %E

• A/ engrossing that the score had now DAR WITH WHITE LINES. DARK WITH r become almost irrelevant. THEY HA E FOUR EYES THEY HAVE C (THE TWO AT" After taking 'n' the screen looked (THET OAT THE A ARE RED). like figure 5. Ideas began to pour in SO ETI ESASPE IAL ONE PASSES, SOMETIMES fi

. HIS FIFTH EYE thick and fast. 'In', 'around' and HIS FIFTH EYE FLASHIN 'transparent' were spotted and the THEN THE OTHERS SLO DO N: THEN THE OT ITS . Th opening was read as 'A tourist IT'S LEAR THEY RESPE T HI CLEAR came from'. The last two words BUT S seemed to be 'their reins'. Perhaps UT THOSE SOFT SHAPES, THOSE the passages was about 'asses'. SHADO Y INSIDE THEIR HARD ODIES SHADOWY INS But how should reins be spelt? No, ARE THEY THEIR UTS... ARE THEYTH the spelling was wrong. Reins must OR THEIR BRAINS. . . ? OR THEIR BR/ be something else, anyway wasn't

there a letter missing? It could not

be 'trains' because 't's have gone,

could it be 'brains'? This level of thinking and

48 ACORN USER MAY .

MICROS IN SCHOOLS

reasoning permeated the whole commander who ruled the others. session which lasted uninterrupted But who were these strange from 1.30 to 3.45 pm. All the pupils people? Where had they ever seen chose to work through break time 'people' whose 'feet' roll on long and some wanted to stay after measuring tapes, dark with white CAME FROM ======school. lines? 'Perhaps they have wheels -

I THE AIR AND SAID: In this session it was getting these people are they cars?' Yes!!'

LE AROUND HERE close to telegram time. What could Suddenly it all made sense. The Q ETA AN ASS. the group now read of the text? space tourist comes to earth and

IR TRANSPARENT PARTS What did it all mean? They were mistakes the cars for the SEjF. THEIR UTS. encouraged to try to read as much inhabitants. The measuring tapes t'r'j as they could substituting a are the roads and the 'special one' pleasuring tapes, nnnnnn for the words which they with the 'fifth eye flashing' is a h white lines. could not guess. With nothing more police car. E OUR E ES than figure 5 to support them the 'Oh what a con!' shouted one

AT THE A ARE RE ). group read: pupil but the pleasure and [S IA PASSES, ASPE ONE 'A tourist came from nnnnnn in satisfaction was there on the faces

E E . ASHIN the air and said the people of all of them. All were amused and OTHERS S O ON: around here are nnnnn nnnnn intrigued by the final question: I THE RESPE T HI . transparent and ass through their But these soft shapes parts you can see their cuts, Shadowy inside their hard E SO T SHAPES. their feet nnnnn on treasuring bodies INSI E THEIR HAR O IES tapes) tables (no! measuring Are they their guts THEIR UTS. . . number with white lines.' Or their brains? RAINS. . . ? They constructed a telegram: There was no doubt that the session had been exhausting for 'We think it is about a tourist who pupils and teacher alike but measures with tapes'. everyone involved left with a feeling sort of people, they of exhilaration. (The correct text is am time again, What n Australia? wondered, had transparent parts. shown in figure 8.) By taking things »useum models? Were they models in a museum? slowly, and working collaboratively Perhaps you could see their 'guts' in a relaxed non-censorious

not their 'cuts'. It must be 'guts' atmosphere this team of nine-year because 'cuts' would be on the olds had been involved in a

skin and if you can see through process of deep text analysis rarely irrect text. in school. them . . seen the primary mned, but exhilarated. The phrase 'parked in the air' The process had required the was spotted in line two leading to simultaneous application of analytic, much speculation on how someone convergent thinking as well as could park in the air, The tourist creative thought. Pupils had to = r CAME FROM ======must be in an aeroplane, a combine both styles and everyone's N THE AIR AND SAID: helicopter, a balloon, a hovercraft talents were used to the full. 'LE AROUND HERE or a jump jet. E OF METAL AND GLASS. By the time the second telegram

I THEIR TRANSPARENT PARTS was required the screen looked like GUTS. SEE THEIR figure 6. The final section had been Pupils quickly ETROLL laid open and the telegram read: l*VEASURING TAPES, learn to doubt H WHITE LINES. 'We think it is about a tourist who EfFOUR EYES came by plane from Australia, their first who measured hard bodies with /sf THE BACK ARE RED). es a special one passes, dark tapes with white lines, and hypothesis eye flashing. she or he didn't know if it was their guts or their brains.' : others slow down:

=? they respect him. There was thus still much One of the most clear-cut effects confusion but the group hung of repeated use of Tray with a ;e soft shapes, tenaciously to the theory that the group of pupils is that (hey quickly ' inside their hard bodies tourist came from Australia (despite learn to doubt and question their their guts. . . the fact that the letter count was first hypothesis, becoming more

BRAINS. . . ? wrong) and that these strange open to alternatives. With this, their

people were museum models. first experience of using Tray, it was By the time the screen looked a long time before someone

like figure 7 it had become suggested that these were beings possible to read almost everything. from a different world, that the The 'special one' was like a tourist came from outer space and

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50 ACORN USER MAY MICROS IN SCHOOLS

that the spaceship had been clinging tenaciously to them even parked in the air because there against mounting evidence. Perhaps TEN POINTS was no gravity. it is this last point which most of all Tray does something more than makes Tray a significant new all other current software designed teaching tool. TO NOTE for language work. It allows Tray consists of a program to children to read in a new way, a play the game and keep the score way both magical and powerful. It as well as a program to allow the Language development is is based upon the assumption that user to set up text files. These files concerned with improving are separate from the program and pupils' abilities to talk, listen, can be stored on cassette or disc read and record. Clearly for later use. The teacher can thus identify which of these is Tray allows create a piece of text which fits in helped by a particular program. classroom well with current Do not accept any program children to learn activities so that the emphasis can which does not use upper on the meaning rather than the be and lower case when the in a new way spelling of individual words. pupils could. The initial version of the program was developed on a computer Poor readers should not which used capital letters only. This suffer additional difficulties good reading and writing often is unacceptable as pupils should so check that the screen and grow best rooted in a rich subsoil see text presented on the screen in the printer use true of good talk, and links reading with a way that is as close to normal text descenders. talking, listening and writing. as possible. Thus letters should Ensure that programs have Tray thus brings to language have true descenders and upper instructions written at an work much of what Logo brings to and lower case letters made appropriate level of difficulty. maths. Readers are set in a available. Tray is now being 'microworld' where: Some games, particularly developed as part of an MEP even mistakes become profitable adventure games, can stimu- • project, Developing Thinking Skills learning experiences; late pupils to increase their in Primary School, which is based • a trial and error approach is range of vocabulary and at the Davidson Centre in Croydon. possible allowing exploration creative writing. Teachers who are interested in with a structure imposed from taking part in the serious evaluation The easy availability of word inside rather than outside the of this program should contact processing could revolution- group; Heather Govier. ise the relative importance of • discussion and hypothses testing Even when schools operate on mechanical and creative writ- are possible at all levels from the integrated days, pupils rarely get ing skills in the same way simple spotting of words to the the opportunity to pursue a task that calculators dramatically complex analysis of deep uninterrupted over a long period of change the balance of skills meaning; time. Use of this program shows in mathematics. • final understanding results from that when the task is sufficiently combined analysis and synthesis Information retrieval systems using elemental building blocks. can help to develop pupils' linguistic ability because of Further, it encourages co- Pupils rarely can the need to refine the criteria operation in an atmosphere in pursue a task for searches. which it is recognised that everyone has a valuable contribution to uninterrupted The computer's role as a make. This is an important aspect neutral referee and score- of Tray. By requiring consensus the over a long period keeper can provide the teacher encourages the members reassuring framework for of the team to argue their point of pupils to undertake complex view, explain and persuade. absorbing pupils are perfectly reading and interpretive tasks. Through such a process, weakly capable of persevering with full Reject programs which pur- thought out ideas are tested and concentration for three hours or port to teach spelling but more strongly supported ones tend more. essentially test only short to be adopted. This may lead to On Inset courses the same term memory. problems when a well reasoned happens with teachers who happily and strongly supported hypothesis abandon their coffee break and Avoid games which 'reward' is opposed by a new more powerful have to be reminded to stop for mistakes by giving a more one. In text analysis, as in science lunch. It is also interesting to note exciting display than that for or maths, individuals find it very that the same text can be used for correct responses. hard to abandon their theories, teachers and pupils alike.

Next month: Information technology in the curriculum

ACORN USER MAY 51 THE PROGRAM THATS LEAPS AHEADOFALLTHEREST

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52 ACORN USER MAY INTERFACING

Having covered 1 MHz bus theory, Paul Beverley gets down to practice INTERFACE BOX FOR THE

Hlaving looked at the theory of supply of 1 MHz clock pulses are trying to read them. Thus if you hardware connections for the 1 MHz readily available. accidentally try to write to the ADC bus, here is a practical application Figure 1 shows the address you won't get the problem of the - an interface box for the BBC decoding used. I t places the two data bus drivers and the ZN427 micro. This brings out both user DACs at &FCF0 and &FCF1, and trying to write different things onto and printer ports as well as adding the two ADCs at &FCF2 and the same data bus! two fast eight-bit analogue to digital &FCF3. Those who read last Another mistake in the last converters (ADCs) and two eight-bit month's article may well have article concerns the read/not-write digital to analogue converters noticed one or two deliberate line. Following Acorn's Application

(DACs) so you can output voltages. mistakes. For example, I suggested Note on the 1 MHz bus, I said this You may wonder about adding two that when connecting up the was just an extension of the more when there are already four in address lines to enable various read/not-write line of the main 6502 the machine with higher resolution devices, you could connect directly processor with extra buffering. In - 1 2 bits as against eight. The point from a 74LS138 address decoder fact it only ever goes low (= write) is that the on-board converters are to the chip select lines of the when you are trying to write to a extremely slow - each one takes 1 converters. This works with the device on the bus. This doesn't milliseconds (ms) to work out the ZN428 because its chip select line make a great different practically, digital equivalent of the voltage is negative active, but the ZN427 but we might as well know the truth. applied to it. This means it is has an 'output enable' input (pin 2) This will avoid any confusion which virtually useless if you want, for which is in fact positive active, and might have arisen if, when fault- example, to look at a voltage not negative active as suggested. finding the interface box, you had waveform and display it on the Therefore, since the lines from the looked at the 1 MHz bus read/not- screen - like a digital storage 74LS138 are normally high, and write line. You would have expected scope. The ADCs used in this only go low when the particular to see a continuous train of pulses interface box can do a conversion address appears on "the address as on the processor's read/not- in about 10 microseconds (ys). lines, we have to invert them before write line, but would have found it

They are only guaranteed to work at applying them to the output enable was sitting at logic 1 unless the a clock rate of 600 kHz, giving lines of the ADCs. bus was being accessed. them a conversion time of 1 5/js, but Since we have to put an extra if run at 1 Mhz they do a complete inverter into each line anyway, we I he decode logic also provides conversion in 9jjs. Despite the might just as well add a third gate four spare lines - &FCF4 to &FCF7. quoted maximum clock rate of 600 as suggested last month to gate Two of these can be used to kHz, the ZN427s I have tried work these output enable pulses with the provide 'start convert' pulses for the at 1 MHz. Using 1 MHz is read/not-write (R/NW) line on the ADC's since if you read or write to, convenient because the bus we are bus. This ensures the outputs of the say, &FCF4 then the 'NFCF4' line using has, as its name suggests, a ZN427 are only enabled when you (figure 1) will go low for just a

y*r 74-L302

ics 1 7-4-L5I5B r ] lcg *74LS N PAC 1 Apci IMH Z O- A2 -> NPAC 2 R/NW ?btc o- A? 1 >

-rSV p 7+LS20

A+ > £ > AS< IC6 At ( > * circuit *7' Figure 1 . Address decoding

ACORN USER MAY 53 INTERFACING

go low for just a fraction of a microsecond - but long enough to 34-way 26-way 20-way

initiate the conversion. If the system connector connector connector clock is being used for the 1 MHz Bus Printer Port User Port

conversion, is real - there no need to 1 GND 27--AO 1 -CA2 1 - +5 volts use the 'end of conversion' (EOC) 2 - R/NW 28--A1 2- GND 2-CB1 output of the analogue to digital 3- GND 29--A2 3-PAO 3 - +5volts 4- 1MHz 30--A3 4- converter since, because we are GND 4-CB2 5- GND 31 --A4 5-PA1 5- GND using the 1 MHz clock signals, we 6-NNMI 32--A5 6- GND 6-PB0 know 9/jls. If conversion takes you 7- GND 33--A6 7-PA2 7- GND really want to use the EOC signals, 8-NIRQ 34- - A7 8- GND 8-PB1 either attach them to the input lines 9- GND 9-PA3 9- GND of the user port, or to the two spare 10-NPGFC 10- GND 1 - PB2 11- GND 1 1 - digital input lines on the analogue PA4 11- GND 12-NPGFD 12- GND 12-PB3 ports (15 way D-type connector) 13- GND 1 3 - PA5 13- GND which go to the internal versatile 14-NRST 14- GND 14-PB4 interface adaptor at &FE40. 15- GND 1 5 - PA6 15- GND 16-ANALOGIN 16- GND 16-PB5 17- GND 1 7 - PA7 17- GND Mnother point which hasn't been 18 -DO 18- GND 18-PB6 19-D1 made strongly concerns the 19-CA1 19- GND 20-D2 20- GND 20-PB7 problem of what the Application 21 -D3 21 -NC Note calls 'possible address 22-D4 22- GND decoding spikes which may occur 23-D5 23 -NC during the 1 MHz high'. The 24-D6 24- GND inference drawn from this was that 25-D7 25 -NC (NC= no 26- GND 26 -NC connection) it was not a problem unless you were trying to attach a lot of devices onto the bus, for example if Figure 3 - Pin Connections on the various connecting you were interfacing to an extra cables

memory board. Indeed I had successfully attached two DAC's and an extra 6522 VIA onto the bus pulse!) What you have to do then is the user port and the printer port without becoming aware of the to use one of the circuits given last there is an earth line inbetween seriousness of the problem. The month to 'clean up' the select line each signal line for screening. reason for such blissful ignorance for page &FC (NPGFC) before However, on the printer port they was the use of the DAC 0800 chips applying it to the 74LS138 decoder are the even numbered pins; on the which cannot be directly interfaced (figure 1). user port the odd numbers. to the bus and I was therefore The operational amplifiers on the using two 74LS374 octal latches to inputs of the ADCs are just unity read them. This created no problem I he User Guide does not make it gain amplifiers to provide a higher because these chips are clocked desperately clear which pins on the input impedance and to prevent the on the positive-going edge of the various connectors are which. All it ZN427 chips being blown by clock pulse. (So here's another gives is a circuit diagram from excessive voltages. If you apply too - deliberate mistake I said that the which you have to count the pin large a voltage to the analogue 74LS374 was clocked on the numbers. Figure 3 shows clearly inputs you just blow up the 741s negative-going edge of the clock which are which. Note that on both instead which are somewhat

-ZN4-2U DAC 1 (P*Cl) ,01 VO )PJ

Nc i CH NDAC I- OS

ADL/lU I CWDAC 2) i D*

(A0C/IW2; . P7 i<)oa. _L L i-TI -O 1 Sv W JOOnF w w CtTAmiC w ^7

Figure 2. Analogue to digital converters (DAC notation in brackets)

54 ACORN USER MAY INTERFACING

cheaper (1 4p instead of £7). The outputs of the DACs could be protected in the same way by Semiconductors Cost adding the same operational ZN427 A to D converters (309-464) 13.16 amplifier circuits, but I have not ZN428 D to A converters (303-523) 9.56 bothered since I feel it is less likely line to do something silly with an 74LS138 3 to 8 decoder 0.27 output. 74LS20 2 x4-input NAND 0.13 74LS02 4x2-input NOR 0.22 741 Operational amplifier 20p ea 0.40 i\ parts list (figure 4) is given for Capacitors the main circuits, including printer 1 uf polyester 1.68 and user port connectors, but 4 42p ea excluding any protection on the 4 100 nF ceramic 7p ea 0.28 DACs. Most parts can be bought 8 10 nF ceramic 4p ea 0.32 easily from RS Components, but Resistors more cheaply elsewhere if you shop around. You can make the 1M circuit up on Veroboard, but the 82k 2p ea 0.20 company mentioned in the parts list 3k9 will give you details of a printed 390R circuit board, kit of parts or a built and tested board. Hardware The other thing missing from the 20-way jumper lead with DIP socket 1.85 parts list is the box in which the 26-way jumper lead with DIP socket 2.10 unit is to be housed, and the 34-way jumper lead with DIP socket 2.70 sockets to connect up equipment, 20-way transition connector (468-147) 1.44 because these will differ according 26-way transition connector (468-1 53) 1.80 to your application. In my college 34-way transition connector (468-1 69) 2.30 for example 4mm sockets are the 2 1 8-way DIL sockets 16p 0.32 standard. 3 16-way DIL sockets 11p 0.33

3 1 4-way DIL sockets 10p 0.30 2 8-way DIL sockets 9p 0.18 Wiith this interface box you are mixing analogue and digital Veroboard or PCB signals, so care is needed with supply lines and earth lines. In PCBs, kits of parts and fully built and tested boards are available from: particular it is important that parts Electro Technical Services 55 Raymond Road, Hallesdon, Norwich, of the circuit which require an NR6 6PN(see page 64) analogue earth - marked on figures as an earth symbol with an A'in it^s? Figure 4 - Parts List - should not be connected to the line which is supplying the zero volts to the various chips on the the BBC micro's own power supply Services, there should be no boad. I have referred to this as the unit which has both supplies as problem as there is space on it for digital earth V- It is also important volts. mounting plug. to decouple the supply effectively. well as +12 These are a board Each chip should have a 10nF intended for disc drives, but the In designing the front panel ceramic capacitor connected across power we need is fairly small. The you will have to decide exactly

ony problem is getting hold of the which facilities to provide. I have its supply lines as close to the chip are not included the four as possible. In the case of the appropriate connector. They BBC's ADC the same as the six pin QM inputs, the spare digital inputs used ADCs I have used 100nF. Operational amplifiers should have multipole connectors in the RS by the paddles and the lightpen 10nF capacitors on the positive Components catalogue even though strobe input, all of which can be and negative supplies. they look similar. In fact they are brought up on a multi-way made by A-MP and are distributed screened cable from the 1 5 way D- by Ampliversal of Terminal House, type connector that plugs into the

I his brings me to power supplies. Stanmore, Middlesex. back of the computer. Various other

Where are you going to obtain the There is another slight problem lines from the 1 MHz bus have also +5 volts and -5 volts to power for those using a disc drive that been brought out to sockets. For these circuits? There is a +5V does not have its own power example, the analogue input is a supply on the user port, so with a supply. You will need to get useful tool for 'listening' to what the separate external supply for the -5V yourself a suitable socket as well computer is doing. If you put one there is no problem other than as a plug to take power from the finger on, say the interrupt line choosing a suitable connector. As PCB to the disc drive. If you buy (NIRQ) and another on the an alternative, there is an outlet on the board from Electro Technical page 64 k-

ACORN USER MAY 55 '

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• 1 • •• ••••« • • 1 • • 1

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CENTIPEDE (32K) £6.50 FROGGER (32K) C6.50 ROAD RUNNER (32K) £6.50 ALIEN DROPOUT (32K) £6.50 Incredible arcade Based upon Ihe arcade game of ZYGON, type game featuring mush Not |ust another version of Frogger this is Ihe The only lull feature machine-code version ot the rooms, bul our version improves upon Ihe original arcade snails, (lies, spiders and the cenlipedes ol proper high-quality version lhat you've been arcade game available for the BBC micro. game itself You have to shoot the aliens out of course Excellent graphics and sound 6 sKill wailing for Graphically brilliant, with gaping- Fealures include scrolling screen, radar display, levels, hi-score. rankings, their "boxes" before the "boxes" lillup. Once lull. bonuses, and in- rnouthed crocodiles, diving turtles, and frogs thai checkpoint flags, fuel gauge, smoke screens, 6 Ihe aliens fly down relentlessly, exploding creasing difficulty as Ihey as Ihe spiders become more flex theii legs as they |ump along Increasing skill levels, rankings, increasing difficulty, and hit the ground. Suitable for use with keyboard or active and the number ol mushrooms increases difficulty, hi-score, responsive controls, sound sound effects joysticks. "Visually this compares well effects, etc. game with the Suitable lor use with keyboard or pystlcks. "Do not be tooled by their placid purple appear- arcade version, being colourful and clear." ••• NEW RELEASE ••• ••• NEW RELEASE ••• ance - these moths are out to get more than the YOUR COMPUTER clothes in your wardrobe " YOUR COMPUTER

SPACE FIGHTER (32K) £6.50 GALAXIANS (32K) £6.50 INVADERS (32K) £6.50 FRUIT MACHINE (32K) £6.50 Arcade-style game based upon leaiures from Fast action version ol the popular arcade game 4 Superb version ol the old classic arcade game, Probably the best Iruit machine implementation DEFENDER (in initial and SCRAMBLE 5 of men- ol Galaxian 3 screen formations) it all types types including a lew exlras 48 marching invaders drop on Ihe market This program has . HOLD. acing alien fire at you and may attempt to ram you swoop down individually or in groups ol two or bombs lhat erode your defences, and two types ol NUDGE. GAMBLE, spinning reels, realistic Iruils Separate attack phases, fuel dumps, repeating three 6 skill levels, high score, rankings, bonus spaceship lly over releasing largo bombs lhat and sound etlecls, multiple winning lines This laser cannon, asteroids, smart bombs, hi-score, laser bases and increasing difficulty Superb penelrate through your defences. Increasing is THE Iruit machine program to buy rankings. 6 skill levels, sound effecls sound effects and graphics difficulty, high score superb graphics and sound "The graphics are very good and with a little imagination "Botrt are well-produced, with colourful you might be able to convince yourself you are m Vegas " YOUR graphics, responsive controls and the usual Las bunch ot extra-terrestrials " YOUR COMPUTER COMPUTER

DISC SOFTWARE AVAILABLE NOW PLEASE ADD 50p per order lor p & p SUPERIOR All our programs are ready for despatch on 5% discs at £9.90 each VAT ,.' SOFTWARE WE GUARANTEE THAT:

1 ) All our software runs correctly on all current operating systems 1 We pay 25% royalties for high quality Dept ji'l All our software is available before we advertise AU2. programs (3) All our software is despatched within 48 hours bv first class post. 69 Leeds Road, Bramhope, Leeds. (4) In Ihe unlikely event that any ol our software fails to load, return your cassette or disc to us and Tel. 0532-842714 we will immediately send a replacement Dealer enquiries welcome

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56 ACORN USER MAY wm

I he AY38910 sound generator is a readily available chip which at around £6 offers all that is needed for the generation of fairly complex SOUND OUT sound effects, such as gunshots, space sirens, helicopters and explosions. (programmable sound OF The PSG AN ATOM generator) contains three separately For £20, you can build David Tilston's programmable output channels: a white noise source, two eight-bit sound board and produce effects, I/O ports and full ADSR (attack, decay, sustain, release) control of including envelopes, to rival the BBC the output. It can continue to produce sound after the initial micro commands have been given, thus releasing the host processor for other tasks.

The circuit diagrams and J S8 software illustrated in this article 57 |- PBo will allow Acorn Atom owners to Port use this chip to add special effects ici B to their favourite programs. The /TN AY 3 «gio circuit can be constructed with a Bn- minimum amount of effort using D7 - PB7 only a handful of readily available Bc-i components, for about £1 9. PA (6 The circuits makes use of the i/o Atom's two I/O ports and requires PA1 the 6522 chip to be fitted inside the A© of A7 Atom; it uses the eight lines port- A9 B and lines PAO, PA1 of port-B. The I/O - Nfcsr only other components needed to A0 interface this IC are an audio ffiocfc 8-n amplifier circuit, which can be created easily by the use of an LM386 audio amp IC. Figure 1 . Circuit diagram • 64-way A&B Eurocard connector with right angled pins (or wire-

to fit on the back wrap pins) PL6 1 32 of the Atom. 6ND VS.S — 1 ^ 4C — vcc 5v A NC — — Nc • 64-way A&B Eurocard breadboard t t r An*Jo0ue S — ANALO60K -C 5v Ov with correct patterning for DAO A^^logut A Rear view of atom euroconnector type DIN 41612 NC — DAI or DIN 41617. 1087 — DA2 IOSfe — — DA3 • AY38910 PSG with data sheets. IOBS — AY-I9IO PIN ATOM p.N DAO 37 PBO A lO It is important to obtain the data — DAS IOB+ DAI 3b PB1 A9 sheets as they contain all the IOB3 — DA2 is P82 A 8 necessary information on the lO 62 — — DA7 PA3 34- PBS A 7 IOB1 — BC1 PAN- 35 PS+ A fa structure of the PSG. and how to 8C2 DAS 32 PBS A 5 PAfo 3i PBfc A 4- program it. 10A7 — — BD1R DA 7 3o PB7 A 3 4 40-pin socket, 8-pin socket, IOAfe. NC IOAS AS 2-5 PAO 2o single strand wire. 5C 1 A IOA4- — — A2- BC2 28 + 5V + 5V • LM386 audio amp available from IOA3 RST 8 DIR 27 PA1 Al<) Tandy etc. CJ-OCK- IOA1 20 2J IOAO • 220 to 500 microfarad electrolytic A-5 2+ OV Ov capacitor, and any small type. CLOCK 22 Y4 ^ B2<5 • 10k linear variable resistor, any NS-ST 23 R.ST 8fc small type, eg rotary. 8-ohm loudspeaker, low power • Figure 2. Pin configurations type.

ACORN USER MAY 57 »

ATOM

BUILDING THE PROGRAMMING THE SOUND CHIP

BREADBOARD VERSION THE programmable generator first. If the values in listing 1 for Y creates sound by producing square are changed in lines 500 and 510,

waves on any or all of its three the tone will change in frequency. If I he circuit can be built on a output channels. The faster the rate the value in line 530 is made Eurocard breadboard using the of the output the faster the rate of smaller the sound will become following tools; soldering iron vibration and the higher the sound quieter. (low wattage with small tip), pitch (figure 3). The frequency sweep routine solder, wire strippers, wire Frequencies of the square waves (listing 2) runs through all the snippers and sharp knife (figures on the three output channels are possible tones from a single 1 and 2). controlled by the three 12-bit tone channel, starting from the highest. First, solder the Eurocard con- registers: Changing the step rates in lines nector onto the Eurocard 520 and 540 will produce some ensuring correct orientation so Channel A registers R0 and R1 unusual variations, also changing the component side faces up Channel B registers R2 and R3 the wait period in line 560. and the board will stick out of Channel C registers R4 and R5 On this soundboard, all three PL6 (see below). If you have the channels are connected to the connector type with wire-wrap Registers R0. R2 and R4 form the same amplifier. Hence if more than pins you will carefully have to lower eight bits of the three one channel is enabled at a time bend them at right angles with a channels, while R1, R3 and R5 the resultant wave will be a pair of small pliers. form the upper four. The values combination of the channels. It will Con« parent RtA* of Atom programmed into any of these three sound like a chord, rather than a £ registers control the frequencies of pure note. Onntc+or --* the output waves on their Register 7 is used to enable or

Next, solder on the 8 and 40 corresponding channels (figure 4). disable the output channels and

pin sockets, followed by the The width of each high low of the I/O ports (table 1). For example, capacitor, resistor, loudspeaker the square wave is determined by a value of 240 (11110000 binary) connection. Connect all data the register value, ie the number of will set port B to output, set port A lines from the 40-pin socket to clock cycles in any high or low to output, enable tones on their corresponding port lines on section of the square wave is equal channels A,B and C, enable noise the connector. Connect all the to the register value. Three registers on channel A. control lines, ensuring that; BC2 all act on their corresponding Registers 14 and 15 correspond (pin 18), A8 (pin 25). VCC (pin channel in this manner. The three to two eight-bit input/output ports; 40), are all connected to 5V. Vss output channels can be enabled or A and B respectively. These are (pin 1), A9 (pin 24), are disabled independently, and are simple ports and using the I/O connected to 0V. NRST (pin 23), enabled or disabled by the lowest registers has no effect on sound joins pin B6 on the connector. three bits of register 7. The generation. CLOCK (pin 22), is connected to amplitude of a wave determines the As well as simple tones, a white pin B29 on the connector. BC1 volume of the sound produced. noise source can be mixed with the and BDIR join PA0 and PA1 The amplitude of each channel three output channels. Noise respectively. is controlled by its amplitude creates a hiss smilar to that on a Now complete all the other control register (registers 8,9 and radio which is not tuned. The PSG connections and thoroughly 10 correspond to channels A,B and creates noise by adding small check your work for solder C). The amplitude of each channel 'glitches' to the output wave. The bridges and correct connections. can take any one of 16 values (ie degree of noise is controlled by Now you're ready to insert the the lower four bits of the register register 6. a five-bit register, and so AY38910. Do this carefully, are used.) A value of zero hiss values can be in the range taking care not to bend any pins. corresponds to silence whereas a to 31. The mixing of the hiss with

Avoid touching the pins if value of 15 corresponds to the the output channels is controlled possible to avoid static damage loudest volume. by bits 3,4 and 5 of register 7 in

to the chip. Then insert the Listings 1 to 4 give examples of exactly the same way that the tones LM386 taking the same care. simple tonal effects. Note that are enabled. Noise may be enabled

program 1 must be entered and run onto a channel independently of

AMpli'+ude. Amplitude AfnplH-ude. Anufiberof docx cycles - re.g i^er yakie

Uow ftendency give

Figure 4. Single tone on channel A Figure 3. Frequency and pitch Time Ti«ne

58 ACORN USER MAY m ATOM

CONSTRUCTION DETAILS Program 1. FOR PCB VERSION Listing 1 . 10 DIM LL4 Single continuous tone 20 P.$21 30 P=#2800 500 X = 0;Y= 120; LINK W

: tone value 40 [ low byte: Channel 50:LL0 A MOUNT components on the 60 510X=1; Y = 0; LINK W LDA @ 03 component side of the printed 70 STA #B801 : tone value high byte. 80 STX #B800 Channel A circuit board, ensuring corrent 520 X = 7;Y = 90 LDA @ 02 254; LINK W orientation. Pin 1 is marked tor : enable Match data tone channel A both ICs. 530 X = 8;Y= 15; LINK W 100 STA # B801 Ensure the electrolytic cap- : set volume level 1 1 STY # B800 (maximum) acitor (100 - 500uF) is oriented 1 20 LDA @ 00 540 END correctly. Mount the variable rlatch tristate signal 130 STA # B801 resistor (100Ko, linear variable 1 40 RTS type). 145:LL1 Listing 2. Frequency 1 50 LDA @ 03 sweep rlatch address 500 X=7; Y=254; 160 STA # B801 LINK W : enable channel 1 70 STX # B800 A single 180 tone LDA @ 01 510 X=8; Y=15; LINK W e~9- : initiate read : set volume level 1 90 STA # B801 520 FOR A=0 TO 1 5 STEP 1 200 LDA @ 00 Connect +0 220 STA : step through course # B802 values (£ntre.+«p 230 LDA # B800 530X = 1;Y= A; 240 STA # 80 LINK W 540 FOR B=0 TO 255 250 LDA ® 00 STEP 1 : step through fine .set bus tristate 260 STA # values B801 550 X=0; Y=B; 270 LDA @ # FF LINK W 560 WAIT Fit the Eurocard connector 280 STA # B802 290 RTS : slow sweep down ensuring correct pin orientation 570 NEXT B 300 ] (row a and b, pins 1 and 32 are 310 580 NEXT A P.$6 590 END marked on the board.) See pin 320 ?#B803=255;?#B802=255 configuration diagrams if unsure.

330 W LLO ; R LL1 340 END The connector may be mounted in either of two ways: Listing 3. Varying tone component Routine 500 Side LLO writes data to one of the X=0; Y = 88; LINK W AY-3-8910 registers, : set tone on channel A x - register 510 X=7; component no (0 to 1 5) Y=254; LINK W y-data connector Side. __ (0 to 255) : enable channel A 520 X=8; Y=16; LINK W : set 'envelope' mode on Routine LL1 reads channel will

550 X=6 ; Y=6 ; LINK W 560 LINK#FFE3 570 GOTO 500 Component orientation 580 END

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ACORN USER MAY 61 ATOM L^ p- page 59 RI3 1 - output 0- input value Ampli+tfde pa H-ern bit 7 port B control bit 6 port A control 1 - output 0- input bit 5 channel C noise enable 0- enabled 1 - disabled 0,1,2 bit 4 channel B noise enable 0- enabled 1 - disabled " a a or 3 V bit 3 channel A noise enable " " a a bit 2 channel C tone " " " " " bit 1 channel B tone bitO channel A tone 1, 1, or 7 A Table 1 . Register 7 functions

the tones. A value of produces a in the corresponding amplitude high pitched hiss, whereas 31 control register setting 'envelope' \N\|VNsN\ produces a low rumbling hiss. The mode), the output volume will vary listing below demonstrates this: according to the wave pattern 500 X=6; Y=15; LINKW (envelope pattern) selected. For 5. : set noise level examples, see figure V 510 X=7; Y=247; LINKW The envelope period control

: enable noise on to channel A register controls the time periods 520 X=8; Y=15; LINKW for the envelope pattern. This is a

: set volume to maximum 16-bit register formed by combining 10 wwww- 1 1 1 2. 530 END the two eight-bit registers, and to the most useful Now we come Register 1 1 forms the lower eight register of all, envelope control. We bits (fine tune) • and register 12 have seen that simple or multiple forms the upper eight bits (coarse NT tones can be created with set tune). This period varies from a few the volume levels. However, in microseconds up to several production of complicated more seconds; ie, a low value (eg 20) will sounds the AY38910 offers full period of a few \2 produce a time A444WH ADSR control of the output microseconds, whereas a maximum sustain channels (attack, decay, value of 65536 will produce a and release). This allows volume period of several seconds. levels of channels to be varied in 13 A accordance to specific output

patterns, eg sounds can be made Bbefore entering any data, it is to drop in volume from maximum to advisable to write zero to every zero over a specific period of time. location in the AY38910. This 14- AvVVV- Envelope mode is enabled onto cancels any sounds and can be any channel by placing a volume done by: amplitude value of 16 in the corresponding FOR X=0 TO 15; Y=0; LINK W; A amplitude control register (set bit 4 NEXT X in registers 8,9 and 10). When a sound has been

1 4— Envelope period When an envelope is chosen for programmed into the registers, it Figure 5. Envelope patterns a channel (ie 16 has been placed will continue until altered or reset,

SOLDER SIDE

COM'T SIDE

A MllllHIDIIIIIIIIIIIIIIIIIIIIIIIIf 32 bi Patternsafor double-sided board. Holes must be plated through USER MAY 62 ACORN 001 INVADERS

Arcade quality full feature Space Invader game,

written in machine code using Mode 1 colour graphics. Hi-Score, Mystery Ship, Bonus Base, Advancing, Walking Aliens.

Runs on a model B for £6.95 inc.

004 DISASSEMBLER 002 GALAXIAN 003 APOLLO BLACKJACK. TEXTPRO.

1 tape containing 3 programs representing Arcade quality game using machine code, vivid Lunar Lander with a difference! 4 stage game Range, Mid Range. incredible value for money. Mode 1 colour, Moving Stars, Hi-Score, Bonus comprising Orbit, Long BLACKJACK is like the arcade game, but uses Ship, Flagships. Swooping Aliens and Exciting Detailed Landings, Limited Fuel, Hall of Fame, much better graphics - so real you could pick Sound Effects. Sound^.Moon Walk etc. them off the screen! Runs on a model B for E6.95 inc. Runs on a model B for £6.95 inc. TEXTPRO is a simple word processor, offering text scrolling, cassette routines, line editing, t; *: t-c l • I X o »« •- E Ml o justification, insertion and deletion, variable line 2 € > ** 3O0 3 width and page length, data verification, line centralizing and printer commands including page

scrolling, large print and variable spacing. Full AND instructions and function key labels supplied. DISASSEMBLER lists object code and Assembler

mnemonics. Includes a pause function, printer II II II 1 option, page mode and only occupies 4.5K of IP " U SftLOOH RAM. Full instructions and function key lables STORE ™ supplied. NOW Runs on a model B for £6.95 inc. siliillB m

-X- t GUNSMOKE

005 GUNSMOKE is the latest release from SOFTWARE INVASION. It's completely different from any

- game you've played before. Superb realistic sound effects - high speed animation • nail biting action fantastic highly detailed graphics, mixing colours to produce brown, grey and olive in addition to the

normal shades. You play the part of a Wild West Gunslinger, dodging bullets and trying to to shoot

bandits as they appear in doors, windows, alleys and on the roof. There's sixteen different bandits who

need no provocation to fill you full of lead. If you manage to kill them all, it's not over, day turns to night and the nightmare begins again. 50 Elborough St., Southfields,

If you're quick on the draw, this game's for you!

GUNSMOKE runs on a BBC Micro model B and costs just £7.95 inclusive. London SW18 5DN.

ACORN USER MAY 63 ATOM

and thus releases the Atom to performed to write to any register: Once a register has been latched it continue with its program. A sound will remain latched until a new

can be modified by changing the Write register address is sent. This allows required registers. On entering a 1. send latch address signal. multiple read and writes to a

new value into any of the registers, 2. send address (0 to 1 5). register. Reading any register will

the generator will take immediate 3. send latch data signal. give its present value. action and create a sound relating 4. send data bus tristate signal. to the new values. Before entering any of the example programs, the Read

main program must be entered and 1. send latch address signal. I o conclude, the AY38910 offers run. Once the program has been 2. send address. good quality sound effects at a

run it can be deleted, since the 3. send read data signal. modest price and is easily adapted

machine code it creates is placed 4. read data. to interface most small eight-bit out of the way. (NB the machine 5. send set bus tristate signal. micros. Programming simple tones code can be relocated to any and notes is child's play, but

desirable address since it occupies Acorn User has arranged for a complex sounds require a little only 60 bytes). high-quality circuit board to be more work with up to 13 data The best way to see what sort of made up for use in the circuit registers. The chip can produce outlined in this article. The cost of sounds the AY38910 is capable of sounds that vary in volume as well a double-sided silkscreen printed is to experiment. When using the as pitccan made to die or circuit, with plated through holes be write routine, to the start of set W and component overlay is £5.38. increase i volume or even repeat. If the write routine, X should be set to This includes VAT and UK postage any Atom enthusiasts are thinking the required register number (0 to (write in for overseas prices). of expanding the capabilities of Kits of parts, as well as fully 15), and Y should contain the data their machines then the Ay38910 built and tested boards are being to written. with be Use LINK W. prepared, prices on application. offers an inexpensive addition, of With the read routine R should be Write to Acorn User Board particular interest to games set to the start, X should be set to Offer, Electro Technical Services. fanatics. Atom owners using Forth 55 Raymond Road, Hellesdon, the required register number. #80 also have the possibility of Norwich NR6 6PN. Discounts are will contain the data read. envious available on large orders. Please stimulating the sound and Because the PSG is latch driven allow 28 days for delivery. envelope commands of the BBC the following sequence must be micro. INTERFACE BOX FOR THE

>page 55 analogue input, you can hear the the interface box. This has the since it has^a 74LS244 buffer on it noise of the continuous stream of added advantage that if you have a which is uni-directional and

interrupts which the machine is set of eight LEDs you can monitor permanently enabled. Thus if you producing. This can be useful in an data on the lines going to the do try to input to the printer port educational context. printer - this again has obvious you may blow up the chip. The educational value, advantage of having the buffer chip Whilst on the subject of the is that the drive capability ol the

If using a printer with a parallel printer port it is worth saying again port is thereby increased markedly

interface, you may decide not to that it is configured for output only over the PA port on the 6522 use the printer port for interfacing. versatile interface adaptor from

There is no harm in simply leaving Acorn User has arranged for a which it comes. If a given line is at high-quality circuit board to be it off the circuit since none of its logic 1 it is capable of supplying made up for use in the circuit lines is essential to the working of outlined in this article. The cost of 1mA with hardly any voltage drop the circuit as a whole. On the other a double-sided printed circuit, and can manage up to about 5mA. with plated through holes and the printer port it is at logic it 'sink', ie hand, since can component overlay is £11.95. When can only be configured as an output This includes VAT and UK postage draw into the chip, something like (write in for overseas prices). and since it has a buffer chip to 10mA, and I have tested it up to Kits of parts, as well as fully give it extra driving capability, there built and tested boards are being 25mA with no obvious ill effects. prepared, prices on application is no harm in using the port for But in practice I would work on (should be about E80 for com- logic 1 both purposes. However, to avoid pleted board). being able to supply 2mA at connecting and disconnecting the and sink 1 0mA at logic 0. Write to Acorn User Board sockets underneath the micro, it Next month: Applications for the Offer, Electro Technical Services, would be worthwhile mounting an 55 Raymond Road, Hellesdon, interface box and some test Discounts are IDC plug on the box and wiring it in Norwich NR6 6PN. routines if you decide to make the available on large orders. Please parallel with the sockets, the circuit yourself rather than buy it so allow 28 days for delivery. printer could then be plugged into ready-built and tested.

64 ACORN USER MAY Beeb-calc A ROM based spread sheet program, like Wordwise this firmware is very fast and simple to use — yet is a powerful spread sheet analysis program, considerably better than the original 'calc' program — full floating SB point maths Works in 80 or 40 column screen modes variable column widths Works with either cassette or disk This ROM coupled with Wordwise can turn your micro *»

2 machine code programs — one in ROM, one on tape Essential for the machine code programmer. An ideal compliment to the assembler built into the BBC machine. Contains a full machine code monitor allowing examination and alteration of memory, registers, setting of break points and even single stepping through machine code programs.

ROM based £ 1 9.00 + VAT cassette £10.00 + VAT DlSK DOCtOT A ROM containing useful disk utility programs Enables the recovery of any data off the disk including deleted files etc The full disk editor allows the alteration of any bytes directly on the disk (or in memory), or the loading and saving of any track or sector on the disk Automatic transfer of programs from tape to disk and visa versa Includes a whole host of other useful utilities— string search, function key editing, the ability to format 35, 40 & 80 track disks £igoo + vat punter toolhit RON This includes routines for high resolution screen dumps for both the EPSON and NEC printers Will work in any graphics mode with automatic grey shading of all screen colours The most useful feature of this program is its 'spooling' capability, this enables data such as a program listings or high res screen dumps to be automatically spooled from your disk to the printer while using your BBC machine for running other programs £19.00 + VAT Quantity discounts starting at five oft. Wordwise < Wordwise The word processor for the BBC machine. THE WORD PROCESSOR FOR THE BBC MICRO This ROM based word processor has received superb reviews. A powerful and flexible system — it's greatest strength being

that it is fast simple and very easy to use. No other existing word processor (even ROM based, costing twice as much) can compare with the flexibility of this system. Supplied with full spiral bound manual and cassette containing an example document and free typing tutor program.

£39.00 + £1.50 + VAT J**>.. p&P Now available from stock Quantity discounts starting at five off

all ROM based software requires new series 1 Operating Systems We X2 are now in the position to supply 4&P 1.2 ROM's for £5.00 + VAT when w* buy any of the software. & you above CASH OR ROYALTIES

t)mputer I .oncepdsi ACB 16, Wayside, Chipperfield, Herts,WDa 9JJ. telC09S"7"7J 6S"727_

ACORN USER MAY 65 6

EXTENDED COLOUR-FILL GRAPHICS E.C.F.G. GIVES YOU A CHOICE OF BBC MICRO !! 4 BILLION + !! O •cienfclf ic S. educational application* O

SHADES FOR TRIANGLE FILLING COMPLETE HARDWARE S SOFTWARE PACKAGES FOR MODEL B BBC MICROCOMPUTER SYSTEM IN BBC MODES 0,1,2,4 k 5

* PLOT 81 and 85 commands for triangle-filling Professional Joystick 35 BO have been adapted to use the ECFG fill— shade Environmental Monitoring Packages currently selected by new ECFG user— friendly -Temperature, niuminatioo, Humidifcy eta in-nn commands. GCOL is still used for line colour. lOOyear Clock -Calendar Unit 35-5Q * Easy choice of 17, 289 8c 6561 subset colours

between those normally available in 2, 4 & 1 colour MODEs. Further options include colours, ALL SOFTWARE PROVIDED ON CASSETTE

angles, spacings 8c widths of cross— hatch etc.

manuals only availabla at 75; )

* ECFG commands can be used in BASIC, typed • i kage purchase from the keyboard, accessed in Assembler, or and in future BBC Micro languages. ECFG is MOS- ALL PRICES INCLUDE P*P VAT adaptive, and proven with versions 0.1 to 1.2 for datalla of thaaa and othar products * Bootstrap from cassette rapidly builds an ECFG plaaaa aand a. a. a. to l- module at a RAM address pre-defined by PAGE, Chris Hall Software Engineering which is then automatically increased 512 bytes apartment B to allow immediate LOADing of programs etc. 47Bueh Lana Fraoklaton PRBSTOCM PR4 1SB Price : £10 inc : Mail Order only GAELSETT (ECFG) BBC MICRO CLOSE, STEVENAGE, HERTS. SGI 4PW. 44 EXETER C09L -effective Instrumentation for- Home 01 Si hool (Tel. Stevenage 51224)

WEST OF Bourne Educational Software SCOTLAND BES makes /earning fun BBC

WORLD WISE (Code P19) £7.95 BBC & ATOM DEALER AND Constructive geography programs allowing children to build databases covering both the UK and the World. SERVICE CENTRE — Choice of 10 categories in each program eg. rivers, antiquities, towns, mountains etc.

-Powerful review and edit facilities to correct entries if necessary. HARDWARE — Save or load the database at any time. — adjustable! Model A £299.00 inc. Sound adds interest — and level is — Motivates children as computer tries to guess what they're thinking of. Model B £399.00 inc. -Encourages use of atlas and reference books as children create the Postage & Packing £6.00 inc. database. — Maintains extensive information on individual children's entries. -Suitable for ages 7-15 and for Model B. SOFTWARE WORDHANG (Code P20) £7.95 Acornsoft Bug Byte Program Power also Educational version of 'hangman' word game, with limited allowance of wrongly guessed letters. 30 Golf Fruit Machine Dodgems — Learning to spell no longer a chore as children try to keep him alive. -Full colour graphics and simple screens appeal. full list Send SAE for — Includes lists totalling 260 words. Your own word lists easily created and saved too. MONITORS -Adjustable time limit for each guess. PRINTERS — Monitors details of individual childrens performance, list used etc. -Suitable for ages 5-13 and Model B. A selection on display A ANIMAL/VEGETABLE/MINERAL (Code P21) £4.95

Think of an object and see if the computer can guess it correctly. The Upgrades carried out computer asks a series of questions as it tries to guess the answer. The correctly or asks for a question to distinguish the Disk and Econet interfaces fitted program either guesses object from the incorrect guess. Also a wide selection of books and magazines — Stimulates fascinating and education discussions as to eg. the difference between an alligator and crocodile. — Encourages use of reference books. WEST COAST PERSONAL COMPUTERS — Monitors details of childrens entries. 47 Kyle Street Suitable for ages 7-13 and Models A&B. AYR For 24 hour despatch send cheque/PO to: BES, Dept AU3, Bedfield Lane, Headbourne Worthy, Tel 0292 (285082) Winchester, Hants S023 7SQ. Tel: (0962) 882474

66 ACORN USER MAY REVIEW

Typeface and manual spoil excellent graphics from fast Olivetti printer, says George Hill

THE Olivetti printer is of a type not seen before in the home-computer ITALIAN PRINTER. GOOD FOR GRAPHICS market as it operates on the 'ink-jet' principle. The ink is not liquid, but is a compressed solid, in a small, easily replaceable glass tube. Ink is 'fired' at the paper by a spectacular electrical discharge, and the resulting black dots are directed by electrical fields. In effect it is a dot- matrix printer, and must be judged by the standard of others in its price-range (£360). The Olivetti is very compact, but

its big advantage is that the dots are very small which means superb - graphics printing I doubt whether any other printer can rival the

resolution. It prints 110 dots per inch in the horizontal direction, and an amazing 220 vertically. The picture of the film star's face (Marilyn Monroe or Jean Harlow?) per line; and double width, double and has a curious 'squashed' beloved of printer adverts can be height, and double width-and- appearance. Changing to a nine by reproduced in amazing detail on a height in each of these spacings. seven matrix would have produced

rectangle less than two and a half Unfortunately it does not seem such a huge improvement that the by two inches. possible to mix single and double minor decrease in speed would On sending a single escape height characters on a line, and the have been well worth the sacrifice. code ESC CHR$(45), the image can linefeed is automatically doubled The character set is 'international', be reversed, and another sequence when printing double height. Thus as befits an Italian printer, with the

ESCCHR$(47) doubles the picture it is possible to produce super- ability to produce German, size. The resolution is in fact scripts, but subscripts are less Norwegian and French characters. greater than that available in any successful. The 96 character font does not Atom or BBC graphics mode. Printing is fast, giving 50 full include 'chunky graphics' characters Graphics dumps are easy to lines per minute at whatever or italics, and characters from 128 write for the Olivetti. A minor spacing. Maximum speed is 120 to 255 feebly repeat those from to quibble is that there are 880 dots in characters per second, and an 127. the horizontal direction, while most average during program listing of Also the linefeed arrangements computers use multiples of 320 on about 60. leave something to be desired. You this axis. The Olivetti has enormous can select linefeeds from one line

The image is defined in terms of potential, but (and it is a big but) upwards, so the paper always bytes both horizontally and the ship seems to have been advances at least one line vertically, which means the whole spoiled for a ha'p'orth of tar. The whenever the printhead returns to

picture is defined in a single character font (in ROM) produces the start of the line. This is not escape sequence at the start of the characters on a seven by seven dot selectable, and you are thus

program. The manual is as usual matrix. This means capital letters debarred from overprinting.

confusing on this point. I would are printed on a notional line one The printer is clean in normal

explain it as follows. The sequence dot below that on which lower case use, producing an unsmudged

is: I ; ; letters (figure 2). output. if leave the ESC G ; m n o ESC Z appear Thus However, you although g, y etc, have 'true paper stationary after a dense

I is the number of dots skipped in descenders', so do all capitals and graphics dump (eg a 'reversed' the left margin. numbers. picture), the printer leaves a faint m is the number of dots on the X The print is thus not letter quality, black line on the paper where ink axis divided by 8. has been deposited from the paper n is the number of dots on the Y guide. axis divided by 8. Finally, to my bete noire, the o is the spacing between rows of manual. Do manufacturers deliber- dots. ately set out to confuse their ; \ _!~" ' ^ ':': '"'; - As usual these parameters are igrfltflljBBHI customers? Have they no idea their critical, and miscalculations cause product may be bought by people ; chaos! with no experience? The Olivetti's The printer has a good variety of 1 'Little Red Book' is one of the worst. printing styles (figurel), including Four pages are devoted to the three selectable horizontal spacings trivial task of using the roll holder,

giving 80, 97 and 147 characters The Olivetti JP 101 Dry Ink-Jet Printer and feeding paper into it, while 12

ACORN USER MAY 67 BBC OWNERS Why not consider the HOBBIT FLOPPY TAPE SYSTEM for your computer?

The HOBBIT gives you all the facilities you would expect from a floppy disc at a fraction of the price.

Brief Specifications ft Read/Write speed of 750 BYTES per second ft Capacity: 101 K BYTES per CASSETTE ft Average access time 22 seconds ft Up to 138 FILES per CASSETTE ft Completely automatic - no buttons to press ft Fully built, boxed and tested. Just plug in and go ft System can support TWO DRIVES

Available from stock PRICE £135.00 plus VAT

Also available for NASCOM computers PRICE £120.00 plus VAT Access and Barclaycard accepted For more details contact:

Ihrjn Computer Products

KILN LAKE, LAUGHARNE, CARMARTHEN, DYFED, SA33 4QE. Tel: Laugharne (099 421) 515

The bbc Microcomputer

Drop in for a frank discussion and expert Specialists advice on your requirements or arrange a demonstration. We give a full and backup to ALL our sales. GUILDFORD COMPUTER CENTRE offers expert a complete range of Computers for Stockists of:- BBC/Acorn, Torch, Oric, Home, Business and Educational Olivetti, Hitachi, TRS-80, Commodore, applications. Dragon, Sharp, Sirius, Osborne, IBM, Epson, Seikosha, Cumana, Large stock of additional equipment Newbrain, available includes:- Printers, Hard/ etc. Floppy Disc drives, Monitors etc., for most makes. An extensive range of Business software GUILDFORD (Accounts, Stock, Payroll, Word COMPUTER Processing etc.). •E-N-T-R-E HITACHI £s commodore <§> 1 The Quadrant, Bridge Street, HCORN TRS-80® Guildford.SurreyGUl 4SG Olivetti IPUTER OCD0 Telephone (0483)578848 .

68 ACORN USER MAY 1

REVIEWS

pages are wasted on technical details of the interfaces. The only important piece of information in 12 Of }RAC fEf-

r r - the latter section, the settings of the and HON *t* little characters at 13 c haracters ps . .: DIP switches, contained a serious misprint in the numbering. oc ters pe~ i neh The section devoted to operating i F IS Q 1 commands occupies a mere nine is Qt 12 CHARACTERS pages (omitting pictures). A curious convention is used throughout, with 18 characters per inch hexadecimal numbers represented by fractions! These are nowhere Figure 2. Close up of the offending type design translated into decimal, and in some cases are omitted altogether. The only program examples concern graphics, and use LPRINT, rendering them difficult for Atom or :> O UBLE Jr r~i BBC users to translate. Finally, in common with most printer manuals, OUBLE height there is no alphabetical index. t So, if you want to produce ! ! I DOUBLE wide U G Ht!_ J. L3UNf I I legible program listings and superb pictures, the Olivetti is as good as Bock b c normal

anything in its price range.

However, if letters and circulars are your aim, better print quality is Double underlining available from a conventional dot matrix printer for the same price. Next month: A Basic graphics Figure 1 . Sample output (also see listings in Joe Telford's article, p27) dump for the Olivetti.

BBC Spectrum ftO/COm CLEAR AND CRISP GIANT ADVENTURE GAMES CHARACTERS AND GRAPHICS 1) COLOSSAL ADVENTURE: The classic mainframe game "Adventure" with all the original treasures & creatures + 70 extra rooms 2) ADVENTURE QUEST: Through forest, desert, mountains, caves, water, Get the best from your BBC/Acorn by using the RGB tire, moorland and swamp on an epic quest vs Tyranny output 3) DUNGEON ADVENTURE: The vast dungeons ot the Demon Lord have survived His fall. Can you get to their treasures first? Get crisp, clear graphics in full bold colours with one of our Every Level 9 adventure has over 200 individually described locations and is TV/ Monitors fitted with a 6 pin DIN input socket. packed with puzzles - a game can easily take months to complete. Only sophisticated compression techniques can squeeze so much in! Each game needs 32K and costs £9.90 Each is a TELEVISION! • BBC FORTH, FORTH TOOLKIT Each is a COMPUTER MONITOR! "rq FORTH" runs on 16K or 32K BBC Level 9 Computing are pleased to

micros and costs £ 1 5. It : announce a new toolkit for buy just a monitor * follows the FORTH-79 STANDARD "r q FORTH" on 32K BBC micros. Why when you can have a standard TV

and has f ig-FORTH facilities; It costs only £ 1 and adds the follow- as well? * provides 260 FORTH words; ing facilities to FORTH: * is infinitely extensible; * a 6502 assembler, providing - - * has a full-screen editor, machine-code within FORTH; A2102/5. 14}" £295.54 A6100, 20" £365.68 * allows full use of the MO. S; * turtle graphics, giving you A3104/5, 16" - £327.08 A7100, 22" - £399.1 * permits use of all graphic modes, easy-to-use colour graphics; 0-2 * decompiler routines, allowing the even (just!); A8400, 26" - £499.35. Remote control (ideal for schools) » provides recursion easily; versatile examination of your * runs faster than BBC BASIC; compiled FORTH Programs; * needs no added hardware; * the fi_: double-number set; All prices include VAT, carriage, 12 month warranty and a * includes a 70 page technical * an example FORTH program: and 2m 6 pin DIN lead. manual and a summary card; demonstrations of graphics; * has hundreds of users. * other useful routines. AHIfAHI Asteroids m/c,g £7.90 The TVs are from GRUNDIG's range. Remote control and ImrWIII Galaxy Invaders m/c.g £5.90 stereo sound also available. Extension Basic £15/£30ROM Missile Defence m/c,g£7.90 Adds 30 new keywords to BASIC Super Gulp eb.g £4.90 Compression Assembler 2 £12 5-games cassette misc £5.90 contact: Small Source + high speed (FULL RANGE IN CATALOGUE) ALL PRICES INCLUDE P I P AND VAT. All programs are in stock and will be sent within NEWARK VIDEO CENTRE 2 days of receipt. Please send order or SAE for catalogue, describing your micro, to: LEVEL 9 COMPUTING 108 London Road, Balderton, Newark, Notts Dept A Hughenden HP1 , 229 Road, High Wycombe, Bucks. 3 5PG Tel: 0636 71475. Open 6 days a week.

ACORN USER MAY 69 . a

FOR THE BBC MICRO REGISTERED REFERRAL BRITAIN'S LARGEST SINGLE CENTRE FOR THE BBC PROJECT -MICRO USER GROUP

BRITAIN'S LARGEST COMPUTER USER GROUP DEVOTED EXCLUSIVELY TO THE BBC MICRO MEMBERSHIP NOW EXCEEDS 16,000 16,000 members can't be wrong — BEEBUG provides the best support for the BBC Micro. BEEBUG Magazine — NOW 68 PAGES devoted exclusively to the BBC Micro. Programs— Hints & Tips — Major Articles — News — Reviews — Commentary. PLUS members discount scheme with National Retailers. PLUS members Software Library. 10 Magazines a year. First issue April 1982. Reprints of all issues available to members.

July Issue BEEB INVADERS and other programs plus articles on SCREEN SHOTS FROM PROGRAMS 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 hints and tips. September Issue: High/ Low Card Game, and Hangman Programs. Articles on Logic on the Beeb, Debugging, Moving multicoloured 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 Software Reviews. November Issue: Program Features: Racer (excellent 16K racing car game), Mini Text Editor (Mk2), Transparent Loader, Music with Memory, Harmonograph Emulator, New Character set for Modes 2 & 5; and cassette block-zero - bug retrieve. Plus articles on sound and envelope design — includes indispensable envelope editor program; Debugging Part 3, BBC Basics Memory Maps and addressing explained; Serial Printer Port (RS423) 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 (invader-type game), Breakout, Artist (Joystick painting program); Rescue (miraculously retrieves programs after bad loading or 'Bad Program' message); and Pack — program to compact Basic programs. PLUS Disc System Review, Software reviews -including Wordwise, Book reviews, Adding Joystick interface to model A; How to access the video controller chip; and ideas for the newcomer; plus a new crop of Hints and Tips. February Issue: Program Features: BEE BMAZE Find your way through the random maze, guided by 3D views from inside the maze - an excellent game. FIVE DICE -A Beeb implementation of YAHTZEE(R), a novel dicegame. Alsoa listing of WINDY FIELD - a creation from Acornsoft, SPIROPLOT screen dood- ler, and a complete memory display program in a user key. Plus Machine Code Screen Dumps for the Epson and Seikosha Printers; articles on USING FILES,

IDEAS ON AN I MATIONI Including a Rotating Cubeprogram), an Introduction to the Use of Procedures, a Survey of Books on the BBC Micro, and a Roundup of Disc System Hints. PLUSa variety of HINTS, TIPS AND INFO, includingasingle VDU command toperforma SIDEWAYS SCROLL. WIN A COLOUR MONITOR. WORDWISE WORD PROCESSORS AND ACORNSOFT GRAPHICS BOOKS IN OUR THIRD SOFTWARECOMPETITIOM. March Issue: Program Features: Life (32K). Artillery Duel (16K 32K), Square Dance. 3D Rotation (will rotate any object). Printers for the BBC micro - Review of Epson, Seikosha, Tandy and Olivetti. What to do with the new Operating System Chip, Disc Formatter Program, and full Disc instruction set, Newcomers, article on Text and Graphics Windows. PLUS How to get a new Operating System ROM and a special deal on Wordwise (members only). SPECIAL ANNIVERSARY ISSUE THIS APRIL INCLUDES FREE BBC MICRO REFERENCE CARD, AND COMPLETE INDEX TO VOLUME 1

SPACE CITY DEC 1982 3D ROTATION, MARCH 1983 BEEBUGSOFT: BEEBUG SOFTWARE LIBRARY offers members a growing range of software from £3.50 per cassette.

1. Starfire (32K). 2. Moonlander (16KI. 3D Noughts and Crosses (32K). 3. Shape Match (16K). Mindbender (16K). 4. Magic Eel (32K). 5. Cylon Attack (32K). 6. Astro Tracker (32K). Utilities: T. Disassembler (16K). Redefine (16K). Mini Text Ed (32KI. ^Applications: 1. Superplot (32K). 2. Masterfile (32K). 13% DISCOUNT TO MEMBERS ON THE 'EXCELLENT WORDWISE WORD PROCESSING PACKAGE-THIS REPRESENTS A SAVING OF OVER £5.00.

Send £1.00 & SAE for Sample Membership: UK 5.40 for six months, 9.90 for one year. Overseas one year only: Europe £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

ACORN USER MAY REVIEW

ACORNSOF REACH DIZZY HEIGHTS

FIVE minutes on Starship Command and I was hooked - but dizzy. It's a Star Trek and Asteroids combined with keys controlling rotation, thrust, brake and fire (for starters!). There are two strategies. You can sit tight and let the enemy ships come to you (saving energy and dizziness) or chase them, dog fight style. The dizzy spells come in because everything rotates around your ship, which stays in the centre of the screen.

Once your ship's energy has gone, it self- destructs - but there is an escape capsule and you can get another chance. It's all in black and white, hi-res graphics on a model B. Acornsoft produce the game for £9.95. Another neat feature is a 'freeze' option, so you can stop, answer the phone, and re-start. - TQ

BASIC MY DEAR WATSON TURF PROGRAM WONT

Elementary Basic by Henry Ledgard BEAT THE BOOKIES and Andrew Singer (272pp, Coronet, £4.95) 'Holmes' book for Horse Race Forecast Program, by THIS unusual book is aimed at Pascal Professor Frank George, Sporting people who are keen on learning to uses same programs Forecasts, £19.95 It purports write serious programs. and ideas to be an unpublished Sherlock as Basic THIS program enables you to enter Holmes manuscript which reveals version data about all the horses in a race and then evaluates the good bets. how Holmes got his hands on Covers are A word of caution to the get-rich- Babbage's Analytical Engine. identical except quick merchants, however: It Through the eyes of Dr Watson for name doesn't claim to be infallible! (being his usual doltish self) the of language The author, according to the great detective uses the engine, unlikely to be of much use outside booklet which accompanies the programmed in Basic, to solve a program, is professor of cybernetics the context of this book. This is not of number criminal cases. On the at Brunei University and 'an expert surprising when you consider that way, Watson (and the reader) are in all aspects of forecasting'. What their main function is to illustrate shown a great deal about program his program does is to accept infor- different aspects of programming structures, functions, subroutines, mation about a race (so you'll have and problem-solving. The last data files, algorithms, etc. to equip yourself with a serious chapter entitled The Final Pro- Holmes's main emphasis racing paper like The Sporting Life gramme', consists of a piece of or The Sporting Chronicle) con- throughout is on the necessity of

software some 20 pages long, but I taining to 40 horses. Using the adopting the 'top-down' approach up doubt if many readers will be paper, you feed in information on in designing and writing a program. prepared to type it out when the something like ten factors. In essence this method requires end result is only a word processor. However, the program takes no the programmer to design the account of factors which some Against this it should be said program in a hierarchical system of fanciers of horse flesh may hold to that all the programs in the book different levels. At the topmost level be important: such as jockey, are laid out with tremendous clarity the more general aspects of the handicap, racetrack, and the going. and documentation. The Basic problem are defined (probably in The chief drawback of the used conforms to ANSI (American English rather than a computer program (apart from its limited National Standards Institute) Basic, language), and the more specific range of important variables) is the which means only the file handling questions (such as the internal rep- amount of time it takes to feed in statements will need amending for resentation of data) are worked out data: a 10-horse race took me 30 the BBC micro and Atom. minutes to evaluate, including the in increasingly fine detail in Basic The Sherlock Holmes gimmick is time taken to rummage through on the lower levels. well-sustained both by the spoof Sporting Life. It is certainly the most rigorous Conan-Doyle prose style and by Still, afficionados of the turf tired approach, requiring the author to reproductions of Sidney Paget of always backing a donkey may have thought through every aspect while drawings from the Strand magazine. find this a useful companion of the before writing a program risking their shirts. Do not, however, Certainly a book with a difference. single line of code. think this package is a gateway to Unfortunately, the programs are Simon Dally your fortune!

ACORN USER MAY 71 HINTS & TIPS

* page 32 string to contain the characters problems based around this However, Acorn quite rightly point from which the user may choose. technique, but the main problem out that their implementation of Some GPIR's include a range of was that we had to self-modify functions is procedure-like, in that a such strings built into them. This code in one program line, and then function can have many lines, and version doesn't simply to save use that line to call a procedure. once in a function any number of executed. space. One suggestion is that in a I have recently received a few Basic commands can be setup section early in the program, letters from readers pointing out a Finally, because a function is define strings such as: much more elegant approach. It is regarded as a mathematical

always gratifying to see that expression, it can be called during cap$='ABCDEFGHIJKLMNOPQ readers will not only digest the execution of the EVAL statement. RSTUVWXYZ" written word, but will spend time The result is we write all the low$="abcdefghijklmnopqrstuv improving on it. necessary procedures as functions, wxyz" Look at program 1 1 . This is the as in lines 180 to 400, then we can "!#$%&•()=-,<>+*" pun$= coding which Acorn suggested call them by a line like line 70, +CHR$34 could demonstrate an improved which is set up by the input line of nos$="0123456789" - method of calling procedures. line 60. If EVAL cannot find a plus any other special valid strings The theory behind the coding is function to match Q$ then the error such as "YesNo". Then call up the that while dynamic procedure calls trapping set up by line 10 ensures GPIR by a line like are not covered under version 1 of that we don't fall out of the Basic, functions are. The reason for program. name$=FN gpi(21,3,cap$+low$) this is that the reserved word EVAL Of course this approach is

which would allow any name of up is intended to enable the user to extremely useful, but if you re- to 21 characters to be entered, type, during the execution of a examine the self-modification tech- using only letters. Initial letters program, an expression which the nique in February's article, you will would be capitalised. computer can decode. The User find that it can be easily modified to only and In February, I explained a Guide warns that EVAL can handle *SAVE method of dynamically accessing evaluate mathematical expressions, *LOAD commands, for

1 Basic version . I hope to detail procedures. I mentioned that this for example: was rather naughty, but worked A$ = "M*X+C" these in the near future, unless you quite well. There were several P. EVAL(A$) know a better way?

BBC SOFTWARE TIMESHARE YOUR COLOUR QUALITY SOFTWARE PRODUCED BY PROFESSIONALS MONITOR WITH THE FAMILY And used in hundreds of schools throughout Great Britain Present their latest tape: FUN WITH WORDS £8.05 Stan your fun with alphabet puzzles in GUESS A LETTER. Continue your play as you learn about VOWELS, know the difference between THERE it THEIR and have games with SUFFIXES. After working so hard reward yourself with games of HANGMAN. Learning should be fun. The tape includes GUESS A LETTER, VOWELS. THERE/THEIR, SUFFIXES and HANGMAN.

EDUCATIONAL 1 A or B C8.05 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 MATH1, MATH2, CUBECOUNT, SHAPES, MEMORY (Model B only). SPELL and CLOCK. EDUCATIONAL 2 A or B £8.05 Although similar to Educational -1 this tape is more advanced and aimed at 7 to 12 year olds. The tape includes MATH1, MATH2, AREA, MEMORY (Model B only), CUBECOUNT and SPELL. GAMES OF LOGIC & CUNNING A/B £9.20 For children and adults alike. The tape includes AUCTION, FLIP, REVERSE, TELEPATHY and HEXA 15 (Model B only). SUPERLIFE B £9.20 Fast (machine code) version of a popular 'Game of Life' in a large universe. KATAKOMBS B £9.20 Are you cunning enough to discover and seize the treasure in the Katakombs AND return alive? What and where are your enemies? Can you outwit them? Yes? Then your adventure will take you through unending forests, besides tumbling streams, over lonely plains to desolate ruins and finally underground to the tortuous Katakombs. Be prepared for anything! UTILITIES A/B £8.05

Behind the mundane title lies an assortment of useful procedures and functions which can save you hours/days of programming 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. Add 50p p/p per order, Please state your model. Cheque/ PO to GOLEM Ltd, Dept A, 77 Qualitas, Bracknell, Berkshire RG12 4QG. Telephone (0344) 50720 Also available from reputable dealers and on Micronet 800

72 ACORN USER MAY 1

SIR Computers Ltd Official BBC CARDIFF Programmers Kit

Agents for Acorn, BBC and TORCH Computers forall BBC Microcomputer users!

Microcomputers BBC De-luxe BBC Programmers Kit consisting on BBC Model B with 1.2 operating system Li99 * 1 00 sheet flowchart pad with Model Bwithdis< interface £509.00 de-luxe BBC grip binder Single I00K disi drive £249.00 Dual J Mink disi drive . 089.00 #100 sheet screen layout pad with The disc manual and utilities disc are both mi luded de-luxe BBC grip binder Dim interface for the BBC Micro (kit) I 9 (fitted) ii 10.1)0 *1 00 sheet symbol design pad with Upgrade 0< BBC Model A to B !. 90.00 grip binder Please telephone tor up in date information on Prestel, teletext, speech de-luxe BBC synthe: PLUS super quality BBC ringbinder to store your programes and notes TORCH Computers items finished Z-801 ir the BBC Microcomputer £S95.00 All This unit connects to the BBC Vlicro in the same wa^ rn il dis< inOfficial Livery i BBC drive, but as well as offering a d under BBC

BASIC or othei languages il pro\ ides the option ol using the wide range

ot CP.'M software available lot business and data proi essing applications. Ihe firmware supplied with the ma< hine allows swit< hing between BASK and cp\ a powerful ope tem developed from CP/M

This is R.R.P. In addition to the dis< pack a second processor is supplied a Z- only 80A with its own 64K RAM card communicating with th< 6502A in the (incVAT) BBC computet through (he Tube', typically the speed ol execution ol

- ms undei the twin processoi system is increased by up to >0 compared with a conventional single putei

A third pi ssoi the 16 bit 68000 will shortly be available.

TORCH ( F240 £2795.00 (Ex. VAT)

This is an extension ol '<>< omputer/Torch disc pa< k system, available in a single unil Ihe. mtains a BBC-based peripheral

"'i'"'. ; computer dual • pro eS50l I ted " the main Z-80 a 2 400K di»

1 drive as described above, a high resolution ter) coli iui i i ^nrtocrt

anda< omplete British reU < om approved 1200 baud modem It is the only microcomputer which has been granted permission tor dire< t connection oincfer PubiU Switched telephone Network both In the UK and the United States The TORCH can communii ate eithei directly with another TORCH or

with virtually an> othei I putei via Prestel Using the Gateway

fa< iin, foi the rORCH to /asl amount- 61 information stored bi private organisations on publii d terns,

allows • rhe vtailbox fa« ilit^ of Prestel also the use ol lei tronk mail, screen flow < ; hard r< 1R1 ii ii.: vtB disi drive feyout ..' I ( 1 1240/21 i\s above bul with a MB hard dia drive. tvncfer ohai Peripherals

Seikosha CP I00A printei £229 NLC PL 8023 printer £389.00

Mil rovltei 14 ' RGB Monitoi £299.00 Kaga 12 RGB Monitoi £280.00 Sanyo 14" RGB M 01 £26 High resolution 12 black/green monitor i 85.00

Epson l\ 80 ...... £475

Software iPMWMMUWMM. aaaMMMW

ihe mllowing -uppliei- We i urrenth. hold in stoi k program- imm Available from •\c ornsofl Level 9 Software

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. \i Gloucestershire^ 1BR. i i GL6

SIR Computers Ltd 91 Whitchurch Road Cardiff Trade Enquiries welcome. Telephone (0222) 21341

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

I) 356 496 Fill shapes in one of 23 colours (Mode • "! Draw points lines rectangles ellipses and circles D Smooth curves Wire frame diagrams Hidden line removal Draw in perspective Measure scaled distances Ekta sketch lines Half tone facility Mirror images Repeat images, SS, enlarged, reduced, stretched Actual colour displayed

Store up to 1 ellipses or circles in memory Redraw any one of these at cursor position Change any actual colour for one of 8 others Clear screen, load screen, save screen Print characters or numbers at any pixel point Error messages for incorrect input Fully comprehensive manual

This programme has been purpose designed by professional Graphic Designers for simplicity and ease of use, and is undoubtedly the most versatile drawing programme on the market at this time. There is no need to input any numerical data, as all judgements are made visually. The BBC Micro is the finest drawing designs machine in its price range. Find out what it can do.

The A.B. Designs drawing programme costs only £35 for over 70 (unctions (Model B). When ordering send Cheque/PO and include 50p (or P&P. Please include phone no. with all correspondence. For further information send SAE and phone no. to A.B. Designs. 81 Sutton Common Road, Sutton, Surrey. 01-644 6643 (closed all day Thursday).

BBC C0MPUTER-EPR0M PROGRAMMER WITH AUTO-RUN FACILITY FEATURES COMPLETE BOXED UNIT | ftlff COMPREHENSIVE eprom programmer RKl I MM r wa-t INCL f 0^^f%^\ VAT for 24/28 pin packages 251 6/271 6/2532/ £120 P&P 2732/2564/2764/27128/27256. " DISCOUNTS AVAILABLE AUTOMATICALLY RUNS a user YOUR for Schools, Colleges & Clubs, programme on power-up or Trade enquiries welcome pressing BREAK, FAVOURITE EASY CONNECTION with Send cheque for order to:

BBC via 1 MHz bus interface. Advanced PROGRAMME RUNS on PROGRAMME Technology BBC models A and B. Products FULLY AUTOMATIC configuration ONTO Limited foralleproms.

EASY USE with full operator Station Road. Clowne. Chesterfield prompting. EPROM S43 4AB

For further details send a stamped

AUTO-RUN self MICROCOMPUTERV addressed envelope to the COMPLETE with C10 cassette containing programme, cables, software listings and ON address above. full explanatory manual. Model A's may require a 34 way RESET Please allow 28 days for delivery. connector fitting onto the 1 MHz bus. VERSION ALSO AVAILABLE FOR USE ON ACORN ATOM, SYSTEM 3, SYSTEM 4

74 ACORN USER MAY COMPETITION

Simon Dally offers £60- worth of software and examines a difficult issue SOFTWARE PIRATES SET FOR THE BIG TIME

Hlow many microcomputer owners January's problem proved a few notable exceptions, Tandy can put their hands on their hearts mite difficult for many of you software is notably inferior to other

and claim that they have bought all (no doubt you were too busy TRS 80 software (especially its the commercially produced software trying to locate the Beale disk operating systems), Tandy in their library? The answer is treasure). There were 26 resolutely refuses to acknowledge precious few. And yet the vast correct entries. The first the existence of anything other than majority of micro-enthusiasts are message (a substitution code) its own programs. Even more wholly law-abiding citizens who read: to all substations new deplorable was the behaviour of would be appalled to hear signals section chief is a right Commodore, who market the Vic themselves described as thieves. XXXX he says we are lazy with and the Pet. They ran an The grossest culprits might security and make too many advertising campaign claiming that concede sotto voce that they miftaks eeee mistakes new Commodore-approved software was occasionally indulge in a little cipher replaces existing pro- in some way 'good' for your

'piracy' - an agreeable, romantic cedure and starts twelve machine. It later transpired that all and swashbuckling-sounding word hundred hours tomorrow based that was necessary to obtain the

- but to suggest that by breaching on a famous poem every day I officially approved' label was to someone else's copyright they are hate poetry. pay Commodore some money to indulging in theft- well! The second message was a advertise your products. Evidence shows that illicit book cipher based on Gray's Against this dismal background, copying is virtually universal. A Elegy ('The curfew tolls the with the bad swamping the good

recent analysis of the owners of the knell of parting day . . .'). It and with many consumers feeling popular Acornsoft game Snapper read: to all substations I hope 'ripped off, you have only to place concluded that less than one in fifty this took you as long to the normal human desire to get had purchased their copy of the decipher as it took me to something for nothing and you program. User groups are particu- encode the problem is how have all the ingredients for a larly guilty here. Whenever micro- much wood could a woodchuck flourishing pirate trade. And the

owners congregate programs are chuck if a woodchuck could problem is that when pirates swapped to and fro like cigarette chuck wood. flourish good software gets ripped cards. All this may seem fairly The winner, to whom £50 off even more frequently than the innocent and friendly. After all. the worth of Acornsoft packages bad, sloppy stuff flung out to make pooling of knowledge and the have been sent, was M. Booth its slapdash creator a few bob. passing on of hints and tips is the of Morecambe, Lanes. Considerable ingenuity and fuel which powers the engine that expertise have gone into the keeps our hobby moving. But from yourself up as a software supplier business of software protection in the point of view of the software your investment is limited to buying recent years: the most commonly- authors and distributors these trivial a micro and some advertising used methods are tapes which run

little transactions, multiplied by the space in magazines. It is amazing automatically upon loading and thousand, add up to a massive loss how trusting people are in sending cannot be listed, and diskettes of revenue. One software writer off comparatively large sums of formatted in non-standard ways.

friend of mine has lost count of the money to advertisers they've never There is a growing trend to number of times he has been heard of for products they haven't produce expensive software on offered an expensive accounting seen and which all too frequently EPROMs (erasable programmable package at user group meetings. do not live up to their description. ROMs) or to insist on 'dongles' being The would-be traders have no idea Most of us learn this lesson fairly resident in the system (a dongle is

that he himself wrote the program! quickly: one of the first programs I a small piece of hardware marketed This at least is the conventional bought for my first micro was an with the software which has to be view of software piracy, that tens of 'expert' chess program which not plugged into something like the thousands of pounds are being only proved to be wholly ignorant cassette interface before the

taken from the mouths of the of the en passant rule but was also program will work). There is little starving legitimate dealers because inordinately fond of illegally evidence that any of these methods of widespread theft. But is this view castling through check! adds significantly to the protection.

necessarily correct? Moreover, the attitude of many No cassette program in the world is One of the more disturbing hardware suppliers has not helped. immune from straightforward reel- features of the software market Some dealers chuck in a load of to-reel copying - on decent worldwide is the extent to which (pirated) software in order to clinch equipment the quality of the rubbish has become the norm a sale; others try feebly to cash in backup will be only marginally rather than the exception. This is on an area they don't know much inferior to the original. People hardly surprising when to set about. Despite the fact that, with a openly market tapes and discs

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

The BBC Microcomputer system is generally identified by performing tests selected from a menu regarded to be the best micro in its price range you of standard tests. 'Organic'is a program dealing with can lay your hands on. So, if you're thinking of organic compounds. buying one or already own one, you'll want to know Learn more languages. about the software that's been specially designed LISP (price £24.35) is the fundamental for it. language of artificial intelligence research. Not surprisingly, it's made by Acornsoft, the software division yJCORNSeFT LANGUAGES of Acorn Computers Ltd., who ylCORNSeFT LANGUAGES designed and built the BBC Microcomputer. So naturally you can expect the highest quality software with the built-in ingenuity to fully exploit the FORTH USP for tt*» BBC Microcomputer Model B tor rr»B8C Microcomputer Models AandB BBC Micros potential.

Further education lor everyone. Number Balance (price £11.90) contains two programs on cassette for practising simple mathematical operations from numbers! to 20.The object of the exercise is to make a balance level by inputting the correct missing number into one sideof a simple equation. Incorrect answers will tilt the balance in the appropriate direction; after three incorrect It is easy to learn, and is widely used for attempts the program responds with the correct writing substantial and sophisticated programs,with answer. practical applications including design of education Chemical Analysis (price £13.80) contains systems and medical research. three Chemistry programs on cassette and a booklet It comes complete with a book that introduces 'Elements' presents a series of mystery elements you to programming in LISR as well as some which the student is asked to identify. 'Inorganic' fascinating applications. presents a series of inorganic substances to be 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 language is also accompanied by a specially written book explaining all you need to know.

Mind-boggling games. Sphinx Adventure (price £9.95) is a full-sized classic adventure game in which you move through caves, fight with trolls, collect treasure and finally make your way to the sphinx

76 ACORN USER MAY •

>*CORNSaFT GAMES How to get Acornsoft programs. Monsters If you re a credit for the BBC Microcomputer Model U card holder and would like to buy cassettes of the programs shown in nr, nsw. nnnnnnsif ntu; n this advertisement, or if iWjWMiri : you would like to know the address of your nr. niu nnriniAv raw. » nearest stockist,just phone 01-200 0200. OX V

Monsters (price £9.95) is a game where your Acornsoft catalogue. man is pursued by monsters who chase him up and Please allow 28 A Word Processor for the ladders walls. down and along The only hope of days for delivery. BBC Microcomputer Model B survival is to dig holes in the walls trap and the *S? Credit Card monsters by Idling them in. Complete with sound Holders. Ring effects and high score. 01-2000200. Increase your business acumen. n VIEW (price £59.80) is a program that enables To Acornsoft, e/o Vector Marketing, Denington Estate, Wellingborough, INorthants your machine, together with a printer, to operate as a NN8 2RL. Please send me the fbllowing:- (Code fully operational word processor. For convenience ViiniMill PROGRAM THICK Q! with TOTAL the program is in so that it can become a ROM Number Balance £11.90 SBKQ8 permanent feature of your machine. (It can easily Chemical Analysis £13.80 SBK12 Lisp £24.35 SBL02/SBD04 be fitted by your local dealer.) You'll find out more Forth £24,35 SBL01/SBD03 by going to your dealer or by sending for the free Sphinx Adventure £9.95 siico: catalogue. Missile Ha.-. Y ').<>:> SBG18 Monsters t ').<>:, SBG03 TOTAL

I enclose PO/eheque payable to Acornsoft Ltd. Or charge my credit card. Card Number (Amex/Dinere/Visa/Access (Delete) Please send me the Acornsoft brochure D Please send me the VIEW catalogue Name Address

Postcode Signature Registered N<>. 1524763 VAT No. 215 8123 85 dCORNSSFT

ACORN USER MAY 77 -

COMPETITION

is is for under-1 3-year-olds only. Please give your school and class with your answer. A prime number is a whole number exactly divisible only by itself and 1 . 1 , 2, 3, 5, 7, 11 are all primes. For many years it was thought that both the numbers 1,757,051 and 222,221 were prime numbers. Why aren't they?

B) Use the accompanying diagram to form seven-digit numbers by starting at any number and moving to any adjacent number but using each digit once only. How many numbers can be formed which are exactly divisible by 1 1 ?

Answers on a postcard please May to Competition, Acorn User, Rocket Raid, 53 Bedford Square, LONDON Meteors and WC1B 3DZ before 1 Planetoids June 1983 The first three just three of winners picked will win the possible prizes £20 of Acornsoft packages. Please state which machine you have.

which are claimed to copy any companies sell their manuals per cent of UK households will other tape or disk (the advertising independently of the program at, have a home computer), it appears usually claims that it is to enable say, half price, presumably likely that wholesale piracy for you to back up your valuable reasoning that if you've pirated their profit will become professional and personal software but who are they program half a loaf is better than ruthless. A recent case occurred of trying to kid?) Dongles can be no bread from their point of view. a dealer in the home counties circumvented by amending the part Others refuse to sell manuals selling a word-processing program of the program which checks to without proof of purchase of the for the Beeb which he bought from see if they're in residence. And for program. a man who had walked into his around £10 a reasonably competent Best of all would be a plastic shop with a packet of EPROMS pirate can build himself an EPROM membrane which can be attached and demonstrated it. It later copying machine. Ironically, an ad- to the VDU, without which the emerged that this person had - vanced and user-friendly machine program would make little sense merely copied it from another like the Beeb makes a pirate's life but this clearly poses practical commercially available package and even easier. It's fairly simple to dump difficulties with machines like the the dealer had to pay out £2000 virtually any block of memory on to compensation to the aggrieved disc and thence into an EPROM. The 'Wholesale piracy copyright owner. How frequently one area on the Beeb which looks as this sort of thing is occurring is if it may increase protection is the use for profit may anyone's guess, but it is certain to of plug-in cartridges. become professional increase in the future. All this means that the job of The video-cassette and music copyright - and hence revenue - and ruthless' industries have been brought protection for software authors is virtually to their knees by pirates in extremely difficult. However, there is Beeb which are not sold with a recent years and it is beginning to one line which can be tried in standard size VDU included. look depressingly as if computer addition to electronic protection Until recently the problem of software will follow the same and that is to market, along with the piracy has been more or less course. The problems - the ease of program, other items which are confined to individual users trading electronic copying, the pitiful legal essential to the running of the 'swops'. There are signs however penalties which the criminals face, program. The most obvious that a far more serious problem is and the indifference of the example is a bulky manual. OK, looming. As the microcomputer consumers who merely want a photocopying machines aren't boom moves from the cottage cheap or free deal - are easy to difficult to find but they do make industry stakes into big business identify. The solutions, alas, are the pirate's job more expensive and (one industry forecast believes that going to be much more difficult to time consuming. Some American by the middle of next year about 1 find.

78 ACORN USER MAY A J SOFTWARE for BBC BBC

'The Record Changer' 32K £19.95 Cass. £24.95 Disc. MICRO for Indexing, membership lists, directories, inven- tories, budgeting, etc.. etc

dont buy a database In the dark — check the spec! INSTANT * Visible File — Scroll around the file UP/DOWN/ SIDEWAYS by function keys * FULL SCRHN UPDATE — Use cursor to overtype; character INSERT/DELETE within field; ERASE rest of field; field MACHINE TAB from to field, etc * Sort — on character and numeric fields

* Search — for a match on field contest * Select — select records satisfying conditions on CODE! one or more fields; or manually

* Total — total numeric fields of SELECTED records Yes, it's true. Instant machine code from a good * Arithmetic — combine one or more fields of your subset of BBC BASIC. Type your BASIC program SELECTED records with any arithmetic expression; into your model B BBC Micro, trigger the put the result In any numeric field compiler, and your program is changed almost * Print print your records with pagi- — SELECTED instantaneously into superfast machine code. nation For £34.95 you get: Cassette version of the * Up to a 1000 records, (typically 330 at length 40) complete compiler (along with a version of the * to fields, number of places Up 20 decimal can be compiler for use with discs, ready for when you specified for numeric fields upgrade, the disc version being dubbed on the * Utility — to ADD/CHANGE /DELETE fields cassette after the cassette version); complete compiler listing; extensive documentation and instructions. The compiler written by Jeremy The Wordsmlth' 32K tor Centronics 737/739 was £19.95 Cass. £24.95 Disc. Ruston. For Reports. Essays, Thesis, etc., etc

Forget control codes — let 'Wordsmrrh* realise your printer's potential THE BBC MICRO

* Full Screen text editor with wordsplll * Unlimited document size REVEALED * Paae numbering, headings, footings, margins, By Jeremy Ruston

indentation '. . .destined to become the bible of all BBC microcomputer

* .' Full Support for proportional, mono, condensed, users. . (Personal Computing Today). If you've mastered the elongated and underlined printing manual, then this book is for you. Just £7.95 * Right Justification maintained even when mixing proportional, condensed, elongated on same line LET YOUR BBC MICRO TEACH YOU TO PROGRAM Simple Word Processor 32K By Tim Hartnell

£9.95 Cass. £14.95 Disc. '. . .takes you further into the cloudy areas of the BBC machine Simple to use; allows you to set margins, justify text, .' than anything else I've yet seen. . (Computer and Video Insert and delete lines of text, set page length or Games). If you're just starting out in the world of programm- force a page, variable TAB, Multiple copies. Save ing, then this book is the one for you. Forty complete text on cassette or disc. View text formatted before programs, including Othello/Reversi, Piano and a host of printing. Works with printer. any dramatic graphic demos. Just £6.45 Options Timetable 32K H4.95 Cass. £19.95 Disc. A must for every secondary school. This programme Interface, Dept. AA helps with the timetabling of pupils 3rd year option 44-46 Earls Court Road, London W8 6EJ choices. Try the effect of any changes to your Please send me: Options Timetable and let the micro do all the donkey work. Has been in use for the last three years ( ) INSTANT BBC MACHINE CODE-tape and book-£34.95 in a 6 form entry comprehensive using a CBM 3032 — now runs even faster on the BBC Model B { ) THE BBC MICRO REVEALED -Ruston -£7.95 Not only the cheapest, but the best Switchable 14" RGB Monitor/Colour TV ( ) LET YOUR BBC MICRO TEACH YOU TO PROGRAM - £250 inc. VAT and cable. £8.00 carr. Hartnell -£6 45 Royalties for quality software

I enclose £ All prices VAT Inclusive Name AJ Vision Service Ltd 61 Jeddo Road Address London W12 9ED

ACORN USER MAY 79 .

Electronequip Authorised BBC Dealer, and service centre

399.00 NEW PRODUCTS BBC BBC Model B Micro Computer BBC BBC Model A Micro with 32K 333.50 VIA 339.50 Disc for BBC BBC BBC Model A Micro with 32K and Utility 469.00 Contains VER FORM35 BBC BBC Model B with Disc Interface 356.00 F0RM40 and FORM80 BBC BBC Model A with Econet Interface 456.00 Cost 9.95 BBC BBC Model B with Econet Interface BBC 8 BBC Model B with Disc & Econet Interface 526.00 99.82 BBC Spark jet Printer BBC 21 BBC Model A to B Upgrade 92.00 New quiet printer BBC 28 Econet Upgrade for BBC Upgrade for Model A . . 34.50 for BBC. Friction & BBC 23 BBC Acorn Memory

, 92.00 tractor feed 80cps. BBC 21 Disc Upgrade for BBC B (inc fitting) ... 287.50 Cost 379. b0 BBC 3U BBC 14" Colour Monitor BBC 33 Sanyo SM12N Green Monitor 15MHz . 113.85 Torch Z80 Disc pack BBC 34 BMC 12E Green Monitor 18MHz 129.95 disc drive BBC 35 Karga K12A 12" Orange Monitor 800K dual 265.00 Z80 processor BBC ill BBC Single 100K. 5.25" Disc Drive (AND01) plus 803.85 with CMP compatiable BBC 43 BBC Dual 800K 5.25 Disc Drive (AND02) .. 205.85 operating system. BBC 44 Single Disc Drive (100K) for BBC (Teac) r '> (Teac) 263.35 Cost 897.00 BBC > Single Disc Drive (200K) for BBC BBC 46 Single Disc Drive (40UK) for BBC (Teac) 343. 85 TORCH Computer BBC 47 Dual Disc Drive (200K) for BBC (Teac) .. 411.70 14" Colour portable Monitor/TV (400K) for BBC (Teac) .. 526.70 800K to 21. 4M disc BBC 48 Dual Disc Drive is not. a modified tele- BBC 4 9 Dual Disc Drive (800K) for BBC (Teac) .. 687.70 This Monitor/TV drives. High res. TV/Monitors are, hut a BBC 50 Epson FX80T L60cps Printer 458.85 vision as many colour monitor. Plus 14" Monitor/TV which has been designed autodial modem. both functions. It has I'.GB ATM 2 Acorn Atom assembled 12K ram 184.00 to perform From 2795.00+vat An KGB ATM 26 Atom New Power Supply 1.8A 9.66 and Composite video and sound. cable for a BBC is supplied as stardard NEW Epson FX80 ATM 21 Floating Point ROM for Atom 21.85 FX80 160cps printer for BBC and Atom, Business, Cost 259.90 Trade enquires welcome in stock. Friction Large stocks of software lists. . comprehensive and tractor feed + and Educational. Send for proportional spacing

I ret? charge and Ihe computer Cost 458.85 Large slocks Prices inclusive ol VAT All Upgrades etc are lilted ol and Batclaycard Welcome All prices inclusive ol postage except micros 3 00 fully re-tested. Access

^f/ICORN COMPUTER Electronequip BOB 36-38 West Street. Fareham. Hants (0329) 230670

EDUCATIONAL IVI SOFTWARE

YOUR BBC COMPUTER IS MORE THAN A GAMES MACHINE! • SOFTWARE • INSURANCE PROGRAMMES AVAILABLE FOR THE MODEL AI32K) OR B ZS1 MATHS • PUBLICATIONS • INFORMATION * Simple equations Ax + B = C * Equations Ax + B = Cx + D * Simultaneous Equations * Linear Equations £r Graphs y = Mx + C MUSE is an organisation for parents and teachers. ZS2 MATHS * Binary Arithmetic (Base 2) MUSE offers its members: insurance, courses, booklets, journals, an * Hexadecimal Arithmetic (Base 16) annual conference, a friendly and unbiassed information service * Trigonometry — Pythagoras k Trigonometry— Sin, Cos, Tan ZS3 ELECTRICAL THEORY MUSE has an extensive library of educational software covering Apple, k Direct Current BBC, PET, RML380Z, Spectrum and ZX81 * Ohms Law ir Resistance in Series has just published a booklet "A Beginner's Guide to the BBC Micro" * Resistance in Parallel MUSE * Alternating Current RMS Peak by Richard LTSilva-a step by step guide to simple BBC programming •k Power Price £1.00 including post and packing • EXAMPLES • NUMEROUS QUESTIONS • ANSWERS CHECKED BY COMPUTER Guides and membership details from: • SOLUTIONS TO QUESTIONS AT YOUR REQUEST MUSE (Dept AU) CASSETTES £8.90ea. or 3 for £24.00

DISC (40 track) £10.90ea. or 3 for £26.00 FREEPOST

(Prices include VAT and postage) Bromsgrove

64 CLOSE LANE Worcs. ZENCOM ALSAGER B61 7BR YSTFMSTOICIVIO CHESHIRE ST7 2JT

ACORN USER MAY electronic monitor manufacturer

THE CE370A NEW R.G.B. COLOUR MONITOR £199.50 BUY BRITISH

* Quality * Reliability * Manufactured in Britain 100% * A moulded case with carrying handle NEW: TheCE370B R.G.B. * Meets British standard safety regulations (BS415) Composite Video and * Automatic black level compensation for tube ageing * Mullard AX37-590x Tube Audio Colour Monitor * Power consumption 60w £250.00 + VAT CABEL offers you a new high quality 14" inch colour monitor

The case has been designed with safety upmost in our minds. This advanced model cuts the component count and incorporates the most sophisticated parts on the market today. Using the MULLARD AX tube, which gives perfect colour registration with reliable and stable operation. Automatic drift (Black level) compensation adjusts automatically with the ageing of the tube. All this and many other features, including years of experience in the data display industry and backed up by our 2 year guarantee. We GUARANTEE long service and reliability.

Price £199.50 + VAT Includes R.G.B. Lead

DEALER ENQUIRIES AND EDUCATION ENQUIRIES WELCOME CHEQUE/POSTAL ORDER, OR FOR FAST DELIVERY, RING US WITH YOUR CREDIT CARD NUMBER

Factory Office Unit 15 Lloyds Bank Chambers, Whitegate Industrial Estate The High Street, Whitegate Road Tewkesbury,

Wrexham LL1 1 1AY Gloucestershire Tel 0684 298840 Tel 0978 350345 Telex 339671 ALD FAB

m Registered No. 1370335 electronic

ACORN USCR MAY 81 BBC EXPANDABLE CONSOLE

Not just a TV/VDU stand but an expansion console which gives your micro the professional look. Protects and encloses your micro with room for disc drives and 2nd processor or teletext adapter etc. All untidy connecting wires out of sight and reach BIG IN LITTLE within the console. Made of light yet strong aluminium with a textured finish in matching BBC COMPUTERS colour. Coming soon, a bolt-on extra module for the console, for further expansion options, ie dual drives, 2nd processor, SOFTWARE NOW IN STOCK PRINTER/VDU STAND teletext adapter joysticks, cass- AT THE VIDEO PALACE BBC owners who only need a ette etc, all in one console. YES, VDU stand will find the stand this console will grow with your slips comfortably over the BBC needs. If that was not all a COME AND SEE with adequate ventilation allow- matching printer stand is avail- OUR FULL SELECTION ed for. After use the micro can able. Rest the printer on the be slid UNDER the stand acting stand and stack your paper as a dust cover when micro not underneath. The console will in use also house the torch disc pack.

THE FROG (Software for All) £ 8.95 PRICES BASIC CONSOLE as shown Superb Frogaer game. Extremely good piece ol programming only £39.99 + £4.00 COWBOY SHOOTOUT (Micropower) Model B £ 6.85 p/p Two player gunfighter game Really good graphics. PRINTER/VDU STAND ARCADIANS (Acorn) Model B £ 9.95 This is the best Galaxian type game on the market only £14.99 + £2.00 p/p THE CENTIPEDE (Superior) Model B cassette £ 6.50 information enclose sae or send cheque to, Excellent Centipede obi disk E 9.90 For further MODEL B INVADERS (UK) £ 5.50 Mail Order 27 Wycombe Rd . game with many options I (7*l i 01-801 3014 GALACTIC COMMANDER (Mictopower) Model B £ 7.99 London N17 High resolution lunar lander game. PLANETOID (Acorn) Model B cassette £ 9.95 A must for all BBC owners disk £11 50 Viewing by 24 hour SWOOP (Micropower) Model B £ 7.99 ansaphone Galexlan with a differs arrangement 3D MAZE (UK) Model B £ 4.50 Please allow 28 days for delivery Mindbogglimi mail CASTLE OF RIDDLES (Acorn) Model B £ 9.95 Highly recommended word adventure game. ROCKET RAID (Acorn) Model B £ 9.95 Superb Scramble game. Our best seller CHESS iBugbyte) Model B £11.50 Graphical chess game STRATTO BOMBER (UK) Model B E 7.50 Blast the alien mother ship and save your pi nnr computer software ELDORADO GOLD (Micropower) Model B £ 6.85 (3BC mis game will get you started with adventure qames SNAPPER (Acornl Model B £ 9 95 lame Joystick option PEEKO COMPUTER (Acornl Model A or B £ 9.95 SECTfl knUflDEFrS Confused with mai nine code' Buv this and solve . ems WORDSWORTH (Ian Copestake) Model B £13 00 Excellent word processor Very good value for money (Acorn) Model pet pair £12.99 JOYSTICKS B *J 4? 'St a$ ft *' i I & Play games such as Rocket Raid. Snappei usi Hk the i £r % CASSETTE CABLE £ 1.95 % & $ « Seven pin oim to J x lack plug PARALLEL PRINTER CABLE (Acorn) £18.40 ! Model B to a Centronics type printer - s

ALL THE ABOVE ORDER BY PROGRAMMES CAN BE TELEPHONE ORDERED BY POST Access and Barclaycard . lot the in'.i end Ifjp tot BS ; (torn. holders may order by Allow up to 28 days lor delivery phone: 01-937 6258 Payment l>v i heque oi po

ACTUAL SCREEN PHOTO FEATURES 14K MACHINE CODE FOR MODEL B OR 32K MODEL A JOYSTICKS OR KEYBOARD. FULL COLOUR FAST/SLOW BOMBS. NEW HIGH SCORE TUNE SOUND ON/OFF. TOP TEN SCORES WITH NAMES PALACE CASSETTE GAMES PROGRAMMERS SAVE YOUR TOP TEN SCORES ON LOAD YOUR OLD TOP TEN SCORES FROM CASSETTE Palace Software, part of a leading film and FIVE SKILL LEVELS WITH COLOUR CHANGES video company, is looking for games for UNIQUE EXPLOSION GRAPHICS. ETC. Atari 400/800, BBC Model B, TI99/4A, Spectrum, VIC 20 and CBM 64 for distribu- ONLY £5-95inc tion in the UK, Europe and USA. High royalties will be paid for top quality and highly original material. Send samples to: Pete Stone, Palace Software, SECTfl SOFTWARE 62-64 Kensington High Street, London W8 14 BRACADALE CLOSE (Tel: 01-937 6258) WESTCOOMBE PARK SOFTWARE COVENTRY CV3 2PS TEL: (0203) 662078

82 ACORN USER MAY PRINTERS

Baffled by the manual? George Hill explains how to get your printer going PRINTING FROM A TO Z

I his article is aimed at those with

a BBC model B and a printer. I 10 REM send A to shall expand on the somewhat Z to screen via PRINT CHR$ 20 FOR I = 65 sketchy (and in some respects TO 90 30 PRINT misleading) information in the User CHR$I Guide, to enable you to start using 40 NEXT I the facilities of your printer to the Program 1 Letters . on separate line full. After unpacking your printer and 10 REM send A connecting up. establish that it to Z to screen via VDU works by carrying out the 'self-test' 20 FOR I = 65 TO 90 procedure (available on almost all 30 VDU I

printers). Instructions for setting it 40 NEXT I in motion will be in the printer Program 2. Letters on same line manual. Normally, it involves switching the printer on while holding down one or more of the symbol to mean 'press single byte (see April's article). The control buttons. The printer will the return key', and CTRL B means code system used is the ASCII print all of its characters and 'hold down the control key (marked code (American Standard Code for maybe some other information. CTRL), strike the capital B once Information Interchange). In this You have now established that and then release the CTRL key'. system the letters A to Z are the printer works and provided that To test your printer initially, try represented by the numbers 65 to the computer does as well, you can the following procedure. Type 90 and the other letters and connect the two and try them out. symbols by other numbers between CTRL B First you must make a crucial 32 and 127. These codes can be PRINT'THIS IS TO TEST THE check. Is your printer connected in PRINTER" sent to the screen in two different serial or parallel? If it plugs into the ways. Programs 1 and 2 illustrate printer socket under the computer, Both screen and printer should the methods. One involves the use

then you have a parallel printer, if it respond of PRINT CHR$n where n is the plugs into the RS423 socket at the ASCII code, but the other quicker >PRINT"THIS IS TO TEST THE back of the computer, you have a and more PRINTER" convenient method uses

serial system. VDU drivers. I advise all BBC users THIS IS TO TEST THE PRINTER The parallel printer socket is to familiarise themselves with the selected by default (if you do The screen will also show > at the VDU codes as they are extremely

nothing about it, then all output beginning of the next line, but the useful and powerful. designated for the printer will be printer is often one step behind, You will notice a difference in

sent to the printer socket under the and it may not print the > until it the outputs from the two programs.

computer). To be certain you can receives the next instruction to Program 1 prints the letters on type *FX5,1 which directs output to print. Next type CTRL separate lines, program 2 prints this socket. This procedure is often C and the printer will print the them all on the same line. Each referred to as calling the printer. missing >. PRINT statement implies a

For a serial printer there is a two- If your printer overprinted at its end, unless it is stage calling process. Type *FX5,2 everything on one line, then type followed by a semi-colon. To make to select the RS423 socket. Then *FX6,0 and try again. This the output of the programs identical

type *FX8,n to select the baud rate. instruction will be explained later. you change line 30 in program 1 to This must be matched between Now type PRINT CHR$I; and PRINT CHR$n; computer and printer to the stop PRINT-PRINTER OFF?" is identical to VDUn. printer from misunderstanding If you now run either program signals from the computer. The (program 1 in the modified form) printer baud rate will be selected in The printer should remain silent, with the printer enabled by CTRL B, the depths of the printer by dip but the screen shows output will also appear on the switches or jumpers. Your manual printer. some printers a PRINTER OFF? But have will tell how to set If buffer you them. > (a memory of their own) and possible select 9600 bits per the buffer stores items to print until

second and use *FX8,7. Otherwise, Your computer transfers all its it receives an instruction to empty,

select the highest rate possible at information about letters and other or it is full. So to get output at the the printer, and choose n to match characters around its circuits as printer type the computer's rate to the printer's. numbers. These numbers must be RUN CTRL B

In the following I have used the between and 255, as they are a CTRLC

ACORN USER MAY 83 PRINTERS

and the printer should print A to Z, and a > (the BBC's prompt), all on 10 REM send A to Z to printer and screen the same line. 20 REM enable printer The CTRL key simply subtracts 30 PRINT CHR$2; R 30 VDU2 64 from the ASCII code of any key 40 FOR 1=65 TO 90 pressed simultaneously. CTRL B is 50 PRINT CHRSI; - R 50 VDU I actually sending (66 64) which is 60 NEXT I 2. to the central processor, which 70 REM empty print buffer if necessary interprets this as a signal to enable PRINT *° OR 80 VDU 13 the printer. Similarly CTRL C sends 90 REM disable printer 67-64, ie 3, which disables the 100 PRINT CHR$3 or 100 VDU 3 printer. We can send these codes Program 3. within a program, using VDU2 and Program 4. Sends 'A to Z' to printer VDU3. Programs 3 and 4 will Change lines in program 3 enable the printer, send A to Z to it and the screen, and disable the moves up to a position other than at the end of a line) it only acts printer. Note the use of an extra the one you wanted, you need to on one of them. PRINT or VDU13 () to reset the dip switches which ensure that the printer empties its You may be able to select some control formlength on the printer, to buffer. of these options by dip switches at match the length of your paper. Characters which are genuine in the printer. In many ways the first is Details of how to do this will be the sense of printing a character on the best option, as it allows you to found in the printer manual. the screen, start at an ASCII value overprint lines. If you had the Now to the linefeed problem. of 32 - the space character. Codes problem of overprinting at the start The BBC micro is set to suppress to 31 have specific effects which of this test procedure and had to linefeeds in its printer output. This are detailed in pages 378 to 388 in type *FX6,0 then you probably have means that when the computer the User Guide. All are important this option. reaches the end of a line it sends and useful, but some are of crucial The *FX6 command is used to code 1 3 and code 1 to the screen, importance to the printer user. suppress any one character in the causing the cursor to go back to VDU2 enables the printer, and output to the printer. On switching the beginning of the line and go micro it defaults to VDU3 disables it. I have used the on the BBC down one line. Only code 13 is same terms as in the User Guide, *FX6,10. That means that the sent to the printer. This may be as these describe the action better linefeed character is suppressed. compensated for in two different than any combination of on and off, By typing *FX6,0 you have ways. Either the printer may which might cause confusion with suppressed character (which generate its own linefeed on the on/off line, and power on/off. does nothing anyway) and reactivated receipt of each return, or it may be Three other codes which affect character 10. Note that only one made to send both codes to the the printer in simple ways are character can be suppressed at a printer. The reason for this flexibility VDU10, VDU12, and VDU13. These time. Try typing is that printers respond in different are linefeed, formfeed and carriage ways to codes 1 and 1 3. There are *FX6,65 return respectively. Most printers four main possibilities. PRINT"AARDVARK" CTRL B respond to all three of these codes, but some (for instance the Amber) • Literal - 13 returns the printhead CTRLC only accept 13 and ignore the to the beginning of the line, and others. The formfeed character 10 advances the paper by one The printer should respond RDVRK clears the screen if sent there (it is line, and returns the printhead. while the screen shows AARDVARK. the equivalent of CLS) and the • Auto-linefeed, with code 10 You have suppressed A (code 65) printer accepts it as an instruction ignored - on receipt of code 13 in the printer output. to advance the paper to the next the printer returns the printhead top of form (top of a page). It is set to the beginning of the line and To test which of the four options when the printer is switched on. advances the paper by one line, your printer has in operation, try the and can be reset by switching the but ignores code 1 0. following test procedure. Type printer mains switch off, moving the • Auto-linefeed with all linefeeds *FX6,10 paper by hand to the top of a page acted on - on receipt of code 1 CTRL B (normally the perforation on fanfold or code 13 the printhead returns paper) and switching back on and the paper is advanced one again. Some printers have a set top line. CTRL J CTRL J CTRL J of form button which you can use • Intelligent auto-linefeed - in this *FX6,0 to avoid having to switch on and method the action is as for auto- CTRL J CTRL J CTRL J off. linefeed in that both codes 10 If you type CTRL B CTRL L (ie and 13 are accepted as enable printer, send [76-64]) the instructions to empty the print CTRLC printer should now move the paper buffer and perform the appro- up to the next perforation, and the priate action. When codes 13 If at step 3 your printer printed screen should blank. If the paper and 10 are received together (as three > signs at the start of the

84 ACORN USER MAY PRINTERS

same line, without the paper 6 linefeeds to the Pinter, print message, \ltu REMKtM IZ I moving, you have the first option. and advance to top of form Step 4 should produce no effect 30 *FX6,0 (linefeeds are disabled and CTRL J 40 VDU2, 10,10,10 50 is code 10). PRINT"TEST PROGRAM" 60 VDU12,3 If at step 6 the paper did not advance then you have the second Program 5. Sending control characters option. 10 REM send A to Z to the printer only If after step 7 your printer printed 20 REM enable printer and send A to Z the > signs with a blank line 30 VDU2 between them then you have the 40 FOR 1=65 TO 90 third option otherwise you have the 50 VDU1,I

last option. 60 NEXT I

If this REM test shows that you have 70 send linefeed and disable printer the second or third then you should 80 VDU1,10,3 leave the default setting of *FX6,10 Program 6. Sends 'A to T to printer only in operation. If you have the first then you must type *FX6,0 before

using the printer. If you have the Acorn refer to this change as produces the desired effect.

last it then does not matter whether correcting a bug in OS 1 , but it is We can avoid the total you use *FX6,0 or *FX6,10. If you a pity that this particular bug has disappearance of wanted material want to use CTRL J or VDU10 to been altered. by judicious use of the commands advance the paper then use *FX6,0. Furthermore, the User Guide, in governing graphics and text Note that any second option its printer section refers to *FX3,n windows, and scrolling only the text printers (like the Amber) will not as the preferred method of area. This involves the use of VDU respond to any code 10 calls in the directing output to the printer only. 4,5,24 and 28 which you should next program, and these will have *FX3 does not exist in OS 0.1, so explore but lie outside the scope of to be replaced by code 1 3. most people will merely get 'Bad this article.

There are two ways of sending Command' messages from any A more pressing problem is how

control characters (those with attempt to use it. There is, anyway, to send escape sequences and codes between and 31) to printer a serious fault in this mechanism, control characters to the printer to

and screen. From the keyboard which is not apparently being get it to alter its style or go into (CTRL a letter) in and and a corrected even in OS 1.2. The graphics mode. I offer, as examples program (VDU followed by a command which should send of this process, translations of two number). Program 5 illustrates the output to the parallel printer only sequences detailed in the EPSON latter process. (*FX3,2) simply does not work. The MX80 type 3 manual, but the

It is often important to be able to BBC micro therefore remains principles are the same for all

send characters to the printer only without an LPRINT equivalent, printers if the examples are given in and not to the screen. The code except for the use of VDU1 (which terms of LPRINT which allows this is code 1. This is not mentioned in the User Guide To control line-spacing you use code has a slightly different action printer section!). For those with OS a sequence given as ESC A + n in OS 0.1 from that in OS 1.0 1 .0, *FX3,1 can be used to disable (note that the + sign is misleading

causing me considerable problems! the screen, and *FX3,0 to re-enable and irrelevant), which is translated

It is intended to work by enabling it, giving a limited LPRINT facility, at the foot of the page as LPRINT the printer, sending code 1 and the but codes 1, 2 and 3 still have to CHR$(27);CHR$(65);CHR$(n) where code for the character. This last will be sent via VDlM.n as they are n is the amount of line-spacing be ignored by the screen but sent intercepted by the CPU and required in multiples of 1/72 of an to the printer. Program 6 illustrates interpreted as commands to inch. Normal line-spacing is 1/6 this and sends A to Z to the printer redirect output. inch (12/72 inch). To double-space, only. Several people have written in to therefore, we must increase the Owners of machines with OS 0.1 ask how to translate the programs line-spacing to 24/72 inch. The may have found that they can use given in printer manuals into BBC sequence for this is ESC A 24 The code 1 followed by a character, Basic. Most Basic's have the codes to be sent then are 27 (ESC) without enabling the printer first, eg LPRINT command which directs 65 (A) 24. typing VDU1.12 sends output to the printer only. Lacking a We must not send the 27 or 24 a formfeed to the printer, but does satisfactory equivalent, we have to anywhere but the printer, as 27 not affect the screen. To have the use VDU 1 to get over this problem. causes the computer to carry out

same effect in 1 .0 OS you must In normal use it probably does not its escape routine, and 24 makes it type VDU2.1.12.3 matter if output destined for the attempt to define a grahics window.

(enable the printer), send formfeed printer also goes to the screen, and It is also important to realise that to printer only, and disable printer. so the sequence the escape key is not used in The same sequence in CTRL escape sequences. characters is obtained by holding VDU2 The command needed is down the CTRL key and typing PRINT'Anything" VDU2, 1,27,1 ,65, 1,24,3 , BALC, then releasing the CTRL key. VDU3 ie enable printer, send ESC A 24 to

ACORN USER MAY 85 PRINTERS

printer only, disable printer. The end of the escape sequences, if using the sequences described in above sequence can be typed in program 7 fails to work. the printer user manual. Program 9 direct from the keyboard, or used in The next program translates one of illustrates how to do this for the a program. The is of EPSON'S bit image printing test Olivetti ink-jet printer, but the course redundant in a program, programs, to test the dual density principles can be followed for any this facility. Set and it is only necessary to use mode of the printer. The program is printer which has points VDU2 and 3 once each at the start shown in program 8 as it appears in up the tab stops (ie the and end of the program. Program 7 the manual, then translated into BBC along each line at which you want illustrates this, and also the use of Basic, using hexadecimal numbers, columns of printing to start), and

the ' character to generate returns. and finally using decimal numbers. thereafter the printer will advance Note that on the type.1 printer Finally, several enquiries have to the next tab stop on receipt of additional commands are necessary arisen about the use of the printer each code 9.

to implement these changes. Some tab function. Printers do not In the next article in this series, I converted type 2's may also need respond to the PRINT TAB(x,y) hope to introduce the principles of

the additions. At lines 50 and 80 format. It is necessary to set up a printing pictures, to enable readers append 1,27,1,50 (ie ESC"2") to the tabulation program for the printer, to write their own graphics dumps.

printer MX 80/FT type 2 alteration for EPSONFPSON 10 REM Linefeed 20 VDU2 singly spaced" lines snouth Ld be 30 PRINT"These three 40 REM alter linefeed 2 50 VDU1,27, 1/ 65 ' 1 ' double spaced" ^.threea should_ houL d be 60 PRINV'but these linefeed 70 REM restore 80 VDU1 ,27,1 ,65,1,12 90 VDU3

line spacing Program 7. Illustrates

BBC(decimal) BBC(hex) 10 REM LETTER EPSON PROGRAM by the seqsequence LINE 20 REM TAB is set NUMBER ditto Z ditto REM P 80 15;60 ESC printing REM ESC 5 o REM bit image length is , 150 30 REM Where line at 15 and 60 (dual density) VDU2 VDU2 the TAB stops are VDUI'27,1,76, enable printer , VDUl,81B,1,84C, 40 REM CHR$(&H1B); 'L"; 160 LPRINT 1 1 ' 1,850,1,80 '! ' °, VDU CHR$(&H50);CHR$(&H0) TOTn sn50 program,! a 1 =1 TO 50 FOR N 1 °0 RE^send TAB FuR N o 59,1, FOR N=1 TO 50 VDU1,255 1,27,1,80 1,56 1 48 1 170 VDU1,8FF 7 VDU LPRINT CHRSC&HFF); 180 NEXT NEXT 49,1,53,1,59,1,54,1,48,1,27,1,90 NEXT VDU 190 VDU1,8A 80 REM new page LPRINT CHR$<&HA) l'!?160n 200 GOTO 160 GOTO 210 GOTO 160

function 9. Olivetti TAB translated Program Program 8. Epson test

damage to the budgerigar,andtheconseq uent your vaccuum cleaner. 90 VDU12 of page 200 VDU13 enclosed will 100 REM space at top hopes that tht PRINT CHR$9;"He 1 1 210 some 110 your grief m CHRS9;"10 Small Street you to assuage PRIN?'CHR S9; enable 120 Small Town PRINT CHR$9;CHR$9;" appropriate way- 130 Mirkshire 1 3 140 PRINT CHRS9;CHR$9;" 220 cl«S9;"Y0U rs f.UhfuUy," 150 VDU13, 13,13,13 230 p°RINT r -'" VDU 13,13,13,13 240 1 160 your vaLued advice SMARM ^ 250 PRINT CHRS9;"A. 170 !SFW^ & printer 260 REM disable 180 D 3 the sad loss of manager regrets VDU3 190 PRINT CHRS9;-The 270

Program 9 continued

86 ACORN USER MAY HAVE YOU GOT A BBC MICRO? THEN YOU NEED:

THE NEWSLETTER OF THE INDEPENDENT NATIONAL BBC MICROCUMPUTER USERS GROUP

IN RECENT MAGAZINES:

Articles: Teletext Graphics, User Definable Characters, User Definable Keys, Sounds, *FX, Telcsoftware, Line Structure and Merging, Epson Screen Dump, Pixel Power, Moving Things, Manual Review, What Primer?, Seikosha Dump, Machine Code, How To Get More Colours Out Of Your BBC Micro, Circles Galore, Conversions for RGB Inputs, How To Use Joysticks, Instant Graphics, Software Protection, String, String, Siring, What Monitor? Speeding Up Your Programs, Computer Conversions, Questionnaire Results, Formatting, Assembler Programming On The BBC Micro, Errors? Focus On Adventure, Diskspot, Computer Programme Review, ADC Corner, Make The Most Out Of Sound, and lots, lots more

Programs: Labyrinth (Game), Pontoon (Game), Artillery (Game), Life (Misc.), Calendar (Misc.), Prism (Educ), Spiral Patterns (Graphics), Bazooka (Game), 4-ln-A-Row (Game), Mortgage (Misc.), Oxygen (Game), Teletext Terminal (Utility), Wordproccssor (Business), Mixer (Graphics), How Many Colours? (Graphics), Disassembler (Utility), Maths Race (Educ), Puzzle Program (Game), TV lest Signal Generator (Utility), Alphabet Tester (Educ), Repeat (Game), Memory Analyser (Utility), Wallball (Game), Dating (Misc.), What's The Time? (Educ), Grand Prix (Game), Nine Dice (Game), Memory Dump (Util.) and lots, lots more

Regular Features: Bookreview, letters, Hardspot, Softreview (we review at least 8 programs per magazine from all sources), Oddspot (a

different graphical program every month), Meeting Place (where we list local user groups), Contacts (spans over 1 page of names and addresses of people who want to get in touch with other users in their area), Competitions, Printereview (we have looked at the Seikosha and Amber 2400 and give lull details on how to use them with screen dump programs), Seasons (a seasonal program every month), Queryspot, Special Offers (special offers and exclusive club discounts). Assembler Programming On The BBC Micro, Software Protection and lots, lots more WE WON'T TRY TO PUSH LASERBUG ON YOU LIKE THE OTHERS - SEND OFF FOR A SAMPLE COPY AND YOU'LL FIND THAT LASERBUG SELLS ITSELF ALSO AVAILABLE FROM LASERBUG:

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Please supply me with: A sample copy of LASERBUG «» £1.00 A 12 Month subscription to LASERBUG (n £12.00 for 12 issues of the magazine A 6 Month subscription to LASERBUG (" £6.00 for 6 issues of the magazine An overseas subscription to LASERBUG «i £14.00 (Surface Mail - write for details of air mail) LASERBUG Dust Covers) «> £3.25 each LASERBUG Cassette Ixad(s) (Please state type(s)) <« £3.00 each

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ACORN USER MAY 87 t * SEIK0SHAGP-100A bbc MICRO MICRO UPGRADES

RAM KITS: Upgrades the Model 'A' to 32K RAM Supplied with full fitting instructions £29.90 + VAT ANALOGUE KITS: Suitable for adding joysticks, FLOPPY DISC DRIVES controllers etc £1500 + VAT PRINTER INTERFACE & I/O PORT: Enables a DISC DRIVES SINGLE AND DUAL Centronic Interface printer to be attached £16.00 + VAT 40 OR 80 TRACK FOR BBC MICRO

includes utility disc and Dos Manual Phone for prices:— MODEL 'A' TO MODEL B' UPGRADE £89.00 + VAT (fitted) • DOT MATRIX PRINTER DISC EXPANSION £80.00 + VAT bbc • 80 CHARACTERS PER LINE DISC DRIVES from £179.00 + VAT MICRO COLOUR MONITORS from £229.00 + VAT • 30 CHARS/SEC BBC COMPUTER MODEL 'A' £262.00 + VAT • FREE HI-RESOLUTION DUMP OUT' LISTING Send for details on other items, cables, cassettes, plugs, BBC COMPUTER MODEL 'B' £349.00 + VAT software etc. BBC COMPUTER WITH DISC £410.00 + VAT £179 + VAT. Carr£6 BBC Printer Cable £16 + VAT WHY NOT SEND YOUR MACHINE TO US FOR BBC MICRO UPGRADING? WORD PROCESSOR CHESS £1 1 .50 ROM £46.00 ASTEROIDS £ 8.95 EPSON FXBO - The printer recommended for the i 3 ifc GLAXIAN £ 8.95 BBC Microcomputer BILLIARDS £ 8.50 :V^S\ Graphics »CSl FROGGER £10.00 • Dot Matrix Printer^^^"* Hi-Resolution GOLF £ 8.00 • 80Cps &^1$£. * Bi-directional Printing

OTHER ITEMS AVAILABLE "%

FOR THE BBC MICRO I. Books, Cables, Joy Sticks, Cassette Decks, Dust Covers, Teletext Adaptor, Speech Upgrade

OUR PROGRAMS ARE NOT WOFtDSC:rf=*!N| _ BBC JUST FUN-they're an education!! FOR ALL BBC MICRO OWNERS - A WORD PROCESSOR ON CASSETTE. Even for those owners with 0.1 Operating System. PUNCMAN Features two animated 'Computer bugs'. Puncman £7.95 writes the stories, and Nosher eats punctuation symbols. Even for those owners who do NOT own a printer. (two programs) You put them back. Interactive fun — a great way to learn. STORY A 'Spanish Gold' an illustrated story-book on the So far, you have used your machine to play games. Now £6.95 screen. Multiple endings selected by the child as the story you can really benefit, using it for WORD PROCESSING. (2 programs) progresses. First in a series and a fine stimulus to creative writing CAPITALS Follow-up to our successful LETTERS program. Capital An extremely fast and easy to use program, £9.95 letters and numerals as designed by Christopher Jarman (5 programs) (Basic Modern Hand). professionally written caters for over 400 by 40 Similar to PUNCMAN, but this time Nosher reverses REVERSALS character lines- of text on the BBC Micro Model B. £7.95 letters (like 'b' for 'd'). You turn them round again. (2 programs) Encourages children to look more closely at their own writing. There are versions to cater for the special facilities PIRATE Follow up to INKOSI. This is our second 'Adventure/ £6.95 Simulation' game for children. Would you make a good of the EPSON MX80 FT3, Sei kasha SP100A and Centronics pirate? A world-wide game based on real events from the printers, but the program will operate on any 'machine past.

3 ANGLEt Graded programs with superb graphics demonstrate compatible " printer. £8.95 Angle as 'turning', degrees, names of various angles. (4 programs) how to use a protractor, with questions to check understanding. Measure angles direct from the screen. Bureau Service available for PRINTING if required. Ages 8 14. 'Edit' your text on your TV monitor. INVISIBLE MAN Draws and labels a grid, and displays a cartoon man who £5.95*t disappears! Feed in co-ordinates to find him in the time 'Save' it on cassette when you have checked it out. allowed. Complete with on-screen compass point clues. fast confidential PRINT service. Ages 7-14. 'Send' it to me for a Epson MX80 FT3 used for Print Service with all features.

COMING SOON Programs marked * are now TOP OF THE POPS available for the VIC 20 with at For Demonstration cassette just send £2 deposit f £1 to least 3k rampack. SPECTRUM TRIANGLES cover p&p. Please state printer to be used. MUSIC INVADERS programs are marked t.

Otherwise, full details of the Package, priced at £15 Send SAE for details to: Lowmoor Cottage (AU4) Bureau Service, minimum charge £2 for 2000 Tonedale and the WELLINGTON words can be obtained froit "Dial Software", 72 Downend tks*{* Somerset TA2 10AL .b« 082 347 7117 Road, Downend, Bristol BS16 SUE. TRADE AND EXPORT ENQUIRIES WELCOME

ACORN USER MAY computer users (see April's Acorn PROSE WHERE User). Prestel and Micronet are paid for by subscription, and are PROSE IS DUE protected by a set of access codes. The two receivers you mention are specific to one system or the Sir, As a piece of journalistic other, as they use fundamentally literature one can hardly fault Acorn different principles. Teletext adapters User. However, don't you think that are already in production, while users of the BBC micro want more Prestel receivers will not be than prose to read? After all, how available for several months. many of us can correctly construct a program from a given set of criteria? your competition page. Would Take RE-CALL it not be more useful and constructive if you were to use this page to show a STATEMENT complete analysis of your solution to the problem, with detailed comments as to how and why you did it that way? Sir, There is one error in Shaw and So, please, become the first computer Ferguson's review of my book journal to help the programmers/ TELETEL (Assembly Language Programming on analysts of the future. PRESTEXT? the BBC Micro. Macmillan) (Acorn

Ian Crawford User, March) which I hope you will Banbury allow me to correct. Sir, What is the difference between a The review states that 'one Teletext receiver and a Prestel receiver? omission is a full treatment of the We have taken your constructive Beeb's powerful CALL statement'. suggestion to heart - so watch the S. Smith This is not so. Chapter 10, pages 180- competition pages for further Birmingham 186, contains a full discussion with developments. In the meantime you applications to integer and string might be interested to know that we sorting. Teletext information will shortly be starting a series on is a set of pages Ian Birnbaum programming techniques. transmitted with TV signals, and Cambs decoded by a special circuitry in It should be said that what you described as 'prose* has proved your television or by a special BBC popular with many readers. micro adaptor. The BBC TV service is called Ceefax, and ITV's is Oracle. The information is free and CANARY Ceefax is also transmitting software DIA VIA which can be loaded into the BBC TWEETERS CIRENCESTER micro and run, using the Teletext adaptor. There is also a computer newsletter called REM on Ceefax Sir, page 700. Would you publish a note in Acorn Sir, In the March issue of Acorn User Prestel is a much bigger system User stating that some members of the information regarding the which uses the telephone network our club are interested to get in distribution of the DAI personal and is two-way (ie you can send contact with British radio amateurs computer is incorrect. information as well as receiving it). already using the BBC Micro for Data Applications of Cirencester For Prestel you need to be coding/decoding both CW & RTTY. (tel: 0268 61828) have taken over connected to a British Telecom line, Many thanks in advance. distribution of the DAI personal either directly or via an acoustic I. Beng computer in the UK. coupler (sometimes called a BBC Micro Club - Tenerife modem). Some pages are free, but PO Box 1297 Lisa Reuben most have to be paid for. A new Santa Cruz de Tenerife for Data Applications additon to Prestel is Micronet, for Canary Islands, Spain

ACORN USER MAY 89 LETTERS

information must also be placed into COPESTAKE'S the EPROM to inform the micro of SIGHT the presence of the chip. Details of MISTAKE this format information are available & SOUND from Acorn at Fulbourn Road, Cherry Hinton, Cambridge CB1 4JN. Tel: 0223 245200 Sir, Thank you for your letter and £20 Sir, Several readers have commented cheque for my 'auto-destruct' tip in the need for better quality sound April's Beeb Forum. about reproduction and higher volume, but However, since submitting the tip I whilst bringing have discovered certain situations SOUNDS the solutions offered, some improvement (eg larger/better where it doesn't work. 1 would be SIMPLE quality speaker or use of the cassette grateful if you would therefore publish do not really an amendment, recorder's amplifier) satisfactory long-term Line 20 should read: provide a answer. Sir, I have been following, with 20 DIMP%6:?514=P<7o:?515 I feel sure that it should be possible = interest, the correspondence in Acorn l'"oDIV256:COPT0:LDA#124: to channel sound through the User on the subject of audio JSR&FFF4:RTS:)*K.10 1:1M television itself, where there is ample connections to the BBC micro. Your volume and quality, and from where, Line 30 should read: reply to the lost chords letter in the naturally, one expects the sound to February edition has finally incensed 30 REPEAT PROCx come. Such an improvement would me to put printer to paper. enhance the already spectacular There are also three places when: I If, like me. your writer owns a performance of the BBC micro, as I'm is printed as I. model B which has no PL16 then the sure most readers would agree. Ian Copestake replies given by you only serve to B. Sharrock Surrey increase the frustration. Bolton My model B has the marking PL16 And our thanks to you for on the left hand edge of the PCB but

pointing this out so promptly. there is no plug or socket connected to There is a technical problem in the board. Is the external connection sending a sound signal to the TV, supposed to go here? Could Acorn because it has no separate audio give us connection details for the two input socket. This means the sound pads on the PCB so that we can make signal would have to be combined EPROMS our own PL16? with the vision signal by replacing A. Turnbull SAVE RAM the existing modulator in the BBC Netherlands micro (that tin box in the far right corner of the circuit board). However, the new modulator would PL16 doesn't need a plug or a Sir, I have recently noticed adverts for have to be exactly the right type, socket. Simply solder a wire to each EPROM programmers. Could you and much bigger than the existing pad (one is ground and the other is please explain what I can program one - consequently, it would be the audio output) and connect to the onto these: can the programs be in difficult to fit. tape input of your hi-fi. Basic or assembler? If I can put my A far simpler and better solution own programs on them, can they be is to connect the Beeb's audio output slot ted into the PCB? I would be to an hi-fi amplifier and through a grateful if you could explain my set of speakers, as explained questions. elsewhere in this section. Colin Rice Merseyside AMBER EPROMs - erasable/programmable BOOB ROMS - are chips which can be used to store programs, rather than using up RAM. They can be re-used, - and function as temporary ROM The Amber printer graphics for example with the BBC micro's dump of February's issue should 0.1 operating system. be amended to read: code and Basic Both machine 1019 REM send carriage return programs may be burned into to clear paper EPROM and plugged into the empty 1020 VDU1, 13, 1,13, 1,13 sideways ROM sockets on the front 1039 VDU1, 13, 1,13, 1,13 right of the main circuit board. For either sort of program, special

90 ACORN USER MAY P.L DIGITISER SYSTEM' Designed for use with the BBC Model B Microcomputer

The P.L Digitiser System enables you to reproduce complex pictures and diagrams, or produce original designs, quickly, easily, and accurately. TO: B. S. Dollamore Ltd, Castle Gresley,

The package consists of the 'Graphics Digitiser' incorporating a tracing pad Burton-on-Trent, Staffs DE11 9HA (mapped out by rectangular grid) 256mm x 205mm and the 'Control Please supply the following: Program' (cassette tape or disk) which handles the information passed Value from the digitiser to the microcomputer. Qty Description Cost P.L. DIGITISER £149.95 WIDE RANGE OF INSTRUCTION scale may be increased or reduced BLOCKS. Instruction blocks by making just two inputs. Price includes post, packing & VAT @ 15% enable: boxes and circles of any STORAGE. Pictures may be saved Each Digitiser is supplied with cassette/disk* Control size to be constructed by specifying on cassette or disk file or Program, key card and comprehensive operating instruction two probe positions; filling area reproduced by a line printer. manual. with chosen colour; drawing of

irregular shapes using chosen FULL COLOUR. The range of I enclose cheque/ P.O. for £ or please charge on resolution; outlining defined area in colour facilities offered by the BBC Access/Visa Card different colour and varying line micro is easily handled by the No thickness; creating lines in Digitiser, in modes 4 and 5. Horizontal, Vertical or Angled Signature ACCURACY. The probe position is modes, with parallel lines in repeat continuously displayed on the Name or multiple repeat styles again in screen and fidelity of image to

selected thickness; write and Address : original drawing is very accurate. position text. NO KNOWLEDGE OF BASIC COMPLETE EDITING FACILITY. REQUIRED. Users can very easily Mistakes can immediately be erased and quickly familiarise themselves *Please delete. and rectified. with the P.L. DIGITISER SYSTEM. Also available through authorised dealers. Contact Leasalink RELOCATION AND SCALE. TM-B. S. Dollaniore Lid, Castle Gresley, Viewdata Limited, Scientific House, Bridge Street, Sandiacre, Images may be relocated simply by Burton on Trent, Staffs DE11 9HA. Nottingham. Telephone 0602 394000 for details of nearest stockist. inputting two probe positions and Telephone: Burton on Trent (0283) 217905

Electronics & compuTing MONTHLY %^ Electronics & Computing Monthly

is Britain's FIRST electronics and computer applications magazine Electronics & Computing Monthly

is designed for the technically aware computer enthusiast. Electronics & Computing Monthly has a unique blend of theory, projects, software and product reviews, plus science and general features on a wide variety of topics. Electronics & Computing Monthly keeps you fully informed on changes in computer technology. Electronics & Computing Monthly

is at your newsagent

ACORN USER MAY 91 -

READER SERVICES

BACK ISSUES BINDERS

July/August The first issue. November Teletext, second Articles on drawing tech- BBC rv series, machine code WE CAN now offer binders which will niques, the series 1 programming lorum, BBC Computer , Programme, machine code Trek III. speeding up easily hold a dozen issues of Acorn graphics, questions and graphics. Bomber game price of £3.95 each answers, hints and lips, sound, listing, 7-tone Epson graph- User at the special interlacing scientific mstru ics dump, Atom graphics (includes postage). These quality ments, dumb terminals lorO 1 manipulation, dumb termina machines, disc drives, Econet lor 0.1 machine, lirework binders have been specially commis- in schools. graphics, editing lips sioned in a maroon, simulated leather finish with 'Acorn User' overprinted in gold lettering. Please make cheques Publishers, September Ceefax telesoft- December BBC TV in schools, payable to Addison-Wesley - ware, Beeb in business, mailing machine code 2 registers, and send the order to BKT (address list. simpleliles,30-Hi>ui Basic programming forum, program course, art on a micro, music. generalors. carols, hints and below). BBC microas a keyboard extra tips, Logo and turtle graphics Alom commands, BBC Basic in schools, introduciion to pro- board, ULA design, teletext cedures, software review. Atom graphics, machine word processing, toolbox re- graphics, analogue input, view. IB-colour graphics on PHOTOCOPIES schools training, 0.1 cassette model A, sorting, sound en- design. I iug patch. velope

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92 ACORN USER MAY BBC MICRO

THE BBC MICRO BOOK ASSEMBLY LANGUAGE BASIC, Sound and Graphics PROGRAMMING ON THE Jim McGregor and Alan Watt BBC MICRO The complete introduction to your John Ferguson and BBC Micro, this book offers Anthony Shaw comprehensive coverage of BBC Developed from the authors' BASIC, plus over a hundred pages popular series of articles in 'Acorn on the machine's extensive sound User', this book introduces the of and graphics capabilities. techniques assembly language programming on the BBC micro. It is intended as a learning tool, and Contents: includes a large number of • Introduction examples to reinforce each new • Communicating with your idea. programs Contents: • Doing calculations • The microcomputer • Choosing alternatives • The microprocessor • Loops • The assembler • Subroutines • Statements within statements • Flags and branches • Handling lists • More on the assembler • Procedures and functions • Indexed addressing • Special effects with text • Arithmetic • Graphics • Logical instructions • Sound • Indirect addressing • Animation • Linking BASIC and machine code • Communicating with the outside world 320 pages 20114058 6 £7.95 • Interrupts

256 pages 201 1 4239 2 £7.95 CREATING ADVENTURE PROGRAMS ON YOUR BBC MICRO GAMES BBC COMPUTERS PLAY Ian Watt Tim Hartnell, S M Gee and An Addison-Wesley/lnterface Mike James co-publication An Addison-Wesley/lnterface There's little chance that in real life co-publication you'll ever be able to explore labyrinthine cave systems, battle You might as well lock the garage dragons, or discover treasure and throw away your season ticket - chests. But with your BBC micro and you won't be going out much over this book, you can experience all the next few months. You'll find this and more. there's too much to do exploring these exciting games and You play the role of the creator, demonstration programs on your devising and developing an entire BBC micro. mini-universe, complete with its own laws and logic. As a bonus, the book From massive ADVENTURE also includes a number of complete, programs, board games, and arcade ready-to-run adventure programs for action programs to stock market you. simulations, biorhythms, and pontoon, this varied collection has 160 pages 20114678 9 £6.95 something to suit everyone's taste. Addison-Wesley Publishers 96 pages 201146401 £6.95

Please send me: 14058 6 McGregor/The BBC Micro Book at £7.95 Signed Date — 1 4239 2 Ferguson/Assembly Language Programming on the BBC Micro at £7.95 Name _ 14640 1 Hartnell/Games BBC Computers Play at £6.95 Address 14678 9 Watt/Creating Adventure Programs on the BBC Micro at £6.95

I enclose my cheque for £ OR Please charge my Access/Barclaycard/Visa/American Express/ Diners Club Account No. Addison-Wesley Publishers 53 Bedford Square, London WC1 B 3DZ au/5 Two top quality programs from Kansas - for four years the Brand Leader in microcomputer software

Don't struggle with your keyboard, the keys ever again 1 Keep at it and speed will follow. Apart from simple working instructions and a finger make it easy with position chart, everything is actually shown on the screen. You don't have to wade through a printed course. You will be prompted the characters to type on the screen and will be shown which are being keyed in correctly and which are not. MICROTYPE At the start you will be given the 'home' keys to practice. The ultimate typing tutor but unlike normal typing tutors, the computer can tell on which keys you are inaccurate or slow and so can give more - now upgraded for the BBC practice on these keys whilst at the same time replacing those on which you are proficient. Recognised as the standard in typing tutors since it was There is also the choice of practice mode or paragraph introduced to microcomputers some three years ago. the mode. So once the program has given, and you have learned, Kansas Microtype has been still further improved and most of the keys, paragraphs can be attempted. converted to the BBC Micro. There are ten short exercises in each lesson, with a So you have a Beebl Which means you, and most likely complete analysis of your performance at the end. This those around you are going to spend a fair bit of time in the includes your average typing speed, accuracy and any keys future at the keyboard. Not just in the near future, but for you mis-keyed. If a response time is set, the program will many years to come, as computers are here to stay. also show the keys on which this time was exceeded. So why not master the keyboard now? Stop chugging Being designed for micro keying, a great many of the words away with just a few fingers and your eyes for ever on the selected by the program are those which are actually used in keys - learn to touch type, giving you speed and accuracy. programming the BBC. But of course, it is also ideal as a Microtype will allow you to teach yourself, and will normal typing tutor, as both typewriter and computer progress as you improve. Just a few short sessions and you keyboards are the same. will see results. Keep at it for say half a hour a day and you will be touch typing within a week, with no need to look at VAT and post paid - £1 2.50

A real traditional Adventure for the BBC. . . DKACULA ISLAND

Ever played a good adventure game on a Micro? If not, you are in for endless hours of enjoyment, with no little hair tearing in the bargain in the attempt to solve it. A traditional adventure always has a purpose and is absolutely logical in that the locations are always in the same place, objects are either in their place or where you leave them, and the conditions depend exactly on the action you take.

Using directions or two word sentences, you set off on your adventure, in this case to kill Count Dracula! But beware, there are many pitfalls awaiting you on your journey and many objects will have to be found, always bearing in mind what happens to Dracula when the sun

- 1 goes down. But it all adds up to days and days of fun and frustration

Being written for the BBC, use is made of the micro's colours during operation, not just because they are there, but to actually help in playing the game.

The programmer says it will take on average three weeks to solve. But there is a bonus, for unlike the adventures already available for the BBC, your progress with Dracula Island can actually be saved to tape. This means that after making progress, you can save the data, and then load it back at a later time to carry on playing from the actual place at which you last HELP! If you get absolutely stuck with Dracula Island, give our adventure finished, and as many times as you want. Unlike others, this one IS logical and IS solveable... expert, Jan Green, a ring - she'll help!

If you have played adventures on other micros, you will find this one exceptional, and if - you have never played an adventure before, it will get you hooked try it . . . VAT and post paid £9.50

SEE US AT THE SHOWS a in for , . ., , firsl , you are

Midland Computer Fair Birmingham 28-30 April

Computer Fair Earls Court 16-19 June

very- eed the

SsKsar SORRY - NO DEALERS yeai& J s ou> tout __ In viewiw of our guarantee and returnretu"*rn post service Kansassas programs can only be purchasedpur direct. tRansas Publishers of the famed Kansas 'Arcade' series -now available for the BBC Micro ^^ Kansas CityCitv Systems,S Unit 3, Sutton Springs Wood, Chesterfield, S44 5XF. Tel. 0246 850357

94 ACORN USER MAY USER GROUPS

has been formed to provide of fun and hope others will HUMBER MICROS talks and demonstrations by follow your lead. local dealers and workshop The Hull and District TRS80/ evenings for help with mods, UNIVERSAL CORBY Beeb Users Group meets upgrades and interfacing. They twice monthly at the psychology at 7.30 on the meet second Peter Wilson is the man to of at department Hull University Thursday of each in month contact if you are a micro user 8pm. Second Tuesday of the Witham. For details phone (Beeb, Vic, Pet or Spectrum) in month is a talk or demonstration (after 7pm) Nigel Ballard (0206 and around Corby. The and the Thursday 16 days later 72889), Dave Watts (0245 Universal Micro Club meets is for members to do their own 358127) or Andy Purkiss (0376 fortnightly at the Spread Eagle thing. For further information 515609). in Oakley Hay. Details from the contact R. Souter (0482 address below. 654117) or J. Lawrence (0482 BEEB DOWN UNDER 493856). HELP WANTED We are very pleased to hear ESSEX NAMEBUG from the Australian Beeb and Would anyone wishing to help Atom User Group which is run set up an Acorn User Group in Attention Beeb users in Essex. from Canberra by Steve the Wimbledon area please The North and Mid Essex McLeod (address below). Good contact Mr A. Quinn, 19 Victory Micro User Group (Namebug) on you, Steve, we wish you lots Road, London SW19. CLUB CONTACTS

• Ru| i • Mr< Rutler • Liverpool BBC • Mi Amateur Computer Club Medway Atom Users Club Microgroup National BBC User Group

SI J c/o Fred Shaw 40 Mount Pieasanl Avenue

• '•aet 14 Albany Avenue

1 • West Midlands 1 itham Computer Group Kent 'SCOt Merseys.de 1.34 2QW 12 Apsley Road • Mr R Lull Oidi • Beebug Kingbee

i • • ifti West Midlands 868 OQZ" 1 Road

. i ... Bottisham Acorn User • Mi i Group Ktngsv. Bedl West MhH.ii a i Rowan Close • Mi J Asfiurst Bottisham Brighton Acorn Computer Cambridge CBS 9BN • Computer Club Users Group (0223)811487 • Mi P Beverley Norwich Area Acorn User scent Road • Peter Smith Group Manchester 8 Fareham and Portchester Amateur Computer Club 8304/43311 • Mr U.L Evans 23 Sandy Close

; ".iad Pelerslield • Ted Norwich NR2 2LJ •v Camp Hants Eastwood Town • • Pa Microcomputer Club Edinburgh ZX Computer Laserbug N P. iBazylei B.,' Club • Harrow Computer Group 10 Dawley Ride iVOOd •.;. lace Road Colnbrook Nottll 16 Si' Pi Bushey Heath Wallord WD2 3LG 9 SL3 OOH • Mi i a Kaj i • iti .-White I SOBAT Computer Club Atom/BBC User Group B25 Ben ms Lta • R A • ' art Pain Harpenden Colour Micro Users Group Microcomputer Group 40a High Street

: Stony Sirallord . 7 ryli

Milton K< • Herls AL5 5RT Tel: (0908) 51 Association ot London • M' '.' Computer Clubs Potbug BBC Users Group • Mr 1 • Mr. D. Coulter Atom Users Group Preston BBC User Group ii

i Drive

li Ingol n • tl Presti '• Liverpool BBC & Atom

Group • . • Acorn Users Group ot BBC Norway Sweden

'• bSH M • Muse

- eposi

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• 1 ' Namebug ; a i .

• 1 TRS/80 Beeb Users Group Bangor & District Micro • M I . Users Group (BAOMUG)

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• 6

North London BBC II

Micro Users Group • El • |i Bognor Computer Group • Pi BBC Users Group (BUG) Universal Micro Club of Canberra ' e Walk lardei l

.- . Australia isse» eat Oakiey M

ACORN USER MAY 95 INDEX OF ADVERTISERS THE P.M.C. A B Designs 74 Interface 79 Acornsoft 44/76/77 Kansas 94 Addison-Wesley 93 WORDWORKER Laserbug 87 J Vision 79 A Viewdata IFC PROFESSIONAL BBC WORDPROCESSOR* ATPL 74 Leasalink Leosoft 33 EASY TO USE AND VERY POWERFUL Beebug 70 Level9 69 Includes full editing ability. Correct and change single words. 50 Bits & Bytes Micro Advent 15 Delete and insert any amount of text any time. Bourne Educational 66 MicroAge 10/17/18 AUTOMATIC REALIGNING Butterworths 33 MicroAid 18 TEXT ALWAYS ON VIEW Cabel 81 Micro Management. ...60/61 length to any size. Hold many pages at one Micro Power OBC Set margins and page Cambridge Processor 34 together. Paper feed between pages allowed for. Midwich 25 time to print out Chalksoft 88 Print hard copy any time on any printer. Multiple copies. CJE 14 Muse 80 IDEAL FOR OFFICE OR HOME Coker, Paul 96 Newark Video Centre 69 Concepts 65 i.e. manuscripts/essays/documents and reports. Computer Off Records 50 Contex Computing 96 ENORMOUS TIME SAVING P L Digitiser 91 Control Universal 91 Eliminate wasted work by typing errors etc. Pentland 6 Cumana 1 Portatel Conversions 72 SAVE WORK AT ANY TIME 88 a (on printer) from pre-recorded work in Dial Software QTec. 88 Retrieve hard copy Digital Fantasia 7 seconds. DrSoft 96 Salamander 9 Sets out standard letters and inserts variable data, /Quotations in a widely used . . No. Secta Software 82 i.e. Change . Name/Account Electronequip 80 Silent Computers 82 letter. 91 Electronics Computing Sir Computers 73 AMAZINGLY LOW PRICE . . . £9.50 Eltec Computers 10 Software For All 52 Make cheque or P/O payable to . . . Paul Coker (Software) Invasion 63 Palace, London 1SS. Gaelsett 66 Software Send to 25 Farquhar Road, Crystal SE19 Gemini 28/29 Superior Software 56 Phone 01-761 2087. guaranteed. Golem 72 3D Computers 56 Tape program reproduction Discounts on bulk orders. Computers 68 Technomatic 4 Guildford Completely confidential printing service available. Twickenham Computers.. 50 £2.00 per 100 lines. Hall, Chris 66 Will adapt and supply hardware for disabled, i.e. Dyslexics. Hessel, Simon W 26 Video Palace 82 Other software available. Hexadecimal 8 Watford Electronics... 20/21 Maze Game. £4.50 (Model B or upgraded (RAM) A) West Coast Computers.... 66 English help. £5.50 (Model A/B) UK Software IBC 8-11 educational. Maths and Windsor Computers 41 All prices all inclusive. Ikon 68 Intastor 73 Zencom 80 "WORDWORKER (Model B or upgraded (RAM) A)

CONTEX Doctor Soft Presents Adult Educational Software A— £7-95 32K for the BBC computer WOLFPACK III A new concept, a new classic.

- TYPING TUTOR 32K True in "space" cumulative motion — unlimited freedom and movement and sound. Specifically designed for the BBC micro the 90 smoothly amazing colour graphics "Sometimes your first warning is a lancing disrupter beam striking from beyond graded lessons teach, train and encourage you to become visual range, sometimes they materialise close at hand. You are either quick or quickly proficient at touch typing. Keyboard display dead!" Prowl lush starfields commanding a mighty fleet o( deadly star cruisers. Carefully highlights each lesson. Word scan error checking, times plan your strategy. Switch control from ship to ship, each has its own mission, (wpm) and recommends next lesson. Audio key feedback, each its own destiny. phantoms using metronomic pacing beat, many user configurable options. Seek out lethal enemy battle stations, planets, cruisers, and base station radar and target data. Instruction booklet supplied £10 inc. to Fight to the death! Detonate the enemy for a harvest of energy to transport base. Lose, and risk a rescue under heavy fire! SPREADSHEET 32K Features include real and enhanced time, docking, refuelling, rotating base station, meteor strikes, rank and promotion, damage reports, crew comments, versatile 'calc' program and tutorial. A complete and hyperspace walk between galaxies and separate briefing programme. A total Models containing over 1 000 cells can be built using up to experience. 99 rows. Equations, constants or text in 26 columns and Other Doctor Software for the BBC Micro includes: - same B.A. Captain who any cell. Emphasis on ease of use includes copy, row/col 747 '32K £6.95 Fullblown flight simulator by the wrote the famous Atom programme. variables, row colours, save insert, delete, totals, headers, Cremlin "32K E6.95-3D mulit-level maze escape with Gremlin Kombat' Maps. and restore. Tutorial, application examples and docu- skill levels, standard or random structure. Harmony "16K £5.95- Delightful, infinite, saleable patterns of light and sound. mentation of the all Basic program for those who wish also Royalties- The Doctor pays top royalties for top programmes, All types of to explore the design. £8 inc. popular machines and all types of software.

NO EXTRAS, prices fully inclusive. Cassette based. Professional software and service Cheques and P.O.'s tot- £1 .50 if both programs BBC always. Special Offer! Deduct Doctor Soft, ordered together. 258 Coneygree Road, Peterborough PE2 8LR. MICRO Cheque/PO payable to 'Contex Computing' (A5) 15 Woodlands Close, Cople, Bedford MK443UE DOCTOR SOFT

96 ACORN USER MAY the one to watch

MODEL A/B

Cassette 1 : Star Trek/Candy Floss (very popular) C6.50 Cassette 2: Family Games (hours of fun) £4.50 Cassette 3: Mutant Invaders/ Breakout C6.50 Cassette 8: Model A Invaders (M/C) £5.50 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 9 MODEL B Invaders (or A+32K) (M/C) £7.50 CASSETTE 10 MICRO WORDPRO. (Cassette W.R 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 All in the Drone aliens in the caverns with • software stock before we your laser tank. £6.50 advertise • for CASSETTE 14 Send SAE 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 II* 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) c]®©®®®®®

CROAKER

CROAKER (B) £6.95 just trying to hop logs People- HUH!! Pity us poor Frogs!! It was tough before, packed with fast-moving traffic. And if over the river. Now you've built multi-lane motorways, and faster and breed ever increasing we qet the family safely over that little lot, you drive faster long will we survive numbers of crocodiles and diving turtles to make things impossible. How the ravages of Human Expansionism? excellent sound and graphics. The Full feature, arcade-standard, machine code program, with Connoisseur!! faster you complete each level, the more you score. One for the

(B) £6.95 SWOOP (B) £6.95 -the NEW GALAXIANS LASER COMMAND of 6 Cities'. Detonate single Galaxian style, machine-code arcade game. Classic 'Defence from THIRTY screaming, homing, bomb-dropping, mines or patterns to counter laser fire recall mine patterns. explosive egg-laying BIRDMEN, swooping alien planets. Store and machine-code arcade game with down to destroy your laser bases. Bonus Super fast, graphics, sound effects, many skill bases, score & high-score, hall of fame etc. superb levels, bonus points, etc.

CHESS (B) £6.95 Our excellent machine code program— now with LASER COMMAND superb MODE 1, colour graphics. Six skill levels, play black or white, illegal moves rejected, 'en passant', castling, take- back of moves, and display of player's cumulative move- time. Options include Blitz Chess where you must nove in 10 seconds, set-up of positions for analysis, replay of a game just played and saving loading, a of part completed games on tape. On game can be replayed. 1 1|72 Spassky/ Fischer

5 9 ®®(o)(g)®®(mjE®®® ®@®®@®[*