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BBC micro, Electron and Atom magazine

SCHOOLS: computers and IT PRINTERS: picture dumps BBC: drawing procedures INTERRUPTS: system control GRAPHIC: CAD displays ATOM: cash forum

is<^ .^: # THE GAP

An example of superior technology, total reliability and outstanding performance, combine to produce the LVL 200K dual disk drive.

A truly professional unit designed to fill the gap between the Acorn lOOK and 800K disk drives.

Also available in a lOOK single drive format. Compatible with the BBC single drive unit Powered from your BBC model B computer Disks are interchangeable with those No chance of data corruption from on-board formatted on the BBC lOOK Drive power supply. Operates either from the BBC DOS (available with the unit) or from our optional Z80 To Leasalink Viewdata Lid Scierititm House, Btidfie Street, Sandiacre, Ni)ltiii[;liani NGIO 5BA card Please send nit CP/M _ 200K Dual Disk Drivels) £389.00 (inc VAT) Supphed complete with all necessary lOOK Single Disk Drive(s) £265,00 (inc VAT) connecting leads, utility disk and full Operating Syslem(s) @ EU0.25 (itic VAT) Current F'rice Li^t Only' I I FREE operating manual.

I enclose a Cheque For^ £ Please Debi! My Access/ Bare laycard/Antex

No . . . , J I 1 1 1 i_

Narne Address: r\7i

Scientific Pom Code. Day tirne Tel No: House, Bridge Street. Sandiacre, Nottingham

"Please enclose s.a.e. Allow 28 days for delivery. NGIO 5BA. Tel: 0602 394000 THE SPECIALISTS

OFFICIAL ACORN DEALER

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MOD A E260.00 + VAT WIDE RANGE OF EDUCATIONAL AND BUSINESS MOD B £346.96 + VAT ENTERTAINMENT SOFTWARE FROM THE LEADING SOFTWARE HOUSES

>lCORNSeFT SOFTWAF BBC UPGRADES £45 + VAT BBS DISK INTERFACE KIT £95 + VAT 2nd PROCESSOR (6502) + 64K RAM £170.00 + VAT 2nd PROCESSOR (Z80) + 64K RAM £170.00 + VAT A + F SINGLE DRIVES; 1 0OK E190 200K £255 400K £345 DUAL DRIVE: 200K £360 400K £480 800K £610 DISC CABLE: SINGLE £8 DUAL £12 BOOKS TORCH ZBO DISK PACK Call in for latest prices CASSETTE RECORDERS, PRINTER CABLES, LEADS, DISCS, STATIONERY, CASSETTES, RIBBONS, DUST DOT MATRIX PRINTER COVERS

EPSON MX80 FT III DRAGON COMPATIBLE EPSONMXIOOFTIIt E395.00 "^ dragon 32 EPSON FX80 FT £395.00 ONLY £195.00 CP — 80TYPE1UNLYE299.00 SEIKOSHAGP100A £180.00 Friction + Tractor SEIKOSHAGP250X £240.00 STAR DP510 — 80 COLUMN ORIC-1 ONLY £325.00 48K £1 55.00 INC Friction + Tractor ONLY VAT COMMODORE 64 iMWiiJIIIJJIJ:IL'm THE PERSONAL COMPUTER FOR ONLY £290.00 + VAT ^SiiyEf^-REEO QUALITY DAISY SERVICES WHEEL PRINTER/ TYPEWRITER SERVICE CONTRACTS TO EDUCATION FOR ONLY AUTHORITIES AT DISCOUNT £399.00 + VAT INC RS232 INTERFACE WITH 2K BUFFER RENTALS MAIL ORDER AND RETAIL SHOP, TRADE AND MiK'lliiliK' EXPORT ENQUIRIES WELCOME. GOVERNMENT AND EDUCATIONAL ESTABLISHMENTS OFFICIAL 4" MICROVITEC 1 431 1 COLOUR MONITOR RGB INPUT ORDERS ACCEPTED Price Including Connecting Lead £249.95 PLEASE ADD 15% VAT + £7 CARRIAGE 2 ZENITH 1 " GREEN MONITOR Excellent Res £80.00 CALL FOR FURTHER DETAILS ON ELECTRON CALL IN FOR FURTHER DETAILS TWILLSTAR COMPUTERS LTD. 17 REGINA ROAD, SOUTHALL, MIDDX. TEL: 574 5271 (24 hours) OPEN 10am-8pm SIX DAYS A WEEK

ACORN USER JUNE READER SERVICE CONTENTS ACORN USER

JUNE 1983 NUMBER ELEVEN Special offer .<

to readers Interrupts What they are and how to handle binders them, by Tony Shaw and on John Ferguson

r.L News that affects YOU Beeb Forum Voice processor release, Three pages of the best ideas Granada TV micro show, around from Ian Birnbaum and Beeb terror show, micro floppy readers

.1 ."•",

THESE quality binders have News feature been specially commissioned Not 100 yards from Big Ben, Schools: 8 page pull-out is in for readers from a major British history the making Information technology: what it manufacturer. They are available means for computing in primary exclusively through Acorn User schools by Tricia Strong and at an introductory price of £3.95 .t.!.. Paul McGee which includes postage and £1100 competition packing. So, keep a year's worth of Two-part quiz begins with BBC *»•• • your favourite magazine in micro, disc drive and printer as first prize •J i prime condition, send for one Atom Forum of these maroon, simulated leather binders. Acorn User is Barry Pickles offers cash • • • printed in gold on the front and for readers' wrinkles, and with few of his own spine of each. Techniques kicks off a Make your cheque payable to Stan Froco kicks off a new series Addison-Wesley Publishers with sorting Ltd, and send it to BKT (Subscriptions), Douglas Road, .: ,—. Tonbridge, KentTN9 2TS. « i « Interfacing » Include your name and Paul Beverley tests out address or use the form on Hints and tips the AU interface box page 92. Allow four weeks for Would you believe a 50p network? delivery. With overseas orders, Read Joe Telford's ideas add £2 for Europe (total £5.95) and £5 for the rest of the world (total £8.95, airmail). Also turn to page 92 for details Reviews of other reader services - Graphics View or Wordwise? subscriptions, back issues, Drawing techniques and CAD by Two wordprocessors run photocopies and reprints. Jim McGregor and Alan Watt Paul Beverley's gauntlet

How to submit articles: You are welcome lo send articles io the Editor ot Subscription Information: Send Acorn l/ser for publication. Acorn L/sercannotundertaketo return them unless a your cheque or postal order made stamped addressed envelope is enclosed. Articles should be typed or computer pavable to Addison- Wesley Publishers written with double line spacing. Black and white photographs or trans- Ltd lo: Acorn User, BKT (Subscription parencies are also appreciated. It submitting programs a cassette ordisc 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.(G732) article elsewhere. Send articles, reviews and information to: The Editor, Acorn 351216 Telex: 95573 User, 53 Bedford Square, London WC1 B 3DZ.

ACORN USER JUNE 2

JUNE content; NOTICEBOARD

Micro books offer ***** *•** to subscribers

i i Acorn User has arranged a special Reviews £1 discount with Addison-Westey Publishers on the following books. Three superb graphics packages Details of this offer (which applies under Mike Milne's scrutiny, to subscribers only) are contained from £10 to £35 in an insert to this Issue. D The BBC micro book

• f * Basic, sound and graphics • * • * *•« *•» Jim McGregor and Alan Watt Printers Normally £7.95 Write your own graphics clumps Subscriber price £6.95 with George Hill's guidance D Assembly language program- Cover illustration ming on the BBC micro • * * by Stuart Hughes John Fergusonand AnthonyShaw « Normally £7.95 Subscriber price £6.95 Readers' letters Editor Tony Ouinn D Games BBC computers play

Sound, radar, bugs. . . it's all here. Editorial Assistant Tim Hartnell,S M Gee and Mike James Plus new personal ad service- Free! Kitty Milne Normally £6.95 Managing Editor Subscriber price £5.95 Jane Fransella *H D Creating adventure programs u.. Production Peter Ansell on your BBC micro Reader services Tina Teare Ian Watt The value-for-money add-ons Marketing Manager Normally £6,95 Paul Thompson Subscriber price £5.95 to get the best from your mag Promotion Manager

* 1 Pat Bitton

i Publisher Stanley Malcolm Authors please note Dealer list Designers and Typesetters We've been inundated with articles GMGraphics, Harrow Hill for publicallon - many ot an ex- Whether you live in Devon, Munich Graphic Designer tremely high standard. Ittakestime or Wellington, we can tell you Phil Kanssen to read them, try listings out and where to go Printed in Great Britain edit them - which is the only way by t.T.Heron & Co. Ltd to maintain standards. Also please Advertising Agents remember that magazines work Coming soon in Acorn User: Marketplace Computer Ltd at least two months in advance. Electron: yet more exclusive 20 Orange Street So please bear with us if you London WC2H 7ED the scoops on way 01-930 1612 hear nothing for weeks (although all submissions are acknowledged). Teletext: the adaptor under Distributed to the News Trade scrutiny by Magnum Distribution Ltd. Thanks for your patience and 72-8 Fleet Street, apologies foranyfrustration caused.

Printers: colour graphics dumps London EC4Y 1 HY Tel: 01-583 0961 ^nH Interfacing: add a second Telex: 893340 Magnum G- keyboard Published by Free personal ads Atom: sound revisited Addison-Wesley Publishers Ltd. 53 Bedford Square, STARTING from the next issue, we Reviews: EPROM programmer, London WC1 B 3DZ plan to run a free personal ad service. utility ROMs, games Telephone: 01-631 1636 It's individuals only, Telex: 881 1948 for no companies Birthday: Acorn User is ISSN: 20M 7002 7 please. See the form on page 89 if one-year old in July! ©Addison-Wesley you've got anything to unload. First Publishers Ltd 1983 come, first served, so get a move on!

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 of tt}e World Rest £24 publisher, Acorn Computers Ltd, or Acornsoft Ltd. Acorn, Acornsoft, and

Ttiese prices are irictusive of post and \ the Acorn symbol are the registered trademarks of Acorn Computers Ltd packing (air mail overseas) for 1 ssues and Acornsoft Ltd,

ACORN USER JUNE Technomatic Official BBC Dealer 01-4521500 01-4509764 01-4506597 Telex: 922800

BBC DISC SYSTEM BBC Disc Interface inc. 1 .2 operating System £95 Installation £20 Model B £399 BBC Sifigle Drive (100K) I price includes VAT. Can extra £81 £230 + £6 Carr. BBC Dual Drive (800K) Complete Upgrade Kit £50 £6 Carr. Installation £15 £699 + Individual Components also available. BOOKS tNoVAT- apftp/Book) All mating connectors with Basic Programming on BBC £5.95 cables in stock. 30 HR Basic (NEC) £5.95 'VIEW BBC Word Processor ROM Let your BBC teach you to Program £6.95 BBC Micro Revealed £7.95 Teletext Adaptor Assy. Lang. Program on BBC £8.95 Program the 6502 £10.75 6502 Games £10.75 Wide Range of Business, Education & Fun Software in stock 6502 Software Design £10.50 BBC Micro An Expert Guide £6.95 SEND or PHONE FOR OUR BBC LEAFLET BBC Computers Play £6.95 PRINTERS LaA.^ iMECPC8023BEC BBC • 80 Cols. 100 CPS • Proportional Spacing • Hi-Res & Block Graphics SYSTEM • • «^e^ Bi-directional Logic Seeking Forward & Reverse Line Feed • International & Greek Alphabet • Auto underline PACKAGE^T^^fl!^ • Super & Sub Scripts • 2K Built-in buffe comprises of a BBC Model B £345 + £8 Carr. This package and EPSON RX80 & FX80 NEW computer fitted with disc interface dual drive, PC 8023 • RX80100CPS80Col. Tractor Feed — -r t'T W.P. ROM 800K NEC • FX80 160 CPS 80 Col. F&T Feed. Full specifications on request. Printer and 12" Green Screen Monitor. RX80E298 FX80£430 MXlOO F/T3£425 Carr. /Printer £8 The system is supplied complete with all SEIKOSHA GP100A £180 + £6 Carr. manuals, connecting leads and software SEIKOSHA GP250 £235 + £8 Cam for stock control, invoice and statements Parallel Printer Lead £13.50 2000 sheets 9 y2" x 11" Fanfold and mailing lists. of £139. Paper £13.50 -I- £3 p&p Serial Interfaces in stock. Package Price £1,500 a saving

BBC COMPATIBLE 5%" DISC DRIVES DISKETTES in packs of 10

These are TEAC mechanism fully compatible with BBC. They are Single Sided 40 tracks £15 Single Sided 80 tracks £24 supplied with independent power supply and housed in BBC Double Sided 80 tracks £32 p&pt:2/pack matching cabinet. Lockable Box 30/40 discs £21 SINGLE DRIVES: 100KE190 200KE255 400KE345 60/70 discs £32 DUALDRIVE: 200KE360 400KE480 800KE610 Library Case £2 Drive Head Cleaning Kit £15

Carr, C6/singie drive ca/Duai rJnve. Disc Cable: Single £8 Dual £12 Disk operating manual & fornnatting diskette £17.50 BBC Compatible Cassette Recorder £26 + £1.50 p&p MONITORS Cassette Leads Microvitec 1431 14" RGB 12" Hi Res Green Monitor 7 pin DIN - 3 jacks £3.50 £249 + £8 Carr. £99 + £6 Carr. 7 pin DIN - 3 pin DIN + jack £3.50 Microvitec 2031 20" RGB Also available Sanyo & Kaga RGB Computer Grade Cassette C12

£319 + £10 Carr. Monitors 50p each or 1 for £4.50

Please send SAE for our detailed price list of electronic and computer components We carry a wide range of connectors and assemblies, Microprocessors, RAMs, EPROMs, Crystals, etc. Price Lists, Leaflets available on request. Large stocks enable same day despatch on most orders. Special pricing for dealers purchasing in quantity. Please check for delivery details.

PLEASE ADD 40p p&p & 15% VAT Technomatic Ltd (Export: no VAT, p&p at CosI) MAIL ORDERS TO: 17 BURNLEY ROAD, LONDON NWIO lED Orders from Government Depts.,& Colleges etc. welcome. SHOPS AT: 17 BURNLEY ROAD, LONDON NWIO Detailed Price List on requesl. (Tel: 01-452 1500, 01-450 6597. Telex: 922800) 305 EDGWARE ROAD, LONDON W2 Slock itemsarenormally by return of post.

ACORN USER JUNE NEWS

Summer micro show on Granada CHIP-IN is a TV series on at the gap between the User groups and com- micros to be shown on hardened user and the puter clubs in the North- Granada this summer. person who is totally west have been approached The programme will run mystified. and one idea is to have two for six weeks while the early 'The series will not cover families taking part in each

evening local news show programming, or lift the lid,' episode.

Granada Reports is off the said Connors, but will If you have any ideas for air. Peter Connors who is concentrate on 'reviewing the series, write to: Chip-In, working on the pilot show software, add-ons and ap- Granada TV, Quay St, described Chip-In as 'aimed plications'. Manchester M60 9EA.

AU author wins ACORN User author Peter Voice processor Voke (see May's issue} won the race to solve Acornsoft's Castle of Riddles adventure game. to plug Beeb liole Details of the competition were released on the same THE long-awaited speech from Basic or assembly day to prevent anyone synthesis chip - which uses language. They take the form: gaining an unfair advantage. the voice of Kenneth Kendall Peter worked on the SOUND -1, number,0,0 - should be available at program over the weekend or and dealers this month. managed to get his SOUND-1 , ASC"char",0,0 Acorn's Speech Processor correct entry in at 8.31 am was due to be launched by In the first 'number' is a on the Monday. case Kendall. . . chip's voice last Christmas, but has been designated value which calls His prize, presented by on early BBC machines held up so the cartridge a particular word, while in Acornsoft's David Johnson- which has now been ROM system could be fitted the second case 'character' Davis, included a choice of covered over). at the same time. is an ASCII code. E1500-worth of hardware Acorn plans to release a The system will initially With assembly language, and software. vocabulary extension and be limited to a vocabulary of OSWORD and OSBYTE can games in cartridge form 164 words, or part-words, be used. The first has the later in the year. Amazed reader but this can be extended by same effect as the Basic Mr Tugwell was amazed to cartridge ROMs or from sound command, while the n Acornsoft's View word be a runner-up in our 'Grin' RAM (see last October's second reads the speech processing chip should now competition in May. He rang Acorn User for details). processor direct. be at dealers (see page 73 in to say how delighted he Former-BBC newsreader A new-found *FX call for comparative review with was that 'ordinary people' Kenneth Kendall provided controls the speech pro- Computer Concept's Word- could win. knows, Who he the voice recordings which cessor. It consists of wise). It costs E70 (including may even win the competition were digitised to provide *FX209,0 to turn it off, and VAT. fitting and 1.2 ROM). starting in this issue. vocabulary for the synthesis *FX209,80 to turn it on. View can be used with

chip. Hence Acorn claims it When the two voice chips most printers automatically, Dumping service is the first English-speaking are fitted (C55 inc VAT and but cassettes are to be (rather than American) voice 1.2 ROM if needed), dealers made available which will

BEEBPRINT is offering a synthesiser. enable the ROM cartridge allow it to use the special printer service for anyone Voice commands are socket. This is located on facilities of each printer wanting a hard copy of their issued using the sound the left of the keyboard (the (italics, bold, double-height programs from cassette. A statement (on channel *- 1), mysterious hole or 'ash tray' characters etc). sample price is El.95 for &20 blocks. Beebprint, 19 Orchard Way, Hurstpierpoint, West Sussex BN6 9UB. August first showing for Electron

THE Electron - Acorn's subscribers will receive a Logo club new hobby micro - will be El voucher against the E2 LOGO users can now join launched in August and entrance fee (children half theif own club (Blug) which will coincide with the price) in the August issue. lACORN plans to produce a quarterly Acorn User Exhibition. Acorn, Leasalink View- newsletter and an annual So it will be the first data and Microage have USER journal. A conference is chance to get your hands already booked major being set up for the on one. as well as using stands at the Exhibition. beginning of September. the new BBC add-ons. Bulk discounts on tick- EXHIBITION Details from Ram Valley London's Cunard Inter- ets are available to BBC MICRO -ATOM ELECTRON (secretary), British Logo national Hotel will host schools for the Exhibition. User Group, c/o Shell- the event on August 15- Details from Acorn User Cunard Hotel London W6 Centre for Mathematics, 28. Acorn User is sponsor- Exhibition, 20 Orange St, 25 -28 August University of Nottingham. ing the Exhibition, and London WC2H 7ED.

ACORN USER JUNE 9

MAIL ORDER AND RETAIL SHOP. TRADE/FXPORT INQUIRIES WELCOME GOVERN WATFORD ELECTRONICS MENT AND EDUCATIONAL ESTABLISHMENTS OFFICIAL ORDERS ACCEPTED. CARRIAGE unless staled otherwise, please add 50p to all Cash orders DEPT ACORN, CARDIFF ROAD, WATFORD, Herts, England UK customers please add 15% VAT to the total cost incl. Car. SHOP HOURS: VAT: S.OOam to 6.00pm Monday- to Saturday ACCESS ORDERS: Simply phone: Tel (0923) 40588. Telex: 8956095 Watford Watford 109231 502M.

36" BBC MICROCOMPUTER NECPC8023BE-C Printer PRINTER LEAD Readv made £11 Model A £299 Model B £399 TOO CPS, Bi-directional, logic seeking, 80 MISCELLANEOUS CONNECTORS ' inc/. VATfcarrC?) columns, 7 9 Dot matrix, superscript and P/ugs Sockets subscript, hi-res block graphics, underlining. RGB (6 pin DIN) 30p ^p to UPGRADE KITS. Upgrade your Model A Tractor/ Friction feed, reverse linefeed, 2K RS423 (5 pin Domino) 30p 40p save Mod. B with our Upgrade Kits and Buffer, proportional spacing. £320 (£7 carr) Cassette 17 pin DIN) 25p 65p yourself £ s s s EC0NET(5pinDIN) 15p 25p Paddles (15 pin 'D') £1.10 £2.15 • BBC1 16KMemorvl8«4816AP-3 lOOnSI E18.00 EPSON Printers FX80 Plug 6 pin 75p - • BBC2 Printer User I/O Port E6.98 DISC Power 10" Tractor/ Friction feed, 160 CPS, 1 1 .' • BBC3 Disk Interlace Kit E75,00 matrix, 137 columns max.. Bidirectional, • BBC4 Analogue I/O Kil E6.40 READY-MADE LEADS for BBC Logic seeking, proportional spacing. Hi-res bit • BBC5 Serial I/O Kit £6.70 CASSETTE LEADS: 7 pin DIN Plug • Kit E6.10 image, Italics & Elite Char, Subscript & Super- BBC6 Expansion Bus to5pinDINPIug + IJack Plug f2,00 • Printer Cable Ready made 36" £11.95 script. £395 (£7 carr) to3pinDINPlug -i- IJack Plug £2.00 • Complete Upgrade Kit Mod. A to Mod, B £43.00 MX100FT/3 to7 pin DIN Plug £2,50 to3 Jack Plugs £2.00 15" Carriage, 136 columns, plus all the facili- ties of MX80FT/3 Onlv£425 (£7 carr) 6 pin DIN to 6 pin DIN Plug (RGB) £2.50

DISC DRIVES BBC Compatible LISTING PAPER Official JOYSTICKS £11.50/pr 8^" or 9^" Fanfold paper plain or ruled

1 sheets} £7 ( 1 carr) ( 000 50p LIGHT PEN " All parts available for the Acorn User's 1 5 fanfold paper 1 1 000 sheets) £9 ( 1 50p carr) "SHINE A LIGHT" Light Pen article for £8.50 Teleprinter Roll (econo paper) £3 ( 1 50p carr) ^^"""^ MONITORS GEMINI'S BUSINESS SOFTWARE MICROVITEC 1431. Written by professional Chartered Accoun- 14" Colour Monitor. tants and coded by competent Programmers. used in RGB Input, (as Ideal for small & medium size companies. Now BBC programmes). stock. US50A - TEAC Uncased, Single sided, available from FREE Interface Lead, • PACKAGE £82 40 track, 5i", lOOK £125 CASH BOOK ACCOUNTS (carrf7) CSBOA-'TEAC Cased with own Power Supply. £249 • BEEBCALC. SPREADSHEET ANALYSIS S/S 40 track, 5J", 100K £180 SANYO 3125 14" Colour. RGB & V.H. Sync. £17 with own PSU, CD50A- TEAC Twin Cased Attractive screened metal Cabinet. Value for • INVOICES & STATEMENTS £17 Single sided, 40 track, bl". 200K £350 money. £199 (carr £7) • COMMERCIALACCOUNTS £17 CSBOE-TEAC Single case with own PSU, • MAILING LIST £17 Single Sided, 80 track, bl~. 200K £250 Interface lead for Sanyo £8 • DATABASE £17 CD50E- 'TEAC Twin cased with own PSU, ZENITH 12" Green Monitor. £17 Double sided, 80 track, 5J".400K E475 • STOCK CONTROL Hi-resoluiion E75(carr£7) CD50F- TEAC Twin cased with own PSU, Doublesided, 80 track, 51", BOOK £599 Mitsubishi Slim Line - Uncased, Double density. BBC FORTH on Cassette Acorn ATOM Double track, 51", One Megabytes, track density Follows FORTH-79 standard and has fig- only £220 UTILITY ROM 96TPI , track to track access lime 3mSec FORTH facilities- Provides 260 FORTH Single Mitsubishi Slimline cased with own words — infinitely extensible— Full screen WEROM is Watford Electronic's own most PSU DSDD. 1 Megabytes (400K with BBC) £275 Twin Mitsubishi Slimline cased with own PSU. editor — Allows full use of MOS- Permits use sophisticated but easy to use 4K ROM based DSDD 2 Megabytes I800K with BCC) 1535 of all graphic modes, even 0-2 (just)- Easy on BASIC extension for Acorn ATOM, Plugs Single Drive Cable tor BBC Micro £8 recurtion — Runs faster than BBC BASIC straight into the utility socket in an ATOM with Twin Drive Cable lor BBC Micro £12 Only £13 floating point. The special features are: Verbatim Diskenes, S/sided £20 10 BJ". FREE 70 page manual & a Summary card. High Speed Tape Interface -Memory Dump, D/Sided £30 10 Verbatim Diskettes. b\", Modify Machine code breakpoints- BASIC BBC FORTH TOOLKIT Error Trapping-READ, DATA and RES- TORE-Full BASIC Keyboard Scanner (BBC Adds following facilities to FORTH. 6502 like)-FULL Disassembler-AUTO Line Assembler, providing machtne-code within GP100A Numbering -PLUS: CHAIN, Cursor Move- BBC PRINTER FORTH — Turtle graphics enables easy to use ment, Loop Aborting — Easily Extendible colour graphics— Decompiler routines ena- further. Supplied complete with instruc- bles versatile examination of your compiled tions. £9.95 FORTH programs -Full double number set — An example FORTH program & graphics demonstration— other useful routines — 64 NEW . . . NEW . . . NEW page Manual. Only £10 3 New Adventure games. May be the best yet written. We strongly recommend Ihem, All have Trac- CASSETTE RECORDER & ACC. over 200 individual locations and packed with Feed. 80 puzzles. A game can take easily months to finish. compression techniques can Tins, 30 Top quality Slim-line, portable Cassette Recor- Only sophisticated squeeze so much in. irmal & derfor Computer use. Mains/ Battery operated double width with counter. £28 ADVENTURE QUEST (32K) £8.60 £8.60 Characters. Dot resgraphics. Parallel Interface C12 Computer Grade Cassettes in library COLOSSAL ADVENTURE (32K) Standard. Our price includes FREE 500 cases 40p DUNGEON ADVENTURE (32K) £8.60 SHEETS of PAPER. Only£175(£7carr) RIBBON CABLE LEADS 36" long • SPECIAL OFFER • (Female Plug at one end, other end free) 2764 EPROM 1 + 425p 25 + 395p • SEIKOSHAGP25aXlO"TractorFeed. SK9 Printer Cable (26 way Female) C2.75 EPROM COPYING SERVICE 80 col. 50 CPS, normal & double width & SK10 I/O cable (20 way Female) £2.00 Now available while-u-wait height characters, RS232 & Centronics SKI 11MHz Bus Cable (34 way Fem) £3.20 Interfaces standard. £235 (£7 carr) SK 12 Tube Cable (40 way Female) £3.70 £2 per chip

ACORN USER JUNE BBC GAMES SOFTWARE BeebPen WHERE? £6.95 (BUG-BYTE) (BBC Wordprocessor in 4K ROM) Do you know 'WHERE?' you are? This well written has been SPACE PIRATES £ 6.95 BeebPen written completely in machine program, using high resolution graphics offers limed SPACE WARP £ 7,80 code for the BBC Micro to facilitate maximum speed tests on the geography of Great Britain. GOLF £ 4.75 and number of functions. It is without doubl one of DRAGON QUEST £10,00 the best thing to happen to BBC Micro since its (32K1 £7.00 FRUIT MACHINE £ 4,75 launch. BeebPen has been designed to be as simple WORLD GEOGRAPHY CITY DEFENCE £ 5,75 to use as possible while still retaining the maximum Beautifully drawn Hi-Res colour map of the world illustrates and aids MULTI-FILE £ 8.75 power and versatility. It has numerous functions this graded series of tests on BACKGAMON £ 6.95 including right justification, block operations, text capital cities and populations of the world. compression, full cursor control with on screen editing and a full set of printer options. WRITING £4.80 BeebPen ROM plugs-into one of ihe ROM sockets, Full screen demonstration no track cutting required. of correct formation of (COMPUTER CONCEPT) Special Introductory Offer; £32 lower case alphabetic characters. Several choice of ASTEROID BELT £ 7.80 sequence, (5 7yrsl, CHARACTERS £ 5.80 HITCHHICKER £ 5.95 NEW . . . NEW. . . NEW 13 SOCKET BOARD £8.00 SNAKE £ 7,80 ROM PROGRAMMING MADE EASY Qq^ WATFORD'S own 13 ROM Sockets Board for BBC - SPACE HAWKS £ 7,80 A new concept for schools A set of workcards to Micro. It simply plugs into one of the four sockets introduce programming to primary school pupils. An currently available on the BBC Micro to give a full 16 invaluable asset to Teachers and Parents alike. The ROM Socket capability (in which all ROMs may be language has been carefully chosen to provide a resident at once). The circuit has been designed to balance between 'Computer Technology' and (MICRO POWERI allow the use of RAM in this area loo. standard language. Bulky and often despised text ADVENTURE £ 6.95 Introductory Offer for the first 250 Boards: books have been replaced by the set of Workcards, ALIEN DESTROYER £ 6,95 KIT Only £19,95 Each card can be handled easily at the Computer ASTRO NAVIGATOR £ 4.95 BUILT & TESTED Only £24,95 Keyboard. Also included are a SUPPORT PRO CHESS £ 6.95 GRAM specially produced to reinforce Ihe work COWBOY SHOOTOUT £ 5.95 covered by the cards and a CHECK LIST for children CAT & MOUSE £ 4.95 and teachers to monitor progress. A must for ELDORADO GOLD £ 5,95 APPLICATIONS primary schools undertaking computer learning. FOOTER f 5,95 CONSTELLATION (32K) £6.50 GOMOKU £ 4.95 The great Bear! The Southern CrossI The Horned GALACTIC INTRUDER £ 6.95 Goat! See the night sky gloriously depicted in hi- res SOON AVAILABLE: Computer Concept's ROM LASER COMMAND £ 6.95 graphics. Constellation has been adapted and based programs; MARTIANS £ 5,95 enhanced from our successful ATOM program, MAZE INVADERS £ 4.95 BEEB-CALC Very fast & simple to use powerful spread-sheet program, MUNCHYMAN £ 5,95 DISASSEMBLER (16K/32K) £6.95 £34 MASTERMIND f 4.95 Relocatable disassembler program. Lists object code DEBUGGING PROGRAM Allows examination & REVERSI £ 4,95 and Assembler mnemonics from and to any alteration of Memory, Registers, setting of break STARTREK £ 4,95 specified addresses. The listing can be stopped and points and even single stepping through machine SWOOP £ 6.95 restarted. Page mode option and output to a printer code programs.

SEEK £ 5,95 are available. ASCII symbols may be output if ROM based £^^ TIMETREK £ 6.95 required. The Assembler code may be stored and CASSETTE based £10 ZOMBIES £ 4,95 modified and the program re-assembled. DISC DOCTOR Contains useful disc utility FILER £8.95 programs. £19

A powerful file handling program for BBC. FILER PRINTER TOOLKIT ROM Includes routines for hires allows the user to build up, manipulate, store and screen dumps for EPSON £r NEC printera. FORTH ROM for BBC retrieve data on the BBC. A very powerful package Works in any graphic mode. Has 'spooling' indeed. capability which enables data such as a program This superb compiling language now available in listing to be automatically spooled from your disc to ROM. Simply plugs into one of the ROM Socket LOGO II £9.95 The printer while using your BBC Micro for running £35 This language is very popular in American schools as other programs. £19 Full FORTH Manual E6.75 it is an ideal educational program. It can graphically demonstrate the ideas of defined procedures, sub routines, loops and even recursive programming. Gives excellent introduction to LOGO language for young and old alike.

NEW. . . NEW. . . NEW. . . BOOKS (No VAT on Books) SIMONSOFT DISASSEMBLER WORDWISE 30 Programs-BBC Micro £ 4.95 The most powerful, (lexible and easy to use Special offer only £35.00 30 Hour BASIC (BBC Micro) £ 6.00 available for Ihe Micro. Disassembiet currenllv BBC Without doubt the most sophisticated piece of 6502 Application Book £10.25 for both B. • Suitable Mod. A & Software yet written for BBC Micro, Wordwise 6502 Assembly Lang, Programming £12.50 • 5 modes of operation from Memory dump to full contains all the usual word processing features. The 6502 Assembly Lang, Subroutines £11.80 disassembly, automatic more complex facilities such as search and replace 6502 Software Design £10.50 • Ability to identify any location in memory with a or file handling commands are menu driven so that ACORN ATOM Magic Book £ 5.50 label. even a beginner can understand how to operate Advanced 6502 Interfacing £10,95 • Operating System Entry Points & Indirection them. Assembly Lang, Programming for BBC Vectors are already labelled when the Wordwise will work with whatever filing system is £ 8.95 Disassembler is loaded. currently implemented. Supplied with full instruc- BASIC Programming of BBC Micro £ 5.95 • Ability to define a 'map' of iipto 72 separate tions and manual. BBC Micro Revealed £ 7.95 areas of machine-code. BBC Micro Instant Machine Code • Output may be directed to the screen or a printer, including Software Cassette £34,00 • Areas of code can be disassembled and the EDUCATION Software Creative Graphics on BBC Micro £ 7,50 output saved on tape or disc in BASIC *EXEC BRITISH GEOGRAPHY £6.95 Discover FORTH-Osborne £1 1 ,25 format for later incorporation into user pro- Easy Prog, for BBC Micro £ 6,50 Teaches a child the locations of Cities and Ports grams. Further Prog, for £ using directional Keys. BBC Micro 6.90 • Machine-code programs may be loaded and FORTH Programmitig (Sams) £12.50 disassembled regardless of their actual run-time CAROUSEL £4.35 Getting Acquainted/Acorn ATOM £ 7.95 location. Aimed at junior school age. Sequences of colours Graphs and Charts on BBC Micro £ 7.50 • The current set of labels, map and associated and sounds teaches a child to concentrate. Intro to Micro Beginners Book {3 Ed) data may be saved at any lime on tape or disc. INTRO TO ARITHMETIC £10.45 £ 9.90 This data can be reloaded at a later date and the Let your BBC teach to program £ 6 .75 4 programs -Additions, Subtractions. Multiplica- vou disassembly continued. Micros in the Classroom £ 4,90 tions & Divisions. Help stage, moving graphics and • Full Error checking and reporting is carried out at Practical Prog, for BBC £ 5.95 colours. & ATOM each step. Programming the 6502 £10.75 Worksheet produced at the end of program. (5-7yrs is • The disassembler operated by typed com- Mastering VISICALC (Sybexl £1 1 .95 old! mands or the user definable user keys. Structured Prog, with BBC BASIC £ 9.5Q • Full instructions are supplied in the form of a JUNIOR MATHS PACK (32K) £6.95 The BBC Micro An expert Guide £ 7.90

'HELP' program. Makes learning fun for 5 - 1 1 year olds. This package • AVAILABLE on CASSETTE or DISC consists of 3 programs (menu driven) that increase Price: CASSETTE £6,95 in difficulty as your child becomes competent. A DISC S/D £9.95 very good supplement to standard educational WATFORD ELECTRONICS DISC D/D£9,95 methods. Tel: 0923-40588; Tlx 8956095

ACORN USER JUNE NEWS

Ups and downs Vision systems adapted to run on model B

for computers DIGITHURST has released {£295 plus VAT) provides images such as maps for an interface to link a model cable connections to both display on a monitor or TV. in Australia B to a home video recorder the video recorder and the This was featured in the and transfer pre-recorded BBC user port. Software recent BBC TV series THE Australian distributor images into the micro. allows the user to analyse Making (he Most of the of the BBC micro, Barson MicroEye can digitise captured images, which can Micro and has now been Computers, recently an- pictures with a resolution of then be dumped onto disc adapted to run on a model 8. nounced a price reduction. 256 X 256. although with the or a printer. Further information from This coincided with the BBC model 8 only 128 x Digithurst also produce Digithurst, Leaden Hill, opening in Sydney of the 128 pixels are used. Microsight, a £500 camera Orwell, Royston, Herts. Tel: first Australian Personal The interface package system, which can digitise (0223) 208926. Computer Show {IWarch 10 - 12) and with a 10 per cent devaluation of the Australian dollar. The model B, which Big success at sea for previously retailed in Aus- tralia for SI 860, will now sell for about $1 650 (£950 able-bodied Beeb micro at the post-devaluation MODELLING the behaviour limits are then used in the rate of exchange). of hovercraft is one of the US and Britain to improve Whilst the price of the latest applications for the their design. computer fell, Acornsoft BBC micro. Vosper commissioned the and BBCSoft products In the heavy swell of the tests, which are being made increased in price as a Solent off Southampton, a by Gifford Technology of result of the devaluation, small fast boat transports Southampton. and the average program buoys with wave and wind The Beeb is run on now costs $33 (£19). probes attached. These are batteries while at sea, and There have been persist- dunked into the choppier dumps its initial results on ent rumours that local patches of water and tape. These are then manufacture of the BBC connected to the Beeb analysed, displayed and micro in Australia is which lives in a waterproof printed out later. planned, which would case on deck. Gifford are pleased with presumably lead to a Movement of the buoys is the results, especially as the further price reduction in detected and measured by programs are in Basic. what is becoming a Buoys dumped in swell the micro. The results can fiercely-contested market. Beeb in sealed box then be taken back to the A number of local com- lab and compared to the panies are understood to way model hovercraft behave be interested, but as yet in similar conditions. no likely manufacturer has The model hovercraft are been named. tested in the same water, Penetration of the Aus- which must be as choppy as tralian market has been possible - hence the fast rather slow to date: the boat moving around to find inevitable supply pro- the best sites. Once the blem, which has now been behaviour and conditions overcome, and the relatively have been compared, the high purchase price having stability limits of hovercraft been the two principal can be determined. These .-ii causes. The majority of machines sold have gone to schools, with relatively few being Microfloppy made in Hungary Disc cliip warning purchased by individuals. However, the price re- A MICROFLOPPY disc sys- disc has an 80k capacity ACORN has warned that duction and a recent tem is being adapted for the and comes in 45-track form. only one version of the advertising campaign BBC micro. Kenda claims the number of disc filing system has should lead to an increase The Bats MCD1 micro- files per disc is virtually officially been released. in interest. floppy comes from Hungary unlimited and that deleted A spokesman said ver- In addition, the first and is based around a 72mm files can be recovered. sions other than DFS 0.9 series of The Computer (3") disc which is sealed in a The MCD1 drive is 85mm cannot be guaranteed

Programme is scheduled cassette. wide, 1 15mm deep, and compatible with other to be shown during Cumana has developed 41 mm high. Each disc- ROMs when upgrades are schools' broadcasts, com- an interface, while Kenda cassette is expected to sell made. The same goes for mencing in June (see April has written a filing system. A for £4. Econet (NFS 3.34). Acorn User). single drive should cost Bats-NCI who import the You can check which Steve MacLeod about £150 (plus VAT). drives are at 53 Ballards version you have by typing Australia Each single-sided mini- Lane, London N3. •HELP.

ACORN USER JUNE NEWS

Thatcher stands firm on cash limit for computers in schools

PREMIER Margaret Thatcher on with. has stood firm against Proposals for more money parliamentary pressure to were put to her in the earmark more cash for Commons by senior Tory classroom computers. backbencher Sir Paul Bryan

The Prime Minister says who thinks it is time the the E40 million due to be government began looking spent between now and at further ways of boosting Mtcrosight camera transfers a map onto a monitor 1986 is enough to be going computer literacy in schools. Sir Paul told Acorn User

he believes it is important to Demon terror build on the obvious classroom enthusiasm for is putty in computers - where more than four-fifths of the micros Beeb's hands supplied under the govern- pound-for-pound NO, this toothy beauty is ment's not an escaped Acorn scheme are BBC micros. programmer, but a Cham- He made a similar point ber of Horrors monster to Mrs Thatcher when he being controlled by a BBC told her during Prime micro. Minister's question time that existing government The Beeb is used to the two synchronise the 10-foot schemes were proving "a demon's movements to a phenomenal success.' soundtrack of grunts, 'Has the time not now growls and roars. come to expand those Once sound and move- schemes on a dramatic ment have been matched scale he suggested. up the programmed se- The government has quence is recorded onto announced a E200 million the sound tape. This can boost for information tech- then be played back and nology. the program operates Industry Secretary Patrick valves and pistons on the Jenkin said the five-year demon to make him move. scheme would ensure the

It can also control lighting competitiveness of Britains on the figure. IT industry, The demon is made of IT and micros in primary plastic and rubber over a education - page 45. steel skeleton, complete with moving limbs, heads, eyes and jaw. Musical launch N.J. Farmer of Leicester did the programming and forQuicksilva you can see these rugged QUICKSILVA has launched features in action at The three pieces of software for Terror Castle on Great the BBC micro.

Yarmouth's Marine Parade. A smash with monsters. . . micro's in control Their pride and joy is Muproc - a music synthesiser

for models A and B. It runs Courses and software aids available to teachers on both operating systems. THE MUSE summer course MUSE, Freepost, Bronisgrove, Place, London WC1. At E15 it's dearer than will take place at Nottingham Worcs 861 7BR. Software on maths, usual, but worth looking out University on July 25-27. And the National Union of physics and biology is for. Lectures are planned to Teachers is running comput- available from Garland Com- Two games make up the - cover all aspects of educa- ing courses at its training puting. Many of the programs trio Protector (E7.95) and tional computing at all centre. Stoke Rochford Hall. simulate practical techniques. 7^?e Wizard {E6.95). Both levels, with several addressed A 13-station BBC Econet Garland are at 35 Dean Hill, make good use of colour specifically to the BBC system is in operation and Plymouth. and graphics; Protector has machine. topics covered include Workcards for primary pulsing (not flashing) char- Topics include: program- primary, secondary and schools to introduce pro- acters, and Wizard has flying ming, Logo, networks, inter- special education. gramming on the BBC micro killer ducks! facing, music, software, Contact Penny Muir, have been released by Both need 32k and organisation, telesoftware - Education Department, NUT, Educal, 28 Ingersoll Rod, Protector only works with to name some. Details from Hamilton House, Mabledon Shepherds Bush, London. joysticks.

ACORN USER JUNE NEWS FEATURE

Beeb micro with Election fever

Martin Laug'ieid

700 bytes and each disc by Bill Penfold holds the profile of around IN A Westminster office 60 - 70 candidates. within 100 yards of Big Ben A pupil at Dr Challoners a BBC micro has been Grammar, Amersham, Dan quietly compiling the mem- has two up-graded model As bership of the next House of at home and is part of his Commons. school's computer group. Before a single vote has Recently he was one of a been cast in the next three-pupil, one-teacher team General Election, the com- from the group which puter holds potted biog- walked off with the El. 000 raphies on just about every first prize in a computing competition run by the one of the future MPs . . . and their chief rivals for the University of Kent and seats. sponsored by Barclays Bank. In a matter of days after The money has gone the Election results are towards upgrading the known the Beeb will be school's own BBC computer ready to begin printing out system. the text of the new edition Now Andy Roth and of a reference book which Parliamentary Profiles are has established itself as an banking on the Beeb essential guide tor politicians speeding the new MPs' of all parties - and Chart into the printers even commentators on the wacky before all the election world of Westminster. posters have been pulled For the next version of down. The MPs' Chart by political For regular readers of the journalist Andrew Roth will Chart, a long-time favourite be ready for publication well has been the section of ahead of its usual schedule pithy comments on the traits and political outlooks of thanks to the BBC B , . , and a 17-year-old schoolboy. various parliamentarians. Over the last few months After the last general Andy and his colleague Judy election for instance Mrs Tench have been completing Thatcher's thumb-nail profile hundreds of snappy descrip- Andy, Dan and Judy. . . with Beeb, Epson and discs was 'Iron Nancy incarnate; tions on each of the hard-working, high standards.' But where there is a requirements included being parliamentary runners. For Michael Foot, who at the computer programmer there able to extract particular Not just the constituency time was deputy Labour is usually a way, and the categories. choices of the Tory. Labour leader, the traits tag was way was provided by Judy's For instance he might and Alliance parties but also 'Pubiically angry; privately 17-year-old son Dan Tench. need to know which politicians hoping to carry gentle; mannered orator.' Dan is part of that rising Conservative backbenchers the colours for the Scottish David Steel's description generation of schoolboy were concerned with ac- Nationalists, Plaid Cymru was given as 'Dark; boyish; computer console stars countancy and had in- and the ever confusing energetic; even-tempered; whose micro mastery is terests in agriculture. Or a spectrum of Ulstermen. charm.' already sending shivers Labour MP concerned with A massive job - but one As Roy Jenkins had not clearly suiting the Beeb. returned to Westminster 'Dan is part of that However, before it could when the last edition was begin Andy discovered they rising generation of published, let's look at what would have to write their schoolboy micro stars' it says about Dr David own special program, as Owen, who is described as none of the commercially- down the backs of ageing education and the pharma- 'Celtic-handsome; v. bright; available packages could veteran programmers now ceutical industry. able; impatient; arrogant.' handle the tiling requirements. deep into their 20s. Soon, thanks to the Beeb Across the road from the

Even Acorn's own disc Though it was obviously and two months' work by House of Commons today filing system was too limited possible to adapt existing Dan, Parliamentary Profiles the new descriptions of our for the journalistic needs of software, Dan saw his job as - the name of Andy's political leaders - plus the - - the job as it holds too few starting from scratch. The company will have the rest of our next parliament files per disc. It was a case program needed to be facts flashing on to the are now waiting on the Beeb of tailoring something for capable of searching by office monitor, and being files to be printed out. the peculiar parliamentary either a candidate's name or dumped to an Epson printer Wonder what those files requirements. his constituency, and Andy's Each MP takes about hold?

10 ACORN USER JUNE w:!Ji:^:€ci:?i\j: SY5TEAA,THAT'S SO EASY J:7Tii n" aiiLi}s PLKf RLDCmSER SVSTEJTl® The PL Digilisfr Syslem enables you lo reproduce complex piciure^ and diagrams, or produce original designs, quickly, easily and accuraldy.

The package consists of ihe 'Graphics Digiiiser' incorporating a tracing pad (mapped qui by rcciangiilar grid)256miTi \ 205mm and Ihc'Coniroi Program" (Tape or Disc), This includes such features as automatic parallel, vertical, horizonial or diagonal lines, construction of boxes and eitclcsfrom two probe positicms.

freehanddraw. fill and outline, move and scale, imtnediaic edit and Ihe abililyio save compiled screens as files or reproduce by line printer

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Everything for the Acorn and BBC microcomputer user. ACORN USER EXHIBITION "="'™'^"'* Cunard International Hotel 25-28 August 1983

The Acorn User Exhibition at the Admission charges: Adults £2 per Cunard, Hammersmith will house the ticket, Children £1 per ticket. argest display of Acorn products ever We have arranged for nearly every assembled under one roof. It will be four exhibitor to redeem the cost of your ticket days of non-stop entertainment and when you buy something from their stand. education for parents and children alike. Group rates: 10% discount for parties The new Electron, the second of 10 or more. processors for the BBC micro, the BBC Buses: Frequent services from central Buggy, all the new software and hardware London. will be on show. There'll be competitions, Tubes: Hammersmith Broadway- prizes, Acorn experts to answer your Metropolitan, District and Piccadilly lines. technical questions, demonstrations and Car Parking: Several car parks in the lots and lots of bargains. immediate area. if you are an Acorn owner, or just For details of exhibition stands and thinking about being one, you can't afford advance ticket sales contact Computer

to miss it. Marketplace Ltd, 20 Orange Street, ,v^ Opening hours: August 25th-27th, London WC2H 7ED. Tel: 01-930 1612. a;.^,10am-7 pm; August 28th, lOam-4 pm.

ADVANCE BOOKING COUPON Miss the queue-buyvourtickets in advance. Computer Marketplace Ltd, 20 Orange Street. London WC2H 7ED. Please send Adult tickets at £2 Childrens tickets at £1

enclose a cheque/ postal order value £ payable to Computer Marketplace Ltd.

ACORN USER JUNE 11 COMPETITION

Acorn system: BBC micro with single disc drive

ink- jet printer plus soTtware

THIS month's puzzle is a bit different any hawk versus hawk contests is from the usual. It's based on the work The competition (-l00+50}/2 =-25. of the geneticist J, Maynard Smith To underline the concept of the comes in two parts and it is developed in a brilliant book. ESS let us look at one possibility. The Selfish Gene*. By all means buy - you are You might imagine that because a - will win hawk- or borrow it if you can but it won't recommended to hawk always any help you win the competition as the dove contest, only hawks will author has significantly adjusted his enter both parts. prevail genetically and therefore conclusions since he first wrote the This month we your computer population consists book. introduce you to our entirely of hawks. As we have |ust Imagine a closed world consisting seen, the average score per contest of a single species where each hawk-dove micro- in this society is -25. Now out of the individual looks the same but world and ask you genetic pool a mutant dove arises. behaves in one of two pre- to determine a The dove does not win a single programmed ways when encounter- contest. Indeed it spend most of its ing another individual. The hawk character mix which life running away from the hawks. behaves aggressively and will will set up a stable Nevertheless, its average score is savagely attack any individual who society. 0, which is a lot better than what offers resistance. A dove on the the hawks are achieving and dove other hand puts up a dignified Next month, the genes will therefore start flooding display of ruffled feathers but will model society gets into the pool. run away when seriously menaced. more complicated Again, you might imagine that a Thus in any hawk-dove confron- society composed entirely of doves tation the dove will flee and the with more characters was a good recipe for success; no hawk wins the contest. When two and you will have to battles, no -100 points for death or hawks meet they tight to the death. injury, in short a paradise apart When two doves meet there is an write a computer from a certain amount of wasted immensely protracted display of program (on cassette) time. feathers before one gets bored or to simulate the The reason why it doesn't work is hungry and backs off. Since our that the first hawk to appear on the model is based on the Darwinian hawk-dove society scene will do spectacularly well. concept of natural selection, the Since there are no other hawks to winners of the contests contribute fight the hawk will win every contest more to the genetic pool than the points for a win, minus 100 points for an average score of +50 and, losers. for death or injury, points for a the genetic pool will begin to adjust

The purpose of our model, loss and minus 1 points for accordingly. however, is not to consider natural wasting lime in a lengthy This notion of the deviant selection, but fvlaynard Smith's confrontation when important things individual undermining the collective concept of the evolutionarily stable like breeding and feeding are strategy of the group to his own strategy (ESS). In essence this can being neglected. advantage is sometimes called be defined as 'the only strategy that Thus when a dove meets a hawk 'treachery from within' and it is at

. . It . once evolved cannot be the dove runs away and scores the heart of the concept of ESS. bettered by any deviant individual'. while the hawk scores +50. When also has a direct counterpart in the

It is important to realise that this dove meets dove, both score -10 real world. built-in resistance to individual for wasting time and the winner Quite often a group of people - enterprise is the paramount scores -1-50. All things being equal, for example, OPEC (Organisation of objective of our model. a dove's chances of winning these Petroleum Exporting Countries) - To do this on the computer we encounters are one in two and his will band together and agree to fix have to allocate an arbitrary system score per contest will be the the price of a commodity to the of points to all contests, which in average of -1 and +40 which long-term benefit of its members. our case is as follows: plus 50 equals 15. The average score in For a time all may work well.

12 ACORN USER JUNE COMPETITION

Simon Dally launches you into a Next month: Analyse our full-

Hawk-Dove microworld in the first blown model and produce a com-

part of our major quiz. Ihe (ult puter program (on cossette) to

blown idea will be a mammoth simulate it, complete with graphics.

task, so we suggest you start Entries will be assessed on how

thinking and get some practice. well the program works, structure

This month: Solve our simple com- and presentation (among otfier puter model ond you coutd win the things, so we don't limit your

first prize of £30 of software, or a imoginotion). you must give me answers with

runner's-up award of a copy of The Remember: Whether you enter this yiHir program next month to qualify

Selfish Gene. month's simple competition or not, for tl^ big £1100 prize.

Sooner or later, however, treachery Genetic Opponent on what sort of population you start from within will lead one member of type Hawk Dove Bully out with, you may see some wild the cartel to start undercutting his Hawk -25 +50 4-50 oscillation in the composition of the fellow members for his own short- Dove +15 population at the beginning. But term benefit and a price-cutting war Bully +50 +25 sooner or later, as in real life, things is sparked off. In the case of OPEC should settle down. Figure 1 . How the types fare it needs only a nodding Of course, the model is very acquaintance with recent news- real world, an individual species crude, taking no account of things papers to observe this process in would not be composed of three or like sex, youth or old age. action. more types: each individual would Nevertheless it's fun and useful to Since, as we have seen, an all- be composed o! a mixture of set up these strategies and see dove population and an all-hawk strategies. Thus you might find that what happens. Next month we'll population are both unstable your in a more sophisticated version of give you a more complicated task is to establish where, if our model an individual would model and introduce some new anywhere, between these two react like a hawk four times out of characters into this one. extremes an equilibrium is estab- five, a bully one in 10 limes and a *The Selfish Gene by Richard lished. dove one in 1 times. For our Dawkins, Oxford University Press, Try to determine what ratio (eg purposes, however, we are taking £8.50, We are indebted to Dr four hawks per three doves) is best. the species as consisting of three Dawkins for his help in setting up

When you've done that you're ready different types. Figure 1 shows what the model. to introduce a new strategic they score against one another. Once you have worked out a character into your modei. One way to organise your model stable hawk-dove-bully mix, send The bully is indistinguishable is to set up a league whereby all your answer on a postcard please from a hawk and a dove. A bully characters 'confront' other characters. to June Competition, Acorn User, rushes round pretending to be a When you've done that you should 53 Bedford Square, London WC1 to hawk until someone fights back, at set up the next generation, basing arrive not later than Monday July 4. which point he runs away. Thus a the mixture on the performance of Please say which machine you bully will win a confrontation with a the previous generation. Depending have (if any). dove but lose to a hawk. When a bully meets another bully one of Three winners in February quiz them takes fright more quickly than the other and backs off - so a bully FEBRUARY'S competition featuring Total = 983 miles. has a one in two chance of winning the travelling salesman problem (Carlisle and Edinburgh can be these confrontations - for an produced nearly a hundred entries, visited in reverse order.) average of +25. score only about one-third of them b) Twelve-city route, London, It is that a society apparent correct. The mileage table was Ipswich, Leeds, Edinburgh, Carlisle, bullies composed entirely of is not drawn from a battered copy of the Liverpool, Manchester, Birmingham, an - again, a mutant will ESS hawk Michelin Guide to Britain and Coventry, Bristol, Oxford, Brighton, create treachery from within. So Ireland (1981 edition) which con- London. Total ^ 1 1 53 miles. your task is to determine which mix tained some bizarre anomalies. For c) Longest route. There are at least of characters will create the most example, according to the table, four equally long routes, one of stable society. London to Birmingham is 121 miles. which is London, Carlisle, Brighton, In setting up your model it is But if you go via Coventry it's only Liverpool, Ipswich, Birmingham, important to realise before your 1 1 7 miles! Michelin in their wisdom Leeds, Bristol, Coventry, Edinburgh, start fighting computer characters presumably take things like by- Oxford. Manchester, London. Total

it is for group that impossible any passes into account. Answers were = 2790 miles. to be entirely eliminated: however as follows ( routes can be followed The winners were: James Boulder poorly one type may be faring, its in reverse order): (aged 10) of St Roberts Primary genes are still lurking there waiting a) Seven-city problem. London, Schools, Harrogate; John Wright of fore if the to come to the Brighton, Bhslol, Carlisle. Edinburgh, Ipswich, and Malcolm Newton of opportunity arises. Indeed, in the Birmingham. Coventry, London. Mickleover. Derby.

ACORN USER JUNE 13 TECHNIQUES

In the first of a series on classic

techniques in computing, ^ Stan Froco looks at sorting <

ONE of (he commonest problems items (where it is invariably the best 10,000 numbers 1,248.53 sees. facing the computer programmer is technique because of its simplicity), 173,878 exchanges ttiat of sorting data into order. and fhe other is for sorting large Methods used by beginners are numbers of items, which are To be fair, the data given is the often horrendously inefficient, and already nearly in order. Donald worst possible for the bubble sort, yet many fast techniques are no Shell used these virtues when he and on average it would take about more complex. devised his Shell sort in the early half the time with random numbers. A method widely used is the 1960s. However, one of the criteria of a bubble sort. In program 1, 100 Shell's technique is to break the good sorting routine is that it numbers held in the array a% (line items to be sorted into small sets should have no bad cases, and in 30) are sorted using this technique. and bubble sort these (which is this respect Shell sort again wins. The array is initially set up with the efficient). These small sets are then These sorts can be easily - numbers to 99 in descending merged into large sets, which will modified to handle other data they order, ie thus be roughly in order, and could use a string array of names, bubble sorted again (also efficient). and the comparison could be for a%(1) = 99 These larger sets are then merged alphabetic order. A word of warning a%(2) = 98 into still larger sets (still efficient) though. If you have data with two or and so on, until a few targe sets are more fields, such as a person's a%{100) =0 merged into one roughly ordered name and his age, and you sort the set, which can again be efficiently names into alphabetic order, and The program then sorts them into sorted into order. then sort the ages into numeric ascending order. The reason (or order, and expect the names of all choosing this set, rather than Program 2 shows a Shell sort for people of the same age to be in random numbers, is that it is a 100 integers. The size of the sets is order, do not use Shell sort. If items severe test of a sorting routine controlled by n%. Each time round are identical (Ie same age, but since the numbers have to be the REPEAT-UNTIL loop (line 200) different name) they may be completely reversed in order. the numbers are broken into n% swapped in the second sort as the The bubble sort works by taking different sets. In this case the first names are ignored. For sorting on each element in turn (the FOR loop time round there are 33 sets, each multiple fields other techniques (of in line 160) and 'bubbling' it up by with three or four items. The outer which bubble sort is one) should swapping it with the element before loop (line 220) takes each of these be used. (lines 250 to 270) until the element sets in turn and sorts them. The first If you wish to know more about before is smaller than the one * (such set consists of items 1, n% + 1, 2 these and other techniques under consideration. There is no as how to sort really large amounts 1 . . . n% + , the second of items 2, need to compare it with elements * of data) the best book is Data n% + 2, 2 n% + 2 . . . up to the before this since they have all been last set which comprises n%, 2 * Structures and Algorithms by Aho, sorted and are thus even smaller. * Hopcroft and Ullman, published by n%, 3 n% . . . The code from lines After each element has been 230 to 360 is virtually that of the Addison Wesley. This is sadly not a bubbled into place the array is in bubble sort, but incrementing and book for the total novice, and the order. rather decrementing by n% instead of 1. examples are given in Pascal Bubble sorting is unfortunately The outer REPEAT-UNTIL loop (line than Basic, However, there is as yet not very good for sorting large 200) is used to decrease the nothing for real beginners on the numbers of items (ie more than number of sets each time round. market, and il you have grasped about 20). Whilst the given program Notice how the number of sets is the fundamentals of programming, sorts 100 numbers in 24.65 not divided down evenly, a you should learn a lot from this seconds, performing 4950 exchanges constant (2 here) is added in. This book. For reference you could look in the process, it takes 2852 helps the sets mix, which improves at volume 3 of The Art of Computer seconds and 499,500 exchanges to sorting. Programming by D.E. Knuth, again sort 1000 numbers. To sort 10,000 Despite being only nine lines published by Addison Wesley, But numbers would take about 80 longer than the bubble sort, this unless you are a mathematician I hours and 50 million exchanges. To program is far more efficient. The would not recommend it. sort the 400 million items that once comparable times are: existed on Rolls Royce's parts list • Hash tables and recursion will would be impossible. 100 numbers 3.04 sees. 316 be covered in future articles. Are There are two cases though exchanges there and other techniques you where bubble sorting is efficient. 1 ,000 numbers 46.76 sees, 4,366 would like covered? Write in and One is sorting small numbers of exchanges tell us. page 16 u ACORN USER JUNE The accessories you need at prices you can afford

The monitor that makes sense for all the family The NORMENDE 14" colour monitor combines true RGB performance with U.H.F. T.V. value. Fully BBC compatible, this dual purpose design compares favourably with most quality, stand-alone RGB monitors while offering far greater value to the whole family.

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for Securicor delivery Also available with REMOTE CONTROL e299.00 inc VAT For mail order please add E7.00

Say goodbye to untidy wiring At last a quality joystick for use with The REMEDIAN TIDYBASE comes complete with your BBC (model B only) three built-in fully-fused power outlets. Forms a Now, Microstyle offer you the chance to strong, safe plinth for your monitor, disk drive etc. use joysticks where joysticks have never Single cable to mains outlet. been used before! Operating directly Designed and built to schools specification in metal with through the existing user-ports on your safety edges (no sharp corners), durable finish. BBC model B microcomputer and all Acornsoft and £29.95 inc VAT available for use with other keyboard controlled games for mail order please add most - joysticks include £2.50 post and even Planetoids these "driver program packaging a machine-code on tape, which converts keyboard commands to remote control operation for maximum enjoyment. PLEASE NOTE- Planetoids aid certain other games may still require tfie use ot some heytioara commands SPECTRAVISION QUICKSHOT deluxe joysticks, (bbc compatible). For mail order please add 75p post and packaging £24.95 inc VAT

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All prices advertised include VAT PEOPLE Please Note: V^hile Micioslyle will endevour lo maintain sufficient stocks of THE HOME COMPUTER items currently or previously advertised we regret Itial all items are offered for sale subject lo awailability from manufacturers. and The Bath Computer Centre The Newbury Computer Centre 29 Belvedere, Lansdown Road, Bath. 47 Cheap Street, Newbury. Telephone; Bath (0225) 334659 Telephone: Nev/bury (0635) 41929

ACORN USER JUNE J5 —

TECHNIQUES AJSoxnnrABE for BBC

^^'\ The Record Changer' 32K £19.95 Cats. £24.95 DIk for indexlr>g. nnembershlp lists, directories, inven- tories. bLXJgetIng, etc.. etc

10 RRM Bubble sort 100 integers dont buy a dcrtabote In the dark — check the spec! 30 DIM aZdOO) 40 @% = 4 * Visible File — Scroll tfie 50 around file UP/DOWN/ SIDEWAYS by function keys 60 REM Initialise in reverse order * RiLL SCR^N UPDATE — Use cursor to overtype 80 FOR i2 = 1 TO LOO character INSERT/DELETE within field; ERASE rest of 90 a%(iX) = 100 - iX field; TAB fronn field to field, etc. 100 NEXT iX 110 * Sort — on character and nunneric fields 120 REM Now sort them 130 * Search — tor o match on field contest 140 startZ = TIME * Select — select records satisfying conditions on 150 one or more fields: or manuolly 160 FOH ]% = 2 TO 100 170 FOR kX = j% TO 2 STEP -1 * Total — total nunneric fields of SELECTED records 180 190 * Arithmetic — combine one or more fields of your REM If bubbled high enough jump out 200 SELECTED records with any arithmetic expression 210 IF put ttie result in aXikX) >= aUkX - 1) THEN GOTO 290 any numeric field 220 230 * Print — print your SELECTED records v^ith pagi- REM Else exchange and proceed 240 nation 250 iZ = a%(.kX) * Up to a 1000 records, (typically 330 at length 40) 260 a%(kZ) = aXikX - 1) 270 aXikX - I) = tX * Up to 20 fields, number of decimal places can be 280 NEXT kX specified tor numeric fields 290 NEXT ]% 300 * Utility — to ADD/CHANGE/DELETE fields REM 310 Take the time and print out the results 330 tiiiie% = TIME - startX 340 The WordsmHh* 32K tor Centronk» 737/739

350 FOR iX = ! TO 100 £19.95 Cots. £24.95 Disc. 360 PRINT a2(i2) For 370 NEXT iX Reports, Essays, Thesis, ete., etc. 380 390 @X = S90A Forget control codes — let 'Wordsmttti' realise 400 PRINT ' "Time taken: " " your printer's potentkil ; ti.eZ / 100 ; seconds- • Full Screen text editor with wordsplll Program 1. Bubble sort • Unlimited document size • Page numbering, headirigs, footings, margins, 10 REM Shell sort 100 integers indentation • Full Support for proportional, mor>o. condensed, "lines 20 to 150 as program 1** elongated and underlined printing • Right justification nrialntalned even when mixing 150 REM This is the outer Shell loop proporttonal, cortdensed. elongated on same llr>e ISO nX = lUO 190 200 REPEAT 210 nt = {nX + 2) DIV 3 Simple Word Processor 32K 220 FOR mX = n2 + 1 TO nX * 2 £9.95 Cass. £14.95 Disc. 230 FOR = j% m% TO 100 STEP n% Simple to use; allows you to set margins, justify text, 240 FOR k% = j% TO m% STEP -nZ insert 25 and delete lines of text, set page length or 260 REM torce a poge, variable TAB, Multiple copies Save If bubbled high enough jump out 270 text on cassette or disc. View text formatted before 280 IF aXikX) >= aX(kX - n%) THEN printing Wortts with any printer 290 GOTO 360 Options Timetable 32K 300 REM Else exchange and proceed 310 £14.95 Coss. £19.95 Disc. 320 tX = aX(kX) A must tor every secondary sct>ool. This programnne 330 aXikX) = aXikX - nX) helps with tt>e timetabling of pupils 3rd year optton 340 aZCkX - = x\X) tX choices. Try the effect of any char>ges to your 350 NEXT k% Options Timetabte let tr>e 360 NEXT j% and micro do all the 370 NEXT mX donkey wort<. Has been In use tor the last three years 380 UNTIL nX = 1 In a 6 torm entry comprehensive using a CBM 3032 390 now runs even faster on ttie BBC fvlodei B. 400 REM Take the time and print out the results Not only ttie cheapest, but ttie best 420 time^ = TIME - starts Switchabte 14" RGB fVlonltor/Coiour TV 430 £250 inc. VAT and cable. £8.00 carr. 440 FOR i% = 1 TO 100 450 PRINT aX(i%) Royalties tor quality software 460 NEXT it All prices VAT Inclusive 470 480 n = S,90A 490 PRINT ' -Time " taken: ; ti.eX " / 100 ; seconds'" AJ Vision Service Ltd 61 JeddoRoad Program 2. Shell sort London W12 9ED

76 ACORN USER JUNE Software News

BBC SOFTWARE from the professionals MOLIMERX EXPANDS INTO THE BBC!

B»»h[|l - June 1983

TODAY a spokesman for Moiinierx programs are going to be translated, the the BBC machine.

l.lci,. ihe TRS-80 Gcnif Sotlware House features unique to the BBC will be Over the years, Molimerx have built up of Bi'xhill. annouiK'Ott Ihat llicy arc utilised to the maximuni. Specifically a catalogue of some 170 pages. The

fiHcrinn Ihc BBC Software market. Molimerx say thai translations will not procedure is that an addition conlaining Uiiiil now. Molimcrx have been supply- iust be a code adaptation, bui will also new software is published every H weeks

iiij5 software for all of ihe Tandy incorporate BBC features. They gave as or so. The existing index is discarded machines plus all of the Genie micro- an example the recently completed and Ihe new addition contains a new

(.ompulcrs, some do/cii machines in all. translation of Shuttle. This is a simu- up-dated index. The catalogue is As ihey have been doing thi.s lor some lation of ihe Columbia space shutile. In punched for a ring binder: hence,

S years, they have accumulated a vast ihc TRS-HO version it is displayed in customers always have a current and up number nt programs — in ihe range of straight text. The BBC version, however, lo dale catalogue. Molimerx say that 4(K1-5(H) in number. Molimerx will be contains a coloured graphic represent- this same procedure will be used for the translating all of iheir besi existing aiion of the ship. new BBC software catalogue. programs together with publishing new The spokesman said that the main Owners of BBC machines, therefore. programs specifically written fur the thrust will be towards new programs should write to Molimcrx for a copy of BBC They are hoping, therefore, to be and Molimerx are actively soliciting new Ihcir current catalogue. For at least a releasing around six new programs per software from both their existing stable while, there will be no charge. month for some time to come. of 120 authors and are also searching for Customers should send an A4 si/e

Their spokesman said today thai where new qualified auihtvrs, experienced on stamped addressed envelope for 1 7p.

TEL: 10424] 220391/223636 MOLIMERXLTD TELEX 86736 SOTEXG A J HARDING (MOLIMERX)

1 BUCKHURST ROAD, TOWN HALL SQUARE, BEXHILL-ON-SEA, EAST SUSSEX.

ACORN USER JUNE 17 HINTS TIPS & ^2^

Joe Telford sets up a graphics procedure library and develops a 50p network

Continuing our examination of library routines, we turn to three shapes for constructing complex graphics on the BBC micro - PICK A SHAPE rectangles, triangles and circles/ ellipses.

Program 1 might appear trivial, but ly it is useful if a large number of triangles need drawing. Suitable calling lines might be: [r*cos(x-»-p),r*&iN(><.p)3 r*cobC><) 100 MODE 2 J 110 PROC__.tri(l 00,1 00,200,1 00. 150,300,1)

The first three pairs of numbers are co-ordinates of the vertices. The r* 9IN (x) last number should be to rkbihl(x:^p)

produce a line drawing, or 1 for a filled triangle.

Program 2 uses program 1 as

the procedure 'tri' to produce a r*(_^iN(>^^a»tp)]

pattern. Figure 1 gives simple /tfcffes - . r Uibf-ance, of this. Line 50 several variations on ^c from cvi^/T. of program 2 shows we are transmitting the usual three pairs of

vertex parameters, plus a final to fiU an^/e^ in recf/ane, produce a line drawing. Figure 2 shows how the contents of line 50 of can be related to the vertices a Figure 2. Locating vertices for program 2 regular (equilateral) triangle. This only works when the screen origin

is moved by a VDU29 command so the triangle can be drawn around it '^46i3 DEFPR0C_cri(Ki,yi,K2.y2.K3,y3;ri (line 30). Try running program 2 ^465 MOVE >a,yi without line 30 to see the effect. "^70 f" I F = £1 R ft H . D W 2 y 2 EL. M 'J E x 2 > y 2 Rectangles are probably the ^475 IFF=Pi 0RfHy:x3.y3:DRftWKi,yi most common shape, so it is well "- ELSE . - c- ; ^ L T 3 5 K 3 ~i;*^.Cx \j v . y worth while having a library routine 94SEI EMDPROC Program 1. Procedure for handling to handle them. Look at program 3, triangles. Note, this must be called up which may be called by a simple ^__ ^^^ from a program (see text) three line program: 5 PEfl PATTERNS 10 M0DE2 IS M0DE4 20 PROC rect(300,200,600,400,0} ^' - .-" S = -508; = '2) ; = 30 END 2 1 2 P 2 ^ F I ^ 3© vDU29, 64e;512^ This will draw the outline of a 40 FOR X=g TO P STEP P/30 rectangle on the screen. Control i ( H '^ 5B P R C _ t r r C S X . * S I N X ^ over the rectangle produced is by r^COS(X + P^ .r-iiSlHiX^P- .r^C05O-^2^^^i= the parameters passed to the ! '^SIN X + Z^'eP'i , 0:- routine. Examine line 9400. The 6 NEXT parameters are x,y,l,w, and f. Here, x 7S END and y are the coordinates of the bottom left-hand corner of the Program 2. Triangle patterns

rectangle, I is the length across the screen, and w is the width up the ^ "> 9 4 D E r P R C _ r e c t- K , v , 1 , w - f screen. The final variable, f, may be 941S MOUEM,y:Df?(:^y>. + i,y 1 or to produce an outline or 2iZi 94 IF^=0 DRhw:-=:+1 . y + w filled rectangle - the opposite of ELSEPL0TS5 , h , y + v 9433 IF^-=0 DR^HWK: y-*-w the triangle routine. Less calculation ELSEPL0TS5 ^ m-H , y + w 9440 fiOyEx,y4.w: = is needed as only one corner's IFr DRhW^.v ELSEMOUEx.y coordinates are required. The 9453 ENDFROC disadvantage is that the rectangle Programs. Rectangle drawing routine can only be aligned along the page 23 18 ACORN USER JUNE HINTS & TIPS

Figure 1 . Variations on program 2

ACORN USER JUNE 19 3

Two of the all-time Arcade greats BOMBER SCRAMBLE

For over two vears our best selling TRS-80 Arcade game was Mike Chalk's acclaimed Bomber Scramble. Now there's a new generation Scramble, in the colours, sound and high resolution graphics of the BBC Micro.

This new one has so much it's unbelievable! Two types of fighters —with their own unpredictable movements. Ack-ack—which no other BBC game. Acorn's included, can offer—with random detonations. Intelligent rockets—which are released as you come on target. Blimbs —another Kansas 'original' to make the game harder.

The game starts fairly easy, then gets harder and harder, with of course the ground and 'top' moving all the time— and completely random, with no two games ever the same. As the game progresses so more and more is 'thrown' at you.

Keyboard or joystick operation giving infinite control of the bomber, the bombs and firing. Top score table and extra 'lives'.

There is no other Arcade game to touch it! £9.50 Vat and post paid

COSMIC FIGHTER As Kansas reigned supreme with its TRS-80 Arcade games in Britain, Big Five Software were our counterpart in the States, with their "flagship' being the famous Cosmic Fighter, This fast-action multi-screen game has been brought to the BBC Micro by Kansas programmer Wal Mansell. •^ ^ «y iBt ^^ Four entirely different 'screens' with four different types of Alien, each with its own brand of attack, and all of them relentlessley homing down on your base. Four games in one in fact!

Move your base to fire whilst dodging their bombs, but as soon as you wipe out one lot, another type appears— and all of them hell-bent on your destruction!

Then comes your Mother Ship, so home onto her to re-fuel, but get it exactly right... Then it all starts again—with a difference— you have to hit each Alien twice to destruct! .4k. Colour, sound, keyboard or joystick control, with of course the usual Kansas top score table. An all-time great. £9.50 Vat and post paid

SNAKE Soothes X4-eS4t^ s^=c» * You have control in all directions of the Snake to devour the mushrooms. It's a real snake, not just a line, pulsating along and -a, o growing longer and longer as each jnushroom is devoured. • -•» =iN 4i Just like the arcade game, you can actually increase speed to try and clear a screen in less than a minute to earn yourself a bonus. But don't devour the toadstools! 1™ : ^ Then it gets harder. And harder. And harder. For as each screen is « t . * cleared the next one becomes more difficult. Not only does the i [CO.* speed automatically increase but you get a split screen. And if you f manage that, a totally unheard of, double split screen! 4h Colour, sound, keyboard or joystick operation and of course the Kansas top score table. £8.50 Vat and post paid * -^ '^ ^ s 1 ••> <^ ^^ SPACE CAB Slow the pace right down now, to a thinking mans" game. Ferry passengers over the random mountain, choosing the number, the amount of fuel and liquid oxygen to get you there and back. It's totally logical—the more passengers you carry the more fuel and for you have to earn oxygen you' I I need. There's a purpose too, enough to pay off the mortgage on the craft or it's re-posessed! Not too easy to play as control must be spot-on or you can run out of fuel, starve the passengers of oxygen or crash!

Infinite control of thrust and braking in all directions allowing you to ascertain the best velocity both in accent and deceleration. VERT SPEEDS FUEL i08 Very realistic sound effects. Colour and totals. hORZ SPEED O)0i5^EC82 ^^^^^^^^^^^^^^^^^^^^^^^£^^/a^n^os^ai^^ PROGRAMS ARE CASSETTE BASED AND RUN ON ALL 32K SYSTEMS Make the most of your micro DATA FILE

The all-srnging, all-dancing Data File, built on five years experience vet purooselv created specifically for the BBC Micro. Experience has taught us that not only do any two people never needthe same in a data file, but even one person wants it to be capable of many things. We think that the Kansas Data File fulfills this need, and will be recognised as the standard. appeal must be its sheer versatility l^"^^"*^"! You can define not only the (enqth ot anv field, but Ifie actual nurnber of fields-iip to 20! So you can ,make it an ordinar? name and adcirf^^^ file, or anything extraordinary that you might wish. And all permanently saved to tape... The number of files available depends entirely on the length of the file. Up to 1 947 with a single field. Here are the facilities of Data File: Create File Define any number of fields up to 20. Define Status Not found in normal data files, this is useful for length of each field up to 255 characters. Name each field it tells you the file name, when u|xlated, files used, and as required. Computer automatically uses maximum memory. most important how many files free. Insert Simply type in pressing Return for next field. Print A most important facility, allows the printing of Search Data File has a most unique Search facility, for the files, as required. it will search any defined field throughout the whole Delete Delates unwanted files, and at the same time file, but not only this, it can be asked to search for the the remaining records will be closed up. item at the start ot the field or in fact anywhere in that field, making it a very powerful facility indeed. Save Allows you to save the entire file to cassette. This can be loaded at the start when Data File is run. Edit Couldn't be simpler—just use the cursor keys. To facilitate the ease of operation, all the above functions Jump A very handy feature, allowing you to jump to any are on the red function keys, so needing just a single particular file you require. key stroke to bring into operation. Sort Not just the normal first field sort, but one which £12.50 Vat and post paid allows you to define the sort field. PERSONAL ACCOUNTS Another exclusive Kansas program, designed for the micro user to keep an accurate check on all accounts.

This program is not limited to personal cash accounts, but Facility is also provided for alteration of any entry, with can also be used in conjuction with a cheque account or automatic update of the current balance. The balance itself even to keeping a credit card account in order. In fact there can be altered, which is useful when using as a credit is little limit to its use, where the transaction of money is card account, as a monthly payment is made. concerned. There is a clever little routine which allows you to estimate As It creates its own files to tape, it can be used for a the effect any particular payment may have on your account, multitude of purposes, each having its own file and thus so you can see if you can really afford it or not! being loaded to handle transactions. A status section lets you see the current balance, file name, It can hold 500 transaction entries! when updated, transactions on file and spare entries. Personal is A great asset of the program is that it can be customised Accounts very friendly in use, with messages by altering any of the 32 items, with in fact 10 already should you do something wrong, such as using the same set aside for this purpose, with the others too being transaction number twice. simple to change. Files can be saved to cassette, and you have the choice of either loading in a saved file or creating Each entry has its own number, together with amount, date a new one, when the program is run. and Item, with all details and current balance shown after each entry. This makes it very straightforward to add Use is made of colour, with the obvious showing of either payments or deposits to the file. deposits or payments. There is also a list facility, even allowing the scrolling through the entire file. £12.50 Vat and post paid

When you buy from Kansas you are buying from the

longest established software publishers in the country

The only company that can give a lifetime guarantee

and assured same-day first class post service

VfSA ^nsas Recognised Brand Leader in microcomputer software ^ ^^ Kansas CityCitv Systems,S Unit 3, SuHon Springs Wood, Chesterfield, S44 5XF. Tel. 0246 850357 HOME & BUSINESS TECHNOUDGY

O

Probably the widest selection^—-'of software available by mail order. S;itiKiirf, Hl-.vcI. Piiuyor All lilt liip manufatiurers ini-kniiiit: Atiirn Siifl. I.IK [Sinclair), Supciiiii BLig HyiL-, I'r.iyidm Poait, ^ AUNEW \ in Stock All / (as long as you're quick) BBC I I COtC-UTraS^ / V MICRO BBC MICHOCO-^mEf^H„*^lfr^S^^

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P.CORH USER JUNE . 53*, 71 j1' 1 1

HINTS & TIPS

^page 19 vertical and horizontal axes. This is Program 4 is an example of how acceptable for most diagrams, but the Yecf routine can be used to readers who need a tilted rectangle build a more complex shape. should put an extra coordinate in Because each school will want to 100MODE2 the triangle routine. Also no!ice the progress along its own lines of 110PEM do sKy routine will produce squares, interest, program 4 is not 120(iCOL0, 6 I 3ePR0C_rect '0,^1 1280, 1 simply by setting I and w to the interactive, and does not attempt to 624 , l^BREM do gross same value. Let's look at three dictate a 'best' approach, The 'best' I50GCOL0 Z simple applications of the 'reef approach is the one which works in 160P ROC .recti 0,0. iZ80,4 00. l) l'^0REM point routine; in education, to demon- your school. won 180GCOL0, strate movement, and for business l<'0PROC_r!?cti;200. 209. 700.400 use. 200PEM Odd bncKs We can also use the rectangle :i0FORY = 20a TO 600 5TEP*,e 220FORX=200 TO 900 STEP3^ Teaching children routine to generate the illusion of 230GCOL0. movement. Look at program 5, 24 0PROC_rect (X, Y, 32,2 4,0) about which should be understandable 250NE^T, shapes 260FORY=224 TO 576 5TEP4S without much explanation. Line 1 1 270FORX»216 TO 884 5TEP32 PRIMARY children's concept of looks strange but in fact is doing 280PROC_rect

340GCOL0 , from simple ones (which the next cause the micro to wait until the 350PROC_cloto (2) MEP Microprimer pack will beginning of the next screen frame. 360PEM downstoirs windows examine). However, the 'reef routine This results in smoother movement 370GCOL0,2 33aPR0C_doto (2) may help teachers to - use the with less flickering remove them 390REM upstoirs windows computer with work of their own, to see how necessary they are! 40eGCOL0, 6 4iQPR0C_dato 12) 420REM Window fromes 430GCOL0. 10 REM Goggle box "-(-BPROC^doto (16) 20 450ENO 46BDEFPR0C_dato(ni 3S ON EPROR GOTO 390 470LOCfiL ly. MODE 2 480FOR IX- 1 TO n 59 490REflD OX.bX.cX.dX.eX

6S REM Draw lots "' 500PPOC_rect(ax.h;;,cX,d'^,eX) 'J 1 c 1 .; Q •' 1 o u e d 510NEXT 76 PEM Boye3 ins: one another. ee 520ENDPROC 530REM door FORX?: = doto TO 512 STEP S 540PflTfl50e. ise GCOL0, 200. 103,200, (X%,/S)M0Di5 +1 55S REM doorfrorae doto 110 PROC.rect fx;; + 560DflTfi500.20S. l2S./'S (5i2-x':>*2, c5i2->:;- 100.200,0 120 ) *2, 570DflTfi580. NEXT 300, , n 8 . 1 130 5S0REM downstair window d.itn 59gDflTfi275.230, I've REM Now Est 150, 130,1 all boyes to block 600D«Tfi4-5.25S,I50,150, 150 610REM UPSt^iir Window dot-, 140 ; = FOR y g TO 15 62eDftTfl700.450. 100,100. 170 .'DUi9. K\ 0.0:0; 430DflTA30a,430, 100. igg, 640REM 130 N E '< T Windowfrome dnto 190 t30D«Tfl2-5,250.?5.75.0 REPEAT 660DeiTfl350,250,75.73,0 670DflTfl273,323,73.73,0 210 REM LOOP through the colours 68aDftTfl350, 325,75.75,0 220 : 690OflTft675,230,75.75.0 230 F0Rx::;=i5 700OflTfl750.230,75,73.0 TO 1 5TEP-1 7I0DflTft673.325.75,73,0 2 "t * F >; 1 9 ^20DOT«75e.323.75.75,0 730DflTfi700,450,30,50,0 REM TurniTig then on sequent 740DflTq73e.450,50,50,0 i ai ij 750DfiTfl750,300.50.50.0 760DflTft700,300,30,30,0 t'DU19,x:;, l,e,-0 770DflTfl300, 430,50.56,0 time=TIME 7S0DflTfl300,500,30,50.0 REPEAT UNTIL TIME) time 790DfiTO350, 500, 50,50,0 *Fy 19 890OftTfl330,450.50,50.0

Program REM and then ofF 4. House-building program!

VDUl? .:: . X 3 , ; f NEXT

REM Use ESC to e '-^ i t UNTIL FALSE 390 M0DE7:REP0RT: END Program 5. Moving graphics

ACORN USER JUNE 23 * 7

HINTS & TIPS

Figure 3. Screen form design SURHRME Designing forms

FOREHRME THE third area which may usefully exploit the 'reef procedure is in TITLE SEX « designing fornns for data input RDR 1 There are two separate parts to input via the screen as a form. The

RDR 2 easy part is design, the more difficult part is using that form RDR 3 during input. Program 6 uses the CODE PHONE 'reef procedure to produce a screen form (figure 3). The program uses mode 4 and creates the form MODE*; from rectangles, each 64 units high Program 6. Screen form design 20 by 32 times the number of 30 PROC_ screen form characters which are intended to fit i^Q END into each entry box. The labels for 50 DEFPR0C_5creenrorm each box plus the number of 60 PROC.rectt0,9i6.11*(32,width,e^ characters allowed (dots) are 70 PR0C_r»ctfii«32, 946. 21^32. widfh.B^ inserted at the correct positions by 80 PRINTTfiBd.l) 5 "SURNfiHE " PRINT TAB statements. Readers 90 PRINTTAB(12, 1) ;' might like to experiment to produce 100 PR0C.recto,882> 11*32, Width 'f^'i their own form input programs, 110 PROC-rect (iHf32, 882. 21*32, Width. 0) based on this example and using a 120 PRINTTftBCl,3) ; TORENftME - general prupose input routine, 130 PRINTTAB(12.3) ' ; © " ' " ' I'^e PROC.rect (0,818, 1 1 »32 , wi d th [ 130 PR0C_rect(li*32,81S, 10*32, Width,©) The third of our graphics routines 160 PRINTTAB (1,5); "TITLE draws and fills circles or ellipses

170 PRINTTPB(12, • 5) ; (program 7). The procedure 180 PROC.rect (21*32. SIS, 1 i *32 . w i d th , , requires five parameters, x,y.r1 ,r2 190 PROC.rect (30*32, 818, 2*32, widtb,0) and f. The first two are coordinates 200 PRINTTflB(22.5) =-5EX "=108(31,5);- of the centre of the circle. If r1 ^ r2, 210 PROC.rect (0, 75'i, 7*32, Width, 0) the shape is a circle of radius r1 . If 220 PROC-rsct (7*32, 754, 25*32. wadth,B> r1 and r2 are different, an ellipse is 230 PRINTTftB(l,7) ; -fiDR I'sTfiBrS,^); produced. The large value between

r1 and r2 decides the major axis of 2^0 PROC_rect(0,690, 7*32, width, 0) the ellipse, with r1 controlling the 250 PROC.rect (7*32, 690, 25*32, width,0-. horizontal axis and r2 the vertical, 260 FRINTTflB(l,9) ; "ADR 2-:TAB(8.9)i The last parameter is our usual f

which may take the values 1 for 270 PROC_rect (0,626.7*32, Width. 0) filling the shape or for an outline 280 PROCrect (7*32. 626,25*32, Width, 0-, drawing. Try using the routine with 290 PRINTTflB(l,ll) " ;"flDR 3 ; TftB ( 8 . 1 1 - ; program 8 which has a CB radio flavour. 300 PROC_rect (0.562, 7*32, Width, 0) 310 PROCrect (7*32, 562, 7*32, Width, 0) 320 PRINTTABd, 13) ; "CODE

' TAB (8, 13) ;"...... Program 330 PR0C_rect(UM32, 562, 11*32, w.dth.B. 8. Using 'crclp' routin* 3h0 PROC.rect (25*32, 562, 7*32, w,dth.,^l 350 PRINTTAB(15,13) 10 H0DE2: v=600 ; PHONE " ; T A " 20 b C L e . 1 9 B ( 2 6 , 1 3 ; ; 2 360 ENDPROC " 30 CLG ^a FOR X= 256 TO 763 STEP 512 30 GCOL0, 95013 OCfl^?iOC_^v-ci^ (H,y. ri,r 2.r-^ 60 PPOC.crciP (V, 931-0 LOCAL z,y.y.,yv V. 200 . 1^0. 1 '320 70 GCOL0,4 MOME^. + r-i , y. M0'v'EH4.pi. y 90 PROC_CrClp(Y + -, 9330 FOR2=0TO 70,V-l0,eg.g0. ^ 6.^5TEF.2 90 GCOL0,0 :< X r .; - :' ; + 1 * c C S :: : = r * f z 2 S I J 100 9350 IFFOi DRAW-v,^+y- PROC_crclprx+70,Y-10.30.30,li eL^E 110 NEXT PLOT35,.T,,,.y-;:Pi_oTS5,XV,y-y^ 120 END '360 IFr=i fiNo z>3.2 z=6.4 ^370 N T E X : E N D P P C Program 7. Circle/ellipse routine page 53 >

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26 ACORN USER JUNE GRAPHICS INTERACTIVE GRAPHICS AKD CAD Jim McGregor and Alan Watt analyse the GCOL statement, _ and show how procedures I he GCOL statement controls ttie based around it can provide might be transfer characteristic, way new values are loaded into the frequency response and so on. The screen memory. Either a new value interactive graphics- line computer program's view of the (or colour) specified for a particular problem is numerical or formula drawing, picking and dragging, pixel is loaded directly into the based, while the engineer's view appropriate position in the screen menu selection and rotation remains pictorial - a tremendous memory, or a logical operation is advantage in most design problems. performed between the new value We now look at the front end of and the current value (figure 1). The such CAD programs: first by type of logical operation is looking at how we can sketch line specified by the first parameter in drawings on the screen, and the GCOL statement. second at how we can pick and Using the GCOL facilities we can drag predefined sub-pictures across implement two classic graphical the screen, input techniques - 'rubber banding' and 'picking and dragging'. Both use the keyboard, but clearly the liubberband line drawing is used principles are the same for either a to build up a sketch or line drawing keyboard or a more convenient on the screen, using line segments device such as a lightpen. Both New VM-OH, whose length and direction are interaction techniques can be used controlled from the keyboard. Figure 1 . GCOL parameters select in picture construction and this operation to be performed between Program 1 starts off by drawing an forms a part of most CAD value in screen memory and new arbitrary line from (0,0) to (640,512). value (computer aided design} systems By using keys R, L, U, and D (right, which enable designers to work in left, up and down) as direction two-dimensional pictures. This RZ indictors we can move the end means for example that an 1 1 point of the line anywhere 1 1 we want

electhcal engineer can work with Key F can be used to 'fix' the end 1 I - 1 1 circuit diagrams and an architect point of the line. In the program 'xs'

1 with elevations or other projections 1 and *ys' always represent the start 1 1 of buildings, rather than just position of the line currently being 2. trical Figure Elec diagram 'y' numbers. drawn and 'x' and represent the CAD techniques are an extensive position of the end of the line being topic, and we shall only concern with alterations to the diagram. moved. The program consists of a ourselves with picture or line- In the same way, an architect REPEAT loop that processes

drawing generation, although it is may sketch in elevations of a house commands until the O (quit) is not out of place to examine briefly and ask for costing, insulation or pressed.

how such techniques fit in. A CAD sunlight calculations. PROCprocesscommand first

program that accepts a picture as Returning to the case of an checks for a valid key. It 'F' has input has to deduce certain electronic circuit diagram, this been pressed, the line being

information from it. An electrical would be built up using picking operated on is fixed and the engineer may draw a circuit and dragging. In this technique a coordir^ates are set for a new line.

diagram as input. A simple but user is presented with a menu of Otherwise PROCdrawordelete is somewhat unrealistic example objects from which he can pick a used to delete the current line in

serves to illustrate the point; say he particular object and 'drag' it preparation for redrawing it in a inputs a series parallel resistor anywhere on the screen. Other new position. One of the

configuration (figure 2). From this operations that might be available coordinates x, y is updated if one of the CAD program will have to on objects are magnification and the movement keys (L, R, U, D) has deduce that a resistor connected in rotation. Again in the case of an been pressed. PROCprocess- series with two resistors in parallel electrical circuit diagram, as well as command terminates by drawing a has a total resistance (RT): the picture-drawing modules there line to the position now specified will be procedures to keep track of by the xy coordinates. A drawing RT- R1 + R2*R3/(R2 + R3) the spatial relationships between sequence is shown in figure 3.

It can then evaluate numerical components. The CAD program The critical statement in the

calculations and output information can then build up a formula program is GCOL 3, 1 [exclusive graphically or otherwise. The CAD reflecting some required attribute OR). This means lines can be program will also be able to cope or behaviour of the circuit. This moved over existing lines without

ACORN USER JUNE 27 GRAPHICS

10 MODE 4 20 xs = : ys = 30 = X 640 : y = 512 40 GCOL 3, 1 50 PROCdrawordelete 60 REPEAT 70 commands = GET$ 80 PROCprocesscommand 90 UNTIL command$ = "Q" 100 MODE 7 : END Start arbitrary line drawn from 110 DEF reOCprocesscommand (O, 0) to (640, 512) 120 IF INSTR("FLRUD",coninand$) = THEN ENDPROC 130 IF coramand$ = "F" THEN PROCfix ELSE PROCdrawordelete 140 IF '"""" commands = "L" THEN X 150 IF commands = 'R" THEN X 160 IF = commands U" THEN y 170 IF = commands 'D"„ THEN y 180 PROCdrawordelete 190 ENDmOC

200 DEF reOCdrawordelete 210 MOVE xs. ys : DRAW x, 220 ENDPROC Line can be moved anywhere 230 DEF PROCfix from {640, 512) 240 REM Permanent draw to fill in gaps where 250 REM moving line crosses existing lines. 260 GCOL 0,1 : PROCdrawordelete 270 GCOL 3,1 280 = xs X : ys = y 290 X = 640 : y = 512 300 ENDPROC

Program 1. Rubberband program without extensions

15 llneoff = FALSE 16 hcursor Key F depressed. First line fixed. = FALSE : vcursor = FALSE Arbitrary line drawn to (640.51 2) 17 printraeasure = FALSE

120 IF INSTRC'FLRUDOHVM", commands) = THEN ENDPROC 171 IF commands = "0" THEN llneoff = NOT(Uneoff) 175 IF commands = "H" THEN hcursor = NOTrhcursor) 176 IF commands = "V THEN vcursor = NOT(vcursor) 177 IF commands = "M" THEN printmeasure = NOT( printmeasure) 178 IF printraeasure THEN PROCmeasure ELSE PRINT TAB(3,3);"

200 DEF HlOCdrawordelete 204 PROCcheckcursors 205 IF llneoff THEN ENDPROC This line can be moved and key F 210 MOVE depressed again xs, ys : DRAW x, y 220 ENDraOC

310 DEF PROCcheckcursors 320 ^^'^ "°^ ^-500, JI,.'i''"''^°'* y: DRAW x+1000, y MOVE X, y 330 IF vcursor THEN MOVE x. y-500: DRAW x, y+lOOO" MOVE X, y 340 ENDPROC

350 DEF PROCmeasure 360 PRINT TABC3,3), ABSCxs-x) 370 ENDmOC Thus any shape can be built up

Extensions to program 1 Figure 3. Drawing sequence using first version of program 1

28 ACORN USER JUNE GRAPHICS

First Draw Second Draw

old plotting new old plotting new

1 1 1 1

1 1 1 1

Figure 4. Lines can safely move over existing ones using GCOL 3 Table 1 . Cumulative effects of draw with GCOL 3

permanently wiping part of them example, to construct two isolated out, as would be the case rectangles we would use a otherwise. Normally, to delete an sequence similar to that shown in object we would replot the object in figure 5. the background colour but this would wipe out intersecting parts of existing lines. Using the above I here are two useful elaborations method, an existing line disappears to make to the rubberband line only momentarily while the current drawing program. First, we can include horizontal and vertical moving line passes over it (figure a line Draw the first rectangle 4). Thus line segment 2 can be cursor line to enable us to up different parts of drawing. This swept over existing line segment 1 a simply another two selections without rubbing it out. This can be adds explained by reference to table 1. to PROCprocesscommand. These You can see from the bottom row of would be:

the table that plotting a 1 on top of 175 IF commands = "H" a 1 in the first draw results in a zero THEN hcursor = NOT(hcursor) that is restored to a 1 by the 176 IF commands = "V" second draw. The top row of the THEN vcursor = NOT(vcursor) table gives the effect of a normal draw and erase function. The This means the H and V key Draw a line to the start second draw thus erases or functions are push on/push off of the second undraws, at the same time restoring keys as we used above to switch a any holes in existing lines made by line off. PROCdrawordelete can

the first draw. (See if you can work now be further elaborated to check out why the behaviour is unaltered if cursors have to be drawn lines if GCOL 3 is replaced by GCOL 4.) (program 1, 200-340).

As it stands the program is Figure 6 shows the cursor being slightly impractical - figures are used in the course of a constructed without the 'pen being construction.

lifted off the paper'. That Is to say Another useful aid is a length device. for Switch off this line (press O) after a line is fixed it Is assumed measuring Consider another line is required. This may example measuring the current x not be the case and the easiest projection of the line. This could be way to incorporate line off/line on is accomplished by: to have another key controlling this 177 IF commands = "M" option: / THEN printmeasure = NOT (printmeasure) 171 IF commands = "0" THEN 1 78 IF printmeasure THEN lineoff = NOT(llneoff} PROCmeasure ELSE PRINT This IF statement sets up a push TAB(3,3);" " Fix the invisible line and press O on/push off key - a mechanism we r shall use again. If the variable 350 DEF PROCmeasure 'lineoff is originally set to false then 360 PRINTTAB(3, 3), pressing the appropriate key wilt ABS(xs-x) set it to true. PROCdrawordelete 370 ENDPROC can then be: Note the string on line 120 must 200 DEF PROCdrawordelete now be changed to 'FLRUDOHVM' 205 IF lineoff THEN ENDPROC and that as the program stands the cursors must be switched off before Draw the new rectangle 210 MOVE xs, ys : DRAW x, y fixing. If the measure option is 220 ENDPROC switched on then PROCmeasure is Figure 5. Drawing sequence using which prevents the drawing action obeyed and prints, using TAB, the improved structure

if the line is switched off. Now, for current x projection of a line. In

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GRAPHICS

Figure 6. Figure 7. Figure 8.

figure 7 the hangers on the suspension bridge were accurately 10 MODE 20 PROCrirawmfnii positioned using this. 30 GCOL 3 , 1 40 PROCplck 50 RRPEAT 60 X = 500: V = 500 PROCdrawordelete(selectionS) W.e have already mentioned 70 RKPEAT picking and dragging so lei's jump SO commands = GET$ 90 PROCproo esse ornna nd ( coranan straight into it. In program 2 we d$ 100 UNTIL f^ommand$ = "F" have set up a menu of objects in no TOOCplok the right-hand side of the screen. 120 UNTIL .selections = "Q" 130 END

An object is selected by typing 1 , 2 140 or 3. In practice, if we were using DBF PROCflrawraenu 150 MOVE 900, 0: DRAW this technique frequently, an object 900, 1000 160 PROCdrawr«aistor( 1000. 600) would be selected from the menu 170 PROCdrawoa pac 1 tor ( 1 000 , 400 180 PROCdrawdiode( 1000, 200) by pointing a lightpen at it. When ; 190 HIINT ; TAB(60, 12) "l" ;TAB(60, 18) -a" ; "3' :TA8(60. 24 ) an object is selected it is dragged 200 CjWUrTtL'L' into position and fixed as before. 210 DEF PROCplck Instead of dragging a line we are 220 PRINT TAB(0,0): "Pick. (1/2/3)"; now dragging a complete object. 230 selections = GET$ 240 PRINT TAB(0,0); " "- The program to drag an object is 250 ENDPROC * identical to the rubberband 260 DEF FROCprocesscommanrl(cS) program (which drags the end of a 270 IF INSTH("FLRUD", c$) = THEN ENDPROC line) except every occurrence of 280 IF c$ = "F" THEN PROCflx: ENDPROC: ELSE PROCdrawordelete is replaced by raOCdrawordelete(selectlon$) 290 IF c$ = "L" THEN X = X - 5 PROCdrawordelete(selection$). This 300 IF c$ = "R" THEN x = ;( + 5 procedure selects one out of the 310 IF c$ = "U" THEN y = y + 5 320 IF c$ = "D" THEN = - three drawing procedures (resistor, y y 5 330 HlOCdrawordelete{ selections) capacitor, diode) and the selected 340 ENDPROC object is drawn at a position under 350 DEF PROCfix control of the directional keys. 360 GCOL 0, 1 : PROCdrawordelete(selectionS) 370 Figure 8 shows the screen during GCOL 3, 1 380 ENDPROC execution of the program. 390 DEF PROCdrawordeletefsS) 400 IF s$ "1" = THEN PROCdrawresistor(x y) 410 IF s$ "2" = THEN FROCdrawcapacttor(x y) iaither common facilities in 420 IF "3" s$ = THEN PROCdrawdiodefx. V) picking and dragging programs are 430 ENDPROC 440 DEF m0Cdrawrealstor(x, magnification and rotation. For y) 450 MOVE x.y: PLOT 1, 30, example, the dragging 460 PLOT 1. 10: above 0, PLOT . 1 60 , 470 program, another key option could PLOT 1, 0,-20: PLOT 1,-60, 480 PLOT 1, 0, 10: PLOT 0, 60, be M for magnify and T (turn) for 490 PLOT 1, 30, rotation. The structural alterations 500 ENDPROC 510 DEF PROCdrawcapacltorfs, now required in the program are y) 520 MOVE X, y: PLOT 1, 30, significant. In particular have to we 530 PLOT 0. 0,-30: F1.0T 1. 0, 60 540 PLOT change the way in which we store 0, 20. 0: PLOT 1, 0.-60 530 PLOT 0, 0. 30: PLOT 1, 30, shape information. Currently this 560 ENDPROC information is embedded in the 570 DEF FROCdrawdiodeCx, y) drawing procedures as parameters 580 MOVE X, y: PLOT 1, 30, 590 PLCrr 0, 0,-25 PLOT 1. 0, 50 of the PLOT 1 statement. The most 600 PLOT 1.25.-25 PLOT 1,-25,-25 convenient scheme is to store the 610 PLOT 0.25. 25 PLOT 1, 30, current displacement coordinate 620 ENDPROC values for an object in an array. These displacements will of course Program 2. Picking and dragging change as a function of the angle of rotation. Initially we could set up

ACORN USER JUNE 31 GRAPHICS

an array for a square, for example, as: squarex(1) 100 squarey(l) 440 DEF PROCdrawsquare(x, 100 y) (2) (2) 450 MOVE X, y (3) -100 (3) 460 FOR i = 1 TO 3 470 To draw the square in any PLOT 1, x(i), y(l) (dragged) position from x,y we need 480 NEXT i PROCdrawsquare (program 3). This 490 DRAW X, y is the same scheme as we have in 500 ENDPROC the component drawing procedures (above) except that we are now storing the displacements in an Program 3. Example procedure array. Now, pressing T would make the L obiect rotate by a predetermined angular increment of, say, 10 510 DEF PROCrotate degrees by altering the relative 520 sintheta = SIN(RAD(10)) displacements. To do this we 530 Gostheta = C0S(RAD(10)) simply use a standard two- 540 FOR i = 1 TO 3 dimensional rotation transform. The 550 = X X(i) : y = y(i) procedure that services the rotation 560 x(i) = x*costheta + command is PROCrotate (program y*sintheta 570 y(i) = 4). Each time the key is depressed -x*sintheta+ y*costheta 580 NEXT new displacements are calculated i 590 from the previous one. Note the ENDPROC

figure is stationary while it is being

rotated, it cannot be rotated using Program 4. Rotation procedui this structure and dragged at the same time.

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ACORN USER JUNE 33 INTERRUPTS HOW TO HANDLE INTERRUPTS

Interrupts allow external devices While the program is running, type such as alarms, temperature John Ferguson and LIST and press Return, The sensors, timers etc, to demand characters will not appear on the immediate attention from the Tony Shaw explain screen and you might think it has computers microprocessor. They not received your command - but it force it to abandon its current task has! The characters have been and initiate a completely separate what interrupts are captured and stored in an input program call an interrupt routine. buffer using an interrupt routine. The concept ol an interrupt is and how they work, Once the program above finishes similar in some respects to a the command LIST will appear and subroutine call. In both cases be performed. program flow is diverted to a with examples Finally, the analogue to digital separate program (a subroutine or converter (ADC) uses the system an inlerrupt routine) which is then from one of its internal timers, VIA to pass its 'end of conversion' executed before control returns to updating the real time clock. signal to the microprocessor's IRQ the main program, However, there The 6850 ACIA serial interface inpuL New samples are taken are some important differences. chip can be programmed to approximately every 10 milliseconds Subroutines are called at specific generate IRQ interrupts whenever a with an interrupt routine updating a positions in the main program serial character is received at the table of results for each of the four using a JSR (Jump !o SubRoutine, RS423 port. input channels. see January issue) instruction, in Whenever a key is pressed a Because the machine is contrast an interrupt routine can signal initiates an interrupt using continually generating interrupts, occur at any time, initiated by an the system VIA. The interrupt great care is needed with any external device sending a signal to routine decodes which key has routine where execution time is one of the microprocessor's been pressed, evaluates its ASCII important, ie any 'real time'

interrupt pins. code, and places it in the input programming. For example, a The 6502 microprocessor in the buffer. common method for producing a BBC micro has two input pins to The simple routine below time delay is to use a simple

detect interrupts; illustrates how the operating system program loop. If interrupts occur NMI (Non Maskable Interrupt). is still active capturing depressed during the loop the overall This input is 'edge sensitive', and keys even when running a Basic execution time is increased by only initiates an interrupt routine program; including the interrupt routine.

it when detects a high to low 10 FOR N = TO 30000 ; NEXT Although the machine operating transition. ID HEM USING INTERRUPTS IRQ (Interrupt ReQuest). A TO INITIATE ZO REM A PERIODIC "EVENT" level sensitive input, active at 30 REM (FOR OP. SYSTEMS>=1 .0) 40 REM USE KEY 9 TO START logic zero. 5Q •KEY9-CALLSDa65 |M" As the name implies, the non 60 0SASCI=!FFE3 ?0 OSW0HO:ftf FF1 maskable interrupt has a higher SO 0S8YTE^aFFf4 90 priority than IRQ. Further important EVNTV=B0220:REM EVENT INTERRUPT VECTORS TOO iressage=8DD01 differences between these two will 110 REM SET UP TIME CONSTANT FOR INTERRUPT 1 20 constant -ines53ge»50 discussed later. be 130 constant ! -SFFfFFDFF:?{constant'-6)=SFF 140 REW INSERT MESSAGE (UP TO 49 CHARACTERS) 1 SO Sfl,essage="TIME TO TAKE THE DOG A WALK" I he operating system of the BBC 160 FOR PASS=0 TO 3 STEP 3 micro makes extensive use of 170 PX = fne5saget1 00 180 COPT PASS Interrupts {figure 1), Both the floppy 190 .START LDA KEVENT MOD 256 \POINT TO EVENT disc system and the Econet 200 STA EVNTV \HANDHNG ROUTINE £10 LDA «£VENT OIV 256 network use non maskable 220 STA EVNTV+1 230 LDA interrupts. Software to IfU-.Lax #5 \SAM£ AS tF)(14,5 handle these 240 JSfi OSBYTE \ENABLES TIMER EVENT 250 interrupts is provided in special -SETUP LOA #4 \SELECr TIMER 260 LDX ROM chips Issued with each #constant «0& 256 \P01NT TO TIME CONSTANT 2 70 LOY ((constant DIV 256 system. The User Guide suggests 280 JSR OSWORD \STAHT TIMER 290 RTS NMIs should be avoided by the 300 .EVENT PHA:T){A;PHA:TYA:PHA:PHP \SAVE REGISTERS 310 user and left only for the machine's •'^'' '^^SS \OISPLAY MESSAGE 320 JSR SETUP \RESTART TIMER use. Interrupt request (IRQ) is also 330 PLA:rAy:PLA:TAX:PLA:PLP \HESTORE REGISTERS 3A0 used by the operating system with RTS 350 -MESS LDA #7:JSR OSASCI \BLEEP the microprocessor receiving inter- 360 LDX #0 370 .AGAIN rupt signals generated by two on LDA message, X \geT CHARACTER 380 JSR OSASCI \OUTPUT - 390 board chips the 6522 VIA ^"^^ \NEXT CHARACTER 400 '^"'^ *K0° \WAS IT A C-RETURN (versatile interface adaptor) and 4 10 BNE AGAIN \jf NOT BACK FOR MORE 6850 ACIA. 420 "^^ \MeSSAGE COMPLETE 430 The system 6522 VIA (&FE40- 440 NEXT PASS Program 1. Using the interval timer to 450 &FE4F) provides periodic interrupts E"*^ initiate an 'event'

34 ACORN USER JUNE INTERRUPTS

system makes extensive use of IRQ interrupts, the user can easily add Tube IMHz bus interrupt handling routines. In theory, this should be possible with IRQ IRQ riNMI any of the machine operating systems, but it has not been A to D documented for release 0.1. The Clock Keyboard converter remainder of this article deals only with the interrupt handling facilities offered from release 1 .0 onwards. Also, page D locations are used by the disc operating system and the User System Floppy Econet BRK handling routine should be ACIA VIA VIA disk network placed elsewhere if your machine has discs. The contents of &202 and &203" should be altered to point to the new home of the BRK IRQ t NMI handling routine. i 6502 Microprocessor Xo simplify interrupt handling the BBC micro's operating system contains some ready made Figure 1 . Interrupt schematic of the BBC mrcro interrupt software that can be used to handle interrupts generated as the result of an 'event' within the Disable Enable Event machine. A typical event would be buffer a pressed key, or completion of a *FX13,0 *FX14,0 Output empty task by the ADC. The complete list *FX13,1 *FX14,1 Input buffer full

of events is: input buffer empty; *FX13,2 *FX14,2 Character entering input buffer input buffer full; depressed key on *FX13,3 *FX14.3 ADC conversion complete keyboard; start of TV field pulse; *FX13,4 *FX14,4 Start of vertical sync. 'timeout' condition on interval timer; *FX13,5 *FX14,5 Interval timer crossing zero escape condition detected. *FX13,6 *FX14,6 Escape pressed The user may decide to detect a

particular event or ignore it. Figure

2 gives the list of *FX14 commands Figure 2. * FX commands used to enable and disable events used to enable events and the corresponding *FX1 3 commands that disable events. (See Acorn = OF FUNCTION User, May issue.) A SUMMARY When an event is detected the Read a line from the current input stream to memory operating system can be diverted 1 Read the elapsed time clock to the user's own event handling 2 Write the elapsedtime clock routine. Two vectors, EVNTV and 3 Read internal timer EVNTV+1 (&0220 and &0221}, are 4 Write internal timer 5 Read a byte in the input/output processor memory used to point to the start of the 6 Write a byte in the input/output processor memory handling routine, (This routine event 7 Generate a sound must terminate with an RTS 8 Define an envelope for use with the sound instruction to return control to the statement main program.) The User Guide 9 Read pixel colour at screen position X,Y Read dot pattern of a specific displayable suggests the routine should last no A character longer than one millisecond and B Read the palette value for a given logical should preserve the processor colour registers. Note: All OSWORD calls use a parameter block somewhere in Program 1 shows an example memory. On entry X(LSB) and Y(MSB) are used as pointers to timer initiate using the interval to an the START of the block. event every five seconds. The timer

is configured using an OSWORD Example = 3 means 'read interval timer'. call with the accumulator equal to 4 A The interval timer is incremented every 1/100 of a second. (figure 3). The X and Y registers are The time interval is stored in 5 bytes pointed to by X and Y. set up to act as pointers to the A = 4 means 'write interval timer'. starting location of a five-byte time On entry X and Y point to the 5 locations containing the constant that is loaded into the new time constant. timer. The timer increments by one Figure 3. System OSWORD call summary every 1 /1 00th of a second and

initiates an event when it reaches

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10 RIEM CHf^NGINC IRQ1. UECTDRS routine makes use of A, X or Y then :'0 RFM (OP. syste:m >=i.o) these registers should be saved at the start of the interrupt routine and 40 DSAECI^&KFEa restored at the end. 45 RF-^M INSiERl INTERRUPT ROUTINE

60 R;i-,^vOi;i01 During the interrupt routine the I 70L flag is set preventing interrupts on JOO.RUPT PHA XSAVE ACCUMULftTOR the IRQ input. 11" UlA *&4K.JSR OSASCI \PR1HT "A" When an IRQ interrupt is 5° I'L NRESTORE ACCUMULATOR J f received the activity followed by the '"^ri \Rt:TURN FROM INU.RRUPT J^^-l processor is similar to that for NMI. REM ];^0 CHANCE IRtJl UECTORS TO POINT ID ABOVE ROUTINE As with NMI, an IRQ interrupt waits until the processor has finished its ^BO.GO 1..DA *RIJPT MOLi 256:STA IRQIU ^0 current instruction. The processor LDA *RUPT [IIU 256:STA IROiy-J-l l^f^ \HACK then checks the interrupt flag in the :ij^.| TO BASIC processor status register and if the ??0 CALL GO flag is set ignores the interrupt and Program 2. Disabling IRQ interrupts during a timing loop continues with the main program. If

flag is clear lir.i REM DiSRBLING the the microprocessor IHQ IN i EFvh'i Ip fS 20 OSRSCI^ii^FF&J sets the flag to prevent fuilher IRQ Sei 0SRDCH=i!.FFE6l interrupts and then proceeds to store the porogram counter and the ^MrS-^, '-'^-.^ ^DISABLE IRQ INTERRUPTS processor status register on the stack. Vector locations &FFFE and 39 jSR OSRscx sOhFU S;-RF(-N &FFFF are then used to point to the 1 mo first instruction in the interrupt lie CRLL £iTRR-[ l£:i^ END n handling routine. As before this Program 3. Disabling interrupts disables the keyboard instruction is usually an indirect jump through two RAM locations. zero. Line 130 sets up the time written to capture and store data Again, an RTI instruction is used to constant to &FFFFFFFDFF in from the ADC at say 10 minute return the microprocessor to its memory locations starting at intervals. At the same time a original program and restore the address 'constant'. Ttie machine student could use the machine, processor status register. code program begins by setting up completely unaware the micro was Two instructions give the the event vectors to point to the performing a second job. Provided event handling routine event, and any programs used did not then proceeds to enable interrupts overwrite the event handling routine IRQ or BRK instruction from the interval timer using the or the captured data, a short machine code equivalent ot program run at the end of the day *FX14,5. would display the captured data. The event handling routine begins by saving the processor's O'n receiving a high to low registers and displays the message: transition on the NMI input the No / it a BRK \ -TIME TO TAKE THE DOG a WALK'. processor completes its current \ instruction? y Before returning control, the routine instruction before carrying out the initialises the interval timer for a following sequence of events. new event, ensuring events The program counter followed by Yes ' ' continue to occur at regular the processor status register is intervals. The routine ends by pushed onto the stack. The Indirect jump Indirect jump restoring the processor's registers. microprocessor then goes to through BRKV through IRQ1V (&0202) to BRK After assembly, the program can memory locations &FFFA and (&0204) handling routine be executed by pressing function &FFFB to find the ADL and the key 9. Now, any activity, the ADH of the first instruction in the Points by default machine is performing will be. interrupt routine. With most systems interrupted at five second intervals this is an indirect jump through two with the reminder to take the dog a RAM locations that can be altered Check out source walk. Even typing NEW and to point anywhere in the memory ot interrupt, and service entering another program will not map. On completing the interrupt stop the repeated interruption. routine, control is returned to the Pressing Break however will original program using an RTI disable the timer event and restore instruction. RTI restores the If not found indirect jump normality. program counter and processor through IRQ2V (&0206) The example may seem trivial, status values which were placed on to user routine but this relatively simple technique the stack at the time of interrupt. will enable the BBC micro to The program counter and perform several different tasks processor status are the only Figure 4. Operating system apparently simultaneously. For registers saved automatically on IRQ/BRK handling example, an event routine could be entering the interrupt routine. If the

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38 ACORN USER JUNE INTERRUPTS

programmer control over IRQ 10 REM CHRNrjING IRQl VEHTHR:-; interrupts: SEI {set interrupt 20 REM <0P. SYSTEM >=i.e> disable); CLI (clear interrupt 30 iRQ:L'v'=ri,0sei4 40 0SRSCI-^:FRt3 disable). The first is used to set the 45 REt'l INSERT INTERRLIPr ROUTINE interrupt flag in the processor 50 p:-:»Sj0D0i status register thereby disabling 70C IRQ interrupts. CLI clears the lee.RUPT PHR -.SRVE RCCUriULRTOR 110 i*a<41 ^ JSR OSRSCI vPRINT "R" disable flag, enabling I RQ interrupts. 120 PLR .RESTORE RCCUMULRTnR Program 2 shows how both 130 RTI \RETURH FROM INTERRUPT instructions can be used to protect 1403 160 REM CHRNGE IRQl vectors to point TO RBOVE ROUTINE a routine where the execution time i70C are worth important. Two points l&0.Gn LDR *fRUPT mod 256 -STR IRQIV attention. Setting the interrupt 1^0 LDR #RUPT DIV 256. STR IRQlV+5. 200 give f;:ts \BRCK TO BRSIC disable flag will only 2103 protection from IRQ interrupts, not 220 CRLL GO from NMI. Furthermore, disabling Program 4. Changing IRQl vectors - take care! interrupts within the BBC micro will 10 REM result in problems with some of its ENABLING INTERRUPTS FROM CBl OF USER yiA 20 REM USING IRQ2 yECTQRS TO normal housekeeping duties {for POINT TO INTERRUPT ROUTINE 30 REM (OP. SYSTEM ;=!. 0) example, the real time clock will 40 IRQ2V-&0206 lose time). Program 3 shows a 50 0SfiSCI-&FFE3 60 REM FIRST INSERT INTERRUPT second problem that will arise if ROUTINE "RUPT" 70 P7.=tomi interrupts are disabled when the 80C 'get a key' routine OSRDCH is 90.RUK' PHA \SAye ACCUMULATOR 100 used. The program is the typewriter LDA *&4i:.JSR OSASCI \PRINT "A" no LDA example given earlier with the -^'^E^-> \CLEAR INTERRUPT FLAG 120 PLA \RESTDRE ACCUMULATOR addition of an SEI instruction. 130 RTI \RETURN FROM INTERRUPT However, the program 'hangs' in M03 U.O REM OSRDCH, waiting for the key which ENABLE INTERRUPTS DN C&l OF USER VIA lAO REM AND POINT interrupts TO INTERRUPT ROUTINE is never detected since 170L

are disabled. 1 BO . GO LIlA tOlBTA &FE6C \SE1 UP PCR TO DETECT H-L TRANS. 190 LDA *iiP:STA &FE6E \D1SAHLE ALL BUT CBI ?00 LDA *&90:STA S,FE6t \ENABLE CBl INTERRUPTS Unce an IRQ interrupt is received, ?iO\CHANGE IRQ2 VECTORS 10 POINT TO ABOVE ROUTINE ^'^'0 LHA 4RUPT the operating system follows the MOD 256 : ST A IRCJ2V 230 LDA *RUPT KIKI 256: SI A IRQl'U+l routine shown in figure 4. The \BACK TO BASIC routine first checks the processor's ?50T 760 CALL (50 status register to see if the interrupt 270 END was caused by a BRK instruction {a Program 5. Using software interrupt described later). CBI on the user VIA to initiate an interrupt

If not, vectors point at the 10 REM ENRBLING INTERRUPTS FROM CBI OF USER VIR >; USING OSBVTE machine's own routine to handle 20 REM IRQ2 VECTHRc POINT TO INTERRUI ROUTINE interrupt signals from devices such 30 REM ';0P. S'VSTEM = 1.0 40 IRQ2V=S,0'£gi6 or the real time clock. as the ADC 50 OSRSCI*a.FFEr-i The machine's interrupt handler 60 QSBVTE=&FFF4 70 REM then interrogates each of these FIRST INSERT INTERRUPT ROUTINE "RUPT" 80 P.'';=&i0D01 devices to determine which has to 90C If source of the be serviced. the 100. RUPT PHR ^T.XP^PHfl^TVR^ PHR •SRVE REGISTERS 110 #s^41 interrupt is not found the handier LtJR JSR nSRSCI ^PRINT "R" 120 LDR #&96 vRERD PORT E assumes it came from a new 130 LDX #i6a-JSR OSBVTE RNC' CLERR INTERRUPT source, eg the VIA or the iMHz 140 FLRG PLRaRY:pLR!TRX'PLR RESTORE REGISTEfJS 1 50 bus, and progresses using an RTI -RETURN FROM INTERRUPT 160J indirect jump through locations 170 REM EHRBLE INTERRUPTS DN CBi np USER VIR &0206 and &0207 {IRQ2V) to a ley REM RNU POINT TO INTERRUPT ROUTINE user supplied routine. 200. GO LDR #ii.57iLDH Hi6C It may sound complicated, but -SELECT PCR ON USER VIR 210 LDV #3 ' JSR OSBVTE help. ^SET UP TO DETECT H-L TRRNS. the following examples should 220 LDR #li,97 LDJ-; WiSE SELECT lER ON USER VIR 4 begins by mserting a 230 LDV Program *P^6P^JSR OSBVTE ^DISRBLE RLE BUT CBI INTERRUPTS 240 LDR short interrupt routine to place the m-37 LbX #3..SE ^SELECT lER OHUSER VIR 250 LDV #i:90^JSR OSBfTE .„ .^,_ . Only ENRBLE CBI,^ . INTERRUPTSiM,c:,..n,u character 'A' on the screen. 260 LHRNGE iRQ2 VECTORS TO POINT TO RBOVE ROUTINE" is preserved since 270 the accumulator LDR **RUPT MOD 256 'STR IRQ2V ' 230 this is the only register used by the LDR *;RUPT DIV 256 ^ STR IRG2V+1 290 ^~^-- --.BC-iCK TO BRSin routine. The second part of the 3003 program then sets up the IRQl 318 CRLL iO 320 vectors to point at interrupt routine END Program 6. As program 5. but using OSBYTE 'RUPT. page 62

ACORN USER JUNE 39 BLACKJACK, TEXTPRO, DISASSEMBLER 002 GALAXIAN 003 APOLLO 004 1 tape containing 3 programs representing Arcade quality game using machine code, viwid Lunar Lander with a difference! 4 stage game incredibie value for money. Mode 1 colour, Moving Slars, HiScore, Bonus comprising Orbil, Long Range, Mid Range, 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 C6.95 inc. Runs on a model B for £6.95 inc. TEXTPRO is a simple word processor, offering text scrolling, cassette routines, line editing, t:. I 2 &0 380 justification, insertion and deletion, variable line 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 option, page mode and only occupies 4.5K of

RAM. Full instructions and function key lables supplied. NOW Runs on a model B for E6.95 inc.

'<if* BDNSHOKE

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.

40 ACORN USER JUNE BEEB FORUM

MULTIPLE STATEMENT LISTING OPTION

IN interpretative languages such as IAN BIRNBAUM sets out to improve Basic there is continual conflict, Program £20 legibility your programming techniques on the between program efficiency and earns BBC micro. legibility. The existence of the £20 He will answer reader's questions LISTO command in BBC Basic is in this column and develop their evidence of the designers' wish to ideas - as well as giving some of his reduce this conflict. However, a own. But the real aim is for readers major cause of illegibility is the to provide the questions and the use through the first piece of code. It answers. of multiple statements on a line can turn the listing option on by separated by colons, which LISTO CALL&D2F. At least E5 will be paid for any tip published, with E10 for those which does nothing to tackle. CALL &D24 and CALL &D2F are merit a one-star award and £20 for Listing 1 checks the output potential causes of disaster since reaf humdingers! stream for colons and precedes any finger trouble in typing could The idea must be original and be each by a carriage return, line feed cause a system crash. For this described clearly and fully. It should and five spaces. Colons which reason lines 320 and 330 assign not have been published before. appear in REMs and text strings function keys fO and f1 to perform Your contribution should be typed will be affected also. However, the calls (fO turns the listing option or printed, with any substantial listings on cassette, colons tend not to be used in such on: f1 turns it off). but only included to a point. circumstances and the inconveni- Finally, the listing option make Send your hints or questions to ence is usually minima!. deschbed above can be used in BBC Forum. Acorn User, 53 Bedford When run, the program loads conjunction with LISTO. However, Square, London WC1 B 3DZ. Please three machine code routines into when using edit and copy keys it is include a self-addressed envelope if memory page D (which is reserved recommended to all listing disable your contribution is to be returned. for user routines in non-disc options. We cannot answer letters machines). individually, but a cross-section of - The first routine loads lines 60 NB, If you have discs, or any common and interesting points will

190 into memory DOO - D23. It other upgrade which accesses be covered. checks for a colon and outputs the page D, use &C00 onwards extra characters and colon if instead of &D00. Change 270 to SCREENS TAPE detected. If one is not detected it #&C instead of #&0. Change ON simply outputs the character. The line 30 to &C00 instead of &D00. MR H. Edwards of Oxney has scheme is similar to that on page Also change lines 320 and 330. written to ask how to save the 457 of the User Guide. This excellent idea could be screen contents on tape. This is Lines 200 - 240 form the second slightly improved if text following easy, as long as the screen has not routine in D24 - D2E. This restores an ELSE was also separated out. been allowed to scroll since the the vector WRCHV to its original However, this Is not easy. Again, last clear-screen. Use *SAVE to value and provides a means of LISTO will not indent the save from HlfvlEM to the top of turning the listing option off using portions of text separated out RAM (&7FFF in a model Bl. CALL&D24. between colons, but modifying However, if the screen has scrolled, The third routine (250 - 290 in this is even harder. Readers with HIMEM will not correspond to the D2F - D39) IS for changing WRCHV these or other modifications are top left pixel. For this reason always so the output stream passes invited to write in. clear the screen before using *LOAD to get back the display.

C OPT PASS PASSWORD LEGIBILITY 200 LDA • START CMP #58 210 STA MR E, Robertson of Edinburgh has BM SI 220 LDA #y^ written to say there is a problem LDA #10 230 JSR A^ STA V^l with the March password program. 240 RTS I^A If the program is listed on a printer, #13 250 LDA JSR A^ #0 the 'invisible' three lines appear. 260 STA V^ LDA #32 This does not detract from 270 LDA #£D J3R A^ 280 Benjamin Finn's idea, but can JSR A% STA VJ^I 290 HTS anyone improve on it? As well as JSR Ajg 300 J correcting the printer display, JSR A^ 310 HIXT JSR A^ readers might like to think of ways 320*KXY CALL^D2F LDA IM of making it difficult to erase the #58 330*Kir 1 SI CALLi:D24 iM JMP A^ 3^0 STOP three extra lines. Write in with your "-'Sting 1. Multiple suggestions - the best will be state ment listing option published. page 43

ACORN USER JUNE 41 ^-^^ ^^^ » The London ACORN-BBC Centre to Schools and Colleges Atom: Suppliers Full hardware and software support. Maintenance Contractors Tapes: BBC: New Showroom: Model A £299 Top Tape; see adverts in Radio Times. OFF Records would expect you to buy Model B £399 OFF Records beats all published prices. best value- Spend some time in the Memory up-grades £21 .99 Stationery: relaxed atmosphere of our new Repair service and component supply. Moore Paragon main agents. Large showroom to find out exactly what you selection of continuous stationery, Printers: are getting for your money. SeikoshalOO £215 forms and labels. OFFware: Epson MX80FT/3 £385 Books: CHARAID for the design of a block of 4 SCM Daisywheel £485 Browse through the Computer Book characters in any graphics mode Department for educational, scientific Cassettes: including mode-7. Outputs VDU23 and business applications. Matched Cassette Recorders £26 commands, teletext commands and Monitors: printer commands to screen or printer 12" Green Screen COMPUTER HOUSE together with actual design. Substantial (Hitachi/Phoenix) £110 58 BatterseaRise software with more than 20 well- 12" Colour (Kaga) £255 documented commands, Indispensible Clapham Junction 14" Colour (BMC/Cable) £255 for graphics work. London Discs: SW11 1HH £7,50 p.p. & VAT incl. TEAC40-track £199 Telephone 01-223 7730 ATlLITYcontains seven essential Shugart twin 40-track £299 routines for the disc based Atom: TORCH dual disc drive with Z80 L^'.. 1' III.. .1.1 'COPY, 'COPYT, 'COPYD, 'RENAME. a Minglci Frum HH(L|J(,I-'I" J.Jn..L 1..1 processor, 64K RAM, CP/M and BH aioharti JuMcEim am W/JI,33.'fi,t9.fi»,71, 1/(1, 315> •PURGE, -BACKUP. 'AUTORUN Tiihe Clapha", Cf-nrntFTt FREE software £780 £25p-p. aVATincI, SI JOHNS HILL LAVEflDER HILt Eprom programmer: Vacancy: Specially designed for BBC. Programs IM'I-' lUiCMHltS... OFF Records are looking for a bright 12 different Eproms including 27128. .1-1 spark with good knowledge of both

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42 ACORN USER JUNE BEEB FORUM

This must continue until a suitable Quick location is found. retrieval tip from disc using ^ When reading from Ihe file a hash routine from similar procedure must be adopted, Hugh Simpson-Wells advancing the pointer until the correct record is found. Average access time is very short for a file

OPENIN is particularly useful tor and 1 2480 depending on the first which is not too full. writing to files in Basic version 1 on two characters of Z$ which might I put forward the hash function disk. This means, for instance, you be a surname. Assume a file has as an example of the use of can output just one record to a file been opened called NAMES using: OPENIN to output to a fife on disk, without having to rewrite the whole which is apparently not documented. file to X=OPENIN "NAMES" disk using OPENOUT, saving I am sure readers will come up with time and memory. more interesting uses. Now put PTR#X-HASH and check Here is an example of a hash what is there using INPUT#X. If it is function which could be used to If you intend to append to your available we could write to it using generate addresses on disk to file later, it is essentia! to create PRINT#X, (variable), if that's what store for example, names and dummy records, which can be we want otherwise, we must add addresses, and retrieve them overwritten. If this is not done, 120 to our old HASH (since record quickly: space will be lost if other files or length is 1 and set the pointer: 20) programs HASH = 120*((ASC(Z$)-&40)M + are saved afterwards. HASH=HASH+120:PTR#X= Also, when you try to INT((ASC(MID (Z$,2,1))-&40)/6)) append HASH MOD 12480 the 'can't extend' error will crop This generates an address between (this makes the file 'circular') up (disc manual p67).

l->ne spacing Jlfj^ ON ERROR variation PRI!MTX%„y%,Asi, END "^KS^^ .20 ^^ fromA.Ki HROCTEST ernanan ( "SEiCONH" ) Y I DRF PRGCTEST

is it is THERE a rare bug concerning important to be aware of the TOP-PAGE should be 786; if it isn't, global variables that may occur in potential problems. you have extra spaces.

I^LF PRuCLj:nE

page 56 AQORH USER JUNE 43 .

If you're serious about your BBC Micro... get some serious Software!

SOFIAAARE

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MOBODy f\MOWS MOREABOUTSOFTWARE INFORMATION TECHNOLOGY

Information Technology Year 1982 aimed to make people aware of the THE FUTURE FOR MICROS impact of IT. it achieved limited success and by the end of the year 62 per cent of the population had The government clearly believes information technology is vital to heard of IT, although fewer knew

what IT is or how it would affect Britain's industry. It will also play an increasingly large role in them. lives In the same year, the Department our ond education. Trida Strong and Paul McGee outline on [T of Industry extended its scheme to course being developed in Croydon schools for the last in our six put a micro in every secondary school to include primary schools. part series on micros in primary schools. We are now feeling the effets of two large government schemes aimed library studies, computer studies while the IT curriculum would focus at educating the population of this and computer appreciation, A on the undoubted advantages of country. But how should primary syllabus to cover these areas these examples of information schools make Iheir pupils aware of needs to look at the impact of IT on .technology. the effects of microelectronics and information handling in all areas at Once we began to look at what role can the micro itself play? home, school, leisure and work. applications relevant to the pupil IT is not a dream of the future, Consequently much of the material the syllabus grew to include: yet pupils stil! leave school unable will also be encountered in other • What is information? to answer a telephone properly - let subjects, but the purpose here is to • How do we use information? alone use an information retrieval highlight the principles and to set • How is information represented program. But this is not something the applications within the context in a machine? to be left to secondary schools. of IT. • How is information stored and Teachers have a hard job before One way of introducing inform- accessed? them, delving into these fast- ation technology is for teachers to • How is information transmitted .moving concepts, but if the next make pupils aware of the and communicated? generation is to be confident about communication methods used in • IT in education and the home. new technology, provision must be school and to discuss why a • IT in the office. made on primary timetables now. particular method is used in any • IT in monitoring and control. Many schools have prepared given situation. Many teachers will • IT in forecasting and simulation. some kind of course in information need to improve their attitudes to • Machinery of IT technology, either as a separate technology and, in particular, to • Applications and implications of entity or as part of several current ensure that sexist views which IT. subjects. The MEP (Microelectronics allow women to use office products Education Programme) is concerned and men to usee obviously A series of 12 pupils' books with about the lack of suitable materials mechanical or electronic devices, supporting software and teacher's for anything other than examination are not passed on. notes will cover this syllabus and courses in computer studies, and An IT course will stimulate provide the core for a course in IT. has sponsored, in conjunction with demand from pupils for more The course will be practical, though the Dol, a two-year project in suitable styles of teaching and not necessarily using a micro.

Croydon to develop an IT learning and should thus make it Much of the technology referred to curhculum for the 9-1 4 age range. easier for teachers lo use will be too expensive for schools,

Information technology is an computers. The existence of such but it can be demonstrated using umbrella subject taking in three work will provide an IT course with programs on micros, Trying to run existing disciplines; microelectronics, practical, day to day examples. an IT course without using a micro computing and telecommunications. Teaching, learning and working will would be like learning to drive a In schools, this includes com- be transformed by word processing car on a simulator and never going munication studies, office practice, and information retrieval systems. on the road.

ACORN USER JUNE 45 2

SCHOOLS

Each booklet will provide a IT and dispel any feeling that it is a back to school to use where complete unit of work on a topic in technical subject for superbrains possible with children.

the syllabus. The series will not be only, it is important to recruit Several schools - primary, sequential and, although one teachers who are skilled com- middle and secondary - have volume will be an introduction to municators and have an inlerst in volunteered to test and criticise the the course and some will be aimed the technology, rather than materials. Because of the range of at the top end of the age range, the 'spanner-men' and electronics schools, the materials will be used course can be ordered to suit 'whizzkids'. To avoid the risk of IT in many different ways - as they will teachers. Two booklets will be becoming a male-dominated reserve, be in their final form. Some schools

devoted to considering real-Iile it is essential to involve everyone. use them for one or two lessons a applications and the resulting The effects of technology are not week regularly while others, where implications of IT. Through studying confined to men and girls must not the timetable allows, use them as applications the topics covered in be discouraged from enjoying and the core of a project lasting a few other booklets can be put into benefitting from the course. weeks and incorporating related context and the implications Educators shaping schemes of work in the way that many primary become meaningful. (Two of the work have a responsibility to school teachers prefer to work. titles aimed at top juniors are ensure that girls are encouraged to Response has been tremendous outlined below.) take as large a part in this subject and interest expressed by organis- In Croydon, several secondary as boys. Perhaps this course will ations as diverse as the Citizen's schools will be including IT on their help to break down any ideas that Advice Bureau, a word processing timetables in September and technology is a man's domain. association and a women's teachers are already attending magazine. The Equal Opportunities weekly meetings to give them a As ideas for the course are Commission has provided addition- grounding in the subject. They developed, they are presented for al funding to ensure the project is come from a wide range of discussion to teachers in the acceptable to girls, and to provide backgrounds, including geography, weekly meetings. They try out the guidelines for teachers and parents languages, PE and needlework. programs and leaching materials on why and how to encourage girls To provide a balanced picture of themselves and can take them to follow an IT course.

Introductory booklet OUTLINE OF Objectives THIS aims to develop an By the end of the booklet pupils awareness of what information is should: TWO PUPILS' and how we handle it. By • be able to identify their needs studying human methods of for information, formulate information handling an easier BOOKLETS IN questions, find and select understanding of automated resources, evaluate, record systems should be reached. SERIES OF 1 and present the information

have apply it. Objectives mnemonics, flag signals and they found, and {code breaking • have developed these skills After following the work in this coded messages further when using new booklet, a pupil should be abie program is being written to this). technology in the areas of to; support Another section will look at communication and information. • recognise sources of inform- developments affecting the The work in this booklet will be ation, informal as well as transmission of information; the familiar to any English/library specific. printing press, railways, telegraphy, study skills teacher. However, • recognise occasions and photography, telecommunications traditional work has been processes for handling inform- and broadcasting. extended to new technology. It ation - analysing, refining, The importance of availability, begins with the traditional sorting, synthesising and relevance of accuracy and information skills, but incorporat- classifying. information are considered as ing IT wherever possible, eg, • understand the importance of are the effects of information on teletext or viewdata. Organising relevance, availability and planning, organisation and and presenting information is accuracy of information. forecasting. suggested as a practical First we examine what is exercise on an actual project, considered to be information Information skills during whch pupils must also and how our perceptions absorb The aim of this booklet is to practise their skills of interpreting,

it. Next follows a brief history of ensure thai all pupils are evaluating, analysing and record- man's need for information and equipped with the necessary ing information. Various tech- developments in access and skills to enable them to cope as niques are suggested for this.

transmission. It looks at methods people living in an information The principles of a word of communicating information society dealing with real processor and text editing are and the problems involved, situations, in education, at work explained and a demonstration taking as examples proverbs, and at home. program is being developed.

46 ACORN USER JUNE ^mkCRDfiGE ELECTRnniCS

ACORNSORFORBBC 'Snapper,'PlanetO!d,'Mon5ters,'RocketR; 'Meteor 'Super Invaders, Philosophers Quest, Sphinx Adventure, Arcadians, Lisp Cassette, Peeko Computer, Creative Graphics Tape, Graphs and Charts Tape, 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 Model B £399.00 BOOKS Practical Programs for BBC & Atom £5.95 Model B + Disk I nterface £494.00 BASIC BBC Dust Covers £3.95 Programming on the BBC Micro BBC Compatible Single Disk Drive* £5.95 (lOOK) £235.00 Assembly language programming for BBC BBC Compatible Dual Disk Drive* £8.95 (200K) £389.00 BBC Micro Revealed £7.95 Creative Graphics, BBC Dual Slimline Disk Drive* Graphs & Charts, LISP (Double Sided & Density 800K) £799.00 all at £7.50 each SOhr. BASIC Verbatim Single Sided Diskettes £5.95 Let your BBC Micro teach you to 10 for £22.50 program Verbatim Double Sided Diskettes £6.45 lOfor £39.95 Let usfitadisk interface in 24hrs £95.00 RH Electronicscolourlightpen £37.00 BBC MONITORS 14" RGB Microvitec Colour Monitor (as used in the BBC Computer Oa^ies, ProgJIncludinglead £284.00 Printer •B' GPlOO Microvitec High Res. pV^fd^ProctS Colour Monitor £575.00 12 " Zen ith H igh Res. Green screen -p\rAV^n£rnl?£2l5^ Monitor pnce ever. ^^FREE^^ £95.00 The lowest BNCCableforabove £4.95 BBC Compatible Cassette Player price on application BlankDataCassetteslOfor £3.50 POSTAGE RATES £1.30 p&p Small items such as Ribbon, books & DINtoJackLead £2.00 software;- 1 item £1.00, 2 items or more + 75p p&p All Dust Covers £1.00 p&p 50p per unit OfficialJoysticks per pair £13.00 BY COURIER TO YOUR DOOR £1.30 p&p Large items such as Computers, Disk *AIIDrivesinclude manual and utility Disk. Drives & Mon itors:- 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- lOOA now down to £215.00 All Lynx, Oric, BBC, Commodore 64 your guarantee. AP-80A Ribbons £4.95 owners, we pay top royalties for quality V^e accept official orders from educational AP-IOOA Ribbons £5.95 software programs. Please write or establishments. Brand new Epson FX 80 phone for details. Credit card holders can phone in for Contact us for details express despatch. All printers include cable & paper Epson Dust Cover Barclaycard and Access lafe Send large S.A.E. for lists and info pack. £3.95 Parallel printercable £15.00 welcomed All prices include VAT

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ACORN USER JUNE 47 SCHOOLS

SUMMARY OF INFORMATION TECHNOLOGY SYLLABUS

THIS syllabus is not a leaching Storage and retrieval importance of graphics, colour and scheme and the latter has to be Reference books: encyclopaedias, touch sensitive screen and developed by each individual telephone directories (phnted and tightpens as input. Voice input and school. Pupils ot this age are microfiche), timetables and route output. Electto-mechanical devices: unlikely to be ready to discuss maps. Retrieval of information paddles, joysticks. abstract concepts relating to the using titles, contents, indexes and Types of printer: dot matrix, daisy implications of IT which should be cross references. Card-based and wheel, ink jet. Graphical output of taught through applications which microfilm library reference systems. low and high resolution graphics, are meaningful to the pupil. Concepts ol file, record and field, use of colour. Wherever possible these applica- Basic knowledge of computer tions should have direct relevance storage systems - main store, tapes, Control applications to pupils and should involve them discs, videodiscs, associative Idea of feedback systems. Analogue in practical activities. storage. Use of and need for to digital and digital to analogue - computer data bases relational conversions. Control applications in Nature of information and key word. domestic appliances: washing Brief history of man's need for Information transmission machines, central heating. Import- information and significant develop- Modes: serial or parallel; local or ance of the microprocessor. Need ments in communication. Role of remote; interactive: electronic. lor standard interfaces. Practical information in modern society. Telephone systems: viewdata experience of controlling simple Effect of information on planning, systems Including electronic mail- devices including those which forecasting, organisation and con- box, gateways, local viewdata accept inputs to control outputs. trol. Importance of relevance, systems and telesoftware. Line and completeness, accuracy and avail- packet switching systems, digital Simulation and modelling ability. The information explosion. exchanges. Local and business Non-mathematical approach to Information representation subscribers: exchanges; message using computers to simulate events Ideas ol data and information. recorders; paging, facsimile and and hence to forecast. General Coding systems, eg post codes. transmission. understanding of applications such Consideration of ease of use, Radio and television systems; as Ernie, weather forecasting, validation techniques, compatibility, phone-ins; telex and telesoftware; industrial process control. Simple loss of information and storage citizens' band; cable systems. practical experience of simulations requirements. Information manipulation of situations from the school Analogue and digital represent- Use and importance of merging, curriculum. ation in mechanical collating, extracting sorting and electronic and Personal devices devices and the consequences for files of data or Information, Electronic games. Educational toys; accuracy, storage and transmission. Comparison of manual and dedicated and general purpose. Graphical representation of computerised systems. Home computers and networks. information. Choice of medium: Office practice Links with television and telephone. effects of medium on author and Written communication: letters, The computer controlled home, recipient; evaluation of medium. reports, memoranda, accounts. Telesoftware via telephone and Information skills Visual communication: charts, television. Computer clubs. Role of Understanding and interpreting; tables, graphs. Importance of the Education Service, links with grammar and literacy. presentation. Analysing, processing and syn- Need for organisation, collection, Computers in education thesising; refining and broadening; classification, storage and retrieval Use of computers for CAT CAL and discussing and questioning; sorting of documents. CIVIL, Role of word processing and and classifying; merging, collating Accounting systems: audit, con- information retrieval for teachers and extracting, trol, forecasting. Impact of IT on. and students. Use of computers in Recording and presenting; the word processing, data processing, school administration, libraries and medium and the message, computer file storage, output the careers. Computer aided Applying; emphasis on information devices. design. lost in coding. Impact on staffing: levels, skills Implications Concept of a system required, training, job satisfaction Organisation of work: skills needed, Relationship between input, output, and expectations. location, changing patterns of work. storage, process and transmission. Man-machine interfacing Privacy and security of information: Comparison of the features of Keyboards, including QWERTY, legal framework, practical problems manual and electronic systems touchpads, special purpose includ- of computerised and manual from the user's point of view. ing microwriters. Use of screens: systems, human considerations.

ACORN USER JUNE . . .

SCHOOLS

I here is a growing need to see education extending far beyond compulsory schooling. People will need to study for their employment; for personal or social needs; or for pleasure- To do this, education should help people to learn and give them confidence to undertake Student's name further study. A: Effective Use of Hardware The styles of learning exemplified 1 Connect and disconnect, as appropriate, a computer witii; by the Open University, the a cassette deck proposed Open Tech and distance a disc drive a monitor learning methods are likely to a keyboard become more common, and it will 2. Switcli on/off in the correct manner. be essential for pupils to use these 3. Display reasonable accuracy on the keyboard. systems. Culturally deprived homes 4. Load cassette/disc. may not be able to offer the 5. IVIake a copy of a program: guidance and support that Ihe cassette to cassette children most in need require, and disc to disc

thus the edcuation system must 6. List unsuitable storage practices for:

enable all people to benefit from i) hardware strong heat improved learning possibilities. excess moisture The IT course is meant to have a excess dust strong practical bias with pupils switched on ii) magnetic media as above, plus learning how to use computers strong magnetic fields rather than only being able to write uncovered about them. To encourage this a do not touch surface certificate of competency, similar in do not write on case approach to scout and guide B. Running Programs.

badges, has been developed at a 7. Load BASIC, if necessary. series of levels. The tasks to be 8. Load and run a named program. carried out successfully to gain the 9. Use files: update an existing file

first level are shown in appendix 1 save a new file 10. Edit an existing program:

list program SOfTWARE identify line alter line Software being developed for the re-run program scheme includes quiz and search 1 1 List correct procedures for appropriate programs. Young pupils often have error messages: syntax error exaggerated ideas about the power not found of computers and instinctively type bad program questions of the sort 'Who won no room 1980?', Wimbledon in and are bad load surprised to receive answers such load error as 'Syntax error'. 'What?' or '????'. mistake The quiz programs are to designed 12. Understand what is meant by the following terms: help young children understand hardware that cornputers only know what software someone tells them. Although this program idea can be developed by writing memory programs the lack of success of so backing store many 16-year olds suggests that RAM even younger pupils would never ROIVI K gain a realistic idea of the power of operating system computers. data Process allows pupils to make debug a multiple up choice test on any disc drive

topic. The finished test is stored on file a data tape for later use. Pupils information retrieval enter their questions and. for each tine printer question, the correct answer and magnetic tape

distractors. The pupil is then asked peripheral to provide messages for those who score well, who gain an average Competency checklist for pupils on IT course score and those who do badly.

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BBC UPGRADE KITS Securuar... BBCA2B Ci>mple(ftAl(jBUiigFii(1(- £44.75 BBC! IBKMemorv £18.00 BBC; Pr.nler User 10 Kil £ 7 50 ACORNSOFT BOOKS FOR THE BBC 3 Disc (merface Kil £9S 00 iinly supplied iruith Dibc Dr.vtib BBC MICRO B6C4 Analogue InpLiIKil £6.70 SBD01 Creative Graphics £ 7,50 BBC5 SeriaM ORGBKit £ 7 30 SSD02 Graphs -Chans £7 50 BBC6 Bus Eipdtision Kii £ B.45 SBDM Lisp £ 7 50 All kits are suppliert wilN (ullfiiimg SBD03 Fodh £ 7 50

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BBC 2 1 Prinrer Cable dnriAmnhurol BBC MICRO Plug Inoi assemblfid) £1300 Algebraii Manipulalu COMPONENTS BBC 22 Us«r Port Connewor and 4516 lOONS £ 2 25 36' PK Cable £ 2 4G CreaTivG Graph its 6622 £ 3 19 BBC 23 CaBSBile Lead £ 3.50 Cassette £8 65 74LS244 C 59 BBC24 7PinDir.Pluc) C 60 SBX02 Graphs Sj Chans 74LS;45 £ 69 EBC2B 6PinDirPluy £ 60 Cassette f 8 65 74LS163 f 034 BBC 26 5 Pin Din Plug f o.eo SBBDl Desk Diary Inr Mann f S 65 DS363'N £ 4.50 BBC 3b Disci 0Cable34WIDClri SBLO; Lisp Cassette £1465 DS8aLS120N £ 4.50 2»34wayCa'dEdijp £12.00 SBLOI Fonh Cassette £14.65 UPO7002 £4 50 BBC 36 Disc Powftr Cable £ 6.00 S8G01 Philosophers Quest £ 6 65 8271 £36 00 BBC 44 Analogue Innul Plug SBG07 Sphinn Atlventure £ 8 65 20 Way Header £ 146 & Leuei SB GO 3 Monslers £ 8.65 26 Way header £ 1.76 B8C66 IMBusConnectQT SSGM Snapper f 8 65 34 Way Header C 2 06 + 36" Cable SBG15 Planetoid £ B.BS 40 Way Header £2 37 S8GD6 Arcade Action £10,36 15Way DSkt £ 2 15 BBC ACCESSORIES SBG05 Rocket Raid C B65 6 Way Dm SH £ 090 BBCab Jovsliclislpef pa £11 30 SBG13 Meteors £ see 6 Way Dm Ski £0 90 BBC 67 EpromPrugrsnir £57 95 SBG14 Arcadians £ a 65 l.)5:ii;nitiioi)l SBGIO Chess E 8 65 BBC SOFTWARE IN ROM Wo'dpiocessor "View'

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50 ACORN USEn JUNE B

SCHOOLS

Process: Program which allows pupils Proctest: Similar to Process, but allows Search: Database software in action, to develop their own quizzes a greater variation in answers, and in having just traced what blue coats are difficulty available

There are editing routines to allow database is implemented. Search changes to be made to the does this. It shows graphically the NINE ESSENTIALS question, answers and comments. structure and operation o! a So far, this program is similar to relational database, a linked list one in the Micro Primer pack but and an inverted database. information technology the next one is rather different. In each case the files used for must be a practical activity Proctest develops the idea of demonstration are small. Two small what the computer can know. The databases can be searched using which builds pupils' con- fidence to use computers. questions are more open-ended moderately complex enquiries and and the computer can be given up the pupil is able to follow the action Knowing about computers to eight acceptable answers. For of the search. The inverted means knowing when and example all the possible ways to database program is almost how to use them rather write 'Henry VIII in reply to the finished and all three programs are than the details of how they question 'Which English king had supported by material written by a work. six wives?'. Not only do pupils learn former school librarian. Pupils should learn to about the limitations and power of use computers sensibly, computers, they also discover a ie, by using the appropriate soft- little about the different ways I he importance of information ware, to perform tasks information can be coded as data, retrieval, word processing and which would otherwise be a topic which is developed more financial spreadsheet packages are unduly tedious. fully in the accompanying books. reflected in the higher levels of the Information will increasingly be Certificate. The books must be There is already encouraging stored or manipulated as data by related to software which the pupils evidence that sensible electronic devices, and schools will can easily use and so a limited activities using computers have to teach a far greater range of word processing package and a have a positive benefit on information handling skills than at simplified Visicalc-type package girls' attitudes if started in present. are being developed. primary school. What information can be Schools which are willing to Information technology can retrieved from a data base and how seriously trial written material and be taught either as a this is performed depends on the related programs should contact separate subject or as a co- structure of the system. Pupils will Trisha Strong c/o Acorn User, 53 ordinated part of many be encouraged by the teaching Bedford Square, London WCI other subjects. materials to use a database to 3DZ. Those who want a draft copy perform tasks which would of the Certificate of Computer Teachers need training over otherwise be tedious, but they also Competence should enclose a a reasonable period of time need a simpler idea of how the stamped addressed envelope. to become confident and proficient in the use of THIS is the sixth and final part of that the program Tray described computers. our initial series on computers in in May's Acorn User was devised Information technology is primary education. If you have by Bob Moy and Mike Blamires the future revolution which any enquiries, comments, or sug- and initially developed at Forest has already happened. gestions for the second series Hill School, London. It is being IT can be taught effectively which will start in the Autumn, extended with the help of the only with sufficient com- write to Tony Quinn, Acorn User, English Centre of the ILEA. Tray puters and informed and 53 Bedford Square, London is one of a suite of programs well motivated teachers. WC1 B3DZ, marking yourenvelope Bob Moy has developed to help 'Education'. teach reading and text analysis Teachers can help pupils Education authorities, or in- up to 'A' level. Enquiries appreciate IT by using dividuals requiring reprints of this should be addressed to: Mr Bob appropriate means of com- series should write to the same Moy (Advisory Teacher for munication in their own address. English at the usual Acorn User lessons. Finally, we omitted to mention address.

ACORN USER JUNE 51 electronic monitor manufacturer

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52 ACORN USER JUNE HINTS & TIPS

^page 24

The 50p network

THE BBC micro is a remarkable machine for communicating with other systems across phone lines using an acoustic coupler. Robin Kennedy of Kensoft in Cleveland has passed on a gem of a program for handling the BBC side. Program 9 runs happily on OS

0.1 , 1 .0, and 1 .2 (but not the Tube).

To understand how it operates we need to look at memory locations

&FE08 and &FE09. The second is

easily dealt with - it is the location of the 6850 ACIA register dealing with transmitting and receiving character via the RS423 port. Any received character enters the BBC through this location, while any character placed into this location is apparently transmitted through the RS423 circuitry. The other

location, &FE08, is more complex. It characters which it receives and transmit from an RS232 port, and appears &FE08 can be read from those it is transmitting. Additional so developed the function key; as a status register for the 6850 coding is required to handle the ACIA. If the first bit is set. it *KEYO *FX8,8;M*FX7,8IM*FX3,5! CR codes at the end of lines. indicates a character has been MLIST!M*FX3,4 While playing with the software received in &FE09. If the second bit shown above, the germ of an idea Because LIST produces ASCII text, is set, it is 'clear to send'. Program arose. While running courses, a and *FX3,5 sends it down the 9 above looks at both these bits in common need is that of loading RS423 port, this function key worked line 40, where it says; 'if there is a Basic programs for teachers to and transmission was successful. character and it is clear to send, evaluate. What was required was Unfortunately the recipient BBC continue'. This is fine for 300 baud, the ability to load each BBC from a micro still had its keyboard locked but the program can be tweaked to disc system. But this seemed at out. The final approach was: run at higher rates. I use the BBC first a non-starter because of the micro coupled to a development 28 *KEYO *FX8,8IM*FX7,8IM*FX3,5I need for multiple disc upgrades. running at 1200 baud (program 10). ML,IMP."*FX2,0":M*FX3,4IM However in OS 1,2, typing *FX2,1 And inter-Beeb communication causes the machine to think the This had the result of commanding is possible at 9600 baud with RS423 port is a keyboard. This the receiving micro to listen to its program 11. Whereas programs 9 it meant was possible to receive via keyboard, by making it print *FX2,0 and 1 made the BBC into a the RS232 port with a single as a direct command. The final terminal wtiich requires the host I command. Each of our BBC micros '*FX3,4 in keyO simply sets up the system to return each transmitted could be configured to receive with transmitting micro to print to screen character so that the user could a function key. only. The connections between the see his/her own keypresses (full two micros can be seen in figure 4. duplex}, program 1 1 acts in a *KEY1 *FX8,8:M*FX7,8;M*FX2,1IM Transmission is effectively a different way. Each of the two SPOOLing/EXECing process and communicating Beebs prints the Eventually I found *FX3,5 would programs can be appended. For the best transmission: fl

• press f1 on the Rx micro; • press Break on Tx micro; • type OLD on Tx micro; • press fO on Tx micro. Oafa tn The lead used is 10 metres long, P»ts in RTS and is taken to the RS232 socket Ne Lead fs ^ettf&zfcJe, crs on each Rx micro in turn 'hosepiping' Basic programs swiftly Figure 4. RS423 connections between two BBC micros into them (10k in 30 seconds).

ACOBN USER JUNE 53 <«^V^t'^tsfS^ fc-a \*

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/^COfl/V USER JUNE 55 BEEB FORUM

error reporting (listing 6), The String HanlU^S, Todd program redirects the BRK vector to the start oi my code. HERE are two assembly language expects an input string up to32^ When an error occurs, the programs (inspired by your characters and will output any offending line is pnnted with the excellent book on assembly Basic line containing that string error highlighted. Then control is language for the BBC micro) to (keywords excluded). The output is passed back to the machine which help write large Basic programs. done in paged mode as it is prints the normal error message.

The first, called 'finder', is extremely 'fast. Instructions are located in page &C as a default but included within the program. Note, these routines will not can be located anywhere by Second, 'error-util' acts as an work with the new version of changing line 100 in listing 5. It extension to the BBC machine's Basic. ~~~ -^"^V. 5....r„dd. 70RFM \j^:l Copvr.oh^ K.s:'.

90 100paqe™?

EV^SNE '"'' nBKt.rXA:LDX «.tar-i tibl b '"—«--' ^^^SR .F FEE n 16ut

17u.chec7t., occurence; LDY #4:SrY S'^y-^-ntrn 't-i. S<7.;.!.neMtt^LD0 ^'-^ .,3,BEa ^o'^df :' = -^^ .p.rt_U L; ILSTl NvfpNE n^^ 'f^"^ =1 tB0,fnund:LDA " 'n^T,* ^^®-'^=-i » n£?! JGR ttS-FFuRTS- cuf nnn^h ^f ': find line^jlDA #0-PT'^i 0) V.BTA .2A.TSR '^fO>,V,STA .2B= V ^^^ulm^^'^^^^^^^'^'l^^^^ mJ: LDA %.. #4j.ne..:t„byt6>i;LDA ^ * ''^^^ ^^^'^ (?.70) S:FFE7s RTE5: . out . Yi CMP #13 RFH InT ™^. lin^-ID 9u.^nd..outUne:JSR ° ^'^' '^'^SSA: INY: JNP Hnd - "? ne.^t Ey^e rnL^TBR^'tpF-/- Rf f --^^ '2o^;s:s?.:^::;2^,--^^- .7t:'.^L:^^;^SB:r^^-^"^-'"^ ^.7o,,y,^.c= ^lO-Emessaqe^" ? dni-f" 2201«n^Btriny-l.EN<4mes5aqG.> 230p-/.=px-flen_.string-M 240Etart_tahlt?=P"/.- "i'P'/.^Mo 250P7.?i=?,A:P'/.?2=&2O-py.".T~3O 260P7.'^4^^127 " " 270 NEXT 2aOFim , Listing 5. 'Finder' to detect string

^UF-,EM Shnuid run an any current Mas """'^^ "'^ P^^^ "'^'= C"nv«n3,^,;t Inlfl n"*" addrB5=.. '^'^^"^'^^'i"" SOREM S^r^"' ^-'^'^ prints out offending line i Fr-^-s;^"^.?^:t;sr:jLr--;-H:s?;:;^ ^--^ ^- —

120paqH=.^

'" '-^''^ -..6„REM 150 ^ [joinl ^rr^r vector to thi=5 code.

160F0R T7. - C TQ Z. STEP 3 170P7.=paqp

^OO.maiih.rmiJMP :!.,B433 ^ go tP m^chin^ srror routine .,,-10. print „I UiesLDY IHs.nejjt i-harslDfl C-Tni v-rwo im'ti t.frfi

Listing 6. Error report extension

56 ACORN USER JUNE ATOM FORUM

No speed penalty to eliminate graphics snow

IN THE letters page of tfie April - the port marked PL7 this is user Barry Pickles hosts a new issue, a routine was given to port PB7 and. to use it for other cash-for-tips column. eliminate the annoying 'snow' that purposes, insert a switch jn the wire Here's a chance to show off can appear whenever graphics link. Once installed, the following your talents - and earn some memory is used. However, this fix short routine will assemble a new crinkly green stuff Into the slows down screen plotting. This is version of the point plot routine; bargain. There are because it waits for the TV 'frame reckoned 10P.S21; P=#21C; [LDA #B800; sync' pulse, which is only sent 60 to be some 40,000 of you out BMI P-3; JMP #F7AA;]; times a second. However, the video there and, bearing in mind P.$6 chip (IC 31) also produces a 'line that the Atom has been This sync' pulse line should begin every (don't worry what it all around for more than two program using graphics. To cal! it, means) every 1/15000 second, on years, you must have use: pin 38. If you have the 6522 VIA accumulated a fair amount of fitted this 9000a pulse can be read by !#222HFE; !#3FE-#21C; expertise. connecting a wire link from pin 38 R. What we're looking for are (IC31) to pin 17 of IC1. Call by GOS. a, everytime you use those little routines, tips and If the idea of soldering onto ICs CLEAR or COLOUR. You will find worries you, hardware mods you've connect pin 3 of PL4 noise is eliminated (except in mode to the fifth discovered. Don't worry if pad from the left of the 0) but plotting is not noticably innermost row of solder pads on slowed. your little wrinkle seems too simple- it's probably just what someone else has been Bad program - but all is not lost looking for. The same rules IT to HAPPENS all of us. You've you are likely to get a list of apply here as in Ian just typed in the latest epic and are garbage. Listing 1 provides the Birnbaum's Beeb Forum.

getting ready to save it, when answer- an ASCII disassembler. It Short, sweet and as original something happens - maybe the shouid be placed in a different area as possible is the name of freezer thermostat has just switched of memory to the one your program the game. I'll start you off, on - and the machine locks up. is in! It displays eight bytes to a but this is - your page, so let's You press break and type OLD line, with the address given at the hear from you! nothing happens! Your masterpiece start of the line. Using it will show Send your has just gone west ideas to Atom as a 'bad where the program is corrupt and it Forum, Acorn User, 53 program'. can be corrected using the ? The Atom Bedford Square, London recognises the end of operator. It prints ASCII, if the a program If by a marker, which is a particular byte is in the correct WC1 B 3DZ. you want it carriage return followed by a range, so you may see some odd returned, enclose a SAE. It negative byte (ie; OD FF in hex). characters where the program line should be typed or printed, Whenever you press break, these is stored. To use the program as an with programs on cassette two characters are inserted at the ordinary hex dump, delete line 20. (with listing if possible). start of the current text area. As a program is typed in, the FF moves along in the next byte. P.$12"ASCII If a bad program error crops up, 5 DISASSEMBLER" all is not lost, but you need to know ""PRESS Shift TO TERMINATE ' how a program is stored, AND" to effect 10 P."copy recovery. If you have a program WHENEVER PRINTING resident, type P.$#2901 (CR). What STOPS"" '$14; ?#E1=0 you should see is the first line of 15 ?#E6-5; @=0; the program! From this, you will IN."START realise thaL unlike most Basics, the ADDRESS"S; P.'&S"- "• DO Atom does not 'tokenise' words, but 20 IF?S>31 AND?S<160P" stores program lines as an ASCII "$(9S1- G 7 25 IF?S<16 ' ^^''^'^^ string, exactly as typed in, The P."0" format is: 30 P.&7S line no. (MSB);line no.(LSB);(line 35zlF 028 P'&S"-" of text);(CR);(FF- if last 40 P." line) ";S=S+1;U.?#B001P-0 45 ?#E1=#80; One way of recovering a bad P.$15'; E. program is ?#29G1 = 0; LIST (CR). Listing 1. ASCII disassembler However, since OLD didn't work.

ACORN USER JUNE 57 -a

FOR THE BBC MICRO

DEVOTED EXCLUSIVELY TO THE BBC MICRO

MEMBERSHIP NOW EXCEEDS 17,000 BRITAIN'S LARGEST COMPUTER USER GROUP 17,000 members can't be wrong-BEEBUG provides the best support for the BBC Micro. BEEBUG Magazine-NOW 64 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.

October Issue; Program Features; Alien Attack; Calendai Generaior; Unian Jack; Memory Displav ulilily. 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 gamel, SCREEN SHOTS FROM PROGRAMS Mini Text Editor (Mk2), Transparent Loader. Music with Memory, Har- monograph Emulator, New Character set for Modes? &5; and cassette block- ?ero-bug retrieve. Plus articles on sound and envelope design — includes indispensable envelope editor program; Debugging Part 3, BBC Basics- Memorv 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 (invaderlype game]. Breakout, Artist (Joystick painting programl; Rescue (miraculously reirieves programs after bad loading or 'Bad Program' message!; and Pack — a 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 ol Hints and Tips. February Issue: Progra(7Tfea((/res.BEEBIVlAZE Find your way through llie random maze, guided by 3D views from inside the maze -an excellent game. - implementation of YAHTZEEIR), a novel dicegame.Alsoa BEEBMAZE FEB 1983 RACER NOV 1982 FIVE DICE A Beeb listing ofWINDY FIELD- a creation from Acornsoft,SPIROPLOT screen dood- Icr, 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. program), an Introduction to IDEAS ON ANIMATION I Including a Rotating Cube the Use of Procedures, a Survey of Books on the BBC Micro, and a Roundup of Disc System Hints, PLUS a variety of HINTS, TIPS AND INFO, includingasingle VDU command to performa SIDEWAYS SCROLL. March Issue: Program Features: Life I32KI, 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, 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 I members only). April/ May Issue Special Anniversary Issue- Contains index to the wfiole of BEEBUG Volume 1. Music Composer -create complex 3 part synthesiser Program. Colour bar chart generator INVASION APRIUMAY 1983 3D ROTATION MARCH 1983 harmonies with this program. Beeb implementation of the Connect-Four Game. Invasion — 16k, Plus Review of Tape Recorders for the Beeb; a Basic Program Editor, which lists variables and procedures, and executes Find and Replace in a Basic Program; Reviews of Acornsoft Games and the Torch Z80 Disc Pack, Disc 1 1 m^-'^ Menu Program Newcomers introduction to Mode 7. How to save the unsavable; and a routine to print Double Height Characters in all modes. BEEBUGSOFT: BEEBUG SOFTWARE LIBRARY offers members a growing range of software from £3.50 per cassette.

BEEBUG NEW OPERATING SYSTEM OFFER BEEBUG members can now obtain the new 1-2 OPERATING SYSTEM ROM at around HALF PRICE See BEEBUG Magazine February, March or April for details. FOUR IN A APRIL/MAY BARCHART APRIL/MAY 1983 ROW As a result of BEEBUG negotiations with Acorn the ROM now may also be 1983 offered by other user groups to their members,

1. Starfire (32KI. 2. Moonlander (ISK). 3D Noughts and Crosses I32KI, 3, Shape Match n6KI, Mindbender (16K), 4. Magic Eel (32K). 5, Cylon Attack (32K1,6. Astro-Tracker (32K1.

Utilities: 1, Disassembler 1 16K1. Redefine (16KJ. Mini Text Ed (32K).

Applications: 1. Superplot (32K). 2. Masterfile (32KI, 13% DISCQUNTTO MEMBERS ON THE EXCELLENT WORDWISE WORD PROCESSING PACKAGE-THIS REPRESENTS A SAVING OF OVER £5,00.

Send £1.00 & SAE for Sample Membership: U K £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 SW84TE Send editorial material to: The Editor, BEEBUG, PO BOX 50, St. Albans, Herts AL1 2AR

58 ACORN USER JUNE 1

ATOM FORUM

INKEY routine- and how to find it

AT FIRST sight, the Atom seems to 95 LI,#21C lack an INKEY routine, as found on LINK#FB7DMwo 100 IF mo = "U- THEN second delay the BBC and other micros. (action! L NK#FB81 - y. second delay However, the machine responds L2;FB83 - x/60 110IF?#80 = ''D" THEN (action seco^ndl quite readily to anything typed at 2) the keyboard, so there must be one Similarly, if a user response to a somewhere. And there is, at question can be defined by a location #FE71 in the Atom ROM. In the latter case, variable X sets single unique character such a It continually scans the keyboard the number of sixtieths. All these routine can be used to eliminate and, if no key Is being pressed, calls can be used in machine code the need to press return. Carrying returns a value of 255 in the 6502's by a JSR # instruction. this theme one step further, Y register. a flashing cursor is a useful way of If a key is being pressed, the Y 95 P."PRESSTHE reminding a user that a response is APPROPRIATE register will contain the value needed. This can be done, using KEY"; GOS.b (ASCII - 32). By calling this routine, the previous routine, by the 1 00 as above we can find the state of any key 110,.. outlined Basic subroutine below, (except CTRL, SHIFT and REPT). which alternately turns the cursor following line The will assemble 9100b?#E1-0; P,""$8; on and off, until a response is such a routine and store the ASCII obtained. LI.#FB8A;LI#21C;IF?#80<> value in free location #80; But what is LINK#FB8A? It's 31 THEN R. another inbuilt Atom routine, this 9nO?#E1=#80; P.""$8' 10P.$21; P=#21C;[JSR#FE71- time providing a delay of 1/10 LI.#FB8A; G.b TYA: CLC; ADC@32- second. Here are some more: STA#80; RTS;]: P.$6 Strings, variables and things To try it out, after assembling, type:

UNLIKE most Basics, Atom However, it means strings can variables are not cleared break. 11 DO LI.#21C; P.?#80; UP by be explicitly positioned, $#3800 is This can be useful, as parameters just as valid as $M and has the and run, noting the value of can thus be passed from one advantage of you knowing exactly

different keys as they are pressed. program to another. However, it where it is. place the A value of 31 will be returned, if no does onus on the Dimensioning strings (or other key was pressed (255+32-256 -this programmer to set variables before variables) can sometimes be a is called 'modulo' arithmetic. All they are used. On power up, things problem. TOP may not be the best eight-bit machines work to modulus are even worse as variables take place to store arrays. The 'free 256). random values! In a string variable space pointer' governs where $M, It is now a simple matter to make say the M doesn't hold the arrays are dimensioned. This is real-time games respond to actual string, but only the address held in locations #23(LSB) and specific keys only, without stopping where it begins. Using unassigned #24(MSB), as an address. Setting

the action as follows (delete line 1 strings can really screw programs up your own vector in these first!): up! locations starts dimensioning from

that address. As a bonus, if the Contused Atom aids protection vector is set equal to TOP, as the first line of your program, you will IF YOU have ever listed an find that the last line has acquired be able to auto-run a Basic Acornsoft Basic program, you will an extra line, but listing the last line program. The way to do this is to have seen the last line is a and editing it doesn't work, nor begin a program with: copyright message number 0. If does LIST 0, Finally, before saving, you've tried to delete it (naughty!), type END to reset TOP. The secret 5?#23-#XX; ?#24 = #YY you will have found it well-nigh lies in !M =#080000, which inserts

impossible. This is because the a new line (0) over the previous then type in the Atom expects line numbers to be #FF marker and then backspaces program as normal. When complete, type P.&TOP (CR) consecutive. Putting line at the once, so the line number is erased, and, using the editor, insert the end confuses the poor thing! Non- making it appear part of the appropriate values in XX and erasable lines are a simple, yet previous line! $M can be any YY on line 1. Save by: reasonably secure method of message, of course. protection. Here's how its done. *SAVE "(filename)" After typing in your program, in M = T0P-1; IM = #080000- (start address]] ' (end address) direct mode, add the listing below. M =M+3: $M = (C) ACORN F141 Having done this, use the ASCII USER 1983"; disassembler to check everything N - LEN(IVl); N?(M + 1)^#FF and you may subsequently use is OK and list the program. You will *RUN, instead of LOAD,

ACORN USER JUNE 59 . GEinini moreprogra;

"Gemini's range of software is in the vanguard ." of the releases for 'serious' micro users. . (WHICH MICRO AND SOFTWARE REVIEW)

INVOICES AND STATEMENTS. . £19.95 Compatible with most micros. See table. Ideal for the small business, A complete suite of programs together with generated customer file for producing crisp and efficient business invoices and monthly statements on your line printer. All calculations include VAT automatically, and the program allows your own messages on the form produced. This program gives you superb presentation and saves time on one of the most tedious CASH BOOK ACCOUNTS tasks in the office.

PROGRAM FOR BBC 32K, COMMERCIAL ACCOUNTS. . .£19.95 TORCH, SPECTRUM 48K Compatible with most micros. See table. A gem of a O III program, all for cassette, with the following features:- Daily NEW £59.95 __mSmM Journal, Credit Sales, Cash Sales. Credit Purchases, Purchases — other. Sales Ledger, Purchase Ledger, Bank Account. One of the most innovative business Year to date summary. A fully interactive program suitable for all programs on the market. Replaces a businesses. Files can be saved and loaded and totals from one file manual cash book system, e.g. Simplex and carried forward to another on cassette. Particularly useful from a cash 'A!l-in-One'. Written by practising Chartered flow point of view, with an immediate accessibility to totals for debtors Accountants, this practical program is and creditors. Bank totally supported with entries for cheque simpie to use and will replace your manual numbers, credits and, of course, running balance. cash and bank records. By giving you access MAILING LIST... £19.95 to vital management information as and '*\ I Compatible with most micros. See table. A superb when you want it, it will enable you to keep dedicated database to allow for manipulations of names more positive financial control of your land addresses and other data, Gemini's unique 'searchkey' business. system gives you a further ten "user-defined parameters' to make The software is extremely well and lucidly your own selections. Features include the facility to find a name or documented, and Gemini provide a full detail when only part of the detail is known, it will print labels in a technical back-up and product up-date variety of user specified formats. policy. Take a look at the information this

program will provide:- DATABASE. . £19.95 • Summary of VAT information for VAT Compatible with most micros. See table. The returns Cumulative receipts and program that everyone needs, the most valuable and _ payments report analysed over the standard versatile in your collection. Facilities include sort search, list

• profit and loss and balance sheet headings Option for departmental print if required. Can be used in place of any card index application; analysis of sales and purchases • Audit trail printout of all transactions. once purchased you can write your own dedicated database to suit • Journal routine for entering transfers between accounts and year your particular needs with a limitless number of entries on separate end adjustment for debtors, creditors etc. • Trial balance at any cassettes, interval - Interfaces to 'Final Accounts' program to produce balance STOCK CONTROL . . . £19.95 account etc. • Spectrum version sheet and trading and profit/loss Compatible with most micros. See table. Dedicated may be used with Sinclair OR 80 column printer software with all that's necessary to keep control of stock. This program will take the tedium out of stock control and M include stock set up, user reference save time and money. Routines FINAL ACCOUNTS PROGRAM number, minimum stock level, financial summary, line print records, FOR BBC 32K, TORCH, quick slock summary, add stock, delete/change record and more.

SPECTRUM 48K £59.95 HOME ACCOUNTS. . £19.95 Requires Cash Book module. This program will take Compatible with most micros. See table. Runs a WFljy your cash book data to the logical conclusion of complete home finance package for you with every facility balance sheet, trading and profit/loss account and necessary for keeping a track of regular and other notes to the accounts i.e. fixed assets, land and buildings and capital expenses, bank account, mortgage, HP,, etc. This program also accounts. Final accounts (BBC version) links to 'Beebplot' for graphic allows you to plot graphically by Histograms your monthly outgoings. data presentation. Format: Torch disk. BBC disk/ cassette. Spectmm cassette. WORD PROCESSOR. . £19.95 Special Offer — Cash Book and Final Accounts together — £95 Compatible with most micros. See table. This program features routines found in much larger and more expensive packages with a typical word length of 5-6

letters it allows for around 1000 words in memory at one time. Ideal for the user who requires a simple program to write letters on his computer. Features include, block delete, block insert, search and replace, edit text, display text and more.

JS " "Simple to use Ideally suited to the way most offices run =SH=.., PERSONAL COMPUTER NEWS

60 ACORN USER JUNE 6 !. nsfor more computers

SPREADSHEET ANALYSIS BEEBPLOT & SPECTRUMPLOT £19.95 BEEBCALC £19.95

in I DRAGONCALC £19.95 Uim, III}} il Mflv^RFR FOR BBC AND DRAGON 32. Spreadsheet niiR m "- fiHV ;!. NEW processors have proved to be important tools for using ., IIIH I^H! '.it-yJ ,ri B micros in business, scientific and domestic financial applications. !7\ HIM >: H 7'. .\ y.ifiH Mil ,,IHH POSITION Al RC SPACE 5185 T 4v. lUt 'L- *- 11 A II B II C II .J. 9 v. \&y. I -J.B. SNOOKER T/A 1 MY . POT-BLACK xev,. iDI L 2 PROJECTED CASH FLOW YEAR ENDED /DEC HMI 9 v. 3 HIUI •\n-A 4 Oct, Nov. >40V 5 £ £ SEP -nTri SEP-J- HOU 6 INCOME OCT 7 Sales 11786 10944 iaH>;~fi,M(1ihS| I MBi'.^ /UWlthj 8 9 Important new additions to 10 REVENUE EXPENDITURE the Gemini family. Present 11 Purchases 500 500 numeric and string data 12 Advertising 500 1000 13 Director's salaiy -I together in easily- 1596 1596 ' V If r 14 Salaries 2216 2216 -[29 understood pie chart, 15 Rent histogram or graph format. 16 Telephone 300 Beebplot 17 Insurance 200 has a built-in 18 Printing, stationary 400 interface to Beebcalc, and 19 Repairs & renewals I both Beebplot and 20 Hire of equipment 60 60 COMMAND BCDEFGPRSTW? Spectrumplot have built in interfaces to the Final Accounts program of Without any programming knowledge at all, you may:- Set up a Cashbook. The facility for [ computerised spreadsheet, with chosen row and column names, mathematical Specify (ormulae relating any row or column to any other. function I plotting is also Enter your source data and have the results calculated provided. The BBC version has a high resolution Save the results on tape lor disk- BBC) for later reloading and manipulation. screen dump for the Epson or CP-8() printers, and the Spectrum Print the tabulated results in an elegant report format, version dumps to the Sinclair printer via the 'copy key. A very useful Experienced users may access saved files and write their own reporting or program that will give superb results either from direct input of data graphics presentation programs for the results. from the keyboard or via simple access to other software data files. A Some typical applications: — must for business and education. Small business accounting applications, e.g. profit and loss statements and Dealer/Trade enquiries cashflow projections, invited— generous trade discounts _ break-even analyses etc. " for quantity. Investment project appraisal- anything from double glazing to oil rigs! ^^ .**. --^ -*. -- ,— Comparing rent/lcase/buy options. Special ACCESS card instant sales ] Tol* II^QSV Processing the results of scientific hotline for prompt despatch... ^ ^m« \M\3^%3mm [ experiments or field studies. Engineering calculation models. 24hrAnsaphone Service. TT'%^TT In fact, anything that involves repeated re-calculation of results pre,sented in All enquiries other than credit r^ I rir> tabular or spreadsheet format. card sales to 03952-5832 VT J.vr\^ Gemini. Functional Software Specialists. 9, Salterton Road. ProgramAvailabilityChart:- Z Exmouth, Devon. EX8 2BR PLEASE SEND URGENTLY hi 1 1 i iM'Sl i 1M^Im^I-S^ hi iik Sinclaii Soedrurr 1fikor48k • • • • • m • Dragon 3?li Of Bik • • • • • • VIC ?0 (Please noie ]te

ACORN USER JUNE 61 I "

INTERRUPTS

^ page 39

Ifeiy REI1 BRK h3,Tidlirr9 rcu.tine Ob i.0

i'dl^i B;E(1 Key 1 - sriabLe h-eQistcr tt-are CB1 130 R£M KEY £ - default. BRK har,d\er. 146 *KEYl "'?'S-e202-8-Wl.?S,ti£0:-^=8,iiiD;i1" +5V (pin 2 of User Port) 150 KKEYS "?a,0e;e£=4,35i?K.ii32ti3=s,B4il1" im FOR PRSS=i!i TO 3 STEP 3 170 PV:=3,0Dr?l ISeCOPT PfiSS 190\s.j.ve h-egistera iii store' area 2ie STfi JfURt sawe R 2Z& TI^R 230 STH STGRE*1 save y, £40 TVR 4K7 2S0 STH STQRE+;a: 268 PLFl ;9et P OH staclf 270 STH STORE+3 £3,ve hffre 2ee STB STORE+4 .»:na here . latffr ccrru.Pted) ij|a..ma,in routiTie^-ou.tPut r-eSiater walaea to dlaPUs JSR PHEFID iPrlTit heaiatr- iiifo LDH STORE i^et H 13 lue 330 J3K' OUT switch 340 LDR STORE-*-l i«et W valut 350 JSR OUT 3e@ LDR STORE+2 .iftet Y v«lij.e 370 J&R OUT 3S0 JSR BINOP JOutPut P in bn^a^J for-m 390 JSR SPRCES 408 LDR a^FE ou.ti'ut iievt t"z address 410 JSR i:CiN\' 420 LDR liFD 430 JSR COHV 448 JSR OSR[>CH iWait for a, kea Prcs? 450 JSR DSMEUL Figure 5. Circuit to initiate 469\r:ie,a-n u.p atack,. restore ft,X,.V a.m P then return interrupt using CB1 control line 4? PLR PLR 4S0 LDR STORE+3

^0 PHFl I sa.we P ori atji.ck 510 LDR ?TOKE+^ tine line On running program, TR'.' J reatore Y 220 executes the short program to 530 LDR STORE+1 540 TflK i restore ;»; vectors. As a 5sa change the IRQl LDFr STORE J restore fl see PLP (restore P result the screen fills with As. Why? 570 JMP <:8.e0FD..' jretu.rn to i-n£trijc:tiorp after BRK Well, the various on-board pehpheral 580S |S0\ *********»:!t;**w****s^ SU&ROUTINES ************************* chips are all demanding attention 600\£U,fciroij.tlTie to Print header ds-tails supplying the microprocessor 610.PHEFID LDW »S,FF and 620.NCHFIR INK with a valid IRQ signal and instead 630 LDR HERD.X 640 JSR QSflSCI of pointing at their normal interrupt CMP H1.0D (cr; terrni nates sr^ring routine the IR01 vectors are 6G0 BWE HiwHRR 6?0 RTS

to the routine ""'^ directing control new output contents of R «a hex o-o screeri 690,CONV^l™''"^!i^r'^'^'^''^'*THX -s«ve d4t* I'n X 'RUPT'. 700 RND #4F8 J9et leftmost 4 bits Normally user interrupt routines 71S LSR Fl 720 LSR R will be indirected through the IRQ2 730 LSR R 740 vectors leaving the IRQ1 vectors for LSR B 750 JSR RCi icc'fvvert to RSOII any interrupts that require top 760 JSR OSRSCI 770 TXfl priority. If (RQ1 vectors are used, 788 RND tHi,0F itaea.! with riQhtr^ost 79© 4 bita the interrupt routine begins by JSR flCl 300 JSR 03RSCI interrogating the various I/O ei0 RTS 820. RC OMF *ii,0R of lis. character 0—9? devices to determine the source 330 ecc OK 34B the interrupt, ie either a user device CLC 850 HDD #7 J add 7 for R-F (eg user VIA) or the operating 860. Ok RDC tti30 370 RTS system (keyboard, ADC, clock etc). 8a0sa.ubrou,tiTie to outP-j.t c:h«r + 4 sPa^res to If the operating system was the 899. OUT JSR CON\ 90a.SPRCE LDR *H£;c.:. source, control should pass to the 910 LD^ #4 928. RPT operating system's own interrupt JSP O&RSCI 330 DE,i< handling routine. 940 BME RPT 950 PTS of Program 5 and 6 make use 96eM.Li.(jroiit:Lyi# to outPUt P in binary form 970.eiHOP IRQ2 vectors to illustrate how an LDH #R 'bit count 9S0.HBIT LDR «RSC< "£V interrupt routine can be initiated by 990 RSL STORE+4 1000 #i."i RDO .iforri'i FiSC-II "1" if carry set a high to low transition on control 1910 JSR 03RSCI line CBl ot the User Port. Both 1020 DEK 1030 BHE Nen programs perform the same 1040 RT?; 10503 function, providing an interrupt 1060 REPl STORE HHD nES:>RGE RREN BT END OF ROUTTHE routine to print A on the screen. 1070 STORE '=P>. 1080 P:-;=p;i+s Program 6 uses the operating 1030 HERD^^PV.

1100 aHER['=" Fl system routine OSBYTE to configure NV_EiDi; NEXT PC" 1 110 P'-;=F-< + ,39 the user VIA. 1120 NEXT pftSS 1130 END Both programs begin by inserting the interrupt routine into Program 7. BRK handling routine page D. The routine is similar to the USER JUNE &2 ACORN .

INTERRUPTS

100 fiX^^.22'Kl.^^?7:'rX^v.-^'~^ :110 FOR F'i"iSS^=^0 rri 'bJ out? 3 :sTt""F" :^ lZ0P>:^t:2B00 It never laeicoPT F"'Rss need ^i--^':-' etc happen again ^'^^ LDX #4 :l.60.RGRIr-i BRK \T.r^r.. h,....p :u^0 DbK YOUR LOCAL newsagent will be pleased to keep by a copy of Acorn User each month to make

certain you never miss it. -^^ newsagents even deliver BRK -...avv::i n...r.^' Many .:::;:;; 8 RTS the magazine straight to your 23i;;o door with your morning "'' newspapers - which means you -. ,...:: Program 8. Program trace using :::.Ol:::i L.i"IuL.;:!.:;;::001>l BRK handling routine receive it as soon as possible.

previous example with the addition in &FD and &FE, An indirect jump To take advantage of these of extra program instructions (lines finally picks up a second address services, complete the coupon 110-11 0) to clear the interrupt flag from &202 and &203. These vectors below (or a copy) and take it in the VIA, The second part of the can be altered to point to a user routine uses the peripheral control defined BRK handling routine round. register (PCR) to configure CB1 to which enables the programmer to detect high to low transitions. determine exactly what should Several different sources within happen when the processor the VIA can generate an interrupt. encounters a BRK instruction Lines 1 90 to 200 ensure only within a program. --gx^ interrupts arising from valid Assembling program 7 places a transitions on CB1 reach the IRQ BRK handling routine in page D

pin on the processor. and sets up function keys 1 and 2 To my newsagent: Finally, the BBC micro's IRQ2 for altering the vector at &0202. Key D Please put by a copy of vectors are set up to point to the 1 selects the user defined routine Acorn User magazine interrupt routine RUPT. On running in page D and key 2 enables the for the program line 260 configures machine operating system's default me to collect each the VIA and sets up the IRQ2 handler at &0B43, month. vectors. To initiate the interrupt Using key 1 to install the routine the simple circuit shown in address for the BRK handler of D Pleasedeliveracopyot figure 5 can be used. program 7 means that each time Acorn User to my door the processor encounters a BRK instruction our own routine will be each month. I he 6502 has an instruction that executed- The purpose of this will interrupt the program flow in routine is to phnt out the register the same way as when IRQ goes contents at the time of the BRK low. instruction. Name... On receiving a BRK instruction Thus placing a BRK in any the processor pushes the value program will result in a printout of Address (program counter +2) and processor register contents at that point, status register onto the stack. assuming the user defined BRK Program control then diverts to the handler has been selected with address in &FFFE (ADL) and &FFFF function key 1 (ADH) - the interrupt handling Program 8 provides a simple routine of the machine operating illustration of this. BRK instructions system. By examining the break have been inserted at several flag (B) of the processor status places to obtain a trace of the register this routine determines if it register contents when the program is a BRK or IRQ that has caused is executed. (The call to OSRDCH the interrupt (figure 4}, The in the BRK handler routine is used machine's BRK handling routine to wait for any key to signal then saves the accumulator 'continue' after a BRK), The output Acorn t/ser isdistributed contents in &FC and computes the listing illustrates the trace obtained to the News Trade by return address (ie the address of when program 8 is executed with Magnum Distribution Ltd. Tel: 01 -583 0961. the instruction that follows the the BRK handling routine of BRK), The return address is placed program 7 enabled. L--.

ACORN USER JUNE 63 C .

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ACORN USER JUNE INTERFACING

Let me begin by apologising for Paul Beverley and Acorn get together to sort out 1 MHz 'glitches' the errors whicti have crept into this

series ot articles. It would be easy to try to lay the blame on Acorn by pointing to the technical problems we have encountered with the TESTING THE 1MHz bus. These have helped delay publication of Acorn's Application Note on the bus {first INTERFACE BOX draft April 1982). However, it must be admitted the errors were caused by publishing articles before the ideas were thoroughly tried and NPGFC U L tested. ^ Not valid data In the April issue we corrected 200 nS D2-D6 Jj^"'- mistakes from March, but further X_J^ tests on the interface board have shown up a fault when using the D7 1 digital to analogue converters (DACs) at high speed in machine code. Fortunately, we were able to 1 MHzE m^UUMUmMMJU change the diagrams in the April 'Glitches' on the output issue before they went to the DAC waveform printers, but we could not change output the text. 1 .3 Volts We explained in the first article Figure 1a. Using original uncleaned page select lines that. as suggested in the provisional version of Acorn's CNPGFC _, Application Note, there might be a , 'Clean' problem with glitches on the page || page select IT select lines of the 1MHz bus. By

the second article it became clear DAC these problems were more serious 2.5 output Volts than we thought. Acorn's method ot T. 3 Volts cleaning up the page select lines Figure 1 b. Using Acorn's original 'clean' page select seemed to work, and only after a number of printed circuit boards had been made up and tested UCNPGFC further, did we discover this method ~| 'uttra-clean' I I [ did not work properly in all cases *, page select '-' '-^ Let me explain the changes. The

timing diagrams in figure 1 show I 3 Volts the various control and data lines DAC o/p when running a particular test Figure 1c. With extra gates added to give 'ultra-clean' page select program (figure Id}. The program

writes the numbers and 1 28 alternately to the DAC. As can be spurious data on the data bus, as seen from the diagram, the page you can see from the timing select line is low at a time when diagram. However, since this is a data on the bus is not valid. Hence fault on the bus itself, how do we .Start every time you write to the DAC. the overcome it? output goes up to almost full The circuit suggested In the LDA #0 voltage for about 200 nano- Application Note to use for seconds (1/5 of a microsecond) cleaning up the page select lines before taking on the correct value. clears the two problems they have STA &FCFO

In the second issue of the recognised, but it does not solve Application Note, Acorn has the problem of this spurious data LDA #128 admitted there is a second problem (figure lb). Its effect in this case is with the page select. Under certain to clean up every other page select STA &FCFO conditions you can get a double pulse: it simply halves the number access of a memory location. This of glitches. occurs at the wider of the two page To really clean up these page JMP start

select pulses in figure la. But it select lines we had to add two extra seems to me there is an additional gates (figure 2b). The timing of this Figure 1 d. Test program problem in that while the page circuit is shown in figure 1 c. As you select line is low you can get can see, the width of the page

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1MHzE CNPGFC INIHzE o- 1 -I UCNPGFC NPGFC X C< u ov

Figure 2(a). Acorn's clean-up circuit (b) Circuit to give really clean page select lines (it works but there must be a simpler way!)

select pulses is now reduced to checks the 'interrupt flag register in Progrjm - something like 250ns, which is not the 6522 versatile interface adaptor l To check Pfl and PB porti ai really what you would expect to (VIA) to see if the appropriate flag output* have available for a device on a has been set as a result of IB «KE¥ia QLDIM 1MHz bus You would expect the touching of CB1 or to ground, CB2 20 INPUT"tghich port", PORT! select IF page to be low for one half ie providing a negative-going edge. 30 ASC(P0RTJ).65 THEN port

of 1 l-PEil ELSE - a cycle of the iVlHz clock, which Program 3 checks to see if CB2 port t.FEt0 4e DIM CODE IS 500ns, This narrower pulse works as output. (CB1 on the VIA 20 50 PX-CDDE removes glitches under all can only be used for input, whereas bt ISEl circumstances we have been able CB1 can be used for either.) The 70 LDA #255 to test, 80 STfl but unfortunately means program simply produces a square port*2 1 90 tart 1 some devices may not work wave on CB2 by altering the 100 INX properly due to the shortness of contents of the peripheral control 110 STX port access time. tried We have the register to output logic 1 and logic 120 JMP start 130 ZN427 and the 2N428 and these alternately. Since this is done in ] 140 CALL CODE work fine as far as we can tell. We Basic there will be some Instability will try to get Acorn to do some in the waveform produced. This is

work on Ihis and pass on any more because the processor is contin- Program 2 - To check information. uously Cfll and servicing interrupts which CB2 working as input affects the output of the square 10 V'lcFEbB wave. 20 V?12»0 30 ?V-0iREM Nlow supposing you have built The next two programs can be clear flags 40 PRINT"Sround CBl" the board we showed last month, to the used check control lines on 50 REPEAT UNTIL (V?13 AND 16,- it how do you test it out? Programs the printer port, but in this case 60 PRINT"OK!" 1-7 form a series of tests to check because of the way the electronics 70 PRINT"eround CB2" 80 REPEAT UNTIL (V?13 the various parts of the board. In all is arranged [User Guide page 503) AND 8)- B 90 PftlNT-DK'" the testing procedures which follow CA1 can only be used as input, you will need an oscilloscope. while CA2 can only be used as Program - The first program tests ports A output. 3 To check CB2 ai output and B are connected correctly. In Program 6 is the one which reply to the INPUT, you enter either originally exposed glitches the on 10 V>I,PE60 'A' or 'B' and it produces square the 1MHz bus mentioned earlier. 20 REPEAT waves on each of the lines of the What the progran-i does is to output 30 V712-128+64 port in question. The least repeatedly the numbers to 255 in 40 V?12-I28t64+32 50 UNTIL0 significant bit, ie PAO or PBO will sequence to the DAC. This is done have the highest frequency of at high speed in machine code, square wave and each tine will and the effect is to produce a Progra« 4 - To check CA] have successfully half the freq- 'ramp' or 'sawtooth' waveform. as input uency or twice the time period Change line 70 to STX &FCF1 to 10 V-I.FE60 for its square wave. This is because check the other DAC, Using the 20 V?14-12B+2 30 V?12"0 tfie output port is working as a oscilloscope to look at the output 40 V?I-B:REH clear flag binary counter. The program is a of the DAC should show a sawtooth 60 PRlNT'Qround CAl" closed in loop machine code and wave as the output voltage hses 70 REPEAT UNTIL (V?13 AND 2) - 2 therefore the only way to escape is from to 2.5 volts, drops back to 90 PRINT"OK! " to press break, At line 1 0, the zero, and rises steadily to 2.5 volts break key is programmed using again. Without extra page select Program "Keyl to get the program back. cleaning, the glitches caused the 5 - To check CA2 as output Program 2 gives a way of output at each step on the 10 V«IFE60 checking that the control lines on sawtooth wave to shoot up almost 20 REPEAT the user port are working correctly to 2.5 volts for a fraction of a 30 V?]2-B+4 40 V?12«8t4+5 as inputs. If you respond to the microsecond, producing a comb- 50 UNTILB prompts by grounding CB1 and like effect on the output. CB2 you should get the replies of One way to .check the analogue 'OK* if all IS well- The program to digital converters (ADCs) would

ACORN USLR JUNE 67 p

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68 ACORN USER JUNE INTERFACING

+5Vo- o Pr sgriB 6 - To chtck 1 thi DAC output 6k8 10 •KEY10 OLDIM 270R 20 DIM CODE 20 30 PX-CODE 40 [SEI 10k 50 .ttirt potentiometer &e INX to ADC input 70 STX o fcFCF0 B0 JMP itirt PAO PA1 90 3 100 CALL CODE Figure 3. Variable voltage source Figure 4. Connecting LEDs for testing AOC to printer port

ProqriB 7 - Uii th« be to read the ADC Input and then tour ADC inputs out to the box itself DAC output to check the ADC input output the number which has just so sockets are available for both 10 MODE been read to one of the DACs. Thus the slow ADC inputs and the fast 20 FOR NX - B TO 255 a voltage put into the ADC input ADC inputs. This program reads the 3B 71FCFB - NX should produce the same or almost four input channels and outputs to 4B ?iFCF4 B the same voltage out of the DAG the screen a binary representation 50 HX « 71FCF3 60 DRAM NXt4, HXt4 output. This of course requires a of the numbers read. If you put 70 NEXT variable voltage source which steady voltages into the four inputs, 80 END could be a 10k ohm potentiometer perhaps by using games paddles, connected across the 5V to OV rail you will find there is a considerable with a 6K 8 series resistor to amount of variation of the last three ProgriB 8 - To ihoH the limit the output voltage (figure 3). bits of the conversion. In other ADC bit pittvrni producid by The problem with this is that it also words it is not in fact 1 2-bit thi on-bo«rd ADC'« requires a way of measuring the conversion but more like an eight input and output voltages. or nine-bit conversion. As an alternative, program 8 The circuits around the ADC in 10 nODE3 shows a way of checking the ADC the machine itself give the reason, 28 PROCinit 30 REPEAT against the DAC directly. The Because of the way the circuit has 40 FOR T-1 TO 4 output of one of the DACs is fed been designed, the earth line 50 M-ADVAt.(T)/U into the input of of the to the one ADCs, coming ADC chip has a 60 PROChytt(M) The program then outputs the considerable amount of digital 70 NEXT numbers to 255 to the DAC in noise on it. If attempting to BO UNTILO sequence, each time reading the measure a voltage to an accuracy 90 10BB D£FPROChyte(M) ADC. The number being sent out to of one part in 4000, which is what a 1010 LOCAL T,H the DAC is plotted against the 12-bit ADC does, you would in fact 1020 0X-4 number which comes in to the need to have the noise ADC limited to 1030 T*204S and should produce a straight line about 1 /4000 of the maximum 1040 PRINTMiCHR*253) graph. This graph is piolled voltage of 1.8V (45pV). Unfortunately 1050 FORH-OTOU automatically by the program. You the noise level on the earth line is 1060 IFBTHEN will see a certain amount of something like 40jjV, The analogy VDU255 ELSE VDU32 1070 T-T/2 randomness in the readings due to this brings to mind is that of trying 1080 NEXT the last bit or two bits of the ADC to measure the height of a 1000 1090 tX'Z output not being stable because of foot cliff to the nearest foot from a HBO PRINTCHRt254(' "i noise. In both these programs It is boat hding in a 30 foot swell! No 112B ENDPROC necessary to provide a 'start/convert' amount of capacitors on the ADC 1130 input for the ADC- This is done by inputs will change the fact that the 1140 DEFPROCinit 1150 LOCAL N taking the output of one of the earth line Is not truly at zero because 1160 VDU19|4i0|23t select lines from the 74LS138 and of noise and therefore it is 1O,32,O|0,O, feeding it into the 'start/convert' impossible to get anything more 1170 N-1 input of the ADC. Then within the than about a nine-bit conversion. 1180 VDU23,253.N. program you need only read or N,N,N,N,N,N,N write to that memory location, and a 1190 N-128 pulse will be generated which will I here are numerous applications 1200 VDU23,254,N,N, start the conversion. for this interface box. Obviously the N.N,N,N,N,N 1210 N-126 The final program Is not for digital inputs and outputs can be 1220 VDU23, direct use with the interface box but used for all sorts of on/off switching 255,0, N, N,N,N,N,B| for checking the ADC inputs of the and for reading the position of computer itself. This is Included switches. because in our interface box we One nice application using the have brought connections to these phnter port is to drive a seven-

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segment LED. This can be done Finally, one idea would be to directly on the printer port because write a program in which a voltage In this series of four articles, it has sufficiently high current could be read by an ADC and Beverley available. All you need do is to stored temporarily before being Paul has designed an connect a 270n resistor in series output on the DAC. This could be interface boxforthe BBC micro which works through the 1 MHz with each segment and connect it done with some sort of deliberate directly to the printer port line delay by going through a loop bus. Acorn User has arranged for a high-quality circuit board (figure 4). where you input the data and put it to which isthe vital You may have seen designs tor in some form of 'stack' and then be made up using the BBC micro as a storage output the data from the other end part of the interface box. The oscilloscope. In other words you of the stack. This could produce cost of a double-sided printed circuit, with plated through can maf

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COWBOY SHOOTOUT (Micropowert Model B f 6-85 HESSEL,GOLEM Two player gunfighter gamt Reahy good graphics THE CENTIPEDE iSuperior) Model B cassette £ 6-50 and many more Excellent Centipede game disk £ 9.90 MODEL B INVADERS (UK) £ 5,50 Super!) Invad«ts game with inanv option-^ GALACTIC COMMANDER (Micropower) Model B £ 7.79 High resolution luiiat lander ijame SWOOP (MiCfopowert Model B £ 7.99 Galaxian with a difference' FROM £1 PER 3D MAZE (UK) Model B f 4.50 MJrdboggling maie game CHESS (Bugbyte) Model B £11.50 Graphical chess game FORTNIGHT STRATTO BOMBER (UK) Model B £ 7,50 HIRE Blasl the alien mother ship and save yoi.r planet ELDORADO GOLD (Micropower) Model B £ 6.85 Thii cjame will get vi^" started with adventure games WORDSWORTH (Ian Copestake) Model B £13,00 Encellent word processor. Very good value tot monev ATLANTIS (UK) £ 7,50 F-ast and addictive submarine game WITH UP TO MOONLANDER (Software For All) £ 6 45 Land on Ihc luriai proPe without killing yourself, Excellenl SPACEFIGHTER (Supetiorl £ 6,50 Very fast Scramble.'DetendRr type game. BUY 25% DISCOUNT

ALL THE ABOVE ORDER BY PROGRAMMES CAN BE TELEPHONE ORDERED BY POST @ Access and Barclaycard Membership £10 Add [jOp ptilp ti>r Thu' hfsi ord I [ip for coch subscqucnl ilcm holders may order by AUow up lo 23 days h,r delivery phone: 01-937 6258 P^yrnfinl hy i hegue <" posial nrdi For Catalogue and Membership Form.Send Name and Address to

RICKSOFT 62 KENSINGTON HIGH ST. LONDON W8. 78, Warren Drive PALACE Hornchurch GAMES Essex RM12 4QX PROGRAMMERS

Palace Software, part of a leaditig tilrti and video company, is looking for games fur Atari 400/800, BBC Model B, Spectrum, VIC 20 and CBM 64 for distribution in the UK, Europe and RICKSOFT USA High tovalties will be paid for top quality and highly original machine code games. Send cassette samples to: Pete Stone, Palace Software. 62-64 Kensington High Street, London W8 [SOFTWARE, (Tel; 01-937 6258)

72 ACORN USER JUNE ^^ REVIEWS

WHEN I agreed to review Acorn soft's View word processing systen Fine choice of I words did not realise what a difficult tasi

it would be. Using Wordwise for a couple of months made it difficult Paul Beverley compares two word processing to be unbiased, especially as the two are so different. chips-Viewand Wordwise. The first is dearer, View comes with two manuals. but are the extra functions worth it? The first is a chatty introduction to

work through page by page. The available in View except for the a replace. This is useful if the second is more of a reference page number. The only facility in sought after word could be at the manual to keep by the computer. Wordwise which does anything beginning of, or in the middle of a Both were written not by Acornsoft, approaching the sort of jobs which sentence, Wordwise on the other but by Information Transfer of are possible using macros, is hand, distinguishes between upper Cambridge. This is a good move in GETFILE (GF), which allows pre- and lower case which means you my view, as the ability to write good prepared text from a disc or tape to would have to do separate software is no guarantee of being be added. This is nowhere near as searches for 'recieve' and 'Recieve'

able to explain how to use it. comprehensive as offered by to correct the spellings. On the

What does View offer? Those macros, and so for work with large other hand if a number of who have used a professional word numbers of form letters, View is occurrences of a word such as processing system will have come without doubt what you need. 'Basic' need changing to 'BASIC, to expect the facilities View aims to Figure 2 provides a comparative Wordwise can make the change, provide. Many of these professional list of the advantages and but View cannot. systems use large numbers of disadvantages of the two systems, A third difference is that function keys as well as text keys. but let's consider some significant Wordwise searches from the The Acornsoft programmers have differences. cursor's present position towards used all three levels available for One interesting difference is the the end of the document, the cursor the function keys on the BBC approach to the search and being left at the last occurrence of

micro. That is, the keys on their replace facility. View is more the match unless Escape is

own, with shift, or with CTRL. This comprehensive in that it caters for pressed. Hence to make several gives 30 possible commands, of a 'wild-card', where instead of just changes through the whole which they have used 29. looking for one specific word you document you have to remember to To give some idea of the extent can look for something with a put the cursor back to the top

of the commands on the function certain amount of ambiguity in it. before the next search. However,

keys, see figure 1 which simply For example, if searching the word this can be done by a programmed names them all. Other functions are 'Frances', which could have been function key (eg *KEY91[I!;01[). typed either into the text itself spelt with an 'e' or an 'i', you can With Wordwise, since the text is s'. (stored commands) or in the look for ' Franc? The question entered directly, and not as it will command mode. A summary of mark represents any character, so appear on the final document. TAB these is available through *HELP. this search would pick up 'Frances', characters simply appear as arrows Comparing the facilities of View, 'Francis', or even 'Franczs'. in the text, until you PREVIEW the with those of Wordwise from the The approach to finding words document. With View, tabbing takes review in February's Acorn User, which could be in either upper or pl^ce as you press the TAB key, so will show View is far ignore lower case is an example where the you can see what the document comprehensive. For example Word- two systems have used opposite looks like immediately. wise does not have any macro techniques, each equally valid. Wordwise only provides two facility, and neither does it have View takes no account of upper or markers, whereas View gives up to any of the number registers lower case when doing a search or six which are all numbered. Two are visible (as in Wordwise), the other four being found by MOVE TO CURSOR. In Wordwise there is no Control Shift Normal simple way of removing the Delete block Move block Format block markers as they don't respond to Next match Swap case Top of text search and replace. Instead you Format mode Release margins Bottom of text have to program a key to move to Justify mode Delete up to character Delete end of line the top, move to marker and delete

Insert mode Highlight 1 Beginning of line character. Default ruler Highlight 2 End of line Contrary to what you might have Split line Go to marker Insert line read in other magazines, you can Concatenate lines Set marker Delete line edit Basic programs with both Mark as ruler Edit command Insert character systems, in exactly the same way. Delete command Delete character First you spool the program into a text file, which can be loaded into the word processor and edited. Figure 1. Function key commands on View Then you save it, still as a text file.

ACORN USER JUNE 73 ^Armmg/fiiiiiim tt

IF YOU HAVE A BBC MICRO THEN YOU NEED

.^l^i2r\^:s:^ is the newsletter ofthe Independent National BBC Microcomputer Users Group. Ifyou want the best source ofinformation on the BBC Micro you can't do without No matter what your interest - hardware, software, business, games or education then E has something for you.

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REVIEWS

before execing il to re-form a Basic program. Sirice View uses all three levels Advantages of Wordwise Disadvantages of Wordwise of the function keys, fhere is no possibility of further programming. Programmable keys, Search and replace more Wordwise on the other hand allows Any number of printer functions. cumbersome and less flexible. you to put your own commands Sample text provided. Load and save slower onto the function keys. These could (not done in blocks). Free touch typing tutor. be actual items of text, such as Not as easy to use on black and words which you use frequently Good use of colour. white monitor. (useful for inexperienced typists). Spooling of text to file. Also they can be commands written Simple to learn. in the form of control sequences.

This is explained in the Wordwise Advantages of View Disadvantages of View manual and allows you to write your own routines, for example to Wild card on search and replace. Control of more than two printer put in a couple of markers and fvlicrospacing with printers. functions difficult. delete a complete line or to Maximum line is 132 characters produce, say, '", , Can process documents > 25k, (200 on Wordwise). Til 5", for a new paragraph format, using continuous processing and each of these can be done from disc. Headers and footers only with one press, of the function key, Six markers {two on Wordwise). single line. while holding shift and control keys Allows macros and number No pad character to enforce down at the same time. registers. single spaces. View needs special software to Tabs and stops visible. Printing is direct from disc use particular is a printer. This or tape, not from RAM. because you can put within the text Printing of pages within Costs e69. 75 against £46.50. one of two 'highlight' commands, a document. which could be things such as Two-sided documents. underlining or italics. These then are automatically interpreted by the Figure 2. Comparison of the two WP systems word processor and sent to the printer as control codes. Wordwise

on the other hand does not have One feature missing from View it first and then print it. Therefore if any such feature, and therefore you but present in Wordwise is a pad you want to make a number of

have to send out the control codes character to force a space at a simple edits, printing it out each

as numbers which appear within particular place in the text. The idea time, you have to save it each time. the text. So you say for example, is that when justification is used, This is tedious with disks, never 'OC27,69' to switch an Epson some items of text may look mind tapes. printer to emphasised text. These strange because of the added Readers will have to make their can be put on function keys. spaces. Also it means that two own decision as to which set of The use of the two highlight words separated by a pad functions is appropriate to their commands on View is fine if you character will be treated as a single particular application. Both systems only want to use two types of word and therefore will not be put have limitations, so bear these special command for your printers. on separate lines. Thus to write '*FX points in mind before making a

However, the Epson FX80 allows 5,2', you would avoid it being split choice. underlining, emphasised, condensed, up with '*FX' on one line and '5,2' Does Wordwise have sufficient pica, elite, strike, next, enlarged, double on the facilities? For example, if you need RAM and international character The way in which the printing is to do form letters with automatic sets, italics, proportional spacing, done is also different in the two addressing etc, there is no choice

etc, etc! Acorn intends to release a systems. In Wordwise printing is it has to be View. for printer driver the FX80, Put done from the text held in RAM, If you choose View, is the person

since there are only two highlight The only addition to this is to use operating it going to be able to

commands, you have to redefine the GF command to get a file from cope with learning what is one each time to use a different tape or disc which has been undoubtedly a more complex facility. So for each facility you have spooled ready to be added into the system? (To indicate how easy a single number and would say, for document. Wordwise is to use at its simplest 35*, example, 'HT 1 1 so each View on the other hand takes level, my four-year-old son can type subsequent occurrence to highlight data for printing directly from the things in and get them printed out 1 would switch on or off say the file system. This has the advantage with little or no prompting!)

underlining. Then after 'HT 1 132', that you can print out a whole set Consider the way text is entered,

each occurrence of highlight 1 of files in sequence to form a single and decide which you think is their would cause a switch between document by simply calling easier; to type it in directly and

American and English character names after the print command. worry about what it looks like later, sets to allow the use of both # and The disadvantage is that to print £ within the same document. some text in RAM, you have to save page 81

ACORN USER JUNE 75 COMPUTERCAT BBC EXPANDABLE CONSOLE Quality Software

BBC MICRO Not just a TV/VDU stand but an expansion console which gives TOUCH TYPIST (32K1 -£9.95 Educational and useful your micro the professional look. Are you a keyboard pecker? Improve your typing skills. Your Protects and encloses your computer is your lutor, monitoring and evaluating your progress. micro with room for disc drives Fully documented. Many already sold to educational institutions. and 2nd processor or teletext Highly recommended OTHELLO (32K)-£8.95 adapter etc. All untidy connect- A favourite board game brought up to date with superb graphics ing wires out of sight and reach and sound. within the console. Made of light SNIG (32K)-E6.95 Addictive yet strong aluminium with a Not just an ordinary snake game but a super-fast arcade type textured finish in matching BBC needing exceptional reflexes and co-ordination. colour. Coming soon, a bolt-on A must at the price BOUNCE (16/32K1-E4.95 extra module for the console, for NEW and FRUSTRATING. Like all ball games it is the timing that's further expansion options, ie important. Kids love it. dual drives, 2nd processor, PRINTER/VDU STAND -£5.95 GRIG BLITZ (32K1 Highly recommended teletext adapter joysticks, cass- A fast action arcade game with scintillating multicolour graphics BBC owners who only need a ette etc, all in one console. YES, and sound. DEFEND your territory by shooting down the GRIG VDU stand will find the stand this console will grow with your INVADERS. Ten play levels of increasing difficulty. Are you good slips comfortably over the BBC needs. If that was not all a enough to reach level 10? with adequate ventilation allow- matching printer stand is avail- DATABASE [32K1-E12.95 Good value ed for. After use the micro can able. Rest the printer on the Organise your records. Add, change, search, delete and display be slid UNDER the stand acting stand and stack your paper routines. Shell SORT. MENU driven and user friendly. as a dust cover when micro not underneath. The console will COMPENDIUM (32K) -£5.95 Three for the price of one in use also house the torch disc pack. 4 up (Version 1), 4 up (Version 2), Poke the peg. Three board games to test your powers of logic. Four colours and sound. A PRICES BASIC CONSOLE as shown challenge for 1 or 2 players. only £39.99 +£4.00 p/p Professionally written PRINTER/VDU STAND £14.99 +£2.00 All programs on cassette with instructions/ only p/p documen ta tion For further information enclose sae or send cheque to,

Price includes P&P • Delivery by return Mail Order 27 Wycombe Rd 01-801 3014 Only London I\I17 Deduct CI per cassette for 2 or more cassettes Client Stop press: Star printer 510 £270 + + £10 carriage. DP VAT Viewing by 24 hour arrangement COIBPUTl ansaphone 224 Chapel Street, Leigh, Lanes. (0942) 6Q5730 Please allow 28 days for delivery

t-A. -1 ^H H^ for the B.B.C.

=] ::f Microcomputer "'^ Small School Study Packages iJ (32k) are designed to a high specification by a team -''" of experienced teachers and programmers for '.,',J''^,,;,H''t,\fV""iSI. use both at Home and in School. Based on Che well established techniques of individual- Full Machine Code ised learning schemes, the Packages consist of a structured suite of objective matched 4 Screens Oi Play computer based lessons, review program and Post Test, using to the full the capabilities Keyboard/Ioystick of the BBC Micro- All packages are supported by a Manual containing package description, Full Colour/Sound user notes, exercise material etc. An AMAZING Game Titles include; The Theorem of Pythagoras (Model B) - Designed to teach the Theorem ZANY KONG is the crazy game in which the player controls a of Pythagoras and its applications, the package consists of a suite of tunning, batrel-fumpinq man. 5 lessons. Review and Post Test with diagnostic plus Manual. In each of Ihe 4 frames ot play a girl (captive of Kong) must be First Steps irt Algebra (Model B) - Designed to introduce experimentally, rescued by climbing ladders and girders. In later stages using animated graphics and 'mappirtg machines', simple operations and conveyor-belts, hits and the use of variables leading to the solution of simple linear equations. lireballs increase the hazards The Package consists of 5 lessons. Review and Post Test plus Manual. ol this task. This version oi Ihe classic arcade game includes Mental Arithmetic Tests (Models A(32K) B) - Designed Co help all of the original's features. & implement the recommendations of the Cockcroft Committee that there fully be frequent practice of Mental Arithmetic, the Package provides Tests at

7 levels and 3 degrees of difficulty and is aimed at youngsters from age 8 £6-50 to 14, covering most areas of basic numeracy. The Package contains two versions, one for Class use, the other for the individual student at Home

plus the Manual. A Tables Practice program is included. SOLAR SOFT, All Packages are priced at £6.95 inc. 5 WESTMORLAND DRIVE, But send for a full descripcion and list of titles available and in CAMBERLEY, preparation to: — SURREY GUIS lEW Small School Software, 41,$inah Lane, Hayling Island, Hampshire P011 OHJ.

76 ACORN USER JUNE ^^ Reviews

Mike Milne examines three graphics packages - two for drawing and one for shading anlurit)

COLOUR 1 iUmUi

1 GRAPHICS 1302

EDG design; fewer functions, BY NUMBERS but faster and more friendly

THE two packages compared here D EDG Graphics Package, These symbols are in a 'text are the AB Designs Drawing Salamander Software, 27 Ditchling window' which displays information Program and the EDG Graphics Rise, Brighton BN1 40L. (Also such as cursor co-ordinates, Package (from Salamander Software). available from Acorn dealers) current drawing colour and drawing A drawing program allows the Price: £24.95 mode (solid or outline). The cursor user to construct on a TV screen can be moved about the screen

various shapes (lines, squares and D AB Designs Drawing Program, using control keys and its speed is circles, for example) with simple AB Designs, 81 Sutton Common variable. The AB system has three commands - typically one or two Road, Sutton, Surrey. speeds, selected by pressing a keystrokes - and then to move, Price: £35.50. single key. In EDG, the cursor starts

repeat or modify these shapes. The oft slowly and picks up speed if the

position on the screen at which the provisional manuals which ran to control key is held down

drawing is to start, and the dimen- some 30 pages. In each case the (acceleration can be inhibited if sions of the shape, are entered by programs loaded successfully first desired). moving a cursor (normally a cross) time, displaying a title page while To start drawing, a program to the appropriate position using the main program loads. EDG then needs to know what you want to the control keys. Additional features makes an intimidating high-pitched draw and where, EDG asks tor the

usually include a 'fill routine', whistle until you select mode 0, 1 function first (the message

which can fill a specified area with or 2, the AB system runs in mode 1 'Function?' appears in the text

colour, and some method of saving only. window): the function is selected by the result on tape or disc. At this point you are faced with a pressing an appropriate key, such Both the AB Designs Program screen which is completely blank as 'C for circle. The message and the EDG Graphics System except for a crosshair cursor in the 'Centre?' then appears, and the {referred to as AB and EDG from middle, and a few cryptic symbols point is 'fixed' by moving the cursor now on) were supplied with at the top (AB) or the bottom (EDG), to the required point and pressing

AB design: perspective, repeat and curve functions make for more creative drawings

ACORN USER JUNE 77 REVIEWS

the space bar. The radius is user. When the repeat function is colours may also be easily defined on the same way, and a called by pressing a key the last changed, providing the user with circle is automaticaliy drawn. In the operation in the picture memory is the usual range of Beeb colours. AB system the commands are repeated at the location of the The EDG system can support eight somewhat different. Points are screen cursor. Thus the repeat colours on the screen at one time defined first, by moving the cursor command is limited to the previous in mode 2, whilst the AB system to the appropriate position and drawing operation, whatever that (which only runs in mode 1) can '1 pressing ', then moving to another happens to be. In the AB system, only support four. This is not as '2', position and pressing and so the repeat function is more serious as it sounds, however, on. For a circle, the two points versatile, ailowing a rectangular because the AB system allows required mark the diameter (not the area to be defined and copied to filling in a mixture of colours - for centre and radius). Finaliy, the another part of the screen. It may instance, if white, cyan and yellow command 'C draws the clrcie. aiso be shrunk, rotated through 90 are selecled, the fill routine will plot The two programs both offer iine, degrees, or reflected as a mirror vertical bars of each alternately, rectangle, circle and fill routine; image. The process is much slower giving a pale green. beyond this, however, their than in the EDG system, because In all graphics systems, fill functions differ considerabiy. This the program is scanning the routines are notorious for getting is primarily due to the dfferent rectangle pixel by pixel before out of hand. This happens when approach the programmers have copying it. there is a break in the boundary of taken. Examination of the repeat In both programs the drawing an area being filled, and the colour function will illustrate this. colour is easily selected, either by 'escapes' into the surrounding In the EDG system, an area of moving a dot along a colour picture. EDG handles this quite memory (called the picture memory) 'palette' (EDG) or by pressing an easily, by telling the program to stores the commands put in by the appropriate key (AB}. The logical page 81

D ECFG from Gaelsett Software, 44 Exeter Close, Stevenage, Herts, SGI 4PW. Price: £10.

THE Extended Colour Fill Graphics program (ECFG) from Gaelsett can

fill areas with patterns of different- coloured pixels to give the effect of additional 'shades' of colour on the BBC micro. The program loads into the lower region of user RAM and

automatically resets page so it is not overwritten when other programs are loaded. The program works by providing two new extensions to the GCOL statement which aflect the way the triangle^filling routines PLOT 81 and PLOT 85 operate. The more additive; ie, the more light you add diagonal stripes and cross easily understood statement takes the paler the shade gets, and vice hatching may be obtained. This the form VDU 18,L,32,C1 ,C2,C4,C8 versa. Thus red and green make statement also operates through where L is the normal logical yellow, which can be confusing PLOT 81 and PLOT 85.

parameter following the GCOL until you get used to it.) The documentation provided is statement, and the 32 instructs the The second statement is less scant, and the only way to get to

computer to accept four further easy to operate. Once again it grips with ECFG is to try it out in as parameters to define the mixture of operates on the VDU 18 command, many ways as possible. Some of logical colours 1,2,4 and 8, Default equivalent to GCOL and looks like the effects are similar to those

colours are red, green and blue for this: VDU 1 8,L,64,R1 ,R2,R3,R4, As given by using the GCOL statement CI, 02 and C4 while C8 is before, L is the normal parameter with parameters higher than 4, but 'flashing'; the parameters only after the GCOL command and 64 there are many others besides-

operate if the graphics mode instructs the computer to accept A word needs to be said about selected supports the required the four following parameters. the term 'shades' used in relation to logical colour. The parameters may These can each have values ECFG. The cross-hatched patterns have values between and 32, so between and 255, allow on/off the program produces are very

setting 01 at 32, 02 at -16 and 04 control of each bit in a four-row visible, especially in mode 2. It is at will give a mixture of two parts high VDU mask. The width of the doubtful whether, for instance, a red. and one part green and no part mask varies from two to eight broad red-and-white check could blue, which results in an orange pixels, depending on mode. By be called a 'shade of pink'; perhaps colour. (Remember that, unlike controlling this mask, a wide range the word 'pattern' would have been mixing paints, mixing colour light is of patterns such as vertical bars. more realistic.

78 ACORN USER JUNE , BBC SOFTWARE Quality software produced by professionals and used in BIT8& fiundreds of scfiools throughout Great Britain present their latest tape: FUN WITH WORDS B £8.05 Stan vout fun with alphabet puzzles in GUESS A LETTER. Continue yout BYTES plav as you learn about VOWELS, the difference between and know THERE THEIR and have games with SUFFIXES. After working so hard reward 44 Forest. I Ifracombe, Nth Devon. Tel: (0271)62801 yourself with games of HANGMAN. Learning shi^uld be lun. The tape includes ALPHA, VOWELS, THERE?, SUFFIXES and HAMGMAN, EDUCATIONAL-1 A or B £8.05 ACORN DEALERS, BBC, DRAGON, Hours of fun and learning for children aged 5 to 9 years. Animated graphics will encourage children lo enjoy maths, spelling and telling the lime. The tape VIDEO GEIMIE SALES & SERVICE includes MATHl. MATH2, CUBECOUNT, SHAPES, MEMORY IModel B EPSON only), SPELL and CLOCK. HX20 COMPUTER 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 MATHl Atom Micros BBC Upgrade Kits MATH2, AREA, MEMORY (Model B only], CUBECOUNT and SPELL. GAMES OF LOGIC AND CUNNING A/B E9.20 Colour Monitors BBC printer interfaces For children and adults alike. The lape includes AUCTION, FLIP. REVERSE, TELEPATHY and HEXA 15 (Model B only). Seikosha GP100A 5^" Floppy Discs SUPERLIFE B E9.20 Printers Fast Imachme code) version of a popular 'Game of Life' in large universe, C-12 Cassette Tapes a KATAKOMBS B £9.20 Epson Printers Cassette Recorders Are you cunning enough to discover and seize the treasure in the Katakombs AND return alive' What and where are your enemies? outwit them? 12" Can you Monitors- B/W Yes? Then yout adventure will lake you through unending forests, besides Continuous Stationery tumbling streams, over lonely plains to desolate ruins and finally Monitors- 12" Green Software underground to the tortuous Katakombs. UTILITIES A/B £8.05 5^" Disc Drives Software Behind the mundane title lies an assortment of useful procedures and functions which (C/WP.S.U. &CASE) written to order can save you hours/days of programming effort: dale conversion, input and validation routines, graphic routines (cube, rectangle, etc), sorts, search and many more. #** SPECIAL OFFER *** Any 3 cassettes for £20.70

DISCS-TORCH Z80 pack-800K. second processor with 64K RAM, REPAIRS CP/M" compatible operating system + system software, £890 inci of VAT Delivery free within 30 mite radius otherwise f 1 delivery charge Add 50p p/p per order Please slate your model & SERVICE chBQue/po !o. OOLEfA LTD, Dept A To all Micros 77 Quaiitas, Bracknell, Berks RG12 4QG, Telephone: 103441 50720

Why haven't you Excet Measuring Unit heard of SOFTWARE SUPPORTED MONITORING INSTRUMENT-BBC MICRO Connection to the 'A to D' Port enables the BBC (B) to measure and display accurately: CUBE? POSITIVE & NEGATIVE-VOLTS* AMPS + WATTS OHMS * TEMP *LIGHT * TIME FEATURES RANGES Up to 6 simultaneous readings Temp -10 to 110 deg C Graphical or digital display Resistance to 1E6 ohms Auto scaling and labelling D.C. Volts 40v. p. d. within +/ Plots any 2 variables ~ 40v range Menu driven options D.C. Current to 2000 mAmps Full software support Power to 80 watts User friendly Light lo 100 iuncalibrated} Unlimited choice of scales Time to 1 E6 sees (hrs mins Event analysis facility sees) Teaching display Mode Event data stored 80 per sec Accuracy: error generally <1 per cent EQUALLY SUITABLE FOR LABORATORY, CLASSROOM OR HOME USE £77-50

Includes instrument, temperature probe, light sensor, electrical probes (3 sets), leads, connections, software on cassette, full instructions, application notes, p&p excet systems 16a High Street llfracombe North Devon

ACORN USER JUNE 79 B.B.C. DESKTOP CONSOLE

£ BBC Model B Microcomputer 399.00 BBC Model A Micro with 32K and VIA 339.50 BBC Model B with Disc interface 479.00 BBC Model A to B upgrade 95.00 Disc upgrade for BBC 3 (inc fitting) 98.90 BBC 14" Colour Monitor 287.50 Sanyo SM12N Green Monitor 15MHz 125.00 14" Monitor/TV Nordmende 259.90 BBC Single 100K 5.24" Disc (AND01) 265.00 BBC Dual 800K 5.24" Disc (AND02) 803.85 Single Disc Drive (lOOK) for BBC 205.85 BBC Utility Disc 1 9.95 Epson FX SOT 160 cps Printer 458.85 NEC8023B Printer 399.00 CP80 Terminal Printer 356.50 TIDY UP YOUR B.B.C. COMPUTER. BBC Spark-Jet Printer 420.00 TELEVISION -CASSETTE RECORDER-SINGLE OR BBC Joysticks 14.95 DOUBLE DISC DRIVE 1.2 Rom Operating System (Pitted) 9.20 Large stocks of Books and Software for BBC ALL ACCOMMODATED ON A PROFESSIONAL CONSOLE THIS ROBUST G.R.P. CONSOLE ALSO HAS PROVISION FOR 10 CASSETTES AND A FOOLSCAP NOTEPAD. The above list in no way represents our full list or range of stock SIZE:- 271 !700mm) „ SIT (800mm)

A WORTHWHILE INVESTtVlENT AT E39-95 INCLUSIVE OF P & P.

Official BBC Service and Information Centre CHEQUE OR P.O. TO:- OOC3 Model A & B Stockists LAMPLAS (DURHAM) LTD, 7/9 RAMSAY STREET, SHoldenhurstRoad, HIGH SPEN, Bournemouth, Dorset T7T=T=T=TT777 I ROWLANDS GILL, Tel Bournemouth 20165 [[Showroom located oDove TYNE&WEAR. COmPUTER CElDlTRE Istewari Greens The Chemist DEALER ENQUIRIES INVITED. ShxkMi for: AN>H, BBC. ZXSI, TW CQMPUTDI SPECIALISTS Spoctnmi,Dragon. , ZX AND ORIC CONSOLES AVAILABLE SHORTLY.

For your Torch or BBC micro A very special offer Horse in Excl. at £19 VAT xForth xForth Motion xForth is an advanced implementation memoslSDphiihcsMFORni . of FORTH, the poueiful yet interactive sustEm tar your cDm(Krfer ^'O'" By interacting with a modern language used for robotics, 4IM' -^^ accounts packages, editors, data base realistic horse ^ handlers and even arcade games. Many RESE>«RCHi

animation explore of I he "Star Wars" special effects were with it. xForth is more the differences ~ created comprehensive and easier to use than - between a walk, Forth 79. while remaining compatible trot and gallop."' with it, 9 The best interface you've ever seen for graphics What PCW said about Slow motion option }* # A super screen editor tor Forth xForth?

. . ."I an xForth licence holder (and and sound. if programs am

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' documentation" . . ."make life easierfor BBC Micro 32K / / # Full CPN file access the novice" . , ."very advanced # Access lo 'FX etc. commands on your EDUCATrON eiictensions" In addition xForth came out BBC micro first in 14 out of 15 benchmarks on Z80 Cassette # Integers, tractions, strings, arrays Forth systems. 9 Recursion CkOPf How to order your xForth SOFTWARE Most software packages only sell a tew hundred, but we aim to deal in bulk, RESE>4RCH71 hence the incredible price of only £19, Send us this coupon by 15th July, 20 Montague Road. Cambridge Cheque or Access orders only. CB4 IBX. Telephone (0223) 353985 To: LIB SOFTWARt. 20 Wandsworth Bridge Rd.. London SW6 2TJ rName n Please send copies "Horse in Motion' of at Address £6 each incp&p and VAT.

I enclose p.o/cheque payable to Lib Software Please send me an xForth disc and manual. value £ £24.15 (£19 + £2 + VAT) made out NAMt I enclose a cheque for p&p ADDRESS to A.I.M. Research or charge my Access account no

I I I I I [ I I I I M II VAX No_^2_27_ Signature Date \± 42J3. 73_; L J

80 ACORN USER JUNE , .

REVIEWS

^ page 78

forge!' the last command. The mentioned; a special memory that picture is automatically re-drawn can store up !o nine circles and ^ page 75 without the fill operation, the ellipses; and, most importantly, a boundary can be repaired, and the perspective facility that automatically as in Wordwise, or to see it being fill executed again. In the AB draws planes, box sections and formatted as you go, as with View. system, escapes are more serious. lines in perspective, and can fill If you only have a cassette The is operation stopped by areas with 'perspective shading'. system, are you prepared for the pressing escape, but any picture To sum up, the differences time involved in saving a file after information under the escaped between the two packages lie in each edit to print it out? filling colour is lost, and has to be the use of the limited RAM Do you have documents larger re-drawn. It is therefore advisable to available to the programmer. The than 25.000 characters long keep a finger hovering over escape EDG designers have opted for a (approx 4,000 words) which have to when fill using the routine. user-friendly approach in which be processed in one single Three useful features that EDG mistakes can be corrected easily, operalion? If so you will have to do not appear on the AB system decisions changed, and pictures use View. are 'grid' which covers the screen saved and loaded rapidly. This Are you prepared to pay E59.80 with a grid of points to which inevitably means the range of for View, plus £9.95 tor the printer cursor movement Is related; 'arc' drawing commands is limited, and driver software compared with which allows any segment of a the resulting pictures tend to be £46.50 for Wordwise? (Also the circle to be drawn only allows collections of lines, (AB coloured free typing tutor with Wordwise is half- and quarter-circles); and squares and circles. belter than any one I have found 'elastic band', which allows you to The designers of the AB system, commercially available.) see the line on being drawn. the other hand, have decided to My personal view is that However, AB has a wealth of cram every available byte of Wordwise is better value and easier commands not implemented in memory with drawing routines, at to use, but certain applications will EDG. These include 'ellipse' (useful the expense of speed and demand the advanced facilities of for isometric drawing); friendliness. 'smooth Pictures can be View. One final comment is thai curve', which connects up to seven sophisticated, but mistakes are not View may well have facilities I did points at a time with a curve; the easily corrected, and saving a not discover, If so, tell us! 'rotate' and 'shrink' features already picture to tape takes a long time.

icroage 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 (BOOK) £799 and Mitsubishi. All prices include VAT. F BBC Disk Interface {inc 1.2 ROM & Open Mon Sat 9.15-6.00 Thiirs 9.15-1,00 fitting 24 hrs: £95 Send this coupon in to obtain a 5"b discount on all products (excluding B & F),

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ACORN USER JUNE '

miero-Kid miero-Kid expand

SOFTWARE Programs llial aie yuiiiflnteed 10 ruril Sawe doufs of tk And woifv wiiti Ihpsp iiiiliiifs and pracliKal iirogiams un cassette or disc to serve you 102 CASHBOOK Double enlrv 4 columns uvilh accounts f 5 95 103 LEDGER Complements CASHBOOK wilh ayeing & analysis C 5 95 with notions. 104 MAILING Holds 2 1 8 addresses Syslpm 6 DISC DRIVES NEW 2 Sorts. Labels. 2 Seaiehes a Update NEW TEAC SLIMLINE PAYROLL In iwfi parts to handle weekly or mnnthly PAVE S Nl f13 90 IWo'Ml (or lOOernployees Supported (Cased with their own Power Supply, 10&a Manual Enlra (Nu VAT) £2 50 106 MEMO CALC Database Xalcsheat witti up to 255 columns slnnc Manual & Format Disc) or numeric data, surls, searches, calculations, wild lull print facililY 9 95 106a Manual E»lra |Nq VAT) 2 00 100k £199.00 -200k £265.00 201 CARDS Beat Bruce Forsyth at his own game 2 95 302 BATTLE Fast muving game simulation of a mmelield 2 95 - !03 HANGMAN Word game French, German. Italian. Spanish 7 95 400k £345.00 800k £619.00 301 BANNER Paper [irintoul of larye lexl S graphics 3 95 302 DISTANCES Giai>hic maps of UK. EUROPE a WORLD CalculalB distance between any two plates 3 95 EPSON FX-80 PRINTER NEW 303 FLAGS Full colour (lags of the world & questions 3 95 NEW 304 STATPAK Statistics offering over 30 results 8 95 program alter It 1.95 A. B 501 SEARCHBAS PROC to search a BASIC & 1 BOcps, 40, 80 or 137 columns. 502 PROCVAR PROC to list uariables used in a program 1 95 AB Variables 1.00 AB S03 PROCFLUSH PROC to clear Resittanl Integer Elite, pica, italic, proportional and 504 PR DCAID A combinaiion ol programs 501 . 502 & 503 345 A B 3 95 A.B 505 DEFCHR Design, display S store graphic characters text in three sizes and 606 SORTMC Machine code sort lor up to 255 integers 1 00 A B emphasised 507 SORTBAS A very fasi BASIC sort 1000 items in 42s 1 00 AB roll 508 UTILITY A A Comination ol 501 lo 507 Superb value 5 95 A 6 nine languages. Tractor, or 600 FORTH Second language ROM lot either OS £34 74 601 WORDWISE HOM Superb last & easy Worrlprocessor OS 1 £34 74 sheet paper feeds. 701 BOOKS Various titles lor the BBC Micro Irom (No VAT| f 5 95 RRP £379.00 SOI CASSETTES CI 2 Computer qualny boxed in 10's C 4.50 35" 810 DISCS MEMOREX Solt Sectored 40 Irack 5 £19.95

901 NEW EPSON f^XaOF T. 160CPS,3FOUNTS, Graphics £379.00 columns, tractor £195 00 SEIKOSHA GP100A Printer 905 SEIKOSHA GP 1 00a Printer BOcps, 80 ;!io NEWTEAC Slimline Disc drives suitable for BBC Micro with Power supply Format disc S Manual cps, 80 columns. Tractor paper feed. 100K Single Sided. -to Track OTHERS AVAILABLE f 199 00 50 £1995 VDU STAND Slainless steel support protects you ' micro £195.00 ADD VAT TO ALL PRICES. FOR COPY ON DISC ADD £1 .00. NO PACKING CHARGE. 5.25" discs - £19.95 for 10 If you want further information before parting with your hard MEMOREX for our new brochure to;- earned cash send CI 2 cassettes - £4.50 for 10 Micro-Aid (AU) 25 Fore Street. Praze, Camborne, Cornwall TR14 OJX. Add VAT to all prices. Packaging included Tel 0209-831274

EXTENDED COLOUR-FILL GRAPHICS EX. E.G. GIVES YOU A CHOICE OF PRIMARY SCHOOL SOFTWARE BBC MODEL B-VERSIONS 0.1-1.2 !! 4 BILLION + !! In conjunction with our local First School we have SHADES FOR TRIANGLE FILLING developed a suite of programs designed to introduce 5-10 year olds to the use of the BBC computer. IN BBC MODES 0,1,2,4 k 5 MOUSE -An introduction to the keyboard. Help the * PLOT 81 and 85 commands for triangle-filling mouse escape from the cat by pressing the key corresponding to the letter displayed on the screen hove been adopted to use the ECFG fill— shade new ECFG user-friendly currently selected by OSCAR — Guide Oscar around the screen using the commands. GCOL Is still "used for line colour. arrow keys and see how many stars he can visit in 200 moves. * Easy choice of 17, 289 & 6561 subset colours between those normally ovoilable in 2. 4 & 16 OSCARADD-A number game for two players. Help colour MODEs. Further options include colours, your Oscar to reach his space ship before your correctly answering the simple sums. angles, spocings Sc widths of cross-hatch etc. opponents by

* ECFG commands can be used In BASIC, typed 0X0 — A numerical version of noughts and crosses from the keyboard, accessed in Assembler, or having three levels of difficulty.

in future BBC Micro languages. ECFG is MOS- HANGMAN — A colourful version of the popular spelling adaptive. and proven with versions O.-l to 1.2 game using words chosen at random from a library * Bootstrap from cassette rapidly builds an ECFG programmed by an adult. module at a RAM address pre-defined by PAGE, All of these programs include full instructions and have which is then automatically increosed 512 bytes ' been designed to be used by the youngest age groups to allow immediate LOADing of programs etc. with a minimum of supervision.

We offer all five programs on a tape for only £16 Price : £10 inc : Mail Order only

I GAELSETT (ECFG) BOQUSt and Pelliny, Microsystems specialists 44 EXETER CLOSE, STEVENAGE, HERTS. SGI 4PW. 9 Paulet Close, Townhill Park, Southampton S02 2EY (Tel. Stevenage 51224)

82 ACORN USER JUNE PRINTERS

WRITE YOUR OWN GRAPHICS DUMP

graphics 'dump' is a to i\ program (191-Y)*16 + X/8 will give the translate the picture George Hill on the screen develops address of the byte containing the into a form the printer can pixel for(X,Y). reproduce. Writing programs to do his series by showing You must now sort out which bit this is not difficult but requires it is from the value of X%8. (For clear thinking and knowledge. confused BBC owners X/8 is To write a dump there are two you how, and giving equivalent to X DIV8, while X%8 is pre-requisites. First, the printer must X MOD)- have some graphics facility. This two examples BBC graphics modes always may be by addressing individual use X values from to 1279, and Y wires a dot-matrix printer, on or may values from to 1023. independent be the block graphics character of mode. This does not imply 1279 set (or may be a programmable mode 2 the number of colours is individually plotlable dots per line character, similar in principle lo the increased to 16, and since the in any mode. In fact, to give an VDU23 characters)- Second, you graphics memory cannot be example, the 16 points in the must be able to 'read' the graphics expanded, the resolution is bottom left-hand corner of the memory to determine the state of a reduced to 1 60 by 256 pixels, 'if we screen [(0,0) to (3,3)] all address the particular picture element - known forego the extra colours, but same pixel in modes 1 and 4. in the jargon as a 'pixel'. For the maintain the resolution, we can In modes 2 and 5, 32 points simple dumps introduced this the pack information into a smaller [(0,0) to {7,3}] address the same month it is only necessary to know memory. Thus mode 4 and 5 pixel Thus the program: whether a pixel is on or off. graphics memories start at &5800, Some information the FOR X-0 TO 1279 about and are identical to modes 1 and 2 PLOT 69,X,500 graphics memory now follows- For in resolution, with fewer colours. NEXT the Atom it is essential to The same principles apply to the understand this organisation, as Atom. This is nicely explained with Plots points making up a horizontal there is no way of reading the state examples in Atomic Theory arid line across the screen. of a pixel other than by 'peeking' Practice. In modes 1 and 4 the program: the screen memory. The BBC There are major differences FOR X=0 TO 1279 STEP 4 screen memory organisation is between the BBC and Atom PLOT69,X,500 more complex, and to compensate graphics memories. The first is in NEXT for this a Basic function POINT, the location of the top and bottom and an operating system call of the memory. On the Atom will plot an identical line four times (OSBYTE) are provided to allow memory always starts at #8000 as fast. In modes 2 and 5 the direct reading of pixels. (hexadecimal numbers are prefixed program: First, the similarities. There is by # on the Atom, by & on the FOR X=0 TO 1279 always an increased memory BBC). The position of the top of the STEPS etc requirement as the detail of the graphics memory is determined by information carried becomes greater. the extent required by a particular will plot the same line eight times Thus the smaller the pixels, the mode. The BBC works in reverse: as fast. Thus when reading the more memory is required lo contain the of top the graphics memory is screen, POINT (0,0) and POINT a 'screenful'; and the colours, more always at &7FFF, but the bottom (3,3) are the same (as are values for the more needed (called memory again- HIMEM) is different according other members of the matrix). They The number of pixels available is to mode. must only be decoded once, described in terms of 'resolution'. The is in second difference how otherwise a lot of time and effort is The greater this is the more pixels, the values of X and Y are used to wasted. and the detail. more The pictures of plot points. On the Atom the range The screen scan must be Bjorn Borg in April's Acorn User of X and Y values vanes with mode, tailored to the graphics mode illustrate this perfectly- Thus in BBC and is equal to the number of being used. The rules are: mode 1 we can have four colours, pixels per line {and the number of • always step 4 in the Y direction and 320 by 256 pixels. This takes bits of graphics memory per line). (vertically) 3, up the memory locations from The Y axis is treated similarly- Thus • in mode 0, step 2 in the X &3000 to &7FFF (20k of your careful arithmetic will enable you to direction (horizontally), precious available memory). With read the individual bit of a byte • in modes 1 and 4, step 4 in the discs, the operating system corresponding to a particular pair X direction, workspace, Basic workspace, 6502 of X, Y co-ordinates. For example, • in modes 2 and 5, step 8 in the X stack, and disc operating system (1 91-Y) will give the row a pixel is in direction. workspace take up a little over 8.5k, for mode 3, #8000 + (19VY)*16 and your program, with its will give the address of the byte at How is this information matched to variables, has only left. 3.5k In the left end of the row; #8000 + the printer? Consider the dot- ACORN USER JUNE 83 PRINTERS

If dot-matrix printer produces addressable printer first. In all your of dots (as is most common), 11 II 1 1 1 bands cases printers require information II 1 II 1 1 1 1 M 1 1 I 1 riAf Ibi'f- sejcnd BvTt ' Ihira' Syie needed. The one byte at a time. Each byte modifications are Phn is in figure 5 for causes the printing of up to eight A method illustrated This byte can address the the Epson and Seikosha printers. dots. Figure 1 . Plan A: line of dots program segments for the dots in two basic orientations. The for Seikosha in In plan A (figure 1), lines of dots 'byte. When 'byte' is multiplied by Epson are (changes = 128 is extra are printed, starting at the lop left of 2, the bit will move left one place, italics, ibyfe byte + the picture (the configuration used and after eight repetitions, it will line); - by the Olivetti and Amber). reside in its correct place the FOR Y=1 023 TOO STEP -32 In plan B (figure 2), bands of MSB of 'byte'. FOR Y= 1 023 TO STEP -28 dots are printed. These bands may The Basic program segment to FOR X=0TO1279 STEP 4 the accomplish this In mode 1 at the vary in width. For example, byte=0 Epson prints a band eight dots top left corner of the screen is; FORy=0TO31 STEP 4 seven dots wide wide, Seikosha byle=0 FOR y=27 TOO STEP -4 and Centronics 739 six dots wide. FORX-0TO31 STEP 4 byte=byte*2 In Plan A it is usual to organise the byte=byte*2 IF POINT (X,Y-yl>0 THEN byte=byte+1 bytes so the most significant bit (ie IF POINT(X1023)>0 THEN byte=byte+l NEXTy the digit for 1 28s) is at the left side. NEXT byte^byle+128 In plan B there is the usual total The byte is initialised to and then VDUI.byle lack of concensus amongst shifted left (bvte-byte"2). If the NEXTX manufacturers (figure 3 shows three pixel is on, 1 is added. The last two VDUl, 10 methods). steps are repeated until eight pixels NEXTY The basic technique for dumps have been scanned. The byte matches pixels to dot wires, so a perfectly produced might have any value These dumps will operate dot wire is fired if the pixel is on in modes 1,2,4 and 5. This may between and 255, It is therefore involves and not fired if it is off. This seem odd, as the pixels are twice essential it is not intercepted by the building up 'printer bytes' (normally in 2 and 5 as in the central processor and acted on as as big modes the vahable 'byte' in the programs two. What is happening is that a normal ASCII value. (This was other which follow), whose bits match the the 2 or 5 rectangular pixel is explained last month, and the use mode screen pixels. The variables X (or being read twice, and so getting of VDU1 Is essential). X%) and Y (or Y%) represent the while the mode 1 and 4 To scan the whole of the top line two dots, current position of a notional pixels get one. of the screen, therefore, we would 'pointer' to the screen, and x and y You will have noticed references embed the first segment in a loop (or their equivalent integer variables) to linefeed (VDUl, 10) or to the to scan the other X values. The make adjustments to X and Y which possible for them. This leads variable x has the values need cause the building up of 'byte'. Let to use of control codes or 0,4,8,12,16.20,24,28 In each scan, on the us follow through the building up of escape sequences to switch to so X must step 32. The data is sent a printer byte in plan A (figure 4). graphics mode, and their con- to the printer by the line VDUl ,byte: The pixel corresponding to MSB of sequences. There is a staggering 1279 STEP 32 the printer byte is read first. The FOR X=0TO lack of agreement between byte=0 result is deposited in the LSB of manufacturers on this. Each printer FOR x-0 TO 31 STEP 4 seems different, and the manuals byte=byte*2 are frequently bewildering. One IF POINT (X+x,1023)>0 THEN that if (as byte=byte-Fl problem that arises is NEXT with the Epson and Olivetti) all VDULbyle codes from to 255 cause the NEXT

A final loop to scan all the Y values completes the picture, The Y loop

must run from top to bottom of the MtiB LS6 i> L^B picture, and so runs from 1 023 to 0. The whole procedure is: ^i* faoW^ n ym 1000 FOR Y=l 023 TOO STEP 4 1010 FOR X=0 TO 1023 STEP 32 r-, V 1020 byte=0 1030 FORx=0TO31 STEP4 1040 byle-byte*2 (J 1) M!ifc 1050 IF POINT(X+x,Y)>0THEN J. byte=-byte+1 u Li* M^ 'A 1060 NEXTx 1. _

1070 VDUl, byte -}& tofiiit Centteitiic^ 'i 1 Tf^/i 1' 1080 NEXTX

1090 REM linefeed if necessary Figure 3. Th ree versions of plan B Figure 2. Plan B: band of dots 1100 NEXTY

ACORN USER JUNE 84 PRINTERS

printing of a dot pattern, then no These sequences must be sent in The printer byte will be made up by code, or combination of codes, can the appropriate places in the scanning the pixels corresponding take thie printer of out graphics program. The process is given as a to the most significant square first. mode once it is in. This is solved by flow chart in figure 6. Six pixels are read in sequence, announcing the number of Some printers have the 'block' finishing with the top left- We scan graphics bytes to be sent in graphics character set (sometimes the cell in the order: advance. This may be necessary called 'chunky' or 'domino'

every line., or for the whole picture. characters). fvlode 7 teletext (o 5

Consequently, if escape is pressed characters are a sub-set of these. in a graphics mode the printer will They are based on a three by two not resume operations matrix, normal until and constitute a set of 64 2 I the necessary number of bytes has characters, printed typically by using the program segment; been received. The only ways out codes 1 28 to 1 91 (though the are to switch printer off, or the send Epson starts at 160). The Microline F0Rx=7 TOO STEP 4 large numbers of Os to match the 80 has these characters as its only FOR y=11 TOO STEP-4 necessary number of bytes. Some graphics facility. Each cell corres- read the Pixel printers avoid this by having a ponds to a six-digit binary number NEXTy NEXTx minimum value, below which codes (0 to 63), and the ASCII code is are interpreted normally. The generated by adding 128 to this. This will now be embedded in Seikosha and Centronics both For example: loops to cover the screen using X interpret codes below 32 normally. and Y. The Centronics graphics characters loom = 'hi Veom^i, byie One major snag arises. There are start at 32, the Seikosha's at 128. - nS'4 39 = 167 normally 80 characters per line of There are three types of control printing. Thus the block graphics

sequence I have come across: i.'bft set prints a maximum of 160 small a single • escape sequence to squares per line. As should have define the whole picture: become clear, it is necessary to P-Vhi • an escape sequence or control have at least 320 graphics 1001 1 I code sent each line to determine elements per line lo correspond to how many bytes to print. the 320 pixels in mode 1. The only • a control code or escape solution, if the full screen is to be sequence to switch to graphics Dumping the screen with these reproduced without distortion, is to mode, and another to switch out. characters uses the same technique. print it in two halves.

^ p rrrfcf byte in f!srJ A ~^ (a) ihi'j. I-, for a vnjle '^^rni.f terttfrne

(j^noty DOOOOOOO n \\] \U 1 cail and. c-oMrol cttersdvr enable pr-'^tv' (h) rht^ Value of W for She ^qi/COce c, c>w«crtr fc/ft* 2 added

A \ 1 OOOOOODi

1 a 2 DQODDOIO

c G OHQDOIDl t 1

10 ODDOiOII D 1 n

7t E 22 OOD/D/iO

'H' f 1 ¥3 OOioKo;

0IOl\ 90 i 91 oil

18t H 187 )OI/0llO

slo( psXjvn »ot»o»»o

Figure '}. Build ng prin ter byte > in plan A

PIWA' Mb6

BdiiS -. (0noi/o(bui9fyl <^ - m.

-^<^.

Figure 5. Building printer bytes in plan B Figure 6. Control sequence control chart

ACORN USER JUNE 85 Available Now Full instructions enclosed IyI I ^^ §\ ^J V ^3 ^# Schools and Colleges

Yes it's here! A complete sound system for the B.B.C. Micro, realistically priced at £21 (Inc. V.A.T.) plus £2 post and packaging. MICROVOC— the BBC Sound System MICROVOC is a complete sound system designed specifically for the BBC micro, capable of use with either speech synthesis or computer produced music. Using the BBC micro's own power, MICROVOC can literally fill the average sized room with a quality of sound you may not have believed possible. Supplied with robust, ultra modern, spherical speakers, which can be free standing, to compliment the BBC machine, or fixed to the wall, or indeed out of sight on the underside of your desk, MICROVOC brings out the true quality of the BBC micros sound facilities. The external speakers can be disconnected at will leaving MICROVOCs volume control to operate the internal speaker of the BBC micro.

OUR GUARANTEE — None of the original components of the BBC micro, including the cabinet need to foe modified in any way to install 'IVIICROVOC'.

Our prime concern whilst designing 'MICROVOC was to ensure that your BBC micro warranty would remain unaffected. MICROVOC can easily be fitted in five minutes and requires no drilling, soldering, or any technical expertise whatsoever. It can just as easily be removed, leaving your BBC micro in its original condition.

MICROVOC simply plugs into existing fittings on the BBC micro and makes use of the 'Reset' and 'Econet' apertures at the rear of the machine.

On later models the reset aperture is covered by a thin plastic film which can easily be removed.

If your BBC micro suffers from the infuriating 'Buzz' then you will also need

'Buzzgo'. 'Buzzgo' simply plugs into the 1 Mhz Bus to eliminate the infernal buzz. If purchased with 'MICROVOC Buzzgo costs an additional £1 (Inc. VAT}. For separate purchases Buzzgo costs £2 (Inclusive).

M I CRO-ADVE NT (A subsidiary of Advent) Ashlyn House, 113 Writtle Road, Chelmsford, Essex. Opening hours 9.30am - 3 pm Monday - Friday. Telephone: 0245 59708

86 ACORN USER JUNE —!ltr— (|?|I nil' in!iv^iii!!i--iiiiir'"ti -nillir-iini-'-ntiir-nttir-^ il:;^ii!i!H 'RINTERS

The printer byte is built up in a split screen tOOO FOR A^OTO 1 similar way to that described for the 1010 START=640*A:FINISH=640*A+639 earlier dot patterns (program 1 j. a time 1020 FOR Y=1 023 TOO STEP -12 step 3 pixels al This type of dump requires no at a time 1030 FOR X=START TO FINISH STEPS step 2 pixels escape sequences or control 1040 byte=0 initialise characters. 1050 F0Ry=11 TOOSTEP-4 read bottom to top In general, graphics dumps left 1060 FOR x=7 TOO STEP -4 read right to written in Basic are slow, taking up 1070 byte=byte"2 shift left to half an hour. Speed can be con- 1080 lFPOINT(X+x,Y-y)>0THEN byte=byte+1 adjust byte siderably increased by two simple 1090 NEXTx alterations. The first is to use 1100 NEXTy integer variables instead value of floating 1110 byte=byte+l28 add on starting

point in FOR . , . NEXT loops (ie to set on Printer X%,Y%.x%,y%,); Printer second is to omit 1120 VDU1,byte send to the variable letter in the NEXT 1130 NEXTX necessary statement. 1140 VDUI.IO may not be Dumps can be used in a variety if linefeed active of ways, in conjunction with Basic 1150 NEXTY betw/een halves graphics programs. Probably the 1160 VDU1, 10,1. 10,1,10, 1,10 space simplest is to save the dump in the 1170 NEXT A form of a procedure. This means the printer byte Program 1 . Building up inserting the statement DEFPROC- DUIVIP at the start, and ENDPROC Program Comment at its end. You will have to merge it VDU28.maxX.31,maxX,31 Define minimum text window at bottom right with your graphics program. This of screen. maxX IS 39 in modes! and 4 and can be accomplished as described 19 in 2 and 5. in the User Guide (page 402}. There right square ot COLOUR 128+n :CLS n IS the colour of the bottom are two methods; save the dump your picture, now filled as text background.

using *SPOOL and call it up using [eg, if n is 3, C0L0UR131 :CLS) "EXEC, (which the Guide prefers, PAGE=TOP+&100 Set address for start of next program, load and run 'dump* but I find slow); save the dump CHAtN"DUMF* normally, and then merge using Program 2. Cheat' to avoid screen messages *L0ADatT0P-2. ^^ The User Guide refers to the the dump as a normal program. It up using *RUN.) latter method as 'dirty', but I find it can be called up and 'hidden' from There are certain undesirable at least as clean as the It other way. the other program as follows. Insert consequences of using the latter has the advantage that if you forget the line PAGE=&OEOO at the end of methods with tape. Unless you to lake care of the line numbers the DUMP (or PAGE=&1900 if you have defined a text window, the (you should remember for both have discs). Then, to call up and messages 'Searching' and 'Loading' methods), typing OLD, followed by run the dump from within the will appear on the screen, removing RENUMBER, wilt correctly ren- graphics program insert the lines sections of your picture. The 'cheat' umber the program in most cases. PAGE-TOP-F&IOO, and CHAIN in program 2 will stop this. You can now call the dump from "DUMP". (A similar effect can be Finally, programs 3 and 4 give within the Basic program by simply obtained for a machine code dump dumps for the Olivetti ink-jet printer inserting the line PROCDUMP. by using *SAVE with toad and reviewed last month, and tor the alternative is to An method save execution addresses, and calling it tried and trusted Seikosha.

1000 DEFPROCOLICUMP define the image 1001 REM CONTROL is the code to 1002 01" CONTROL 15 Z 1000 DEFPROCSKDUMP 1003 $:0NTR0L = CHRSC27)*"61Z0;40;32;2''*CHR$C27)+ 1001 REM cal I printer printer 1 0D4 REW call 'FX5,1 1002 ^ . 10D5 *FXS,1 1003 REM enable printer, and switch to graphTiS mode REM enable printer 1 006 1004 \J0Q2,^,a 100^ ^^^'^ - .,1,1,1 1005 FOR YS; = 1Q23 TO STEP -2f CONTROL to printer via 'DUT 1D08 REM send TO 1279 STEP 4 VI)Ul,tONTROL?I:MEXT 1006 FOR X%=0 1009 FOR 1=0 TO 15: byte^O datd to prin'.er 1007 1010 REW scan screen and send TO STEP -4 -4 1008 FOR yS=27 1011 FOR ^^ = ^o^l to o step b/te=byte*2 32 1009 FOB XZ=0 TO 1279 STEP 1 1D12 1010 IF P0INTtXK,YK-yX)>1 THEN byie=bi'ce + 1013 byte=0 1011 NEXT FOR K%^0 TO 31 STEP 4 10U 1012 Vt)Ul,byte + 1 28 byte^byte'a 1015 1D13 NEXT P0INT(.X%+x2,YX)>0 THEN byte=byte + 1 1016 IF 1014 VDUVIO 1017 NEXT NEXT 1015 printer 1018 VDU1,byte 1016 REM snitch off graphics mode and disable 1019 NEXT 1017 VI)U1,15,3 1020 NEXT 1018 ENDPROC 1021 REM di sable printer 1022 VDU3 1023 ENBPROC

Olivetti ink-jet dump Program 3. Program 4. Seikosha dump

ACORN USER JUNE 87 NEWARK VIDEO CENTRE OAKLEAF computers ltd PRESENTS Education Hobbyist & Small Business Computers SUPER CLEAR COIVIPUTER ITS NOT JUST A TV!!! ACORNS THAT' DISPLAY-AND Jy^f^l^it^"^ LOOK BETTER - ON anOAKTREEI - MONITOR AN RGB WORKSTATION WITH TV RECEPTION THE UNIT SUITS BBCVIC 20 TRS 80 ZX SPECTRUM ETC 141' A2102/5/RGB £275.00 With d built-in accessotyiJrawef lhissm:-in umilurna your setup mlo a 16" B3104/RGB £299.00 pfotessional and business like system The drawer tiolds up lo Remote 50 diskettes or your tape collection dnd lead^ nic 16" B3404/RGB £350.00 CONTROL 'twin user joystick interface atom/BBC ei 3.95 20" B6100/RGB £365.00 Prulfic.l the keyboaid ol your computer by inlert,icing Alan' turn loysticks In It, The loysiicks plug into the interface which m or 22" B7100/RGB £399.00 simply plugs 1 nlueilherlhe Atom Bd way bus the BBC 20way user REMOIt. port lAtom bus units available ai C^ 99 it ordered with the inlertdcei 26" B8400/RGB £465.00 CONTROl Now two people can successfully play games or one person can^ have more control over the computer Full software supplied

ALL PRICES INCLUDE 12 MONTH WARRANTY, A 6 PIN DIN LEAD AND CARRIAGE. GRUNDIG TV's - GRUNDIG APPROVED DESIGN BBC MODEL B QUANTITY DISCOUNTS EDUCATIONAL AND ATOM LATEST NOW IN STOCK AVAILABLE partial upgrades,! M Atom have made it, we f^uH or printers oidisk| slock il Disk drives otf the memories, shell Hardware, books, interlaces etc All available Phone] For further details — Mon-Sat: printers Phone now Prices Prices dropping always competitive or quotation Al current BBCl NEWARK VIDEO CENTRE LTD peripherals stocked] ALL PRICES INCL VATAND P&P 108 London Road, Balderton Please send your remittance to: GRANTHAM. Notts NG24 3AQ 1 21 DUDLEY ROAD Newark, LINCS. NG31 9AD Tel: 0636 71475 ^4C0RN SPECIALISTS TELEPHONE: (0476) 76994

HOME STUDY COURSES WEST OF 30 Hour BASIC A beginner's BASIC programming course. SCOTLAND Available in 3 editions: Standard, ZX81 or Spectrum. BBC & ATOM DEALER AND Structured Programming in BASIC SERVICE CENTRE A second stage BASIC programming course. Beyond BASIC on the Beeb: HARDWARE 6502 Assembly Language Programming. Model A £299.00 inc assembly language. An easy introduction to Model B £399.00 inc courses available now as NEC All 3 Postage &. Packing £6.00 inc correspondence courses. Write for free leaflet/enrolment form. (30 Hour BASIC text SOFTWARE only is available, price £5.95 post free.) Acomsoft Bug Byte Program Power also MICROTRUST SOFTWARE 30 Golf Fruit Machir^e Dodgems 30 Hour BASIC Send SAE for full list 2 cassette tapes containing 62 programs from MONITORS Boxed 30 Hour BASIC, for BBC Micro use only. PRINTERS with instruction booklet. A selection on display A £11.96 inc. VAT (post free). Crossword Puzzler Upgrades carried out Programs to create and play puzzles plus Disk and Econet interfaces fitted 4 sample crosswords, boxed with instruction Also a wide selection of books and magazines booklet. Available in BBC Model B and Spectrum editions. WEST COAST PERSONAL COMPUTERS £5.00 inc. VAT (post free). NATIONAL EXTENSION COLLEGE 47 Kyle Street AYR Dept 45, 18 Brooklands Avenue, Cambridge CB2 2HN Tel 0292 (285082)

ACORN USER JUNE to ours - the only saving would be seemed lo be flickering dimly and that SOUND THEORY removal of the need to add each running the program wilh both shift note duration to the corresponding and caps lock LEDs off caused thcmi Sir. In the article 'The Beeb plays clock [hardly a 'complex solution'). both to flicker. Bach' [Acorn User April) the authors As for repeated synchronisation, Investigation showed that Ihey describe how playing multi-parl music we experimented with both were in fact being driven by high involved 'some tricky queueing and approaches and there certainly frequency square waves from IC32

synchronisation problems', and present appeared to be no perceptible need (74LS259) which is driven by IC3 a complex solution that keeps a clock for synchronisation parameters. [6522 VIA], For each line of the music to avoid However, the 100% accurate relative Whilst this is obviously a bug in

interference between note sequences timing is not documented. Available the series 1 operating system, it does of different rates. documentation suggests synchronis- not seem to produce any other side The designers of the BBC micro ation parameters should he included effects. Could you let me know how sound system were aware of these where possible. We therefore opted to cure this bug? problems and devised the sound queue for the algorithm that permitted their Jonathan Duff arrangemenl to overcome Ihem, inclusion where appropriate. Belfast providing the clock function automatic- Jim McGregor This ally. As a result, it is easy to ensure Alan Wail 'obvious bug' isn't a bug. It channels get independent supplies of acutally indicates when a buffer gets notes, using the ADVAL function to full. Since the sound is buffered, test the queue status. The program BUG? WHAT BUG? both lights come on lo indicate it's sends the next note only if there is full. If you use paged mode (CTRL- N] will room for it, keeping the queues full at you notice that both LEDs Sir, all times. Here's a demonstration: The operating system of my BBC come on at the end of each page micro has recently been changed from (watting for shift to be pressed]. 0.1 to 1.2. When running a program Acorn said, when we asked them 10 REPEAT wilh many sequential sound statements about this, 'it hurts to be told it's a 20 IF ADVAL (-6]> THEN I noticed that the shift lock LED bug. It's meant to be a help!' SOUNDl.-15.RND(10r4-l-48,5 30 IF ADVAL [-7)> THEN SOUNDS.-lS.RNDIlOiM.ZO 40 UNTIL FALSE "^FREE PERSONAL AD service"" A new feature for readers from the next issue. Repeated synchronisation is now Sell bits unnecessary since the relative timing your and bobs, no charge!

is 100% accurate. An initial synch-ed Why not sell that old Sinclair and make a few bob? Just fill in the 'chord' of rests can be used to start the formbelowtoamaximunnof 32 words (one in box) send it parts off simultaneously. each and

to Acorn Free Ads, . This and other sound programming User 53 Bedford Square, London WC1 Use capital letters, and remember your name, address or telephone techniques are fully described in number. This is a free service to readers - no companies please. Creative Sound on the BBC One entry per form only, and we cannot guarantee any issue. Microcomputer; a forthcoming Acorn- soft book. Chris Jordan Acornsoft Cambridge

The problem of synchronisation certainly exists and the programmer who wants to synchronise two or more voices containing notes of different duration must be aware of

it. He must not simply issue a sound statement for each channel in turn. An algorithm using the ADVAL function as suggested above would have a rather similar loop structure

ACORN USER JUNE 89 be added. If the set in question has a 'OPENIN' it will appear in the listing ANTIPODEAN THANKS Thorn chassis (Ferguson, Baird, etc.) as 'OPENUP'. So what is the point of there may be a provision for the OPENIN in Basic II? Presumably so it addition of this variable resistor. provides a read-only method of Sir, Many thanks inr sfinding the John D. Long accessing a file. April copy of Acorn LJser deaUng wilh Leicester As you may have guessed, I hadn't our Antipodean activities. used random access files more than Thanl^ you very much indeed for Poking around the back of TV sets is once or twice before writing the giving us such a prominRnl position dangerous, so unless you know what article in May's Acorn User. Will and for your amazing accuracy down you are doing, check this out with a someone please write in to explain, a 12.000 mih: crackling phone line! TV engineer. for idiots like me, exactly how to use The piece was a real reflccton of the random files? Thank you. situation here and we all appreciate it, Paul Beverley Siriol Giffney PHANTOM POSTMARK BBC Sydney Australia MONSTERS BLOW OUT Sir, I have heard Acorn have had problems in answering letters and Sir, We have a BBC upgraded model READER POLLUTION meeting delivery schedules. The A wilh 1.2 OS and we bought a copy postmark shown may explain the of Acornsoft's Monsters. As an problem. Are they in a world of their experiment we tried jumping the man

Sir, I also have experienced the same own? They use a different calendar through a hole when his oxygen was kind of radar interference as obviously. about to run out, so the oxygen would mentioned by Chris Allard of Dr. R. Flinn run out while he was in mid-air. When

Middlesex (Acorn User. April). Am I University of Birmingham he lands, he lies down as normal, but right in assuming this is because radar his stomach appears to explddo! Is transmissions are around chahnel 36? this normal?

If so. is there any way of adjusting Also, is it true that the Basic II my BBC micro to give a different UHF ROM does not allow certain programs output? My interference also takes the ^i^^ to run? form of a regular pattern of white Michael Isard lines moving across the screen every E. Sussex

six to seven seconds, This I assume is CATCH 64 We got on to Acornsoft and asked due to my proximity to Heathrow. (If the author if the exploding stomach this is the case will the problem is normal - and he assures us it is! Sir, I disappear if I buy an RGB monitor?) have the 1,2 ROM and every As to your second point, all time I press break, location &D00 is The problem also affects video Acornsoft programs run under any set to 64. Is this a bug? recorders which put out their signal at operating system with any Basic. channel 36. When moved to a new S.A.Todd

location, some miles away, I have no Fife problems with my micro or video recorder, No, it's not a bug. The code 64 (&40) VOICE ON VIA B. Holmes is an RTI instruction (meaning Berks ReTurn from Interrupt). &D00 is the Sir, First of all, micro and magazine memory location where the non- are great! Could you please tell me maskable interrupt (NMI) service whether it is possible to add another RADAR SOLUTION routine is placed, and since no sound voice on the CB2 line of the routine has been provided (a DF5 VIA. My friend has a VIC-20 and we would put one there if you had a Sir, With regard to the letter by Chris have done it on his computer. Can I disc system) an RTI is automatically Allard which appeared in the April do it on mine? placed there so the interrupts are issue of Acorn User concerning the A. Wilkinson ignored. 'jitter' appearing in modes to 3 on Kent his father-in-law's TV set, 1 too had this sort of problem. I traced it to the If you have a second 6522 installed fact that the television frame synch BASIC II BOOB (standard on a model B and usually was trying to synchronise on the in upgraded Model A's) then you can flyback signal. The higher resolution MANY thanks to those who pointed use the CB2 line as on the VIC. This modes are the only ones that suffer out that I had misunderstood what line is brought out on the user port from this problem. OPENIN would do in Basic I (Mr connector and connection details are The easy way to remedy this is to Ward of London and Mr Tracy of given on p503 of the User Guide. You adjust the vetical hold variable resistor Coventry, among others). As you would be advised to purchase a 6522 to enable a stable pattern. If, rightly pointed out, OPENIN can be data sheet (£1 from Acorn). They however, Mr Allard's father-in-law's used in Basic I in the same way as need cash with order, and their set is like mine (and many other OPENUP in Basic II, in fact they use address is Fulbourn Road, Cherry modern sets) it will not have a vertical the same token. Therefore, when you Hinlon, Cambridge CBl 4JN. Tel: hold adjustment. However, this must load a program written in Basic I as 0223 245200.

90 ACORN USER JUNE Atwo-minute operation

turns your BBC Micro into tl heart of aword processor.

VIEW 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 Micro4ogether with a printer, as a fully operational word processor. View is supplied as a Rom cliip 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: Tnto View,' that takes many ways in whicliVicw can liclp you, and easy all the you by stages through word the 'View Guide', which provides a quick processing and explains the commands reference to all View facilities.

You 11 fmd that View is, by any

'!,•, standards, thoroughly - a '|-iit'«"afrffo'Af:ffiiVrrifi'fi'-'.- 1 » 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. If you'd likemore information, write to Acornsoft, 4a Market Hill, Cambridge CB2 3NJ. Or, for details of your local Acornsoft dealer, phone 01-200 0200. >lCORNSdR

ACORN USER JUNE 91 READER SERVICES

BACK ISSUES BINDERS

July/ August The li'st issue November Telsiext. secun I offer binders which will \rln,k;s .jri iJrawing tech- BBC rv series machinecjde WE CAN now niques ihe BBC Compuier series I programming lorum easily hold a dozen issues ot Acorn Piuyramrre. machine code Trek III Speeding up yiaphics. questions and graphics. Bomber gamf User at the special price of £3.95 each answers, hints and tips, sound listing, 7-lone Epson graph (includes postage). These quality interlacing scientitic insiru- ics dump, Ainm graphics ments.dumo terminals tot 0.1 manipuialion. dumb lerminai binders have been specially commis-

mdchines. disc drives. Eccnel tor I machine, hrework sioned in a maroon, simulated leather III schools. graphics, ediling tips finish with 'Acorn User overprinted in gold lettering. Please make cheques payable to Addison-Wesiey Publishers, September Ceeldx telesoil December BBCTV m schools and send the order to BKT (address ware. Been in Dusmess, mailing machine code 2 - registers. lisl,simpieliles.30 Hour Basic programming lorum, program below). Overseas readers can order couise, ah on a micra, music. generators, carols hints and binders for £5,95 (Europe only) or BBCmicirjasakeyboarti.ejclta tips. Logo and turtle graphics Atom commands, BBC Basic in schools, Inlroduclion to pro- £8.95 (rest of the world). The binders board ULA design, telelext cedures, soltware review, Alom will air mail. graphics, machine code word processing, toolbox re- be despatched by graphics, analogue inpul, view, 16-colour graphics on

schools training, 1 casselle model A soning, sound en- hug patch. velope design. PHOTOCOPIES ^ii|pwa7jE;i!f'spfra

PHOTOCOPIES of articles in early

October blectron details, BBC January W E P school launch issues are available for 1 6p per page TV series - conlessions, two 'FX commands lor sound, Fpson graphics dumps, second BBC TV senes, mach- (includes postage). Write to Acorn -Seikosha inecodeS-lwopassassembiy. "' GP 1 00 dump. World- User Photocopies, 53 Bedford Square, wide networWing lor BBC disc drives lor the Beeb pro- micro, garbaye handling, wjice gramming Inrum, program London WC1B3DZ- HOMs, sound pilch envelope, protection, micros in schools- Please note this service is sub- moving graphics, ZX printer new series. Commodore Pel lor Atom, RGB colour separ- punier used wilh Beeb, BBC ject to a minimum charge of 50p. ations lor Atom, biofeedback, programs wrillen on an Atom book reviews extra Atom memory BACK ISSUES of these magazines ENQUIRIES about subscriptions REPRINTS are available (except July) for £1.25 and back issues should be sent to each from BKT (address below), BKT. The company will also accept ORDERS can be taken for reprints of which includes postage. Please credit card subscriptions by phone: articles in Acorn User. These can be make cheques payable to Addison- (0732) 351216. done in colour on good quality paper. Wesley Publishers Ltd. For the July/ Overseas enquiries for bulk Costs vary according to the number August issue, we offera photocopy orders should be made to the ordered. Write to: Acorn User Reprints, service (see right). publisher's marketing manager. 53 Bedford Square, London WCl B 3 DZ.

To ensure prompt regular delivery of >tcorn User, send this form SUBSCRIPTION (or copy) to: Acorn User, BKT (Subscription Services) Ltd, Douglas ORDER FORM Road, Tonbridge, Kent TN9 2TS, England.

Pleaseopenoneyear's direct subscription to /Icorn User {^ 2 issues). Annual subscription rates (please tick appropriate boxi: UKei5 n Europe £18 D Middle East £20 D The Americas & Africa £22 a All other countries £24

Preferred Method of Payment: Please complete the appropriate section and delete where neoessary(*).

UK Subscribers: I enclose my cheque/postal order* for £ payable to Addison-Wesley Publishers Limited.

Overseas Subscribers: I enclose my cheque/international moneyorder/sterling/bank draft* for payable to Adriison-Wesley Publishers Limited.

Binders: I enclose a cheque for £ Please send binder(s) at £3,95 each (UK only). Credit Card Payment: Please debit my Access/American Express/Barclaycard/Diners Club/fvlasterCard/Visa* Account number: . _.. .^», . ,, ,. _,.. _, .,. Important Note: If you are paying by credit card, Ihe address you give for delivery of Acorn User must be the same as Ihe address to which your credit card account is senl.

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Position School/College/Company Address

AU11 Please use block capitals 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.

We carry a full stock of parts and should your

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

A full one year guarantee costs just £1 8.40 And a full two year guarantee costs just £27.60

If your Micro is already faulty, and out of

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

& Please tick service required. Warranty Expiry*

n I enclose £18.40 for a full 1 years guarantee Date / /83

If applicable D I enclose £27.60 for a full 2 years guarantee

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

D I enclose £39.1 for an immediate repair and a full 2 years guarantee Surname Access Card No Initials Make/Mode! A/B Address Serial No

Send remittance to: Cambridge Processor Services, or telephone your access card number 25 Parsonage Street, Dept. A to Madingley 210212 Cambridge CBS 8DN.

This offer applies to mainland UK only This guarantee does not apply to major damage caused by abuse.

ACOnN USER JUNE 93 Software Games Authors We are offering five figure sums for your brilliant machine code games.

Supernova Software Ltd, a new force in games software are releasing a NEW GENERATION of arcade games for BBC and Spectrum computers. We will give you the best royalties or "cash up front" deal available so post your cassettes NOW, to:

SUPERNOVA SOFTWARE LTD 9 Salterton Road, Exmouth, Devon, EX8 2BR.

BBC MICRO O scientific & educational applications O

COMPLETE HARDWARE S BaFT\A/ARE PACKAGES BIDSDFT FOR MODEL ' BBC MICROCOMPUTER SYSTEM

Profeasianal Joystick 35- 50

STATISTICAL AJ^ SCIENTIFIC PROGRAMS FOR THE BBC MICROCOMPUTER Environnnontal Monitoring Packages

- lHui-ninHt.on. Humidit.y f?l.i-. Temrier-ar.urf-^ ^ 18-00 MODEL B OR 32 K MODEL A (MOS D.l, l.Q OR 1.2) lOOyear Clock-Caiondar Unit 35-50

Descriptive statislics (lU qroups UKl ilems/grciup) A l^t KLyli program thai allows input, editing and calculation ol rncan, standard deviation and standard error for pach qroup. Croups may t>E compared using sludcnts t tt-st to giui> t and prribabiiity valuer. ALL SOFTWARE PROVIDED ON CASSETTE Additionally, qlotial comparison of all Icn groups irari \ii: used tfi give a diagrammatic significanl/not significant test at any spccilied p value (eg, Q.O^, Q.Ql, U.Otl]), manuals only avallabia aC 7Sp aaL:h r-efi.indL3Dlc.' isg.mnF:-,!. packaqe (.'iJi-^tiaHe Linear regression (lOU data pairs). A ii Ktiytc program taking i,y data pairs, aliowinq editing and calculation of the best fit slraiijiiL line, giving nlope, y intorcept and probatiility value. I7an bf ALL PRICES INCLUDE P + P and VAT 'taught' >; values under coniJitiuns wficn a set nf lines with idcnLical X values must be calculated. Graphical output of data and liiie and interpolation of y values are included among the features of this rug ram. p for dacallB of Chsaa and ot;har products ' plaaaa aand a. a. a. Co ^ Both GRPSTATS and LINREG arc virlually crashproof for example, win: Engineering requesting a number, only the keys 0-9, ., -, . E, RETURN, and IJULt^TE ar Chtris Hail Software a[;tive. Editing options include change data, add data, delete data, sort dal f Oapartmant Q Printer output is a user selectable option. These are high quality aophistieatn programs that will not only provide valuable analytical or educational tools but wi. 47Buah Lana also yield a number of well structured procedures for incorporation into your ow Fraohlacon programs (eg. data entry, crashproof numeric input routines etc.). pnasTON PR4 ISB

GRPSTATS Lf,-9', LINREG It-^i

Ivlail only to: Hiosoft MICRO order BBC 21 Oownhar iDn Heswall Caat;-effec:t,ive Instrument^ation far Home or- School Wirral, Merseysidc L60 SRE

94 ACORN USER JUNE 5

KAltRLIST

Official Acorn dealers

Acorn dealers stock and service the BBC micro, Atom attended technical seminars in Cambridgeto ensure that Computer, Acorn systems and Acornsoft software. The they deal effectively with customers' enquiries. In addition, Acorn dealer not only sells computers and peripherals Acorn supply dealers with specific test and diagnostic but provides vital customer support. Most have recently equipment to speed fault finding.

UONOON CAMBRIDGESHIRE DORSET HUMBERSIDE MIDDLESEX SUFFOLK YORKSHIRE SCOTLAND Arden LandsOAnfl Computer Coinpufa' Far^ihlias DaVinoi Coinputer Wicrp 3D CamgulBi^ 'J^i Managemeni Corn-Tee Eitinbim]nComni.iier pHraonai Cothput&ts Cenire 5r:unlhorpE Snop Ipswich Ot-99E 5S&5 flarnaiey Centra Pel arbor ough Bournemouth High reel Deanaof Kflnflir^tJtDn 0724 8 63197 65 St EdgviHi 0473 59191 0226 4B<372 Edinburgh 0733-47/87 0202 20165 Microage Electronics wa HolaernesB Cornoiitar M'duvicti Computer Co CuatDinisad 031-329 4418 -937 Carnbridge Services Ed^ware 01 7B96 Lid Eieclronfcs Lid escoCompullna Computar Store Hun ai-95S 7119 RlCklngtiall Deans of Kermnaion Le'eds Facilities W2 CambrKjfla Alihlar (nstrumants 09B4 -30225 Ofwae Cornpulais 03/9 898751 0532-732332 02? 3-6 S3 34 HarroLV Ltd MicroSBive SuMolk Compu'.aj Datron Compulars 041-221 OJtO Direcf Data Markelmg Conliol Uniuijrssl Marlon iHumberside) Ltu 01-4 29 1D6D Centre a Supplies Gala Micosyglema UdSrtl Cambridge 0279 412839 ScunthO'pa Twickenliam Bury St Edmunns Shefieid S 1 Dundee 01-834 5016/M96 0JJ3-3Sa757 Compuiers tar All 0724 849596 CorTTpuler Canira 0284 705503 0742-755106 0382 2a I 94 Romlord The TuvlckenKain Group ro E1B Compulei Centre Delrpn Micr? Cenlie Larn Gomputai 01-505 772A 07 08-6072 5 Hull 01-891 1812 SURREY CHESHIRE SheflielUS7 Services Oiretl Data iilaikeiino 0482 262157 T*lll5LatCoii1DUtari CroyOon Compuier Jessao DiaHiwae Computer 0742-535490 Oban Microslecl'tiriics LlO E2 Ltd Visan ConiDuler LIB Centre Centre Ellec Sarvitas LtO 0681 85635 oi-739 3;3a;r!a issi Brentwood Syslema 1-689 1230 BraOtPrrt SlockRori Pen I ionic Ltd Uufli Dar«Se

Leasalink Viewdata dealers

Leasalink is Acorn's UK dislribulor aiitJ has appoinietj a chain ol dealers which it supports.

AVON ESSEX ThH Almaine Gon>PHny LONDON STAFFORDSHIRE WARWICKSHIRE SinCompulEis •SotrraaiM Plus Colna ACL Radirj Services Canonliury RadioNI Coiiiouturama Can, ell ot Huglly Cardill Balh 0282 863 520 01-225 9392 3-9 Bank Siieai 0222 f 5901 0225 61575 StaJloid 03/5 /9B.4 W. Wings Phcitograptiy lAooin Aloni rjniy) 0785 41399 RuBDyCV21 20E Wigan CavHnOiah Sales El SCOTLAND eUCKINOHAMSHIRE HEREFORDSHIRE John yy sag nail 0942 44382 01-247 3453 Slaltord Graham Qepg wneeisr B f Kamnson A L (Acorn Aloin ontyt Mairalieia Computers 0785 3420 WORCESTERSHIRE Wick Qreal Missandan Herelo'd LEICESTERSHIRE El BCIrO- Leisure W1 1 S Elect Phuenii 0955 4/77 Percy Lord S Son tonics Pals sysien 024 OS 2560 0432 3480 01-727 0511 Commscot Wigsian Manstieid SUFFOLK 25 mircesitii Hr,ad 0623 31202 Great Giasflnw CHESHIRE KENT 0533 785033 MANCHESTER C E UattnnwsSCo Malvern Ipswich WR14 4Qy 041 2^6 48/8 Computer City Design Ken] MicrocompuierB Pralt Bros ILelcesterl Bladen Compuier PRMarliey 04 73 215686 W M Coupar & Display Maldstona Blaby Systems Holhngham Emery YORKSHIRE BlairgowriB OS32 52/84 0533 77.3020 Greatrir Manchasler S J «CU W'dnas 0602 2134M Greens Telecom 0250 2438 MRU tituicoll Bunsay OS I 424 999^ 0204 705 310 SP Electronics H Donald Louyhbo rough 0271 62603 Bainsiey J C-Toeh Sottware LANCASHIRE Nottrngham Murllord 0509 214444 0226 5031 hiyde FinQuick 0803 640377 SURREY 0SS3 26477 Stalcom lAcoin Atom onlyl 061 368 3223 FflUlridga Colne The Ssrvice Cenire 0282 886883 LINCOLNSHIRE Sutton Arllnur yatflb SHROPSHIRE Ricon Greenock HomeaBuSinass Greene oi Ot-651 2295 DEDBYSHIRE MIDLANDS 0765 2737 047 5 20228 • FBC Syalams Compulars Gainsboromjh AE Chapman S Co Derby Oldham Gainsborough (Old Hill) SUSSEX WALES ISLE OF WIGHT 04275101 MicroOBntre 963 65280 061 633 1807 Wast r^io lands Bucan Eicall ol BemhrlOya

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Acorn overseas distilbutors Companias have beEo appointed to set up dealer networks in Ihese countries

AUSTRALIA ISRAEL PHILLIPINES DENMARtl IRELAND SOUTH AFRICA WEST GERMANY NEW ZEALAND Barton [jpmputais Aldnda Ltd BerguviElS Lendac Data Sy&len Psion f^ornpular Acorn Overseas Barson ComiJule tWaiouurno HoHiersiaa Dublin rel-Aal dapisj.lij Daiaserva Ltd D'lniormaiiQue Korlsnhoel NORWAY Corripuler Camps rei Hcykiavlk i7«4a9 Luxembourg Mloronor AS Singapore Colombo Tel' 61614 Tel 27193,.2713.i Tel 20/83/20662 Tal 2643553 'el. 98438/93674 Tel 785065

ACORN USEHJUNE 95 . -

INDEX OF ADVERTISERS

A B Designs 68 Garland 33 Midwich 50

Acornsof t 91 Gemini 60/61 Molimex 17 Research 80 Golem 79 Aim National Extension College.... 88 A J Vision 16 Centre 88 Hall, Chris .94 Newark Video Bagust & Pelting 82 Hessel, Simon W 66 Oakleaf 88 Beebug 58/68 Off Records 42 Software IBC Biosoft 94 UK Ikon 42 P L Digitiser 11 Bits & Bytes 79 Psion 44 I ntastor 70 Bourne Educational 71 Interface 70 Ricksoft 72 CSL 71 20/21 76 Cabel 52 Kansas Silent Computers Silverlind 33 Cambridge Processor 93 Lamplas 80 Small School Software 76 CJE 38 Lansdowne 80 Software for All 30 Computercat 76 Laserbug 74 Software Invasion 40 Computer Concepts 26 Leasalink Viewdata IPC Solarsoft 76 Computer Marketplace 11 Level9 33 Superior Software 36 Control Universal 79 Lib Software 80 Cumana 25 Supernova 94 Mail Order Micro 38 3D Computers 64 Dr Soft 96 Micro Advent 84 Technomatic 4 MicroAge 32/47/81 Electronequip 64 Twillstar 1 MicroAid 82 Eltec Computers 22 Video Palace 72 Micro 54/55 Excet 79 Management Micro Power OBC Watford Electronics 6/7 Gaelsett 82 MicroStyle 15 West Coast Computers 88

Doctor Soft \

Presents: ^-"Tv Jp^ Ifcs

£7 95 32K WOLFPACK III A new concept, a new classic.

True "in-space" cumulative motion — unlimited frf^etlom .ind iii(ivi->(nerit amaiing colour graphics and sound. "Sometimes vow firsl warning is a lancing disrupter beam striking from beyond visual range, sometimes they materialise close at hand. You are either quick or dead!" Prowl lush siarfields commanding 3 mighty fleet of deadly star cruisers. Carefully plan your strategy. Switch control from ship to ship, each has its own mission, each its own destiny. Seek out lethal enemy battle stations, planets, cruisers, and phantoms using base station radar and target data. Fight to the deaihi Detonate the enemy for a harvest of energy to transport to base. Lose, and risk a rescue under heavy fire! Features include real and enhanced time, docking, refuelling, rotating base station, meteor strikes, rank and promotion, damage reports, crew comments, hyperspace warp between galaxies and separate briefing (irogramme. A loial Advertisers please note. . ejiperience.

Other Doctor Software tor the BBC Micro includes: These are the copy dates of 747 *32K £6.95- Full-blown flight simulator by the same B.A Captain who wrote the famous Atom programme. Moving dial needles and digital display, or runway, NAV points and hori/on the next three issues of Acorn User. full 3D visual of Gatwick Heathrow Optional wind effects Comprehensive hhefing programme included. Kremlin 32K £6.95-30 multilevel maze estape with Gremlin Kumbatl July issue May 20 Maps, skill levels, standard or random structure. HarmoMv *18K £B.96-Delightful, infinite, saweabte paEtflms of light and August issue June 10 sound,, ^ RoyaltiesJ- The Doctor pays top royalties for lop programmes. All types of September issue July 15 ^'''vwvvT'popular machines and all types of software. NO EXTRAS, prices fully inclusive. copy must be sent to: Cheques and P.O.'s lo:- BBC Camera Docior Soft, 258 Coneygree Road, Ltd, MICRO Susie Phipps, Computer Marketplace Peieriiorough PE2 SLR. 20 Orange Street, London WC2H 7ED. Advertising rates on application. DOCTOR SOFT ADVANCED SOFT\A/ARE

96 ACORN USER JUNE the one to watch

MODEL A/B Cassette 1: Star Trek/Candy Floss (very popular) £6.50 Cassette 2: Family Games (hours of fun) £4.50 Cassette 3: Mutant Invaders/ Breakout £6.50 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)E6.50 Cassette 6: Super Hangman (animated, educational) £4.50 Cassette 7: 3D Maze (fast and intricate; £4.50 BBC 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 a HYPERDRIVE (M/C arcade). Destroy operating systems the Drone aliens in the caverns with • All software in stock before we your laser tank. £6.50 advertise CASSETTE 14 • Send SAE for Brochure STRATOBOMBER (M/C arcade). Keep the enemy fleet at bay in order to destroy the rogue star ships nuclear reactor. £7.50

CASSETTE 15 - LEAP FROG il#^ 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) -^#A^^ ©(I)®®®®®®®®®®®®©®!©)®®®®® ^ PONSAIDE [^ A GREAT NEW BBC MODEL B PROGRAM FROM BRITAIN'S LEADING SOFTWARE HOUSE!

You're flying a highly manoueverable 32K Space Fighter armed to the teeth with a rapid-fire laser cannon and the latest Tryex bombs. Your mission is to penetrate the alien moon defences. Against you are self-firing rockets, nuclear Ack-Ack guns, spacemines, 'fizzers', and meteors, not to mention the network of narrow passageways which must be negotiated. You have only limited fuel which needs to be replenished by either bombing the enemy fuel dumps or docking with the refuelling station. There are 6 phases to get through and 4 levels of difficulty. The game can be started at any phase and on any level. The controls are either from joysticks or from standard or user-defined keys. This exciting program only £6.95!

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