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Sinclair User - Retro Computer Resource

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1. um m t I love as 8 tie bre 5 sloga lete ihis Comp 1 8 bec ause Name 1 Address 1 1 1 M 1 1 1 n London Green Islington Public ations 30 31 jes to ECG ay 12 entries send your on ye not later 7 119819 5 SINCLAIR USER May 1982 teacher s view of theSinclair Another batch of books comes under the scrutiny of reviewer Tom Vests m 1 OME PEOPLE cannot help taking their Sinclair micros seriously while others find it necessary 10 inject elements of humour and occasionally farce into their dealings with the machine It is a tradition dating from the early days of the big mainframe computers Computer people then were sharply divided into two groups One resembled the popular view of a trainee bank manager while the other was a band of cheer ful or manic individualists Both groups produced equally good ideas and programs Those Sinclair enthusiasts who SINCLAIR USER May 1982 are writing books on the machines have already divided into the tradi tional groups While this reviewer prefers the exuberant individualists it is all a matter of style People who approach programming seriously derive just as much pleasure from it as those who take it in the
2. ZX 81 1K GAMES FOR ADULTS inthe Geronimo Pratt Series Album Adventures of Geronimo Pratt 8 flicker free moving graphics programs in which among other things you must MOVING AHEAD WITH ZX SOFTWARE help keep the repair bills down as he drives Uncle Clives new Porche help him pay those repair bills as he gets a job as human cannonball help him crack the code of the combination lock on the bedroom door and when successful find his true love ZX CHESS amp ADVENTURES PROGRAMS FOR THE 80 INCLUDING inside with inevitable results ZXCHESSi _ very popular machine code program with le oe es reduced to 66 50 Plav and anansiysis option Unbeaten except by bum II Pratternization Its Party Time with Pratt ZXCHESS Il A new improved vermon wih a taster response tine multi player album to try out on your friends at your next nowonky 12 99 ENS party See if they ADVENTURES Exciting machine code games with instant response ADVENTURE A 6 00 Sober enough to match G P at symbols Sharp eyed enough to Clone a Pratt or will they Lose their Shirts Bruce Racing inet n Whichever program of the 8 on this album you try them on ADVENTURE C they will need nimble fingers and sharp wits Most games 8 00 this album may also be played solo against the machine or wil they get ox Coming soon J
3. 374A STREATHAM HIGH ROAD LONDON SW16 Tel 01 769 2887 S A E APPRECIATED FOR CATALOGUE KEYBOARD 6 25 70 No soldering just plug in Proper switches Two colour legends RAM PRINTER operation not affected CASE 1030 EXTRA KEYS 48 MUSIC BOARD 5 channels Kit 16 95 Built 18 95 OUT PORT 24 Lines in or out 05 040 2 95 Getting acquainted 4 95 NR 7 23 Mastering machine 5 95 Built 16 95 30 way ribbon 1 40 pode Kit 18 95 Programming for 16 95 applications Tape for above 11 44 REDDITCH ELECTRONICS DEPT SU Send SAE for free illustrated 21 FERNEY HILL AVENUE catalogue 5 x T REDDITCH All prices include VAT and postage WORCS B97 4RU Orders under 10 add 40 BUGIANG Overseas add 1 80 CONNECTORS TEL 0527 61240 SINCLAIR USER May 1982 SINCLAIR 16 RAM pack in January 1981 for the ZX 80 At the time the design was well in advance of any other Some 16K RAM boards cost more than 150 and the minimum size of the board was Bin square Sinclair reduced the number of chips required and reduced the size dramatically to only 3in by 3in by 2in There were numerous initial problems with the design and there are still difficulties which cannot be solved because they are built into the system One of the problems was the number of failures due to whiteouts as they have been
4. MIHI HEP MMMM MMMM MMMM MMM MMMM MME eee LET T 16514 49 zx 81 wins i iplo qunm punt Da UJhat to do nou you have bought your Sindair Don t panic Here is the Sinclair User beginners guide and bought your ZX 81 now what You may have a specific use for the machine in mind or you may simply be fascinated by the prospect of own ing your own computer and keen to learn more about it Here are a few general hints to help you Don t panic If all you know about com puters so far is that they usually try to take over the world in science fiction films do not worry The ZX 81 was designed for you You do not have to be a genius or a mathematical wizard to use it This computer was made with the beginner in mind and will let you learn in easy stages and take you on to advanced computing The ZX 81 is fairly robust and tolerant of mistakes so nothing you do to it in ordinary use will cause any damage to it or to your television or cassette recorder You can enter anything you like from the keyboard it will not necessarily work but it certainly will do no harm If the worst happens and you find strange pictures on the screens or the keyboard will not respond you pull out the power plug wait for a second or two plug it back and your machine is as good as new Remember only to do that as a last resort because you will lose everything you have
5. ATLAN PROGRAM THE ZX81 IN With GAMAL 81 you ca write adve s and with GAMAL y adventure you ll ever want f tte with instructior Tapebook 50 rectangle plus ALL ONLY 4 95 This program takes your BASIC converts it into 280 assembly language ZX AUTOCODER compiles a subset of ZX81 BASIC for the following PRINT PRINTAT PLOT CLS PAUSE GOTO GOSUB IF THEN GOTO and LET statements 6 95 including Cassette and Manual d This is our latest package which includes all the software you need to use a ZX81 in a small business We bring you a full feature system only found on much larger computers This includes PURCHASE LEDGER SALES LEDGER STOCK CONTROL MAILING LIST PHONE DIRECTORY ALL THESE ARE SUPPLIED WITH CASSETTES AND MANUALS INTRODUCTORY PRICE 14 95 YOU WILL NEED 16K RAM ALTHOUGH A PRINTER IS OPTIONAL PACK 16 1 16 24 16 3 Ali prices include VAT and po d packing any two only 5 95 CONTROL TECHNOLOGY opis 39 Gloucester Road Gee Cross TTAPEBOOK503 CASSETTET 2 Hyde Cheshire SK14 5JG TAPEBOOK 50 3 CASSETTE 1 BOTH ONLY 061 368 7558 9 95 OVER MILLION PROGRAMS SOLD TO DATE LX KEYBOARD FULLY CASED wm REPEAT KEY FULLY CASED KEYBOARD 37 95 UNCASED KEYBOARD 27 95 KEYBOARD CASE 10 95 This is a highly professional keyboard using executive buttons as found on top quality computers It has a repeat key and comes complete in its own luxury case
6. 1 0 240RETURN lan Stewart is a lecturer in mathe matics at Warwick University the author of 20 books including Concepts of Modern Mathematics Get Knotted and jointly with Robin Jones PEEK POKE BYTE amp RAM Basic Programming for the 2 SINCLAIR USER May 1982 SINCLAIR USER the best enhancement vet for the ZX enthusiast Make sure you get it monthly the ri C your ZX w month So why What is the best way to guarantee that you today never become bored with your Sinclair Editorial Plans computer May August WHICH September Wheth 5 30 31 ISLINGTON GREEN LONDON 1 SINCLAIR USER May 1982 mm Sinclair 2 81 Personal Com the heart of a system that grows with you 6 1980 saw a genuine breakthrough the Sinclair ZX80 world s first com plete personal computer for under 100 Not surprisingly over 50 000 were sold In March 1981 the Sinclair lead increased dramatically For just 69 95 the Sinclair 2 81 offers even more advanced facilities at an even lower price Initially even we were surprised by the demand over 50 000 in the first 3 months Today the Sinclair ZX8 is the heart of a computer system You can add 16 times more memory with the ZX RAM pack The ZX Printer offers an unbeatable combination of performance and price And the ZX Software library is growing every day Lower price higher capability With the
7. the ZX 81 has had and none has come close The sales of the pocket book sized computer are rapidly approaching 400 000 Looking back to last month s Sinclairvoyance we speculated about the arrival of the ZX 82 com puter A machine with a better specification than the BBC Micro and built by Clive Sinclair is enough to whet any Sinclair user s appetite The ZX 82 is coming very soon Many potential ZX 81 owners are put off this marvel lous little computer by the fact that it does not have a full size keyboard or colour graphics or sound output The Spectrum as the ZX 82 is likely to be called will have all these features plus more With its own matching ZX Microfloppy and retailing for approximately 140 this unit will be available through mail order only until a suit able distributor can be found The new computer is likely to have 32K RAM fitted as standard The ZX 81 succeeded the ZX 80 in February 1981 when the ZX 80 users found that the machine was not quite powerful enough The ZX 80 owners upgraded to the ZX 81 specifica tion by inserting a new 8K ROM with floating point arithmetic to replace the old integer only 4K ROM Unfortunately ZX 81 owners will not be so lucky it will not be possible to interface the ZX Microfloppy to the ZX 81 and there are going to be no new ROMS for the ZX 80 or 81 This is because of the technical difficulties of try ing to get the other features of the ZX 82 on the 2 1 The
8. URN LISTINGS DYNAMIC 7 GRAPHIC PROG JOTTER i easly with the heip of a PRINT PLOTTER FIM RAMS gt JOTTER T 1 X very page ha shows TT 7 p GOODnEUS FOR PRINT PLOTTER FILM 5 used wi p PRINTER w y simi y PRINT or PLOT OWNERS Prat n Potter Products 4 p 3 4 cont m 1804 ordered without JOTTER or LM Keyboard Reef Qo memi PRNTGrd Program PLOT Grid o 100 Sheets Size A4 mmm ttn SU Board backing gt Temm wel SINCLAIR USER May 1982 competition Write a program and win a super Sinclair printer Thank you for your entries in our first competition the lucky winner of a Sinclair printer will be announced next month The prizeis the same in this month s competition And all you have to doistosubmit the best NON GAMES program And because you can use up to 16K all entries must come in on cassette The closing date May 12 Fill in theentry form below and while we will accepta cassette it must be accompanied by a well typed or beautifully hand written listing Yourentry must reach us by May 12 Asa tie break if one is necessary we want you to write a slogan beginning with the words I love my ZX 82 because The usual rules about editor s decision being final and employees of ECC Publications being ineligible apply
9. manual assembly It is at that point that the first test of the equipment is made Bearing in mind that the assembly process has not then reached the keyboard stage the test is to stab lish that the board is alive and well It is called the K test because all it requires is the appearance of the K on the screen notifying the user that the machine is ready for instruc tions If a board fails the test it is then tested on a GenRad 2270 which Testing for faults Inserting the chips identifies the fault and produces a printout denoting the area at fault The printout is then attached to the board which is returned to the re work section before going through the entire process again Assuming that the board has passed the K test the top half of the casing with the touch sensitive key board and connectors is assembled At that point the ZX 81 is again test ed running off a test program on cassette which will display a series of OKs on the screen for every key tested Finally the bottom half of the casing is attached and the completed ZX 818 are packaged for distribu tion There are three main avenues of distribution Jaserve a fulfilment house which deals with mail order Griffin and George school supplie and the W H Smith distribution SINCLAIR USER May 1982 centre Dunstable Bedfordshire Timex has also agreed recently with Sinclair to market personal com puters
10. 3 50 for 100 sheets and the film 2 25 Both are available from Butler Currie and Hook 19 Borough High Street London 5 1 9SE Keyboard witha difference HAVEN HARDWARE has gone one step further than producing a real keyboard and produced a circuit which will make any key on the keyboard repeat after one second It will allow you to cursor right a number of times back to a mistake made in a INPUT line by holding down two keys It is available on the printed circuit board for the Haven keyboard or can SINCLAIR USER May 1982 From black boxes to boards to the point assessments of hardware now on the market beattached to another key board by soldering it to the ZX 800r ZX 81 The keyboard module costs 250 as a kit for another keyboard or 2 50 for the components to mount on to the Haven keyboard Haven Hardware is at 4 Asby Road Asby Work ington Cumbria C4 14 ARR Resolution rise for good graphics QUICKSILVA has pro duced a high resolution graphics board which will produce BBC type plotting of lines boxes and other dot graphics The ZX 80 and ZX 81_ chunky graphics with a maximum High res graphics resolution of 43 x 64 pixels is replaced by a screen offering a resolution of 192 x256 Each dot on the screen can beaddressed byan X Y co ordinate in a REM state ment which may have more than onecommand in it All the USR routines are s
11. This is a genuine professional keyboard and should not be confused with toy keyboards currently available on the market 16K RAMPACKS MASSIVE ADD ON MEMORY FULLY CASED comes fully assembled tested and guaranteed The 16K Rampack plugs straight into the user port at the rear of your computer And of course as in all our products the Rampack is fully enclosed in a matt black slimline plastic case This means you can handle it with complete safety and you do not have to stare at ugly components as in other makes of 16K The Rampack NEEDS NO EXTRA POWER and will operate quite happily on your Sinclair power supply Fully built and tested Don tforget you can always order on the telephone with your credit Six days a week for a same day service WHY WAIT TO PAY MORE FAST IMMEDIATE DELIVERY send me RAM pack s 32 95 each LI Post to __ casedkeyboard s 37 95 each 1 Do Pense sename yos 1095 aan Kayde Electronic Systems s 1 48 49 Exmouth Road Mc cg 1 1 Great Yarmouth Address Norfolk NR30 7867 1 1 All products include VAT are fully 1 Please add 1 50 p p and make cheques payable to Kayde built and tested and come with a J Electronic Systems 1 COMPLETE MONEY BACK GUARANTEE
12. more than one 1 be contacted through the national ZX 80 and ZX 81 Users Club at 44 Earls Court Road London W8 It is only post box so please do Call expecting 0 see someone connected with the club 1 have included two RAM expansions as they all have to start at 18K and work their way upwards That memory must be continuous for basic as the program would crash if it tried to store memory in a RAM location which was not there This is the first attempt of which am aware to try to catalogue all the devices the ZX 80 and ZX 81 use but do not write to me for names of the manu factures of these items The only one lacking the manufacturers name is the floppy disk system which is manufactured by Macronics more details on these devices con tact the manufacturer Memory Map 16K 32K Memory Map 32K 64K Maximum address available TY display nn Hb RAM E ener nna pen TAM om system for ZX 00 s 3d m s Computers packs sereen Technamatie port E n 4 DCP port 24 pasi 21504 nk xn E D H x RAM for ZX 80 and ZX 81 s on switch on x Figure3 1 mL Figures e SINCLAIR USER May 1982 FULLER FD SYSTEM F
13. operating a the expansion port called RAM CS That was included in the design as some method was needed to turn off the 1K of internal RAM when the 16K RAM pack was fitted on the back That was because the 1K RAM was repeated through the whole of the 16K section and would get in the way when 16 separate IKs were installed instead When the 16K Sin clair RAM was installed that was not possible as it not only blocked off any connection to the expansion port by covering it but also used the only free memory locations It also did all of its address decoding inside the pack so could not be turned off by operation the RAM CS line When Sinclair saw that there was market for his computer and that other manufacturers wanted to use it as a basis for experi menting with computers he re designed it giving greater flex ability to the memory map The result was ZX 81 The internal design was much the same as the ZX 80 figure one but this time an extra connection in the expansion port had been E to good was called the pin and by operating it in the same way as the RAM CS pin the RAM could be taken out of the Memory map This was located pin 238 on the expansion port and caused some chaos at first as it was found that the first Sinclair attempt at more external memory the 3K RAM pack did not work the ZX 81 This was because inside the pack tho pin was kept at a permenent Binary 0 and preve
14. peripherals and software in North America Distribution for them will be handled by established Timex shipping agents distribution net work and retail outlets in the U S though Sinclair will continue to sell the 2 81 by mail order from its Boston based subsidiary until Timex sales have reached agreed targets At that stage Sinclair will begin to concentrate on sales of its yet to be released flat screen TV The machines in North America will be marketed under both Sinclair and Timex names and Sinclair will receive a royalty on all sales under the agreement which covers current and future Sinclair personal com puter products and Timex develop ments of Sinclair computer tech nology Timex obviously has a fair amount of confidence in the product it is assembling for Sinclair demonstrat ed by its use of the 2 81 to test printed circuit board of the Nimslo 3D camera assembled by Timex and soon to be marketed in the U S keyboard SINCLAIR USER May 1982 Assembling the keyboard Sinclair believes that such con fidence is well justified pointing to what it considers to be a low percen tage of returned equipment The return figure on the ZX 81 is 2 4 per cent though the percentage return on kits is higher at around 13 percent Chatten claimed that the higher figure of kit returns is due more to poor component insertion and bad soldering than to component failure but stress
15. the goodies yet At any time you can learn your score and there is an SINCLAIR USER May1982 adventure the dragons added bonus if you manage to escape with the treasure Hilderbay is offering a 48K Memotech RAM pack to the person who achieves the highest score before the end of July but I do not think my 46 will be the running At 8 with a word game included Gold is reasonable value but could SINCLAIR USER May 1982 RSS have been better with a few more objects and word rather than letter input Bug Byte offers two Adventure type games the latest of which Dictator is a brilliant simulation of a banana republic since it has no loca tions no objects and no movement of any kind it is not an Adventure sol have not included it The other is The Damsel and The Beast which is a graphics only 9K Basic game The setting is an unlit palace of 35 rooms containing a beast for bashing a damsel for rescuing and a few holes into which you can fall That calamity should be continued on page 20 19 continued from page 19 avoided by using the limited supply of torches available and you also provided with some powerful clubs if you should wish to knock down a wall or kill a monster After being set up randomly the layout of the rooms does not change a logical approach is rewarded Movement and the use of clubs and torches is by s
16. 221 1000 LET e LET AL REM P MOVE N S S INPUT 7 LET IF 1 IF 5 1 40 IF B 1 4EN LET P P 1 se IF 1 HEN LET 1 300 LET 10 0 H 400 REM COMPUTER RESPOND 410 IF gt X 10 THEM ET X 420 IF AND 1 4 430 IF Q vY AND 1 440 IF 2 5900 LET A X 10 Y M 500 REM MUNCH 10 IF Xx 10sY Pii10s0 N LET Z oo GOTO 100 PRINT AT 10 RNDx19 10 RND amp 2 GOTCHA HUMANE GOTO 2000 You enter your direction of move N S W or whatever as shown in line 210 The second ver sion of the program is a little more elaborate in its display and has a scoring mechanism You convert the listing easily for game one into game two You will need more than 1K on your ZX 81 for the game Hartnell 1982 program LET 5 LET A xX LET A P 190 REM PRIN 110 PRINT AT 5 2 15 PRINT 20 FOR D 190 30 IF A D THEN PRI IF R D M THEN F 50 IF AID H THEN PRI 59 IF 10 INT D710 NEXT D 75 IF 2 1 THEN GOTO 1 LET 1 0 0 LET A K4 104Y REM PLAYER MOVE 10 PRINT ENTER YOUR d NENW SE SUD 15 INPUT Bs 16 1 R LE IF IF IF LET e IF IEN LET LET 5 300 LET A REM COMPUTER 410 IF AND lt 12 TH 1 120 IF P X AND X 1 THE 2 10 9 10 E 0 10
17. COS and TAN mean but it is not the way in which they tend to be used in pro grams Try this program 10FOR 0 TO 360STEP 10 20LET X Y P1 180 30 LET A 30 20 COS X 40 LET B 20 20 SIN X 50PLOT A B 60 What have you It circle It isa trifle bent because of the coarseness of ZX 81 graphics The 30s and 20s in lines 30 and 40 are cooked up to get the size and position correct The centre is at 30 20 and the radius is 20 Try varying those numbers and see what happens Change the pro gram alittle and you plot spirals 60 PLOT A B 70 NEXT Y Or you can draw rosettes just change lines 10and 3010 10 FOR Y 0TO 360STEP 5 30 LET R 20 SIN 3 X and run Or change 3 X in line 30 to 4 X 5 X 6 X 7 X There are many other uses In the program S nk the Bismarck in my book with Robin Jones P POKE BYTE amp RAM we and COS to calculate the traje of a shell fired at a ship To end here are the makings of a kind of roulette game with letters There are some useful ideas in the program which should have plenty of applications Rouletters Olan Stewart 1982 Runs on 1K ZX 81 SIN 25 50 GOSUB 200 60 NEXTI 70LET Q 165 80 GOSUB 200 90 1 05 100 NEXT T 110IFC gt DTHEN STOP 120LET Q 37 130GOSUB 230 TOLETI I 1 1501 gt 26 THEN LE 160 220 LET B 16 10 COS X 230 PRINT AT A
18. Prestel adaptor which was due to be launched at the Computer Fair will have to be one of two possible types It will either use the ZX 81 s own 32 x 24 black and white screen for its output or it will have a standard 40 x 25 teletext format If it has the former it will only be able to pick up Telsoftware whereas if it has the latter it would also be able to pick up Prestel pages of information What am leading up to is that if the ZX 82 s ROM could be copied and used in conjunction with suitable colour Prestel adaptor it might be possible to implement some of the ZX 82 s bility on the ZX 81 When the BBC computer was announced Clive Sinclair said that he could meet the specification laid down for about half the price It now appears as though he has done it A working prototype of SINCLAIR USER May 1982 the ZX Microfloppy is due for completion about now and it will probably be very soon that more details of the ZX 82 will appear Mean while work is still continuing between ICL and Sinclair Research on the new digital terminal using Sinclair s flat screen technology One thing that is certain about the ZX 82 is that it will use a similar language to the ZX 81 Back in December Clive Sinclair was quoted as saying we believe our language Sinclair Basic now merits serious consideration as the standard Does it use the same cassette format use my ZX 81 add ons with the ZX 82 O
19. Timex to pro duce the ZX 81 when it was intro duced in March 1981 Since that time production at the Timex plant at Dundee has increased from 10 000 to 60 000 units per month while production of the Sinclair printer also in the Timex factory is now running at 15 000 units per month David Chatten production con troller with Sinclair explained that although the company does not undertake its own manufacturing it is very thorough in its analysis of SINCLAIR USER May 1982 prospective component manufactur ers We get people who are good at manufacturing particular compon ents then get everything assembled in a good production plant he David Chatten inside sinclair The rate of growth of units pro duced at Dundee not only reflects the success of the ZX 81 but also justifies Sinclair confidence Timex company which had little experience in the assembly of elec tronic equipment Allan Johnston project manager of board assembly at Timex explain ed that the company decided to expand into new technology when watch technology began to change He said Our experience at Dundee was in mechanical watches but development in quartz and digital technology led us to consider expan sion into other areas So Timex and Sinclair began dis cussions on the production of the Allan Johnston Sinclair flat screen tube and Micro vision pocket TV for which Sinclair has announced
20. a 5 million four year capital investment programme Because Timex had no experience in electronic assembly it was decided that the production of the ZX 81 would be a first step in the learning process added to which Timex was prepared to make the capital outlay for equipment needed for such assembly Chatten also stressed that assem bly staff at Timex are of very high calibre the best of whom wi initi ally taken off line to train in ZX 81 assembly Chatten added continued on page 54 53 continued from page 53 Getting Timex to do the assembly on the ZX 81 may have been a risky decision in the short term but in the long term it provides us with con siderable security giving us the Building up the circuit board opportunity to build good working relationships before full production on the pocket TV begins Whatever the risks production of the ZX 81 seems to be proceeding smoothly with only minor difficul ties still to be solved according to Chatten The process starts with the build up of the printed circuit board including the addition of diodes and resistors The board then goes through a flow solder machine After soldering which solders all the components into place and includes a cutter to tidy the leads It is only at that point that the chips are added to the board They arrive at the Timex plant in anti static tubes and are fed into a slide dispenser to ease the process of 54
21. books The boards are available kit or ready built form The firm knows Sinclair Research equipment well as it was one of the few which supported the first inclair effort in comput ing the MK 14 long after Sinclair had abandoned it Redditch Electronics is at 21 Ferney Hill Avenue Redditch Worcs B97 4RU 0527 81240 0900 12 1400 1700 hours Plugs into edge connector A BLACK BOX which plugs into the edge connec tor of the ZX 80 or ZX 81 giving 5K of Basic memory and an input output sort is known as the pack the basis of the DCP system It is accessible from Basic via the PEEK and POKE com mands and the port is memory mapped The input output section can be attached to two other modules one at a time to give A D D A con version or larger current handling capacity via replays The D A pack is known as the A pack and the relay as the pack The price of the P pack is 37 95 pack costs 19 95 and pack 29 95 They are all enclosed in tough black boxes and like the P pack contain instructions for use with other circuits A speech talker will soon available DCP is at 2 Station Road Lingwood Norwich Nor folk N13 4AX 0603 712482 SINCLAIR USER May 1882 Memotech s New Memory System for the ZX81 Itgrowsas youprogress MEMOPAKIGH MEMOPAK 64K 646 How to order your Lester B
22. described That is mainly because of faulty RAM chips which are not checked during manu facture Tighter checks initiated by Sinclair produced improvements but only after public pressure and the major weakness of the RAM pack is its edge connector It can also be caused by mains fluctuations The edge connector fits on to the ZX B0 or ZX 81 printed circuit board direct and that is smaller than the RAM packs edge connector expects It also consists of shiny solder covered copper tracks and they become very dirty The only cure is to clean them with methylated spirit and to prevent the contacts becom ing dirty by coating the printed cir cuit board with petroleum jelly Because the edge of the board is smaller than the edge connector the RAM packs tend to wobble and that is not helped by the fact that the key board tends to lift the RAM pack off its surface Originally Sinclair had intended that the 16K RAM was the only extension which would be produced for Sinclair machines and so cut off anything connecting to the computer when the RAM pack was connected So you need to use a motherboard if you want to use the RAM pack with other equipment The only other problem was the way that Sinclair had reduced the number of components for the RAM pack That was done by simplifying the ADDRESS which turned on the 16K RAM pack The 2 80 for which the RAM SINCLAIR USER May 1982 Sinclair s star add on taken to
23. fact it is but if you square the opponent has chosen if ly restrictions on the number of haveever played acomputer version you do not know the correct matchesa player can take say one to of the game it tends to be very easy response three per move to beat That is because it is not a Therefore for each move the com The game can be put on your 16K game of chance but simply of using the correct moves at the proper time agame of total skill not counting the chance about where the opponent is going It is that fact which can lead to computer learning its mistakes hence finding all the correct moves and hence having a perfect skill rating To make the computer learn its mistakes requires very little work In simple terms the computer if it goes first can go in one of nine squares to puter would have a list of moves for each move the player made They can be produced at random at the start of the game If a game is lost the computer s last move is thrown out and a new move put in its place which has not been tried previously If all the moves have been tried at that point the move prior to that is altered In that way the more games played the computer will show more skill until it should be unbeatable This type of game can be put on ZX 81 with no difficulty In the meantime you could try to produce such a game which you could com pare to the one I have written Your ZX 81 is perfect for produc ing such mind puz
24. feature just described but that adds to the cost or the capacity to mmers many computers can decreases store numbers The ZX 81 has a very good The handling particular version of Basic text information better than most micros some very expensive ones The integrity of data depends on the design of the machine and the reliability of components and con of the good it is including nections The electrical design ZX 81 is in general vulnerable however nicrocomputers to strong elec erence on the mains supply I as are most SINCLAIR USER May 1982 Making sure it works properly To run business program the machine must be reliable writes Mike Salem have used a ZX 81 from the same power point as an electric typewriter Sw hing off the typewriter while ZX 81 was loading would usual ly abort the load The components used are general ly satisfactory The occasional rogue memory chip appears now and then in Sinclair and other com puters Usually the problem is inter nittent The chip is perfect when tested but causes trouble warming up The presence of a faulty chip may be revealed by say incorrect letters appearing here and there in a program or by the appear ance of program lines which are not valid Basic invalid lines keyed into the ZX 81 In such a case a faulty RAM pack must usually be exchanged or repaired Rogue chips usua
25. from Oasis Software Lower North Street Cheddar Somerset Toh Cheddar 7463409 HARDWARE REQUIRE Dealer enquiries welcome TARP ARE REQUIRED TNs Video Genie s Mov LE LEVELT JOK RAM 16 ZX81 with 16K RAM PACK 6 GAMES ON CASSETTE FOR ONLY 3 50 Postfree butSIX e games on one high quality Koss rin sedii of ourree what odds which vary trom race me to game GUNFIGHT Shoot desperadoes Get t ROULETTE For yon with t they get you against the 2 81 The classic different betting options and simulated schoolboy game brought up to a naval gunner will you be ONE ARMED BANDIT Your own fruit mac screen Hold facility and constantly updated sc of your progres displays with ng that is a stylish and spoils tre of six games ergonomic plinth for theZX81 It raises and toda tilts the TV to avoid eyestrain holds the SEND TODAY MONEY BACK IF NOT DELIGHTED in place and hides the wiring and power supply Price includes cassette library inlay documentation This very professional unit costs 15 a built in and postage power switch is 3 plus postage at 1 50 inc VAT Send 3 50 cash PO cheque to Peter Furlong Products t25Catford Hil London SEG MOVIEDROME VIDEO 501 Callers by appointment please 01620 7799 Viso Access 19 Leighton Avenue Pinner HAS S
26. from its mistakes OW THE end game of chess as bya computer has little skill involved was explained last month Most tend to advance their pawns as top priority which is satisfactory if the other player lets you do it mostly though he will have you in checkmate while you are messing about Now am going 10 tell you how a computer can be made to learn its mistakes and so build its skill factor The game in question and Crosses which you may Noughts isa start one of seven squares on the second move and so on To see which square it should choose we must look how a human player would make his move One thing he would do is to look at the computer s move that is the single most vital point affecting the square where you go When we had seen what the computer had done he would use his judgment to decide from past experience the best square The word past is vital because it is no use knowing what any microcomputer with about 16K of memory you might like to try it using your ZX 81 If you do would be interested to see it and I could include part of it in one of these pi ext month hope to produce a listing of a game called Nim an old game about piles of matches Two players take it in urn to take some matches from one pile at a time There could be nine piles for example with say six in each or any other combination There are usual simple game In
27. of the same title for the ZX 80 with the requisite amendments and more important deletions It is not designed for anyone who has yet to bang their heads for about 50 hours working out Basic pro gramming techniques Most of it consists of solutions to problems of which the beginner is not yet aware and explanation is kept to a minimum The general style is along the lines of So you ran into that problem too here is the solution which seems best to me at the moment Oh and by the way here are two things to avoid because they can really tie you in knots There are good sound suggestions and techniques in the book but in my opinion it is designed for the committed and dedicated although others could find it useful as a reference I liked particularily Hewson s warning about machine code pro gramming Unfortunately writing lengthy programs in machine code is rather like solving The Times cross word It is a pleasant intellectual challenge once you get the hang of it but until that time it can be a time consuming and frustrating busi ness They are worth keeping in mind There is very little to say about Mark Harrison s Byteing deeper into your ZX 81 beyond my opinion that it is one of of the best manuals on offer for the beginner It assumes a small amount of general knowledge on the part of the reader but starts by des cribing what computer is and leads through to the most advanced tech niq
28. real tuli your 2 81 Simply unscrew your 2 81 printed c black Sinclair case and plug into Pro FULLY BUILT 64 95 inc VAT More accurate faster typing with bigger and real keys 40 colour coded key tops for easy reading big computer construction prepared for more add ons to come New edge connector provided for Sinclair and other manufacturers peripherals Key legends can be changed for future new ROM function Sinclair fully enclosed and room for much more If you feel you ve outgrown your ZX 81 don t sell it for peanuts and move to another system Add it to Protos and make your ZX 81 grow For details large SAE please For orders add 2 50 post and packing Cheques to Frome Computing Protos Computer Systems keyboard in a top quality case for uit board from its Frome Computing 20 Ashtree Road Frome Somerset 1125 SINCLAIR USER 1062 BIPAGESID PROGRAMS for both the ZX 80 and the ZX 8 MIN ARE in command Sh of tanks in Minefiel the 1K ZX 81 game Before lies enemy minefield through which you must pass How many of your tanks will be lost finding a safe route When you run the program the 4 computer will generate a mine field a different one each time you play Drive your first tank across the screen using the forward up and down keys Be careful not to use other keys 1f you
29. somewhat greater accuracy The final question is from Roger Hurr of Coventry He writes I am writing a program to test my son arithmetic but I have found that my ZX 81 sometimes gets the answer wrong know that some early ZX 81 ROMs made an eror with the square of 0 25 but my machine does not make that mistake Is this another bug He sent his program and it became apparent quickly that the fault lay with his program and not with ZX 81 The routine which wa fault set a problem in division and then compared the user s reply to the result calculated by the ZX 81 Unfortunately for him the routine often rejected correct replies It is often impossible to convert decimal number exactly to a binary floating point number and that was the source of Roger s problem An analogous difficulty can occur when converting some fractions into deci mal we are all familiar with the fact that 3 cannot be written as an exact decimal The program was rejecting the user s reply even when it differed by only a tiny amount from thecalculated result The following program asks you lo entera number divide it by 10 and enter the result It then prints the floating point representation of your result and its own result for the same calculation If you run the program a few times you will see that your answer and the answer produced by the ZX 81 often differ by one in the least significant digit of the mant
30. spirit of Monty Python s Flying Circus Publishing house Macmillan leaves no doubt as to the approach of Randle Hurley s book with the title The Sinclair ZX 81 programming for real applications Other computer titles from Macmillan include three manuals on Basic programming and digital techniques Hurley has aimed his book at someone who is not a computer expert and who has read the Sinclair manual without understanding some of the more esoteric functions and techniques completely More significantly he adds that the reader may bea teacher as he is himself The programs and techniques are based on his experience with the ZX 81 at his school He assumes that the reader has the 16 RAM pack with the machine It is not a book for the small busi or club secretary who wishes mainly to have a system up and running and to acquire a little programming technique on the sid but it is one for anyone who wishes to extend their knowledge of the Sinclair and wishes to make use of it in a practical way It would certainly be useful for any teacher who wished to make use of a Sinclair The tone overall is schoolmaster ish in the best sense Hurley lets you know what he intends to do and then shows you how to do it At the begin ning he provides a large number of tips on how to approach program ming particularly on the most diffi cult part of all in writing long programs how to keep track of what you are doing He blasts
31. to disappoint ment for the purchaser Thank you for your assistanceand good luck Derek Tidman Work Force Luton Beds Discipline and guidance ONLY a week after I bought a ZX 8 and 16K praise where it is due 2 realise that as a commer cial enterprise you must Tasi keep a weather eye sw advertising but the kind of discipline you could help impose can only be good worked in hours and for products and users and for your circulation in thelongrun RAM your welcome problem magazine appeared in the calculate hours newsagents Excellent tim worked during a week ing if I may say so from data recorded on Itis obviously early days timecards thus for you but I hope that your reviews of hardware and D software will be frank and e mo ow o critical as well as giving 27 supplied Wed The Pri Tobe adduced rom da T E Newman Worcester Park Surrey I look forward to future issues and certainly wish Thanks for the compli you well Meanwhile ments and we have sent wondered if youcould give your problem to Andrew some guidance to help me Hewson Hopefully he resolve programming provide a solution Editor ean THE LADY IS NOT FOR TURNING BUT ARE YOU Ever thought you could run the Country bett RATE introduce SOCIAL REFORMS and try stay POPULAR the Electorate GAME SECTORS COUNTRY Information about the C
32. typed in S O YOU have taken the plunge The programs you put in will stay there only while the power is Setting The instructions for setting up your computer on page seven of the manual are reasonably comprehensive and you should normally have no problems It is worth checking if you have just opened the box to make sure you have all the correct pieces a 2 81 a power supply unit manual an aerial lead and a pair of cassette leads Connect up turn on the power remembering to keep the TV volume low to save your eardrums and tune to channel 38UHF You may have slight difficulty locating the UHF tuner on your TV because some manufacturers manage to con ceal it fairly skilfully If you have push button model switch to an unused channel and turn thepush button On other models the tuner is at the back of the set or sometimes in a pull out tray at the front Once you have tuned in you should see a black square in the corner of the screen with a white K like the picture in the manual If the does not appear double check that you have everything plugged in to the correct sockets and that power is on then re set the machine by unplugging the power for a second or so and try tuning again The K will take fractionally longer to appear if you have a 16K memory connected If the picture remains fuzzy or unsteady you may need to adjust the vertical or horizontal hold on the TV and chec
33. with four BONUS omes ARCADE GRAND PRIX and maybe hole none plos fun SWAT ALGOR 16K ZX81 and ZX80 ROM PROGRAMS ON CASSETTE nm MINES AND NEWSOFT PRODUCTS FOR THE RAMPAGE Memory mapp Tower London Caste ot COMING SOON VALLEY forthe zm 16 K SAE for detas Sach any two lor Cd each NEWSOFT PRODUCT 12 WHITEBROOM ROAD EMPSTEAD HERTS L Hemet V D U Screens EDUT SOFTWARE GCE 0 LEVEL MATHS 3 fu 16K JUNIOR MATHS Y Long JUNIOR MATHS 2 Arcos JUNIOR ENGLISH 1 16KB1 2 3 50 SHELOB S LAIR The ECONOMY GAME 1 1681 4 4 00 CHEOPS TOMB 1 COMMODITY GAME oponenta Buy materie on the mar J6KB1 X 550 COMPILATION of e witha 80 page man 1681 5 300 THE FINANCIER to Dovercourt Ra Normampton NNS SHW TURN IT INTO CASH SINCLAIR ONLY PRIVATE ADVERTISERS DON T LEAVE THAT OLD COMPUTER OR PERIPHERAL LYING AROUND SUPERMART AND 1 0 000 READERS FOR ONLY 5 00 POSTAL ORDER OR CHEQUE WITH ORDER PLEASE 5 00 PLACE A SMALL AD IN REACH OVER 66 2x8 USERS FIGHTER PILOT You 6345 MOTHERBOARD Tw ALL PRICES INCLUSIVE See US THE 2x81 MICROFAIR DIGITAL INTEGRATI Maii Order Only CROSSWORD PUZ
34. 2 81 it s still very simple to teach yourself computing but the 2X81 packs even greater working capability than the 2 80 Ituses the same micro processor but incorporates a new more power ful BK BASIC ROM the trained intelligence of the computer This chip works in decimals handles logs and trig allows you to plot graphs and builds up animated displays And the ZXB1 incorporates other operation refinements the facility to load and save named programs on cassette for example and to drive the new ZX Printer complete course n BASIC programming rom les to complex programs Higher specification lower price how s done Quite simply by design The ZX80 reduced the chips in a working computer from 40 or so to 21 The 2 81 reduces the 21 to 4 The secret lies in a totally new master chip Designed by Sinclair and custom built in Britain this unique chip replaces 18 chips from the ZX80 New improved specification Z80A micro processor new faster version of the famous 280 chip widely recognised as the best ever made Unique one touch key word entry the 2 81 eliminates a great deal of tiresome typing Key words RUN LIST PRINT etc have their own single key entry Unique syntax check and report codes identify programming errors immediately Full range of mathematical and scientific functions accurate to eight decimal places Graph drawing and animated di
35. 5 3BR quire a VAT receipt enclose a cheque postal Name Mr Mrs Miss Address FREEPOST no stamp needed der payable to Sin to my Access Barclaycard Trustcard account n owe Tort Code Item price E E 2 49 95 6995 895 8 49 05 2 49 95 17 1995 TOTAL air Research Ltd for 295 l l l Lulu rd RI fcc LEARNED machine code the of hard knocks clutching my Mostek Z 80 programming manual which is now very tattered and the Nascom 1 documentation which was not particularly helpful They were heady pioneering days but this series of articles is designed to take you through the machine code hoops so that your cranium does not suffer too much pain It will start with first principles and culminate in the production of a machine code based game Why make the effort to learn machine code Three main reasons spring to mind It is faster in operation than the equivalent Basic program It occupies much less space in the memory than the equivalent Basic program that is critical on the unexpanded 2 81 It gives greater scope for the imagination than Basic With Basic you are tied to the menu of instruc lions the manufacturer has given you in the brain ROM of the computer With machine code you can make the operating system do things outside the set menu make the screen scroll printed
36. 7 iF G Y AND THE PRINT AT 2 10 jani Pues LET R X 10xY M REM HUNCH IF X 10sY P41040 100 PRINT AT 1Q04RNDxiQ GOTCHA HUMANE 2000 N LET X N LET 2 10 LET Ys AT 9 10 N LET YzY AT 9 10 THEN LET Z NT eaa MOVE 1O RNDS2 SINCLAIR USER May1982 35 ANIEL KING of Headington Oxford suggests that the 1K ZX 81 Jackpot program could be used for school fund raising days charging fivepence for people to press NEWLINE for a spin on the ZX 81 fruit machine They are paid eightpence for two identical symbols and 15 pence for three That King assures us means a profit of 25p on 20 games Simply RUN the program then press R to roll or return If you have more than 1K enter a routine to total your money wins and costs automatically A HOLD would also enhance the game Running the program gives a very effective impression of reels of symbols spinning before settling on one in each window 36 PRINT ri SINCLAIR USER May 1982 NDREW LOVERING has many hours with his 1K X 81 in Maidenhead in pro ducing the fine game of Catch You will see when you press RUN an open box near the bottom of the screen Pressing 8 moves you to the right 5 moves you to the left You have to try to catch a rapidly descending ball dropped from a random position at the top of the screen To confuse you and to i
37. 81ZX81ZX81 lan Stewart amp Robin Jones The reader friendly guide 10 getting started with the Sinclair 2X81 Includes an intro duction to looping and branching graphics subroutines and debugging techniques with over 50 programs designed to run on the standard 1K memory 110 pages Paperback 4 95 ISBN 0906812 178 Published by Shiva Publishing Ltd 4 Church Lane Nantwich Cheshire CW5 Telephone 0270 628272 Order from your bookseller or fill in the coupon Please supply me with copy copies of PEEK POKE BYTE amp For ist Class Postage please add 25p Price 4 95 per copy Cheques payable to Shiva Publishing Ltd NAME Capitals please a For payment by Access American Express Card No Signature R Crossword is S playedon screen andtests your S knowledge of 4 ZX81 terminology one cassette Anagram be Price 4 95 played against the 3 computerora human opponent Three levels of D difficulty Send cheque or postal order to Computatutor 3 Thalia Close Greenwich SE109NA SINCLAIR USER May 1982 On the production line A piece of cake in Dundee Lynd Church goes to Scotland to discover just how the ZX 81 is manufactured N KEEPING with its philosophy sub contracting all manufac turing processes Sinclair Research appointed
38. BW SINCLAIR USER 1982 5 NY COMPUTER which is to be used in real applications ust be reliable The ZX 81 ss then perfect reputation ir ct but all the problems can be solved we will see how Essential requirements are that all calculations must be done correctly tents of must be without being corrupted or vanish ing entirely that it must be possible that re hat the memory stored to store programs and data reliably programs and to data properly set up load and generated by a system The correctness of calculations is almost entirely dependent on the program It is possible for hardware ign errors to occur which cause odd problems but they are usually found and corrected by the manufac after turer relatively soon elease of a new machine The ZX 81 had such a problem early machines did things such as 3 0 00000000000001 7 and 0 2 31423844 That was soon correctes and the old machines were repaired the giants of the computer not such Even ndustry free from problems Computers also have idiosyncra ies which must be understood by prog obtain a number such as 3 9999999 by adding 0 1 4 0 1 repeatedly If am then tests whether the answer is 4 or takes the integer the result will not be what is wanted is the programmer s responsibility It is easy to design a computer without the particular
39. E ZX KEYBOARD keys and will greatly increase your programming speed It is fitted with push type keys as in larger computers The keyboard has been specially designed for the Sinclair computer and is supplied ready built It also has facilities for 4 extra buttons which could be used for on off switch reset etc 27 95 Numeric Pad 10 00 4K GRAPHICS ROM The dK Graphic module is our latest 2X81 accessory This module unlike most other accessories fits neatly inside your computer under the keyboard The module comes ready built fully tested and complete with a 4K graphic ROM This will give you 448 extra pre programmed graphics your normal graphic set contains 64 This means that you now have 512 graphics and with there inverse 1024 This now turns the 81 into a very powerful computer with a graphic set rarely found on larger more expensive machines In the ROM are lower case letters bombs bullets rockets tanks a complete set of invaders graphics and that only accounts for about 50 of them there are still about 400 left that may give you an idea as to the scope of the new ROM However the module does not finish there it also has a spare holder on the board which will accept a further 4K of ROM RAM This can be used with a 1K or 2K RAM chip for user definable graphics so you can create your own custom character sets 29 95 MEMORY 80 81 16K RAM Massive add on memory for 80 81 32 95 2K amp 4K RAM Static
40. ES complete trigs package 8 POLYNOMIAL EVALUATION operations zero s int real complex and Descartes 10 BARCHARTS FOR ARCHITECTS a simplified version takes away the tedious task of manually handling the problem 25 BANK ACCOUNT calculate your bank charges whilst keeping your account 5 HOLDCO GAMES See our special advertisement in this magazine Prices include VAT Post amp Packing COD Orders 2 extra HOLDCOLTD 14 BRITTON STREET LONDON EC1M 5NQ Tel 01 251 3090 16 SINCLAIR USER May 1982 Fillinga market need I FIRST heard of your magazine at the ZX Microfair but I thought it would just be two pages of old news for members of a user club am very pleased to find it on general distribution such a reasonable price The magazine seems to fill market need judging by the amount of ZX informa tion which has been appearing in magazines I feel there are three ways in which the maga zine could be improved First the introduction of an advertisers index in an easily locatable part of the magazine Second how about having a small sec tion on the old MK 14 ranging from a piece about what it was to regular hardware and software spot Third find one of the most informative parts of computer magazines in the letters page and hope you will introduce one The queries raised and ideas suggested through letters pages have often prompted me to try ideas I woul
41. Load you then enter hex and decimal argu ments to derive the ZX 81 code which is added to the manual draft Using M C Edit the ZX 81 code is entered together with break points required So when the routine is proved the M C Load program is used 10 enter the finished routine in memory continued on page 12 continued from page 11 MCIS can be contacted at 62 High Road North Gibbons 14 Avalin Road Orpington Kent BR69AX Weald Bassett Essex CMI66BY Dangers 3 froma Banking starship ANOTHER GAME for the soon to be released system Michael Orwin Cassette units and you only have 70 A SYSTEM which enables Three requires 16K of hours for repairs before vou 10 keep detailed M memoryand willbeoneof your next inter stellar records of bank transac incorporates a machine 10 or so games the cass jump tions and thus produce a code load save feature ette Starship Trojan puts There are other dangers better statement than that which permits the storing you in the unfortunate lurking but at least you are of your bank can is of transactions in data files position of being the only armed with lasers and stun able to users of the 2 81 on cassette separate from survivor on starship grenades The game pro 16K RAM system Personal the program That facility which has been badly mises to be at least as Banking System offers faci saves and
42. M chip prices have fallen dramatically and the price of a 416 chip on the retail market is some where in the region of 45 pence The design in early 1981 was inexpen sive very efficient and small in size but it has not been improved to date neither has the price fallen in response to the fall in the price of chips The 16K RAM pack therefore is looking over priced to people who can now obtain a better version no humming and better reliability for about 35 Manufacturers have now had sufficient time to produce a design which includes buffering so that more boards can be driven direct and still turns off the internal 1K ADDRESS CHANGEOVER Figure 2 Layout of the 16K RAM pack line on line 2A of the expansion port permanently off They have also produced RAM packs capable of giving the Sinclair Basic 48K maxi mum RAM to use for program and data That applies only at the moment to ZX 81 A 64K RAM pack has just reached the market with 48K of Basic memory and 8K of memory for machine code swapping data RAM pack is 79 Sinclair has made plenty of money from the 16K RAM pack and now other people have produced cheaper and apparently better versions including more memory than 16K for owners of ZX 81s think it should be retired and replaced with a better or cheaper model giving the customer the advantage of the RAM by holding the RAM CS between
43. May 1982 The independent magazine for the independent user 60p helpline mind games new produ book reviews I BUG ATUEMTURES 773752787 1 Dana ZX81 SOFTWARE BUG BSIBR UTILITIES INVADERS BUG SAMES PAGANS 2 OTHERS Editor goi Clark Consultant editor editor Harold Mayes Design William Sc Advertisement director Simon Horgan Editorial director Advertise Morton Editorial production assistant Margaret Hawkins Sinclair User is published monthly by Publications Ltd It is not in anyway connected with Sinclair Research Ltd NI ABI pay 10 for each program and 50 for each article i should be approximately 1 000 right 1982 5 SINCLAIRVOYANCE The new Sinclair machine the ZX Spectrum is expected any minute now We peep at its facilities 7HARDWARE WORLD whole batch of hardware goodies examined by our add on expert 11 SOFTWARE SCENE As more and more software floods on to the market we testa few programs for your delectation Andrew Hewson the Marjorie Props of the ZX world problems This month he tackles numbers 17 LETTERS Your letters have already started to roll in and we prewn a selection 18ADVENTURE GAMES Role playing games about to take off in a big way Phil Garrett looks at part of what ison offer 22MEMORY MAP Exp
44. O18STEP 1 40 PRINT TAB 4 Y TAB 13 Y 180 PI 50NEXT Y Right angled triangles Given a right angled triangle with an angle A name the three sides like this horizontal More formal terms are opposite for vertical adjacent for horizontal and hypotenuse for slanting Then when theangle A is measured we have SIN vertical slanting COS A horizontal slanting TAN A vertical horizontal Soif we know two of the sides and the angle we can determine the other side For instance suppose I stand 100 metres away from Nelson s Column and measure the angle to the top at 73 degrees How high is the column continued on page 44 SINCLAIR May 1982 SIN COS and TAN continued from page 42 jx ME know the horizontal and we want the vertical so we have to use TAN A vertical horizontal So vertical horizontal x TAN A 100xTAN73 We have to use radians remember Now 73 degrees is 73 PI 180 radians So we can find the answer by using the ZX 81 in command mode Just type PRINT 100 TAN 73 P1 180 Do not forget that TAN is key E in function mode not T A N You should obtain the answer 327 08526 For some problems like this you will need SIN or COS instead For instance to find the distance between you and the top of Nelson s Column you PRINT 100 COS 73 PI 180 whichis 342 03036 Circles Circles are what SIN
45. OR ZX80 81 THE MOST VERSATILE SYSTEM FOR EXPANDING YOUR ZX STANDARD KEYBOARD AND CASE This splendid keyboard and case houses your ZX81 printed circuit board which is simply screwed into place the keyboard plugs into the 2 You can now enter data with ease The 40 key switch board is a custom unit not made up out of other manufacturers parts The keytops are our own design and have the ZX Qwerty and functions foil printed onto them Access to the user port TV MIC and ear sockets are as per the ZX case Built keyboard and 36 70 or 30 70 as a kit plus 2 10 posta and packi The case is designed to house not only the keyboard and ZX but also our motherboard power supply RAM cards and two other boards not necessarily of our manufacture The injection moulded case measures 200 mm x 350 mm x ich board the extra keys Built keyboard and case 39 95 or kit 33 95 plus 2 50 postage and packing Motherboards 15 95 plus postage and packing 16k RAM board 35 95 64k RAM board 79 95 Keyboard Only Available Built 24 95 Kit 18 95 P P 80p Send SAE for details to FULLER MICRO SYSTEMS The ZX Centre Sweeting Street Liverpool 2 Announcing VERIFY Do you SAVE six times and wonder if every copy is corrupt VERIFY will make a bit for bit comparison of your BASIC program on tape with the contents of RAM and tell you whe
46. POINTS O X MUST FOR BEGINNERS amp ADVANCED USERS 7 50 KE KIT 1 FILES Save NEW DRAW A BORDER e KEYBOARDSCAN FLASHING CURSOR S CLEAR PART OF SCREEN LOAD ANY CHARACTER TO WHOLE SCREEN INVERT VIDEO OF PART OF SCREEN MEMORY LEFT CLEAR SCREEN BY SCROLLING UP DOWN LEFT OR RIGHT Ji 5 70 PICTURESQUE 6 CORKSCREW HILL WEST WICKHAM KENT 988 ALL FOR ONLY 5 95 11 90 SINCLAIR USER May 1982 MICRO GEN QUALITY PRODUCTS 2 81 A D CONVERTER BOARD This 4 channel analogue to digital conv inally developed for joystick control be used for such measurement of voltage temperature light intensity etc The board fits in between the RAM pack and the 2 81 No skill is required to make this connection and it actually improves the stability of the RAM pack Pricenow only 18 50 JOYSTICKS FOR THE 2 81 only 9 50 each The most exciting add on ever for the 2 81 free yourself of that dead unresponsive keyboard 1 or 2 joysticks may be connected via our A D board Turns yourZX8 1 into a true programmable games machine Extends the capability of the ZX8 1 imagine the tremendous variety of games and applications that now become possible Details supplied on how to use the joysticks in your own programs Please note that you cannot connect conventional analogue joysticks directly to the digital inp
47. Ram memory expansion for the 80 8 1 They both work with onboard Ram i e 4K plus onboard 5K This is the cheapest small memory expansion available anywhere 2K RAM 14 95 4K RAM 19 95 16K 81 SOFTWARE DEFLEX This totally new and very addictive game which was highly acclaimed at the Microfair uses fast moving graphics to provide a challenge requiring not only quick reaction but also clever thinking One and two player versions on same cassette 3 95 3D 3D LABYRINTH You have all seen 3D Labyrinth games but this goes one stage beyond you must manoeuvre within a cubic maze and contend with corridors which may go left right up down Full size 3D graphical representation 3 95 CENTIPEDE This is the first implementation of the popular arcade game on any micro anywhere Never mind your invaders etc this is positively shining the speed at which this runs makes ZX invaders look like a game of simple snap 4 95 16K GRAPHIC ROM SOFTWARE CENTIPEDE Graphic ROM version of our popular centipede game SPACE INVADERS The only real version of space invaders on the ZX computer Please add 1 p amp p for all hardware Software p amp p free Specify ZX80 8 1 on order ALL OUR PRODUCTS ARE COVERED BY A MONEY BACK GUARANTEE 23 Sussex Road Gorleston Great Yarmouth Norfolk Telephone Yarmouth 0493 602453 4 SINCLAIR USER 1982 ZX 82 will be around soon other personal computer has had the sales
48. ZLE for ZX81 16K Graphics Tests knowledge of Basic Also ANAGRAM Three levels of play Two games on one tape for 4 95 Computatutor 3 Thalia Close Greenwich SE109NA 2 81 MICRO ZX PRINTER 16K RAM ICL Training Manual other accessories for sale all together 115 ono Hardly used perfect working order Contact Leicester 0533 892408 after 5pm 2 81 LARGE KEYBOARD plus case for 25 Brand new un used 4 rubber feet custom built textured case 40 well printed keys Easy to fit Bargain P Ralphs 1 Duxford Walk Moston M 10 9JN NEW GAMES FOR 2x81 have devised something differ ent which you can share For 2 x 15p stamps you will receive a fully detailed list D Rist 31B Kinver Road London SE26 4NT 2X81 PROGRAMS One arm Bandit full screen graphics dis play includes Hold Feature also calculates your money Break the Bank Only 500 ZXCALC Normal Calculations plus sine cosine tangents percentages Only 2 00 Kevin Reed 129 Arnesby Avenue Sale Cheshire M33 2WH 2X81 16K Computer Printer 3 months old v g c new ROM lots of software 175 ono 225 new might split Call 28 Buckhurst Close Redhill Sur Tel Redhill 61612 after 6pm SINCLAIR USER May 1982 PACK 16 1 inch AIR TRAFFIC CON busy airport shown y INVADERS SELF friends and r PACK 16 3 ir l 500 v MASTE iL ONLY 4 95 ALL ONLY 4 95 FACETAS nii The breakthrough you ve waited for
49. ZX81 16K SOFTWARE SPACEINTRUDERS 4 95 by ANDREW HEWSON 4 25 MET ES ue for money SYNC pe lemen PROGRAMMERS th TOOLKIT 6 50 16K RAM 34 95 Copy nimo RAM he me sel 64K RAM 479 00 y and rm ear pe IXEN Cane wed LANGUAGE DICTIONARY 375 1K STATISTICS 375 Cheque with order or quote Access or Barclaycard number to HEWSON CONSULTANTS DEPT SU 7 GRAHAME CLOSE BLEWBURY DIDCOT OXON OX11 5 ar Tel 0235 850075 SINCLAIR USER May 1982 Exploration into t Stephen Adams demonstrates how free space on the Memory map has been utilised make the ZX 81 more flexible HEN Clive Sinclair designed his basic com puter it was to contain only three things within the memory map the area where all the instruc lions to operate the computer are stored The area is easily accessible by the Z 80A microprocessor and it is easy to program uses for it The memory area is divided into 65535 locations 64K by the 16 binary address lines 0 15 which are used to indicate the loca tion at which the processor wants to look Sinclair required only a place to store a program a place to hold instructions to operate the computer when it was first switched on ROM and a location in memory which would translate the TV pic ture So he divided the Memory map
50. al beasts Straightway we hit the first snag Sensible people measure angles in degrees from 0 degrees for no angle at all up to 360 degrees for a full circle You can go further say 720 degrees for two full circles see example Then a right angle is 90 degrees a straight line 42 180 degrees Cut up a square slice of bread to make two triangular sand wiches and the smaller angles are 45 degrees Computers and mathematicians prefer not to measure angles in that way their favourite unit is the radian Draw a circle of unit radius measure unit distance round the edge that gives you angle of 1 radian I will not go into the reasons why this is a good idea but the point is that you must be able to convert from degrees to radians or back again to make use of SIN COS and TAN The crucial gadget to do it is the number 1 3 14159265358 which is the distance half way round the edge of the circle So 180 degrees the angle half way round the full 360 degrees must be PI radians In consequence To convert degrees to radians multiply by PI 180 To convert radians to degrees multiply by 180 1 Here are two programs which will illustrate how this works type them into your ZX 81 and run them Note that PI is key M in function mode if you type P followed by the compuler will not understand denotes space 10 PRINT 11 DEGREES X Pl 180 50 NEXT 10 PRIN DEGRE 20PRINT 30FOR T
51. ane Kinver Stour bridge West Midlands DY7 6EQ Ten games onone cassette A CASSETTE with 10 games to run on the ZX 81 with 18K RAM offers a wide choice Recorded on both sides the cassette offers all 10 games twice but in a different order depending on the side of the cassette used SINCLAIR USER 1982 The games include board and card games such as Othello and Pontoon and combat games such as Laser Bases It also offers Rectangle where the object is to form rectangles with a bigger total area than those formed by the computer The skill in this game form rectangles which are fairly big without having them blocked and at the same time to use your points to block the rectan gles the computer tries to make The user and the com puter take turns to choose a point neither knowing which points the other has chosen unti one calls show The games assem bled on the Cassette Two which costs 5 are avail able from the Michael Orwin ZX 8 Software Catalogue 26 Brownlow Road Willesden London NW109QL Orwin is putting 10 gether Cassette Three which includes a game called Princess of Kraal wherein the princess has to be rescued from a dungeon six levels deep and where you the rescuer having chosen the level of diffi culty time period of the game and type of maze find your way to the rect room via perils includ ing rockfalls monsters and floods The
52. any of the devices which I could continued on page 24 Sinclair s Intended Memory Memory Map O 16K xar x Wen Hardware micro Gon Floppy Joynieks 880 smo nan Memo tech m nom nom ma Floppr disc VO ports mos w s PROGRAMS e s Ec Techno pe 2 sereen Memo graphics 11008 graphics vAnADLES IK oon 10140 P paci Floppy D p ADDRESSES AREIN Pies THISSECTION a M ox 1192 Haven PEEL board Bi Basic ROM s gt SINCLAIR USER May1982 continued from page 23 find plus their addresses They also show by putting into different columns the devices which cannot be used together If have omitted any devices which fit either the ZX 80 or the ZX 81 would people please send me the name and address of the manufacturer and what it does and how many addresses it covers That includes all the ports if it contains
53. appreciate the ability of your ZX8 1 NOW ZX81 MONOPOLY for 16K at 8 00 inc VAT and postage Cash with order from the publishers WORK FORCE 140 WILSDEN AVENUE LUTON BEDS LU1 5HR Ovenvensordes 1 00 PAP NEW ZX81 16K SOFTWARE The Diggles Kitchen Recipe Cassettes Celebration dinners to simple suppers Volume 1 5o pages world wide recipes 4 99 inc P amp P and VAT Volume 250 pages European recipes 4 99 inc P amp P and VAT Special price for two volumes 9 inc P amp P and VAT More volumes to follow Please specify which volume s Mail order only Send remittance 10 MICRO COMPUTER SOFTWARE Unit D6 Pear Industrial Estate Stockport Road Lower Bredbury Stockport SK6 2BP Tel 061 494 2441 SINCLAIR USER May 1982 IWANTED E We ore the major US distributor of hordwore devices and soft ware pockages for the Sinclair ZX computers We con market your product in United States If you hardware developer or software author we want to hear from you We re porticularly interested in Intellectual games Relational dota bases Accounting software ond other business oriented programs COME BY OUR TABLE AT THE 3rd ZX MICROFAIR ond tell us about your product Give us chance to review it with an eye making you sound royalty offer the some time pick up copy of our catalog and our Software Author s Guide MINDWARE co Products that supp
54. assette and users 14AvalonRoad manual Orpington Kent sendlarge S A E BR69AX for details There are only two suppliers of supported 2 81 software this isone of them Coming soon Bank Reconciliation Module a separate program cassette that utilises data Supplied by the main program S A E for full details the only expandable system for the 2x81 The Personal Banking System is also available from the Buffer Shop Streatham London and Branches of the Computer Bookshop Group tuli maintenance stilt ZX81 MONOPOLY Occasionally during the life of a Micro a program is written that can go on to become standard 2X81 MONOPOLY could be such a program Most computer simulations are solitary affairs using a program that caters only for one or two players 2 81 MONOPOLY allows six players to compet with the machine doing all the boring bits acting as board rule book umpire dice throwe accountant No cheatingis allowed and when required a list of a players properties and the development situation for each can be listed No need to worry about missing the rent either yourZX81 is also trained as a rent collector The program is well driven a clear MENU at the start of each players turn and after the dice has been thrown ZX81 MONOPOLY also allows the game to be SAVED with a WINNER far report Th program requires 16K RAM and comes compl with instructions Let all your friends and family
55. beginning of the variables area is held in VARS at locations 16400 and 16401 chapter 28 of the ZX 81 manual Thus the loop at lines 40 to 60 prints the contents of the five bytes which hold the floating point version of the number entered e The first of the five bytes is the exponent E and the remaining four bytes D represents the mantissa If the original number is positive A lies in the range 0 to 127 If it is negative A lies between 128 and 255 The following program re con tructs a number from its Sinclair floating point form 10 PRINT ENTER THE EXPONENT AND THE FOUR NUMBERS OF THE MANTISSA ALLENTRIES TO LIE BETWEENO AND 255 INCLUSIVE 20INPUTE 30INPUT A 40INPUT B SINCLAIR USER May 1982 50INPUTC 60 INPUT D 70INPUT E MANTIS 80 PRINT THE NUM A lt 128 1 2 E 160 256 128 lt 128 B 256 C 6 D those two programs for a variety of numbers You will see that the exponent is about 128 for numbers close to 1 and 1 that numbers close to 0 have small exponents and that large positive and large negative numbers have large exponents Tt is also noticeable that the value of the fourth byte D has little or no effect on the value printed by the second program In computer jargon s called the least significant byte The ZX 81 prints results to eight decimal figures at most rounding the result if necessary although calculations are made to
56. bers held using the technique occupy five bytes each The second method is used internally by the Z 80 micropro cessor which drives the ZX 81 and can be used for whole numbers only Each number occupies only two bytes and a variation of the method is used to store the line numbers at the beginning of each Basic program line To communicate to the user the 2 81 uses a third method the character form in which each decimal digit and the decimal point occupies one byte each All the ques tions this month concern the floating point method The first is from James Tucker of Solihull who asks What does floating arithmetic mean Why use it Would it not be easier to use the decimal system The use of floating point arith metic implies that numbers are stored and manipulated as a mantissa which contains the digits in the number and an exponent which indicates the position of the decimal point It is relatively easy to convert decimal numbers into a decimal floating point representa lion and some calculators can dis play decimal numbers in that form The calculator manufacturers refer tothe form as scientific notation The great advantage of scientific notation is that very large numbers numbers which are very close to zero can be written approximately using a limited number of digits Thus calculator which can display only eight digits at time can display a number larger than 99 999 999 using scient
57. d never otherwise have thought of Hoping that you will maintain the same high quality William Nuttall Lewes E Sussex As you can see points one and three are now taken care of We still thinking about point two What do other readers think Not just propaganda T HOPE that in future you will not merely publish propaganda for Sinclair Research because SINCLAIR USER May 1982 although the ZX 81 is undoubtedly an excellent machine it has its faults and the Sinclair organisa tion still leaves something to be desired An advertisers index at the back of the magazine would be very helpful I wish you every success in yournew venture A Maclure Witham Essex See page 65 for the adver tisement index Monopoly information EXPRESS my thanks for the information relating to ZX 81 Monopoly We were pleasantly sur prised this morning to find an order in our post for it As you are probably aware it is very unusual to Obtain direct response from press release especially so early after the publishing date We wish you luck with Sinclair User and enclose information for your next issue We feel sure our investment will be reward ed with increase in turn over We would ask you if possible to advise your readers that 2 81 Monopoly requires 16K RAM to function We ask it because it was omitted from your editorial and we would rather not take orders which eventually will lead
58. ds in the form of subroutines which are then COMPILED into machine code so that they run faster than their Basic equivalent Forth is available from Artic Computing 396 James Avenue Hull North Humberside joy of real joysticks THERE ARE now proper joysticks with a smooth action and fire button like the expensive computer games machines available for the ZX 81 The joystick is attached to the ZX 81 via controller board which plugs into the back of the ZX 81 and has a connector the back for the 16K RAM pack printer Thejoysticks are used by selecting the movement to High quality joysticks be tested UP DOWN LEFT RIGHT and then using the PEEK command to see the position of the joystick That can give a result between 27 and 114 but it can be altered on the board All the instructions can be in Basic or machine code and the cost of the joysticks is 9 60 each with the controller board costing 129 80 Space Invaders and a Maze game are already available from Micro Gen 24 Agar Cres cent Bracknell Berkshire 0344 27317 Experiment with blank boards BLANK printed circuit boards are now available for experimenting with the expansion bus or mother board of ZX machines They have a gold plated edge connector on them in which only a slot for the keyway needs to be cut they are coated on both sides in copper you can design your own circuit to use th
59. e 2 81 as troller of devices and then etch away the copper at home That leads the way to even more products for the ZX machines as the cost of making experimental boards falls Cambion Electronics produces the board for 3 and can be reached at Castleton Sheffield S30 2WR As easy as drawing on paper THE LATEST device from RD Laboratories for its 8100 system is a light pen which when used with the slow mode of the ZX 81 can impact with the pro gram on the screen That means that drawing pic tures on the screen using alphanumeric characters or plotting using pixels is as easy as drawing them on a piece of paper It can also be used to select from a menu of items as in a multiple choice question without making a mistake by push ing the wrong button All that can take place using Basic or machine code The light pen system consists of a Micro Mum RD8100 motherboard light pen and access unit 808180 plus a free demonstration tape of soft ware The cost is 49 50 from RD Laboratories 5 Kennedy Road Dane Ware SG12 OLU 0920 84380 It is one of the many modules available for the system Redditch sticks with Sinclair REDDITCH Electronics will supply everything from a ZX 80 81 edge con nector to a programmable timer counter oscillator on one board It can also supply motherboards key boards A D and D A con verlers and power supplies as well as
60. e code display hund s ZX ZOMBIES Can you escape from the man eating zombies by leading them into the pits Eight levels of play Very SILVERSOFT NEW NEW NEW Arcade Games attentively m c coded SPACE INVADERS Simply the best yet the closest thing to real Invaders on the ZXB1 Full arcade features including 1 or 2 player option and software to drive the QS character board ASTEROIDS Authentic tation of the arcade game including d fire controls 5 levels of play and alien DROPOUT g new arcade game Can you destroy the aliens uiid up in their column rwhelm you ASTEROIDS DROPOUT 595ea OTHERS 4 95 When ordering 2 or more deduct 1 0 Send SAE for Catalogu Cheques POs payable to SILVERSOFT WANTED E ity Software zxe1 16K RAM Pack gt M 1 software MULTIGRAPHICS 23 rea BRIDGE SOFTW 36 FERNWOO STOCKPORT 5509 F RETAIL SHOP IN LEICESTER FOR ZX81 ACCESSORIES KEYBOARDS RAM PACKS 1 0 PORTS MONITORS GRAPHIC ROMS LIGHT PENS MUCH MORE MICROWARE 3HVMOHOIIA FUN ADVENTURE SERIOUS amp BUSINESS SOFTWARE S A E BRINGS CATALOGUE MICROWARE 131 MELTON ROAD 9 30 am LEICESTER Closed 5 30 pm TEL681812 Thurs MICROWARE SINCLAIR USER May1982 Teaching Sinclair noughts and crosses Philip Joy describes how to make the ZX 81 learn
61. e going to binary 1 and the MREQ going to binary 0 together turn on comecron the 16K RAM pack The A14 signal is combined with the two RD and WR signals so that the output of the NAND gale is binary 0 only when A14 is binary 1 and either signal is binary 0 indicat ing that the microprocessor wants to pass some information to the RAM The output of those gates should be binary 0 from the OR gate which is used to change over two of the address decoders figure two to look at the address lines A7 A13 The reason those address lines are not connected directly to the RAM chips is that they have only seven address ADDRESSES DIVIDER AT A13 OR GATES GATES EI SI JEE 16K TRANSFORMER pins The RAM must therefore be addressed in two stages ROM address and COLOMN address The address lines A13 A7 act as the ROW address and A6 A0 act as the COLOMN address The changeover from ROW address to COLOMN address 15 controlled by the divider chip That chip also provides the REFRESH address used by dynamic memories such as the 4116 16 x 1 bit chips used in the RAM That is because although the REFRESH signal is given out by the processor at the correct time the address given by the Z 80A processor is incorrect because the refresh register R within the processor is used by Sinclair for another purpose putting out the cha
62. ed that if any component failure is found the 10 which kit MAMAS Ci 7 A customers have to pay for ZX 81 to be serviced is returned He admitted that of the 2 4 percent returns of supplied 2 815 around one percent of failure is due to power supply faults an area in which Chatten believes there could well be In fact it is Clive stated aim for a return per centage of one percent overall and it is partly to that end that he recently appointed a quality assurance manager David Fuller While an aim for continued improvement in machine reliability is necessary part of successful business practice the gamble of engaging a company with little experience in electronic assembly seems to be paying off Chatten commented There is some room for improv ment in the assembly process perhaps greater use of automated production lines but on the whole we are very pleased with Timex work LTEXT AND ZTEXT j ZX81 WORD PROCESSORS FOOTBALL MANAGER lower case characters 3 7 zu he ZX printer t icti on the ZX printer Addictive 7 50 g um 4 VIDEO for the pair for AS MANY SEASONS YOU LIKE 4 DIVISIONS amp PROMOTION amp RELEGATION FULL LEAGUE TABLES x X TRANSFER MARKI XINJURIE LEVER OF PL am exciting and highly of Football Manager ing your club here and FREE listing Please stat All prices include VAT and P amp P available
63. ent systems for example Ssinciai 6 Kings Parade Cambridge Cambs CB2 1SN Tel 0276 66104 amp 21282 the ZX Printer for only 49 Designed exclusively for use with the 2 81 and 2X80 with BASIC ROM the printer offers full alpha numerics and highly sophisticated graphics Aspecial feature is COPY which prints out exactly what is on the whole TV screen without the need for further intructions How to order your ZX81 BY PHONE Access Barclaycard or Trustcard holders can call 01 200 0200 for personal attention 24 hours a day every day BY FREEPOST use the no stamp needed coupon below You can pay Atlast you can have a hard copy of your program listings particularly useful when writing or editing programs And of course you can print out your results for permanent records or sending to a friend Printing speed is 50 characters per second with 32 characters per line and 9 lines per vertical inch The ZX Printer connects to the rear of your computer using a stackable connector so you can plug in a RAM pack as well A roll of paper 65 ft long x 4 in wide is supplied along with full instructions by cheque postal order Acces Barclaycard or Trustcard EITHER WAY allow up to 28 days for delivery And there s a 14 day money back option We want you to be satisfied beyond doubt andwehaveno doubt that you will be To Sinclair Research FREEPOST Camberley Surrey GUI
64. ermind and Reversi included it is good value for the nimble fingered Adventure from Simpson Soft ware has its origins in the Crowther and Woods original but is set in a 20 mythical castle containing evidence of an estraordinary mixture of living beings hobbits dwarfs and pirates among others It is a non graphics adventure with 25 logicall y connect ed locations written in 113K of Basic The method of processing instruc tions entered by the player is unusual instead of checking for individual words as most Adven tures do the input string is compared in a large series of if then state ments That makes it reasonably fast but means there is a very limited vocabulary e g you must refer to a Ming vase not just Vase One weak point answers to Yes or No questions are not validated so a NEWLINE stops the program There are plenty of treasures dotted about hidden lower level and a maze into which you can fall A score is kept though my earliest attempts ended in negative scores It is an unpretentious program reflect ed in its price of 3 It would make a good introduction to anyone new to the concept of Adventure who wants to start with something reasonably simple Phipps Associates offers three complete Adventures on one tape plus a detailed instruction program All the games are written in 15K of basic and the first two are based on Trevor Toms Adventure writing program fr
65. est value for money of all the Adventures I have seen so far Next month will examine 12 more programs including the three machine code Adventures from Artic Abersoft 7 Maesafallen Bow Street Dyfed SY24 Hilderbay Ltd 8 10 Parkway Regents Park London NW 7A Bug Byte 98 100 The Albany Old Hall Street Liverpool 3 9EP Serious Software 7 Woodside Road Bickley Kent 265 Simpson Software 21 Tuttles Lane West Wymondham Norfolk Phipps Associates 99 East Street Epsom Surrey KT17 SINCLAIR USER May 1982 Learning BASIC with your Sinclair ZX80 Robin Norman Microprocessors for Hobbyists Ray Coles ook pate prions RO peges Robin Norman 4 50 0408 004142 92 pages 3 95 Coming shortly 26 BASIC Programs Q amp Aon for your Micro best rom io Personal Derrick Daines Computing The 2 81 Basic 1K version facilities offered expansion RAM Sinclair 2X printer origi and for those confused by jargon and who isn t there is glossary technical terms Robin Norman assumes n 0408 00555 6 96 pages perfect rng 0408 01178 5 ORDER NOW from your local bookseller 495 Peter Lafferty Newnes Technical Books Borough Green Sevenoaks Kent ZX81 HEWSON CONSULTANTS ZX81 HINTS amp TIPS forthe
66. f the string handling facilities of Basic Until two years ago Adven ture was strictly the preserve of computer professionals but the growth of micros has resulted in far wider use For this review of Adventure games for the ZX 81 decided to look at every Adventure and Adven ture type game I could find They vary a great deal from the tradi tional descriptive type to real time graphics games so have tried to judge each on its merits rather than compare one toanother My employer told us recently to take Adventure off the computer at work as we were running out of disc space That being such an unreason able instruction checked how much memory it used and found that the program and the data it required occupied more than a quarter of a million bytes So not surprisingly all the ZX 81 games require 16K RAM packs The logical program to start with is the Abersoft Adventure which attempts openly to pack as much of the Crowther and Woods original into 16K as possible As was usually hopelessly lost in the maze in the Adventure at work I was hoping that perhaps lack of memory had forced them to omit the maze from the Sinclair version Not a chance on the first attempt I went straight into it like a homing pigeon The maze seems like quicksand the more you struggle to escape the deeper you sink At that point I asked a friend who had acquired a good knowledge of the original Adventure to try from the be
67. f the 7 80 chop To get back from machine code routine you must end the routine with the code for RETURN ie 201 Then enter the following simple program using the loader Decimal Nemonic Comment 1 Load the BC register 1 LDBC O1 ve Value 1 RET Run the machine code loader then enter 1 Newline 1 Newline 0 New line followed by 201 Newline You will then see in the REM statement two small black squares followed by space followed by TAN all is then well Then delete lines 4 5 20 30 40 and 50 from the program and add line 10 and 20 figure two you then run the program shown in figure two a figure 1 will appear on the screen That shows that your first machine code program has run correctly You have loaded the BC register pair with the value one the program has returned from machine code to Basic success fully and printed the value of which is the value contained in the B and C registers as a pair Those then are the rudiments of machine code writing for the ZX 81 and from these humble beginnings much can be developed Figure 1 T C LET Teter GOTO 4 Figure 2 10 LET R SR 20 PRINT A 1 MMMMMMMMMMMMMMMMMMBMPMBBPPPPDP HMMMMMMMMHHMMMMMMMMMMMMHMMPMMMMMM HMMMM LET T 16514 cus LIST 1 INPUT C 1 REM Sa
68. f the display file 10LET A 0 20 LET E 236 30 FOR C 1 O21 40 FOR 1 TO21 50 PRINT 60NEXTG 70 PRINT 80 NEXT 90 LET G 0 100 LET A 1 PEEK 16396 PEEK 16397 256 110 FOR C 0 TO20 120 POKEA C 1 130 POKE 140 NEXT 22 20 150FOR C 1 TO 21 160 POKE 22 170 POKE A 22 C 180 NEXT 190 INPUT D 195 IF D gt 9 OR D lt 5 THENGO TO 190 200 GOSUB 320 210 IF D 9 THEN 380 2201F PEEK GOTO 190 A F 128 THEN 230 POKE A E 0 240LETE 250 POKE A E 19 260 LET D RND 4 4 270 GOSUB 320 280 IF PEEK A GOTO 280 90 POKE F 128 300 LETG G1 310 GOTO 190 320 LET F E 330 IF D 5 THEN LE 340 IF D 8 THEN LE 350 IF D 6 THEN LE 360 IF D 7 THEN LE 370 RETURN 360 PRINT YOU SCORED 128 THEN SINCLAIR USER May 1982 R ALAXY PATROL written R Goss of Shearing Hill Nottinghamshire places you in command of a galactic patrol ship which bears an uncanny resem blance to the letter V Your V wing fighter starts with 50 gallons of uel which decreases slowly The amount of fuel remain ing is in the top right of the screen the screen printout the fuel figure is 33 You re fuel your fighter by hitting any of the random fuel dumps inverse spaces Each time you run through a fuel dump you receive 25 gallons You control your craft by touching the M key Holding down the M moves you to right lea
69. g or not to your taste there are plenty of books available for the 2 81 Check your local bookshop and find one which suits you Many people feel that the best way to learn is to plunge in at the deep end and see what you can make the computer do Refer to the manual if you have difficul ties You can ignore the functions and calculations initially and experiment with PRINT state ments to get the feel of your machine The beauty of having your own computer is that you can learn at your own pace in the style which suits you best Keeping your programs You lose the program contents of your computer when you turn off the power but you can take a copy of the program because the ZX 81 can reproduce the from instructions you have typed in as coded sound signal which you can record on to ordinary cassette tape When you want to use the program you play it back to the 81 and it translates the coded sound back as your program To record a program you SAVE itand to play it back you LOAD it Chapter 16 of the manuals tells you in detail how to do it You may have problems occasionally LOADing usually with tapes recorded by other people Or way to deal with that is to wind the tape to the middle of the pro gram and type LOAD followed by NEWLINE then slowly turn up the volume of the recorder with the tape running until the television screen shows four or five horizontal black bands If you the
70. ges of pro gramming in ma chine code SINCLAIR USER May 1982 So sit at your ZX 81 keyboard switch on and type it in There are approximately 100 letter Ms after the REM statement to reserve space for machine code When the program is in run it then type POKE 16514 128 do not use a line number this is called IMMEDIATE and remem ber that POKE is entered by pressing the letter O key once What you then see is that the first letter M after the REM statement has changed to a black square The reason is that although 128 is the 2 80 op code for adding the contents of the A and B ers in the Z 80 chip it is also ZX 81 character code for a black square The computer tries to display any number POKEd into the display file Then try the following POKE 16514 124 The black square will have vanished and a question mark is displayed That is because code 124 is not a character code so the com puter displays a question mark instead Then we can enter our first machine code program but previous ly we call a machine code program using the USR function and the Basic statement as follows e g 10LET A USR 16514 That tells the program flow to jump to and execute the machine Code routine starting at address 16514 An additional piece of infor mation which can often be used to advantage is that the value given to the that contained in the B and C registers combined o
71. ginning She found that all the locations and objects were in the correct places although the location descriptions were shorter She even discovered a new area she had not entered previously The program is written in 13K of machine code and 13K of Basic with more than 70 words which can be recognised as commands or objec and a large number of locations The game has been written with remark able efficiency location descriptions are built up from individual words and phrases rather than stored en bloc Being machine code the pro gram is very fast At any time you can find your score and also save your current position on tape to con tinue later At 10 it is an expensive program but it isa remarkably good version of the original Adventure and well worth the money if you want to see what sparked the entire process Hilderbay is best known for being the serious software company supplying business programs but it has also forayed into the world of games and its Gold is a non graphics 13K Adventure written in Basic The object is to search for gold hidden in network of caves and mines in the Yukon All instructions are entered as a single letter O for Open G for Get including references to objects such as Gold and Keys There is a sizeable network of logically connected caves and rooms although there are few objects If you manage to find the gold things change mysteriously and I have not been able to extract
72. he 2 81 42 BEAMSCAN Beam analysis for architects and engineers 25 APPLE Ii Payroll 35 HEWLETT PACKARD 9845B Superspline general purpose interpolation and tabulation COMPETITION MEMOTECH64K Memopak 79 WINA 64K MEMOTECHI DO YOU HAVE DIFFICULTY LOADING TAPES We have the answers and for well under 10 or ames ak d Contact us for more details A64K Memotech will be sent tothe CROFTON PROFESSIONAL KEYBOARDS MONITORS VDU s Player who sends us the highest Prices include VAT Post amp Packing COD Orders 2 extra ED prizesof blank cassettes for your programs TAPE HINT Don t use the first 20 seconds of your cassettes most tape problems are found near the ends of the tape HILDERBAY LTD 8 10 Parkway Regents Park London NW1 7AA Telephone enquiries for Hilderbay Ltd will now be handled by HOLDCO LTD Tel 01 251 3090 ZX81 amp 16K SOFTWARE EQUATION PACK linear and quadratic equations sets equations of higher degree 8 MATRIX ROUTINES the matrix statements of normal basic MAT 8 CALCULATOR PACK the equivalent of RPN calculators 40 operations and functions 8 ELEMENTARY 5 mean variance stand dev stand err covariance corr coeff anal of variance lin regression 10 METRIC IMPERIAL US CONVERSIONS length surface volume weights and measures speed 6 TRIANGL
73. hit a mine the tank blows up and you must try again with the next tank They are multiple mines and will destroy every tank which hits them Your score is displayed at the top of the screen If you are success ful in finding a way across the pro grams stops You will find you become profici ent at avoiding the littered battle field as the game progresses The program was adapted by Tim Hartnell from the original program written by 1S Howson 015 Howson 1982 SINCLAIR USER 1982 NGULF is for the 1K ZX 80 by Charlton of Rise Park Romford It sets you against a vengeful computer After you press RUN large black square will appear That is the playing area You have five controls UP DOWN LEFT 8 RIGHT 9 SCORE After pressing 5 6 7 or 8 followed be NEWLINE you will appear as an addition sign with an inverse space CHR 128 next to it Every time you move the computer will place a black square next to your piece The idea is to avoid being trapped or engulfed as long as possible Once you have been caught press 9 10 see your final score Charlton s best score is 154 You can make the game slightly easier by deleting line 280 which prevents the computer placing a black square where a black square already exists The game shows PEEKing and POKEing to the display file in action The crucial line is 100 which finds thebeginning o
74. ific instead of ordinary notation For example the distance from the earth to the sun is about 5 892 480 000 000 inches Thirteen I HAVE had many letters in recent digits are required to write the number in ordinary notation but when it is re written in its scientific form as 5 89248 x 1012 only eight digits are required neglecting the x 10 which is common to all numbers written in that way The mantissa is 589248 and the exponent is 12 The exponent by the way means imagine that the decimal point is to the right of the left most digit of the mantissa i e between the 5 and the 8 Now move the point 12 places to the right filling spaces with zeros if necessary The scientific form of course is not accurate because only eight digits of which six only are in the mantissa are allowed whereas in the ordinary form 13 are available although in our example the extra d are all zeros We count in tens and so calcula tors display numbers in decimal for our convenience Digital computers count in binary as explained in chapter 24 of the ZX 81 Basic pro gramming manual but the principle of floating point binary representa tion is the same as that of decimal scientific notation The ZX 81 uses a n zeros and one for the one byte with one bit reserved for the sign of the expon ent and a string of 31 zeros and ones for the mantissa four bytes with one bit used for the sign of the mantissa Floating poin
75. information downwards the Sinclair menu gives only a scroll up So machine code can be packed tighter run faster and produce more imaginative effects outside the manufacturers original Basic instruction set Machine code is a set of numeric instructions called bytes eight zeros or ones in any combination which when addressed to the Z 80 chip central processing unit make it perform some sensible function The Z 80 would not understand a Basic instruction such as PRINT directly A very complex piece of machine code called the Basic Interpreter breaks PRINT into numeric instruc tions for the Z 80 chip to produce the required effect from the com mand PRINT Those hexadecimal codes number base 16 for convenience are listed under Z 80 Assembler in the ZX 81 Manual pages 181 to 187 Itseems a little daunting but really the fundamental things you can tell the Z 80 chip to do are really simple but the overall effect can be very powerful Here is a summary of the main things you will ask the Z 80 to per form during a machine code pro gram you ask it by simply feeding it the appropriate code Add one to the contents of regis ter called increment A register is somewhere in the chip where you can hold a number value to do some thing with it Take one away from the register decrement Save the contents of the register elsewhere so you can use that regis ter for something else Push Bri
76. ingle letter com mands and the beast continues to move of its own accord while you decide what to do The game is not desperately fast and while in progress there is little to look at although you are provided with a map of the events at the There is no score given but there are three levels of play and found even the easiest of them difficult enough It is not game for Space Invader addicts but if logic and patience are your virtues it is one to consider It ison the expensive side at 6 50 Quest from Serious Software is clearly based on the non computer Dungeons and Dragons fantasy role playing game with the computer man pitting his strength constitu tion and dexterity against wandei ing monsters It is a non graphics game written in 123K of Basic and is made up essentially of vampires rats werewolves and suchlike If you can keep the fiends off your back for long enough there are potions keys and other objects to be found and substantial amounts of treasure to be acquired Movement and fighting is done by single key input which can be con fusing since the same key may mean different things depending on what is happening around you e g F may mean move Forward or Fire magic arrow You can always ask for a status report and if you can put together sufficient treasure the delights of different levels are offered My reactions cannot cope with this one but at 5 95 for Quest plus a Star Trek Mast
77. into three sections 0 16 for the ROM 16K 32K for the program RAM and 32K 64K for the TV pic ture That was done by using only the top two address lines A14 and A15 to tell which section was rating at the time This divided the Memory map into the four sections as shown in figure one with the ROM and RAM repeating itself again and again address line A14 is used to turn on the ROM when the condition is Binary 0 and when it is Binary 1 the RAM is turned The A15 Address line is used to operate the hardware which puts out the TV picture it operates only when A15is Binary 1 As A14 can also change state from 0101 while A15 is operating the hardware the RAM can be used 10 store the screen display The soft ware in the ROM makes use of that fact and has only to pick up the where the screen is between 16K and 32K and then add 32K toittoputit on the TV screen Theonly problem with this system is that ROM between 32K and 48K cannot be used as it would upset the TV picture It also meant that the ROM appeared in the 8K to 16K section blocking out any other use for it as it could not be turned off That was the situation which existed in the ZX 80 and only inter nal modifications to the computer circuitry could sort it out The only place left to put new devices produced by other manufacturers was to steal some of the RAM space to fit in the new device That was done by turning off the RAM
78. issa 30 PRINT 40 INPUTI 50PRINT 60 PRIN 70 PRINT E 80INPUT 90 PRINT YOU ENTERED 100 LET K 1 10 IS K T lt 0001 K THEN WRONG 150 PAUSEN 160 RUN 170PRINT 180 PRIN 190 PAUSI 200 CLS 210 PRINT REPRESEN 2201 230 GOSU 240 PRIN 250 LET M 19 260 GOSUB 300 300 FOR L 310 PRINT PI 16401 L 320NEXTL 330 PRINT 340 RETURN 1f you wish to avoid problems of that nature then you should alter statements like THENGOTO 170 to IF ABS K lt 0001 THEN GOTO 170 In the first case the program will jump to line 170 only if and J are identical down to the last digit In the second case the jump will be made if the difference between and is less than 01 percent Copyright Hewson Consultants 1962 15 HILDERBAY LTD PROFESSIONAL SOFTWARE Ifyou don t believe that the Sinclair 2 81 can doreal work come and see usat the Computer Fair Exhibition Earls Court 23rd 25th April and the ZX Micro Fair Central Hall Westminster London SW1 30th 151 May 2X81 amp 16K SOFTWARE Reviewed in Your Computer Feb 1982 Payroll for up to 30 employees Meets all regulations 25 Stock Control Fast big and versatile 25 Budget 15 Critical Path Analysis Up to 500 activities 15 VAT amp Mortgage amp Loan 8 GOLD Areally good adventure together with the intriguing Picka Word 8 RELIABLE 16K RAM Pack for t
79. it caves and wandering round long abandoned mine workings Adventure is for you Your powers of memory logic and patience are tested to the limit as you take life and death decisions in your search for fame and riches all without leaving the comfort of your chair and with only one risk to your physical well being That is a severe headache after bashing your head against the wall then your latest seven minute Adventure failed to load for the fifth time Adventure is a role playing game where after being told about your immediate environment you enter commands such as Go west Take keys Throw knife The computer will then provide an appropriate response such as a new room description You missed some other message You many encounter fabulous treasures or perhaps only mundane objects although they may if used correctly be the key toa still greater fortune You will probably need to make a map as you proceed to have some chance of re tracing your steps to the entrance Natural and unnatural hazards abound to prevent your escape and it should take many delvings to discover all that an Adventure contains Computer Adventures are a surprisingly recent invention the Original having been written on a mainframe in 1976 by William Crowther and Don Woods at Stanford University in the U S It is a remarkable achievement when you consider that until recently Fortran the language they used had none o
80. k the aerial lead for loose connections If all that fails try another set before you send for a replacement It can save family arguments if you can afford a separate TV for your 2 81 you can buy a cheap portable set for around 50 or Oblain a second hand one even more cheaply Similarly it makes life easier if you can find a corner somewhere to leave your equip ment permanently set up unplugged You will find that you use a few power sockets for your system and a four way block con nector on a short length of exten sion cable helps to tidy trailing leads Talking to your ZX 81 The ZX 81 like a pocket calcu lator understands numbers and signs like plus and minus It is far more sophisticated however than a calculator and can also cope with letters and words those on the keyboard provided they are presented in the proper way A calculator follows the rules of arithemtic the ZX 81 uses an artificial language designed for X812X812X812X812X812X812X812X81ZX81ZX81ZX81ZX81ZXB1ZXB1ZX81ZX81ZX81ZX81ZX81ZX81ZX81ZX81 2 812 8128 50 SINCLAIR USER May 1982 3122 812 812 812 812 81 computers called Basic There are many computer languages but Basic is good general purpose one fairly easy for non computer specialists to learn and found widely on microcomputers Most manufacturers have their own slightly different version or dialect of Basic and Sinclair is no exception What this means in
81. lement nature s computer 70 BOSTON POST ROAD WAYLAND MA 01778 USA 61 358 7175 Finding out about The trig functions on the ZX 81 are generally regarded as the least used on the machine Here Ian Stewart looks into the mysteries of SIN COS and TAN Y DICTIONARY claims that M SIN is moral depravity COS acurly variety of lettuce and TAN a colour caused by exposure to sun can imagine computer pro grammers engaging in acts of depravity with a lettuce on the Costa de Sol but doubt if they would admit to it underneath the W E keys of a ZX 81 keyboard So that is not the explanation They are of course FUNCTION keys What is a function It is some thing to which you give a number and then it gives you back another number Try typing PRINT SIN 14423 on your ZX 81 in command mode it will print you out a number In general for any number A you get back certain numbers SIN A COS A and TAN A but for what are those outlandish things A schoolteacher would call them trigonometric functions a fussy word for things used to measure triangles Surveyors use them of course but need anyone else bother with them The answer is that they must and the reason is that they are very wide ly applicable Fortunately you can learn some of their uses without undertaking an uninteresting course in trigonometry Radians SIN COS and TAN are really about angles and angles are funda ment
82. lly make themselves known fairly quickly It also possible for tapes to be pro cannot be duced which load perfectly with some recorders but which cause pro gram corruption similar to that pro duced by faulty memory chips or simply refuse to load with others t is more common with dupli tapes than with recordings REFRESH YOUR WHICH MICRO amp SOFTWARE REVIEW 4 n THE ATO Z OF MICROS 5 Revie SINCLAIR USER May 1982 Ew direct from the ZX 81 In the short term reliability is improved by load ing at the highest possible level In the longer term such tapes must either be re recorded by the user or replaced by the supplier The choice isthe user s The most serious problem with the ZX 81 has been the sudden loss of all the contents of memory That is due almost invariably to the connec tion between the ZX 81 and the Sinclair RAM pack The RAM pack plugs into the ZX 81 but has two feet when the keyboard is used the RAM pack and the ZX 81 move slightly relative to each other One of the 43 may be interrupted with catastrophic the contents of connections momentarily consequences for memory A number of ways of circumvent ing the problem have been publish we will not repeat them The best solution is to use a RAM pack which employs a tight connector of high quality with gold plated tacts and which does not in anyway touch the surface supp
83. loads the pro damaged a meteor absorbing as previous lities such as automatic gram varibles only storm It is satisfactory to Orwin cassettes and will posting on the statements Personal Banking bea survivor but you have available from Michael of all standing orders due System is available for torepairthedamagetothe Orwin 26 Brownlow Road monthly quarterly six 9 95 inclusive of cassette ship before the total air Willesden London NW10 monthly or annually and and user manual from level drops below 3 000 9QL 2 81 SOFTWARE FROM VIDEO SOFTWARE LTD 1K amp 16K 16K SOFTWARE PRICE NEW VIDEO INDEX NEW VIDEO SKETCH 2X81 only Move the cursor to any Q How do you store 57 000 characters in a 16K RAM part of the screen Draw or rub out as you move it Mix in Use VIDEO INDEX text or graphics Save picture in memory Save picture Catalogue your cassettes your record collection references 10 magazine articles Amazingly versatile Capacity for 1 000 individual references each of which can generate 57 characters of text Powerful search facilities once the index has been created How is it done The system cannot really fit 57 000 characters in 16K RAM It gives the illusion of doing by eliminating duplicates For instance an index of articles computer sequence on cassette 7 95 VIDEO PLAN 2X81 only Performs the function of an analysis book Arithmetic functions include addi
84. loration into the memory map can bring new joys rom your ZX B1 2710K RAM Sinclair s 16K RAM opened up new world to user Stephen Adams looks at its capabilities T PAGES OF PROGRAMS Let your fingers do the work Key in our ections of programs There is one there for ZX 80 owners COS and TA 48 MACHINE CODE Moving on from Basic Then this is the serios of articl for which you have been waiting machine code explained in simple Engli SOSTARTING FROM SCRATCH If you have just bought your ZX4M don t panic read our guide to help you understand the system quickly S3INSIDE SINCLAIR Writer Lynd Church and photographer William Sc ke the high road this time to D tofind how the ZX 81 is manufactured 57 BUSINESS Mike Salem continues his series explaining why the ZX 1 be used todo some business applications 60 COMPETITION Don t miss the chance to win a Sinclair printer in part our competition 61 BOOKS Publishers and authors are still producing books galore on the Sin clair machine We read another selection 65MIND GAMES This month Philip Joy gets to grips with noughts and 65 ADVERTISEMENT INDEX Due to popular demand we have started to include an index to help you find the advertisements you specifically want NEXT MONTH The ZX Spectrum analysed indepth Who is THE WINNER OF OUR FIRST COMPETITION Anindepth look at graphics software Now with repeat key facilities to add a numeric pad ZX 80 81 HARDWARE SOFTWAR
85. n re wind the tape the pro gram should load normally at the volume Carry on computing Finally a health warning Apart from any practical uses comput ing with your ZX 81 can bea very entertaining hobby and is almost certainly habit forming You may easily find yourself crouched over your machine red eyed in the early hours of the morning thinking that in another five minutes you will sort out the problem Try to break that habit by getting into the fresh air and meeting other Sinclair users it undoubtedly will help your pro gramming and your non com puting friends poor souls will probably be sick to death of hear ing about computers by that time case By getting a ZX 81 you will find you have joined a not very exclu sive club with many thousands of members many of whom would be only too happy to advise you if you have problems Sinclair User will help you to get in touch with other users by printing a list of clubs each month 12 812 812 812 812 812 812 812 812 812 812 812 81 zx 81 zx 81 zx 81 zx 81 zx 81 zx 81 zx 81 2 81 zx 81 zx 81 zx 81 zx 81 zx 81 zx 81 zx 81 zx 81 zx 81 zx 81 zx 81 zx 81 zx 81 zx 81 zx 81 zx 81 zx 81 zx 81 zx 81 zx 81 zx 81 zx 81 zx 81 zx 81 zx 81 zx 81 2x 81 2x 81 zx 81 zx 81 2x 81 8122 B1ZX812X812X812X812X81ZX81ZX81ZX81ZX81ZX81ZX81ZX81ZX81ZX81ZX81ZX81ZX81ZX81ZX81ZX81ZX81ZX
86. ncludes UK p amp p to LINSAC SU 1880907211011 Price 7 95 2 3 95 Er 5 95 f Fr Ater 2 95 Uh pr Stare RAM pack rg assembled tested ond coved Frut Machine 31 50 ine PAP and Pontoon 21 days deivery Space Rescue 3070 gt Connect Four 15 95 Assembly 81 55 Assembly 8 95 Wen 1870 trm No whatsoever moditicatons v supplied on Dep 50 28 Spiers Close Knowle the widest range available from one supplier SINCLAIR USER 1982 More software delights 7 for your machine Making maths easier A PROGRAM which appears to def y the rules of mathematics has been add ed to the Video Soft ware range of serious software for the ZX 81 Called Video Index the maths defying element is the fitting of 57 000 charac ters of data in a 16K mem ory which is achieved by an ingenuous technique whereby duplications of descriptions are detected and eliminated Written largely in mach ine code for speed Video Index provides a technique for using the ZX 81 to build a catalogue or index which can be stored on cassette and re used The program which is supplied with a demonstration index of computer magazine arti cles about the ZX 81 costs 9 95 and can be obtained from Video Software Stone L
87. ng back the saved value into the register Pop Carry out a machine code routine somewhere else then return to the same point in the program Call and Return Jump backwards or forwards a number of instructions if a register or pert of a register is not zero Jump Relative No Zero jump backwards of forwards a number of instructions if a register or part of a register is zero Jump Relative Zero Load registers with specific numbers They appear to be the build ing bricks of computing power but they are To put machine code into a ZX 81 write a single byte instruction to an address in the memory The POKE instruction takes the general form POKE 1651412 Address Instruction Code The POKE instruction operates on decimal numbers so that all the hexadecimal codes must first be converted to decimal before POKE ing them into the computer memory The decimal code 12 instructs the 2 80 chip to increment add one toits C register The most suitable place for the code it is generally agreed is within REM statement placed at line 1 of the program The machine code loader figure one POKE your machine code into spaces after the REM statement addresses 16514 onwards Easy to a powerfu Mike Biddell begins a series of articles aimed at explain ing in the simplest SINCLAIR USER May 1982 issemble il bricks possible terms the advanta
88. nly one man knows the answers to these questions and he is keeping his mouth firmly shut at moment Let s now look into our crystal ball to see if Clive has anything planned on the software front Clive at one time sold his software in Smiths but because of a high proportion of returns Smiths did not re stock after Christmas That rebuff certainly stung Clive as he is as aware as anyone that there is gold in that there software There seem to be two main options open 0 him Either to develop the software within his organisation or get into bed with an established software company He does not appear to have the resources available to develop his own software and a thorough examination of our crystal ball shows Clive in deep conversation with more than one software company and that a deal could be imminent for new ZX software There are however two stumbling blocks One is the name under which the product would be marketed Respected companies which have been or are about to be given the Smiths seal of approval would want to cash in on their success and continue to market under their own names Clive would probably want the products to carry only the Sinclair tag Second the software companies might well afraid that Sinclair has once and for all blotted his copybook with Smiths as a result of his not very successful first attempt thereby preventing any chance of rich pickings in the high street stores Neither of
89. nted the ROM from being turned on The only solution to the problem was to cut the connec tion to the pin within the pack leaving it unconnected to anything within pack People could then from the side of the computer free some space in the memory map for their use That was a great advantage as many of the people who had bought the ZX 80 ZX 8i did not want to have to fiddle inside their precious computers with a soldering iron for fear of damaging them SINCLAIR USER May 1982 memory he memory map It left many firms which had cut try to use the same areas for differ problem as previously that one port their teeth in the ZX 80 with a vast ent uses Also because the ZX cust covered more than one memory market for adding additional boards omer was not willing to pay location some cover up as much as to the ZX 81 which could greatly a great deal for any extras That of course means that when expand its flexibility and use Many to his machine costs had to one device is using that area no of the people who started in the be cut to fit the market So other devices can be used at field nowlefttheir original jobs they took a tip from Sinclair thesame address to work full time producing add on boards for the ZX machines It also led every manufacture to and reduced the amount of lines they used for addressing That meant that we had the same Figures two three and four show as m
90. ntroduce a little luck into the game a lid appears at random places above the box If theball hits the bottom or the lid the game ends and your score is printed HIRTEEN YEAR OLD Chris topher Lowe who lives in Edinburgh says of his pro gram Large Letters which fits a 1K ZX 81 that it will allow you to obtain an enlarged version of any charac ter ordinary inverse as in th sample printout or graphic Keywords or function commands are not possible The program just squeezes into 1K using such tricks as line 40 to do so To obtain a print out of your words insert the follow ing lines 215 COPY 235 COPY And change line 190 to 1901F LEN M lt 9 THENGOTO 235 tober 1981 issue s copyright Christopher SINCLAIR USER May 1982 INOUGHTS CROSSES o tJ 2 81 users need more memory please rush me the fully assembled tested and guaranteed BYG BYTE 16K RAM PACK Make all cheques amp PO s payable to Phoenix Marketing Oaklands House Solartron Road Farnborough Hants Tel 0252 514990 FULLY INCLUSIVE PRICE 34 95 1 6K JRS SOFTWARE Address AVENUE WORTHING TELEPHONE ant evenings and Weekends oniy 16K RAM 35 969 95 ELIMINATE MACHINE CODE PROBLEMS DEBUG e SAVE amp LOAD vow n ams AT DOUBLE SPEED o REGISTERS DISPLAY amp BREAK
91. om his book The ZX 81 Pocket Book Several months ago typed in the program and was impressed but felt that it would be too difficult to use and that the range of locations and objects would be too limited The Phipps tape proved me wrong Greedy Gulch is set in a Wild West ghost town with more than 20 loca tions plenty of objects which have to be collected and used in a logical sequence and a vocabulary of more than 50 words It is not particularly fast around 10 to 12 seconds to pro cess instructions but it has some graphics in the form of a simple but useful map There is no score but to compensate there isa hint feature The second is the non graphics Pharaoh s Tomb which has more than 60 locations made possible by giving only short descriptions and more than 20 objects It runs slightly faster than Greedy Gulch despite an even larger vocabulary and has a score but no hint feature It shares with the first program some poor spelling although Phipps Associates is by no means the only culprit where that is concerned Magic Mountain has witches wizards and spells and an assort ment of mystified objects It also has maze which as usual discovered very quickly It took me a solid guilt ridden hour of cheating to get out despite using one of the hints avail able in the form of cryptic cross word type clues All three programs are excellent Adventures and at 5 95 complete they are undoubtedly the b
92. orting the 2 1 The final problem is saving and loading programs That can be done very reliably using simple and inexpensive equipment and tech niques Use a mono not stere portable cassette recorder known to be suitable it need not be expensive Try to adjust or to have adjusted the head azimuth angle Make sure that your leads are in good condition Use good quality tape C60 or shorter special lape is mot necessary but do not use bargain tape although it will in most cases work Make duplicate back up copies of important programs and data Use a special loading meter when loading cassettes of unknown properties computer Clean the heads frequently and check them for wear as this is a problem One or more ZX 81s can be used as dedicated machines running 24 hours a day Occasional tape back ups should be made the recording can be started just before a tea break for example If the power supply is less than 100 percent reliable 8V worth of heavy duty re chargeable battery with trickle charge the solution While the ZX 81 becomes per ceptibly warm overheating does not seem 10 be serious problem it is possible to use a true 8V supply rather than the 9V nominal 11V actual of the ZX 81 supply The ZX 81 can be made to operate very reliably The expense and trouble involved is not great certainly far less than that involved living with an hopelessly unreli able system will be
93. ounty s population number of PROFILE naure and Current SHOPPING of varous products 1 BASKET ogether the RPL and A BUDGET DAY INFLATION and UNEMPLOYMENT tc You have the opportunity to make changes to the varus TAX RATES and BENEFITS the tom the Profle and Shopping Basket should be useful to you m the preparation of yow BUDGET REFORM introduce SOCIAL REFORMS OPPORTUNITY yourself POPULAR pick your reforms wisely and watch AT THE END OF EACH YEAR THE COMPUTER WILL PROCESS THE DATA INPUT DURING THE PERIOD AND WILL ADJUST THE MAJOR INDICATORS ACCORDINGLY A TELLING TIME Jnyour Sth years GENERAL ELECTION must ta ELECTION Results will come in dunng the right for each o the Parties willbe incremented accordinghy yox have sufficiant majority you willbe asked continue i Othe fora further TERM IF YOU ACHIEVE MORE THAN 5 TERMS WOULD BEINTERESTED TO HEAR HOW YOU DID IT The Game is called GREAT BRITAIN LIMITED and avaiable on cassette with erased instructions at only 4 98 rom 72 81 SIMONW HESSEL Depts 16K osten Service ather games on request last mont S U re INHERITANCE Fal Money Bat orante Watch for Phil Garrett tries to guide you through the world of adventure games in this the first of two fascinating articles on the subject F YOU enjoy delving into rat dungeons crawling through dimly l
94. p INSTRUCTIONS SPECIAL OFFER Both tapes supplied together for just 10 00 Only 5 50 We may have other games ready by the time you read this S A E for details All our prices include UK postage European customers please add 20p per tape elsewhere please add 50p per tape MAIL ORDER ONLY An advanced spreadsheet program for the Sinclair ZXB1 with T6K RAM This versatile software allows manipulation and inspection of data in the most convenient way ever Ideal for financial planning personal budgeting cashflow analysis and count less other business home scientific and technical applications The screen acts as a window on a much larger grid up to 38 38 of titles and numbers up to 9 digits Change one number or formula and dependant results change auto matically Save on tape or printout for a permanent record Tasks that would take hours with pencil paper and calculator be performed seconds with COMPUTACALC ZX For cassette and full documentation send 7 95 to Silicon Tricks Dept S2 2 4 Chichester Rents London WC2 1EJ Tet 01 603 6074 SINCLAIR USER May 1982 ADUIT GAMES 1K ZX ROYALFLUSH REAGAN 1 mE i BIBLE BAME Pur Microgame Simulations Soccer Supremo Run ucing widgets and compete in Start small and ig You have provided May tandard grid per Compete again popula All prog
95. pieces Adding the 16K RAM to your basic kit certainly makes the ZX 81 even more interesting Here Stephen Adams dissects the kit and finds it now over priced pack was designed originally used only two lines to decode what devices to turn on within the memory map Three devices are used in the ZX 80 memory map the RAM both 1K and 16K the ROM and the screen display The maximum number of devices which can be turned on from two binary ADDRESS lines is four Sinclair uses the line A14 to turn on both the RAM and the ROM The RAM is turned on to it by using binary 1 and the ROM when it is binary 0 The screen display is turned on when 15 is binary When the count is 4 or binary 11 both the RAM and the screen display are on and that is the only time the display is sent to the TV The RAM therefore exists at two places on the memory 16K 32K A15 20 and 48K 64K 15 1 As the 16K RAM continued on page 28 continued fram page 27 pack had to take over from the 1K internal RAM it had to use the same addressing system The address decoding is shown in figure one The RD and WR signals go 10 binary 0 when the Z 80A micropro cessor wants to talk to any device Which one goes to binary 0 depends on whether it is a ReaD or a WRite operation The MREQn signal is called Memory REQuest and tells the device it wants to look at the MEMORY MAP The A14 ADDRESS lin
96. practice is that a program a series of instructions to the com puter written for one machine will not work on another without some modification but if you understand Sinclair Basic you can soon learn the minor peculiarities of other versions and with a little practice adapt them for the 2 81 You do not need to wait to learn the language to start You can copy the programs you find in Sinclair User A word of warning Make sure you copy them exactly You may understand a sentence with a comma or a quote omitted but your ZX 81 relies on those cues and the program will not work without them For that reason it is a good idea to SAVE a program on cassette tape before you press RUN and NEWLINE to make it work That way if you have made a mistake and you lose the program from the computer you can LOAD it back quickly from the tape and look for the error without having totypeitin from the beginning SINCLAIR USER 1982 Youcan also buy a wide variety of commercially produced pre recorded programs on cassette They can vary a good deal in quality and you will need to read the reviews and use your judgment to choose the best A good deal of the interest and fun of having your own computer is in writing your own programs which is easily as fascinating as playing even the best game of Space Invaders written by some one else The manual deals thoroughly with Sinclair Basic but if you find it heavy goin
97. programs The cost of the reduction in chip prices ZX 81 amp 80 OWNERS ACCESS TO THE OUTSIDE WORLD Programmable INPUT OUTPUT Port based on ZBOAP10 giving up to a total of 16 programmable 1 0 lines all TTL compatible Port is NOT memory mapped allowing full expansion af memory Canbe used WITH or WITHOUT RAM PACK amp PRINTER Available in kit form or assembled and comes complete with instructions software notes and cir 13 50 inkitform 15 99 assembled INCLUDES VAT ADD php it ideas NEW ENCASED 4 CHANNEL RELAY BOX toaddon to 1 0 Changeover contacts rated at 240vAC 1 5A 11OvACor 24VDC 3A Allowing programmable control of mains for motors and lamps etc 1499 complete SINCLAIR USER May 1982 ZX81 GAMES FED UP WITH BEING RIPPED OFF HAVE YOU BOUGHT BORING WORTHLESS RUBBISH GAMES DON T DESPAIR TRY THESE KALEIDESCOPE only 3 95 PROBABLY THE BEST VALUE 1K TAPE AVAILABLE ARTIST GAMESTAPE fo GAMES MARKED Machine Code J K GREYE SOFTWARE Dept SU 16 PARK STREET BATH Avon BAI 2 Trade enquiries welcome CASSETTE ONE for 1K ZX81 CASSETTE TWO Ten games in Basic for 16K ZX81 INVADERS 1k 1 had your Invaders React cassette was delighted with this first cassette P Rubython London NW10 PHANTOM ALIENS AY 1 have been intending to wri
98. racter set The dynamic memories must be refreshed within a certain time or the data will be lost The refreshing is done by the chip by reading out the bit and then writing it back again but needs to know what data location within the RAM to next The data lines from the chips are not buffered they can be placed only a short distance from the com puter without causing problems The data lines within the computer are also protected by resistors so any extra loading on to the expansion port to use other equipment must be buffered The 4116 RAM chips used in the design do not require only a 45V supply they also need 12V and 5V The 12V supply can be replaced with 9V and it just works but the 5V supply has to generate in a different way A transformer is used figure two along with a transistor to form an oscillator driven from the 49V supply The transformer then steps down the voltage created by the oscillator to SV As both sides of the transformer are isolated from each other the voltage can be rectified into DC voltage with the positive terminal connected to the OV line That is then passed to the RAM chips alone as the current generated is very small The transformer also continued on page 20 SINCLAIR USER May 1942 s continued from page 28 creates the characteristic humming orbuzzof the 16K RAM pack Since Sinclair produced the RAM pack memory RA
99. rams 16K for 1 player 4 95 for 1 8 90 any 2 12 85 3 16 80 4 Please send cheque PO to 73 The Broadway Grantchester Cambridge olution How long can you stay in FOR THE 16K 2 81 UNBEATABLE VALUE CASSETTE OF 8 PROGRAMS 50K For fun and fortune no programming knowledge needed ONLY 5 DIRECTORY OF 350 SUPPLIERS SOFTWARE ational Busin t and Domesti ve list of HARDWARE items for sale Index of ZX PUBLICATIONS ferences ti views of ZX ware USER CLUBS when and where to meet Price 2 95 from YOUNGS ZX REGISTER 2 Woodland Way Gostield Halstead Essex CO9 1TH Th youw We can also arrange for you to be on PRESTEL EO x SINCLAIR USER May 1982 2 81 16 SOFTWARE STARTREK 16K STARTREK Exciting space adventure game including klingons starbases phasors 8 x 8 galaxy 4 levels of play long and short range scanners etc SUPER WUMPUS 16K SUPER WUMPUS Can you hunt and mysterious wumpus in his underground labyrinth ing underground adventure GRAPHIC GOLF 16K GRAPHIC GOLF Test your golfing skills on SILVERSOFT S 18 h rse Many hazards includ ing lakes trees streams GAMES PACK a 16K GAMES PACK 1 Fo for mone of programs on on 3D MYSTERY MAZE 16K 3D MYSTERY MAZE Amazing three dimensional maze Walk through the maze in 3 dimensions ultra fast machin
100. re are some bonuses on the way but the princess is undoubtedly difficult to find Galaxians invade WHSmith A VERSION of Galaxians the popular arcade game is now available to ZX 81 users through W Smith Called predictably ZX Galaxians it requires 16K of RAM and offers person alised high scoring rou tines swooping attackers full explosions and contin uous status reports The originators Artic Computing believe that it was chosen by W H Smith because it is exceptional Written in machine code the game runs smoothly with no flicker on the screen mostly because it ses pixels which split the characters in two W H Smith is selling Galaxians on a cassette at 495 which includes a dungeons and dragons ran dom adventure game Swords of Peace Artic Computing can be contact ed 396 James Reckitt Avenue Hull North Humberside Helping wit machine code AN EFFECTIVE tool for the speedy development of 2 80 machine code rou lines entails a number of procedures which will facilitate loading as well as check and query errors Developed by Michael Cox Information Services the Load and Edit programs form a suite which retails at 8 90 and is intended for use with a fully debugged machine code program The procedures require you to draft your routine manually listing Assem bler mnemonics and for the instruction codes the relevant hex code Using
101. splay facilities Multi dimensional string and numerical arrays Up to 26 FOR NEXT loops Randomise function useful for games as well as serious applications Cassette LOAD and SAVE with named programs 1K byte RAM expandable to 16K bytes with Sinclair RAM pack Able to drive the new Sinclair printer Advanced 4 chip design micro processor ROM RAM plus master unique custom built chip replacing 18 2 80 chips Kit or built it s up to you You ll be surprised how easy the ZXB1 kit is to build just four chips to assemble plus of course the other discrete components a few hours work with a fine tipped soldering iron And you may already have a suitable mains adaptor 600 mA at 9 V DC nominal unregulated supplied with built version Kit and built versions come plete with all leads to connect to your TV colour or black and white and cassette recorder 16K byte RAM pack for massive add on memory Designed as a complete module to fit your Sinclair 2 80 or 2 81 the RAM pack simply plugs into the existing expansion port at the rear of the computer to multiply your data program storage by 16 b Use it for long and complex programs or as a personal database Yet it costs as little as half the price of competitive additional memory With the RAM pack you can also run some of the more sophisti cated ZX Software the Business amp Household managem
102. t arithmetic is used because it enables a large range of numbers to be stored in five bytes with only a small loss in accuracy Andrew Hewson Your queries numbers ans this column Andrew Hewson author of Hints amp Tips for the ZX 80 and Hints amp Tips for the ZX 81 answers your questions on hardware and software for Sinclair ZX Numbers as big as 10 one followed b zeros can be stored although only the first nine digits or so are accurate If integer arithmetic were used then the biggest number which could be stored in the same space would be 1 099 511 627 776 but all 13 digits would be accurate How are numbers stored in the 2 81 Please explain how the five byte representation of number is obtained writes Peter Stern of London The following program prints the floating point form of a number entered by the user at line 20 10 PRINT ENTER A NUMBER 20INPUTI 30PRINT REPRESENT 40 FOR 1 5 50 PRINT PEEK PEEK 16400 256 PEEK 16401 J 7 70 PRINT 80 PAUSE 500 90 15 100 SINCLAIR USER May 1982 s on storing iswered w amp amp rs re X computers Please address your problems queries and comments on the computers to Andrew Hewson Help line 7 Grahame Close Blewbury Oxon The ZX 81 stores the values of all Basic variables in the variables areas and the address of the
103. te 1o you for some days to say how much enjoy the games on Casset which supplied me with earlier this month Ple into the secret of your first time load E H London SW4 BUG SPLAT Just two our of over 20 unsolicited testimonials Cassette One 1K machine code programs React Invaders Phantom Aliens Maze of Death Planet Lander Bouncing Letters Bug Splat 1K Basic Programs 1 Ching Master PLUS Large sc for when you get 16K Robots Basic sions of Invade aman and Maze 9f Death ready Cassette One costs 3 80 Recorded on quality cassettes sent by first class post from RECTA AWARI ECTANGLES PENNY SHOOT aal PONTOON Gun Command Cassette Two costs 5 Michael Orwin 26 Brownlow Road Willesden London NW10 SQL Mail order only please If you own a ZX80 81 then you need the ABACUS CONTROLLER Developed to eliminate tedious swapping of plugs when LOADING or SAVING programs cassette One switch operation allows selection of TALK SAVE CUE and LOAD modes Using a built in microphone speaker to allow fast and reliable program naming and cueing Send cheque P O for 12 including p amp p to ABACUS ELECTRONICS 186 St Helens Avenue Swansea W Glam Tel 0792 50282 1 ZX810wners Protos Keyboard is here At last A
104. ther you have a good copy Essen tial for serious program development VERIFY even checks taped variables BUFFER MICRO SHOP NEXT TO STREATHAM STATION MLOAD MSAVE Load and dump any area of ROM or RAM to and from tape You can specify NEW SOFTWARE SHOP EXCLUSIVELY FOR addresses in decimal or hex or mix the RS 2 x 8 1 APPEND end of one in memory VPTR Find data or variables within BASIC program instantly dozens of applications Z AID is an ongoing series of packages which provide a comprehensive set of utilities for 2 81 16K programmers similar to those available for more expensive computers Purchasers of this first release can obtain special discounts on future additions to the range Utilities now under development include DATA READ RESTORE TRACE SINGLE STEP GRAPHICS and INSTANT SORT SEARCH All Z AID utilities are fully documented with detailed lucid examples of use and require no knowledge of machine language or the 2 81 operating system For a FREE leaflet giving details of our introductory offer for Z AID just send your name and address to Emjay 17 Langbank Avenue Rise Park Nottingham NG5 5BU England SINCLAIR USER May 1982 PROGRAMS GAMES ADD ONS KKK MOST OF THE MAIL ORDER ITEMS ADVERTISED IN THIS MAGAZINE AVAILABLE OVER THE COUNTER LOADING PROBLEMS TRY OUR INTERFACE BUSINESS amp TECHNICAL DATA HANDLING PROGS PROPER KEYBOARDS CONSOLES VDUS
105. those problems is insurmountable however so we would not be in the least sur prised if we hear an announcement from Clive in the not too distant future that is to start selling some new software LEADERSIN COMPUTER GAMES FIRST CHOICE FOR ZX SUPPORT QS INVADERS 46 50 815 00 QS MOTHER BOARD BD amp Q8 CONNECTOR QS HI RES BD THE COMPUTER FAIR Earls Court 23rd to 25th April 3rd ZX MICROFAIR Central Hall Westminster SOth April amp 1st May ALL PRODUCTS FULLY GUARANTEED QUICKSILVA 95 UPPER BROWNHILL RD MAYBUSH SOTON HANTS ENGLAND Please state Type of machine Which ROM Memory size when ordering SINCLAIR USER May 198 hardware world To save programming time A PIECE of hardware not intended to fit on to the ZX 81 Print Plot Jotter is a pad of paper which consists of two grids one for plotting Pixel graphics and one for printing Alpha numeric characters They are inlended for the pro grammer who wants to improve his programs and save time by planning his displays on the screen before PRINT AT X Y ALPHANUMERIC or PLOT X Y apixel The Print Plot Jotter is also useful to use with the Sinclair printer as was shown at the ZX Microfair by the firm producing an aeroplane plotted on paper more than one foot long A polyester film version is also available for transfer ring book or magazine pic tures to the ZX 81 The Print Plotter Jotter costs
106. through them at a rapid rate to reach the heart of the matter programming techniques many users will probably find themselves back tracking to pick up that wrinkle on program documentation they had forgotten but no one will be able to say that they were not warned Programs of particular interest to teachers include rank ordering examination results analysis and a reading age program to accompany ihe low grade word processing system Hurley promises a more use ful version of the latter in book being prepared on ZX 81 machine code The programs and the listings all ustrate useful techniques and the lines of program code are explained comprehensively line a major plus in books on the Sinclair In keeping with his aim of the reader push the ZX 81 much donp cen continued from page 61 further than anyone expected when it was launched Hurley offers a number of hardware modifications in the last chapter They are a modi fied power supply extra money and hooking the Sinclair to a standard keyboard They are not for the elec tronically illiterate and require the ability to read and understand a circuit diagram as well as to solder neatly which Hurley suggests as the only pre requisite Where Hurley employs 160 pages to show programming tech niques gently Andrew Hewson takes his readers through his Hints and Tips for the ZX 81 at a gallop in 75 pages The book is based on one
107. tion subtraction multiplication 795 VIDEO AD Rotating display of 16 pages of advertising material Set up your own pages and change them as and when required 795 magazines about the 2 81 certain words occur time and again VIDEO GRAPH Planning and design aid Create VIDEO INDEX detects these duplications and thereby conserves pictures charts graphs and store withintheprogram 595 pace VIDEO VIEW Do it yourself teletext Create pages of data Store them within the program 596 Wnetacvosget 1 A machine code master program which sits at the top of This is initially loaded like a BASIC program 2 A demonstration index containing 1 000 references to articles about the ZX8 1 in the popular magazines VIDEO MAP 2X81 only Educational game based on maps Navigate your plane to its destination 595 FORCE FIELD 2 81 only Animated bombardment qu 395 34 detailed instruction manual SPACE RACE 2X81 ony Party game for eight es You may thn proceed orate your own catogues and indones TEE MATCH of a estes IST eua iion eed E tc by fo he but product we have introduced for the 2X81 of Si ara N B There isn t room for a commentary on this cassette so you ll Season Every match played and results shown with enini Wa manual progressive league table 395 2x81 0r ZX80 8K ROM STOCK MARKET 2X81 only An e
108. tive supply which should be quicker and cheaper than Sinclai Si Tricks supply five rolls of elec trostatic paper the same size as Sinclair paper of similar quality The pri for the five rolls is whereas the Sinclair cost is 11 95 Ten rolls cost even less per roll at 14 50 They are available by mail order only Silicon Tricks 2 4 Chichester Rents CI Lane London Wi 1E 01 603 6074 Building memor by blocks A RAM extension kit is expandable in the form of 2K blocks up to maxi mum of 16K as and when you need it It requires no soldering connections and fits in the ZX 81 beneath the keyboard If you later decide to buy an external 16K pack the internal RAM can be altered to fit into the next 16K section so that you can have continuous Basic memory up to a total of 32K continued on page 8 continued from page 7 There are two kits avail able 2 8K RAM costing 8 50 and 2 16 at 9 50 Details are available from East London Robotics Electronics Finlandia House 14 Darwell Close East Ham London E6 4 01 471 3308 Artic comes in with Forth FORTH the language in which you can build a vocabulary of your own commands can now replace Basic on your 2 81 This version of Forth resides in EPROM like the Sinclair Basic and is therefore available when switching on the power with no LOADing problems Forth programmers write the comman
109. tored in a 2K ROM mounted on the board so no machine code REMs are required Drawing lines boxes or only dots can be done in either black or white while clearing the screen requires writing over the dots with the background colour Alphanumeric characters can be used and there are commands to clear the screen in black or white The board costs 85 inclusive and Quicksilva is at 95 Brownhill Road Maybush Southampton FIZ into floppy action CALLED a FIZ Floppy disc Interface for the ZX 81 the Macronics floppy disc provides a standard 5lin floppy disc drive software in a 2K ROM and isc will provide 43K of storage which can be LOADed at a rate of 8K in 22 seconds The disc has 34 tracks and 10 128 byte records on each track for storing data or programs The commands are given 10 routines stored in ROM that RAM is wasted and all the disc commands are written to be used from Sinclair Basic The motherboard pro vides all the power for the system including ZX 81 and interface cards paper printer will be avail able soon There is also the possibility of a networking card soon FIZ costs 303 03 inclu sive and is available from Macronics 26 Spiers Close Knowle Solihull West Midlands B93 9ES Cheaper printer paper IF YOU run out of paper what do you do Do you panic and send next time for twice as much as you need from Sinclair Now there is an alterna
110. ues of programming the ZX 81 Foranyone who has always avoid ed all things technical Peek Poke Byte and RAM by lan Stewart and Robin ones would probably be a better book makes no assumptions of knowledge and is well laid out The idiosyncratic asides along the lines of cat did such and such could be irritating to those who dis like that kind of thing THE KEYS OF GONDRUN journey beneath the Enchanted Forest in search of the missing keys of Gondrun the Wizard Can you discover the keys and stay alive With real time monster fights 6 skill levels Save on cassette feature and alternative responses to give a different game every time Map the caves as you travel through them but beware of the Two Headed Thronga the Jubjaroo and the other nasties which are lurking A great game occupy ng the full 16K RAM PACK CONTAINS 8 INSTRUCTIONS Only 5 50 POP STAR Would you like to be rich and famous This program won t guarantee that but it s great fun all the same Will your records be 7 Can you negotiate a better royalty rate and increase your income Maybe you ll be offered a TV series or film But it isn t an easy and troubles like flop records the taxman and other horrors are always waiting And if you decide to bribe and cheat then don t get caught In this game you could make a million or you could end up broke It s up to you Requires 16K RAM PACK CONTAINS TAPE am
111. unior Geronimo an album based on the best from both adult albums but now suitable for ages 71015 GALAXY WARRIOR 3 00 1K GAMES PACK 6 00 Album 3 50 GALAXIANS the features of the arcade game in a fast machine Albumi 4 00 Both albums for 7 00 6 50 code program Swooning stackers ond ZXBUG n 1 machine code tool 7 00 access registers ond to aod many mora Foracataiogve ging ll please senda A E 10 Artic Computing 396 James Reckitt Aven e Hull HUB OJA a FTLIAREs Rossendale Lancs 884 4NF Tet 0706 220596 SINCLAIR USER May 1982 ZX81 PERSONAL BANKING SYSTEM WITH LOAD SAVE DATAFILES AT DOUBLE SPEED Load the program in the normal way enter amend or delete your transactions 2X81 will automatically scan standing order file and post any items due save the file of data onto cassette in 45 seconds load different datafile into the same program also in 45 seconds enter items etc save datafile only onto cassette 45 seconds repeat operation for any number of accounts datafiles Absolutely no need to save program as all information is held in datafiles a powerful search facility is included Very easy to use unlike other bank accounts Requires a minimum of 16K RAM can use much more modification required on demonstration at next ZX Microfair No 3 Send 9 95 inc to J P Gibbons A B for c
112. ut ports found on most O boards an A B convertor such as ours is required A free copy of ZX AMAZE plus any one of the games listed below when ordering a Joystick and an A D board Programsavailable EEIEIEE now y ne BEST eE E E GE vin A sie ea onyt395 gooo npn von wen vj now only 3 98 time you play On the reverse of the cassette is ZX REFLEX find out how fast you really are now only 3 95 ations as the and sti the best Graphic display of chessboard 6 levels of play Displays record of your moves and the computers Board can be set up to any position Has ability to change sides or level in mid game PLUS CHESS CLOCK on reverse side records time akon by each player gt Resetebl function Single key entry now only 6 50 All out wren Ii nd cen e used with Joysticks or das aniy on with brary caes ahar pave thet od ers second to Hone MICRO GEN afters the following RI To Gur customers 14 DAYS FREE APPROVAL ON ALL PRODUCTS Ail money wil refunded if goods are returned in good condition within 14 days of despatch you write a program which e exceptional please submit ittas We wiorlera royalty ti Cheques and PO s paveble to MICRO GEN Dept 501 24 Agar Crescent Bracknell Berks Please add 40p p amp p to all order
113. ving thekeyboard untouched allows your craft to drift sideways The game ends and your score is displayed either when you run out of fuel or hit an asteroid asterisk Line 130 looks at the PRINT posi tion set by the last PRINT AT in line 110 and if it finds a 23 asterisk stops the game there printing the score S and using an unassigned variable D to halt the game If it finds a 128 the computer knows you are running into a fuel dump so the fuel is incremented by 25 LET F 25 Line 145 stops the game if you are out of fuel i e if F equals zero OR Stubbs SINCLAIR USER May 1982 GALA PATROL NMG 5 958905 SUS025 H 128 THEN PR programs TA ARE two versions of Monster Munch written by Tim Hartnell in which you the inverse H have to escape the monster the inverse M on a 10 x 10grid of full stops Beware however because your task is hopeless No matter what you do you will be unable to evade it for ever and will be utterly and com pletely munched 1a 3e 3 85 LET A ai LET A P 10 0 H REM PRINT OL PRINT RT FOR D 100 IF AiD THEN PR IF E IF ACD THEN PRINT Ip IF 10 INT D710 D THEN PRI NEXT D x 5
114. xciting game of skill ZX printeris useful but not essential Price 9 95 and judgement Buy and sell stocks and shares as prices change in response to world events 395 Mailorder customers add 1 per order PACK 1 VIDEO PLAN VIDEO AD 1795 Altow28 daysfordelivery PACK 2 VIDEO VIEW VIDEO GRAPH 1395 Cashwithorder please VIDEO SOFTWARE LTD 5 GAMES 1995 Stone Lane Kinver 1K PARTY TRICKS 2X81 only 495 Stourbridge Personal callers welcome during office hours West Midlands DY7 12 SINCLAIR USER Moy1982 MORE FUN WITH YOUR 7 81 The addition of our fully compatible assembled tested and guaranteed 16K RAM PACK PUSH ON PLUG COMPATIBLE MEMORY Means more memory for better games and bigger programs ORDER YOURS TODAY FROM CAPS LTD Dept F 28 The Spain Petersfield Hants GU32 3LA Please send postal ordei Byte 16K Ram Pack enclose cheque r 34 95 includes VAT Postage amp Packing Name Address Fully inclusive price 34 95 SINCLAIR USER May 1982 13 weeks asking about the methods used by the ZX 81 to store and display numbers and so have devoted this month s column to the topic The machine uses one of three methods depending on the context The first is the floating point method which is used for all Basic variables and all calculations involving Basic variables All num
115. yPost Fir By Phone 1 bled 39 95 1 1 64K Assembled 79 00 1 SIGNATURE Total Enclosed nave ADDRESS 1 502 We want to be sure you are satisfied with your Memopak so we offer 14 day money back Guarantee products ee Limited 3 Collins Street Oxford OX4 1XL England Telephone Oxford 0865 722102345 If you havea Sinclair 2 81 and want to use it to its full potential then as the experts have all agreed this is the book for you It contains detailed guidelines and documented programs in the areas of gaming information retrieval and education as well as unique listing of the ROM for machine code applications Far and away the best once again Linsac has produced the book for the serious end of the market Your Computer November 1981 The ZX81 Companion i amp most professional product with many good illustrative programs tips and warnings ducation Equipment October 1981 Bob Maunder s attempt to show meaningful uses of the machine is brilliantly successful thoughtfully written detailed and illustrated with meaningful programs To conclude the book is definitely an outstandingly useful second step for the 2 81 user Educational ZX80 81 Users Group Newsletter September 1981 Send your cheque for 7 95 i
116. zles as anagrams and missing number sums 1 hope you can send any mind games I have mentioned so can include them I would also like to any games you have played against the ZX 81 chess programs whether against yourself or computers Advertisement Index Abacus Electronics 30 Emjay 25 Macronics 10 Quicksilva Addictive Games 56 Frome Computing 30 9 Redditch Electronics 26 AP Software 40 Fuller MicroSystems 25 MicrocomputerSoftware 41 R Sheperd 63 Computing 40 P Furlong 56 MicrogrameSimulations 63 Shiva Publishing 52 Automata 63 J Gibbons 41 Microgen 40 Silicon Tricks 62 Bridge Software 64 29 Microware 64 Silversoft 64 Buffer Micro Shop 25 S Hessel 17 Mindware 41 Sinclair Programs 52 Bug Byte 2 HewsonConsultants 21 Moviedrome Video 56 Sinclair Research 46 47 Butler Currie amp Hook 59 Holdco 16 NewnesTechnicalBooks 21 Thurnall Electronics gt Caps 13 RS Software 39 OasisSoftware 56 VideoSoftware Computatutor 52 Kayde 68 M Orwin 30 wWhichMicro 58 Control Technology 67 LeisureGames 62 Pheonix Marketing 39 Workforce 4 D K Tronics 4 Linsac 10 Picturesque 39 Youngs ZX Register 63 SINCLAIR USER May 1982 65 2 80 2 81 HARDWARE D BRUCE ELECTRONICS The Beacon Blackhall Rocks Cleveland T527 48H 5783263612 Phone 0234 46248 tor deta nd cheques or PO B Rae 12 one Clone Bedioni Beds ASTRO INVADERS 16K Oncassette

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