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with information about interupt handling and programming style.
with information about interupt handling and programming style.
[[Category:Magazines]] [[Category:Update_Issue]]

Latest revision as of 08:19, 2 September 2014

Newsletter of the National Dragon User Group.

Issue 6.

Chairman Paul Grade,                                 Editor Jeremy Hoyland,
6 Navarino Road,                                     120 Old Heath Road,
Worthing,                                            Hythe, Co1chester,
Sussex.                                              Essex.

Happy half birthday to us! As a token of our demi-anniversary we now have a name, our thanks to Ken Grade. So let's take stock of the last six months and how they have affected us. The club is now estab1ished, and even has a little money in the coffers, existence is not quite the hand to mouth affair it was six months ago. There has been some 'slippage' in the issue dates, hopefully this edition will have clawed part of it back, again I have to thank Ken who has agreed to take over the distribution. The newsletter is rather thicker than it was and there have been some excellent articles, however I would have liked to hear more from those with advanced systems -a piece on the RS232 port by someone other than Status Quo would be welcome, and has anyone succeeded in porting the p-system on, Oasis claim that their Petite Pascal uses a p-code interpreter.

One of the most encouraging things to happen in the last six months has been the 6809 show, there is to be another one on the weekend of 22nd of March' as yet we don't know whether the group will be there, but obviously I hope so.

I hope that the next six months will be as successfull as the last, but remember, by and large it depends on you - so if you want to keep hearing from us then we'd better be hearing from you.

64K UPGRADE by D. De Wilde.

This is the next installment from the Dragon Upgrade Manual that we had passed onto us by the Dutch User Group. It is a rather more complicated modification than that written for us by Bob Hall but has the advantage that it will work on any 32.

Again I must stress that you should only try this if you are technically competant, these articles have been translated from Dutch and the photocopies I got for the translation were pretty ropey, so there could be errors. I hope that anyone who tries this out and gets it to work will be good enough to write us an in-depth feature on the method that would be more appropriate to people who think that a soldering iron is a thing used for pressing uniforms.

In order to upgrade the computer to 64k you need 8 RAM chips, (4164 /l50 nS) and 8 ic feet (wire wrapping) or ic pins which come loosley wrapped.

         Open the computer.
         Remove all IC's on feet.
         Remove power connector.
         Remove cartridge protection.
         Remove keyboard.
         Remove all screws so that mother board can be taken out.
         Use a very fine pair of pliers to cut away rams IC1 to IC8.
         Clean the holes in the PCB.
         Put the IC feet in position' one by one, without inserting them
         completely. That way they can be resoldered from the top in case
         off faulty contacts.
         In order to avoid any unpleasant surprises you had better test
         every through connection for each socket.
         When all IC feet have been soldered you had better test all pins
         from foot to foot.
         Replace the motherboard in its position in the box.
         Connect the power.
         Switch on and test for 5V at PIN 1 of one of the RAMS.
         Check whether the blue strap connects only the two bottom
         Switch off.
         Replace all 8 IC's.
         Replace the 8 RAMS.
         Screw everything tight.

That's the lot, it still only puts 32k at our disposal, but we can now -via software- use the full 64k, as well as OS-9 and FLEX.

Quite what the software referred to is I don't know, but I hope that Bob Halls routines published with his earlier conversion, and the piece in this edition will do the job. As I say if anyone tries it let me know how you get on.

cassette recorder mod. f.j.fisher.

The following modification was carried out on a Tandy TR12 recorder, but ought to be practical on almost any type.

Open the recorder, and disconnect the motor wire from X.
Solder one end of a piece of wire to X using a standard 2.5mm chassis socket (switched type).
Solder the free end of the motor wire to 2.
Solder free end of wire to 1 and 3 ( THIS IS IMPORTANT).

As a further mod:
Using a sub min. on/off switch wire it across 1 and 2. Using the switch will mean that you no longer have to remove the remote plug or type "motoron/off" when using FF or Rewind.

The socket and switch can be obtained from any Tandy or other electrical store. and the first mod greatly improves file handling as only the motor is switched, not the amplification circuit.

<IMG SRC="IMAGES/DGU006F1.GIF" ALT="[Cassette recorder remote control modification]">


"DRAGON 55" gets its name from the facility to store up to 55 pages(i.e.not quite one Dragon text screenful) of text,notes and other miscellaneous information which can then be dumped to tape. By making the maximum amount of RAM available(one Pokes 25,6 before loading the program)for data storage,you can cram 55 pages of 28 lines into one file.

Please note-it does not pretend to be a database. There are no fields to set up-you merely type merrily away until you run out of pages.

I was quite intrigued by the idea-but not sure how to make use of it-and quite impressed by the lack of superfluous packaging and documentation which has plagued similar programs(in fact programs in general!).

For once,the program came on a very high quality cassette(other firms please copy!),with ALL instructions/information on a "Dragon 55" file following the program. The program is written in Basic incorporating (a) machine code routine(s). The facilities are as follows:-
1)A special "graphics mode" in which the numeric keys will print the block graphics characters;
2)The screen colour can be changed for any page by pressing a key then a number;
3)Cursor position controlled by the arrow keys;
4)Auto-repeat-but of course!-on all characters,including the graphics;
5)A "search and find" routine-to find where you wrote that dirty joke that's too good to lose!
6)Store and retrieve files from tape.

I cannot fault the program in operation. It does everything it is supposed to do very efficiently. The "Search" routine,for example will find the word/phrase you want,and tell you on which line of which page-and politely call that page up. If the word cannot be found,then the nearest approximation will be retrieved. (I wish the much acclaimed word processors could do half as well!)

As to what use this program could be put,I am not really sure. The main drawback is that there is no output to printer,so that discounts half of its usefulness. I am surprised one hasn't been included-it needn't have taken more than five lines(or one,for a complete screen dump of each page) -and it would have had much more appeal(to me,at any rate).

I am not quite certain to what use one could put the "graphics mode",either. If you want to experiment with combinations of block graphics,then it saves you typing "PRINT CHR$(XXX)" every time I suppose,but there's no great gaim in that.

As a store for programming routines,Peeks,Pokes(there are quite a few included in the demo file,as well as some useful Dragon addresses),and any other "notes"(the sort that usually get scribbled on bits of paper),it is quite handy. At the price of 5 pounds(less onepound for D.U.G. members!),it is very reasonable-if you have a use for it!

Ken Grade


In the december issue i mentioned that Microdeal were going to bring out a program called 'Speed Racer' which was supposed to be a Grand Prix simulation.Well it has duly arrived and after extensive playing i'm not sure whether it was worth the wait!

A Grand Prix simulation it certainly isn't,as the object of the game is to pass a certain number of cars each lap.If you don't then that is the end of the game!If you do then onto the next lap you go.This time the cars are going a bit quicker but the number of cars to be passed always remains the same.If you complete 5 laps then you are the winner.And that is about it!

There are four different tracks to choose from,number 1 being a simple rectangle and number 4 containing lots of hairpin bends.By common consent number 3 seems to be the hardest as there is no place where you can really put your foot down.Number 2 is the one i prefer as it contains both straights and tight corners.

The graphic display is as expected in that you are looking from above and behind your car i.e. a 3D view.The actual speed and quality of the graphics are dissapointing.The road scroll is very jerky and for some unknown reason Microdeal decided to put a white line down the middle of the road.Along the bottom of the screen is a Speedometer,milecounter and a bar showing how many cars you have passed. You control your car with only the right joystick.Forward to increase speed,back to break.Pushing the joystick left or right moves the track the appropriate way.

Where the program really lets itself down is in the reality of the game. Breaking is a gradual affair and that means you can easily run into the back of another car.Also you cannot run off the track although if you stay on the shoulder for too long the car stops to get a tyre change.How on earth anyone manages to go round hairpin bends at 170 mph is amazing but thats what the program allows!The worst aspect of the program is having to pass a number of cars each lap.If you pass more cars than needed,the extra amount does not count for the next lap.Also it seems impossible to complete 5 laps as several times i have runout of cars to pass on the last lap.

Having said all that this game is streets ahead of any other on the market.If it had been for the,say Spectrum,nobody would buy it but for Dragon owners this is the best availble. So,if you intend to buy it don't expect too much.I'm sure somebody else could improve on this game.

I received a couple of queries this month.The first is from Jeffery (or Geoffrey) Wilkes.He wants to know how to get to the Water room in Franklin's Tomb.The room is situated in the middle of nine rooms which have a common theme. Work out the theme and then utter a password in one of the nine rooms.As for the theme,Think of Russell Grant!!Also Mr. W Norrington (sorry i haven't got your first name!)wants a reccommended adventure for first timers.If you want a standard adventure then try Salamanders Franklins Tomb.For a very easy adventure you could try Microdeal's Mansion Adventure.Also of note are two graphic programs from Touchmaster.They are Sea Quest and Shenanigans but they might be hard to obtain.If you want a dungeons and Dragons style game then go for Ring of Darkness by Wintersoft.

Doctor ASCI at your service.

Geoff has encountered a few other problems in his meanderings around adventures: firstly he's trying to find the Wine Cellar in Franklins Tomb, as I remember the key to this is going bats in the lift. In Mansion of Doom he wants to cross the pool of acid near the vampire -search me, if he will visit such places... Mountain climbing and water crossing are his problems in Ring of Darkness, again I'm afraid I don't know the answers to these problems. Geoff has suggested an adventure help column -this seems a good idea so you take these two problems to start with I'll gladly print any answers and new problems that you have, so let's be hearing from you.

Following last months hardware screen inverter, here's a software implementation from Ashley Adamson of the Romsey Area Dragon User Group. Ashley and the group can be contacted at: St. Elmo, Slab Lane, West Wellow, Romsey, Hants, S05 0BY.

20 CLEAR 200,32580
30 FOR I=1 TO 184:READ A$:Z=VAL("&H"+A$):CS=CS+Z:POKE I+32580,Z:NEXT
40 DATA 8E,7F,63,BF,1,68,8E,7F,DE,BF,1,6B,8E,7F,F6,BF,1,A1,86,7E,B7,1,67,B7,1,6A,B7,1, A0,39,7D,0,6F,27,1,39,32,62,34,16,8E,FF,C0,A7,84,A7,2,A7,4,A7,6,A7,A,A7,C,A7,E,A7,88,10,A7,9,86,5,B7,FF,22,35,2,34,2,BE,0,88,81,8,26,8,86
50 DATA 20,A7,84,A7,82,20,1C,81,D,26,4,8D,32,20,14,81,80,24,E,81,20,25,C,81,60,24,4,84,BF,20,2,80,20,A7,80,BF,0,88,8C,5,FF,23,12,8E,4,0,EC,88,20,ED,81,8C,5,E0,25,F6,BF,0,88,8D
60 DATA 2,35,96,86,20,A7,80,1F,10,C4,1F,26,F6,39,81,C,27,1,39,34,12,86,20,8E,4,0,BF,0,88,A7,80,8C,6,0,25,F9,35,92,27,1,39,32,62,20,E6
80 EXEC 32581:CLS
100 PRINT@32,STRING$(15,188)
130 X$=INKEY$:IF X$="" THEN 130
140 IF X$="Y" THEN POKE 32644,13
170 Z$=INKEY$:IF Z$="" THEN 170
200 END
    Whenever using a GET command with the inverter type:
         POKE 416,57  first.


Well, we've survived for half a year, more by luck than judgement, so it looks as though we're doing better than the majority of the user groups.....especially former Dragon ones!!.

What we need now, apart from more members, more money, and an offer of free printing (!) is some definite news from Eurohard.They told us, and I believe them, that the Dragon would be back in UK, but since then there have been various delays and and rumours (both good and bad), and no one seems to know exactly how long we will have to wait for the Return of the Dragon.

Come on Eurohard, wake up!!...there will never be a better time for a return than NOW. With Acorn having "suspended trading", the Spectrum out of production, Commodore trying to sell the unsellable C16, etc, the market just HAS to be wide open for a REAL computer.

At the moment I don't know whether or not we'll be seeing you at the 6809 Show....the organizers seem reluctant to let us have a free stand this time around, and there's no way I can justify forking out over a hundred pounds of your subscription money just so that we can put in an appearance there. You never know your luck, we might yet get a "freebie", but if not one or more of us will be covering the Show, and we'll let you know what's new.

As I said in the last Newsletter, we still need more material for publication.....from YOU!. Looking back through the Application Forms it seems that you have a lot of very different interests, so why not write to us about them? You don't have to be a professional writer.....(tho' that doesn't mean we don't want professional work too, Mike!!)....but we really DO want you to contribute something...that's what the Group is all about. OK?.

One final thing....do any of you ex-Dungeon members know where I can contact Pete Woods (the former "Dungeon Master")?..if so, please ask him to give me a call.

That's all for this month. Good luck, and keep writing. Paul.G.

                                                     Orchard House,
                                                     Cleator Moor,

Dear Paul,

Last year I wrote to you about certain programs running on my 32 but not on my 64. I think I may have found the answer.

About 9 weeks ago, I typed in a perpetual-motion type program from "Input Magazine". It would not run, giving an FC ERROR. On checking the line I found that it contained a PCOPY command. After checking the listing several times, I gave up in disgust, muttering dark abuse about certain typesetters.

However, last week, I purchased a Graphics System Program from Salamander. This also gave rise to an FC ERROR. On listing the faulty line I discovered it too contained PCOPY commands. I began to put two and two together. I blew the dust off my 32 and tried the program. It worked perfectly. So it would appear that some 64's (mine at least) will not accept PCOPY commands in the same format that the 32 does.

I have not yet managed to get the magazine listing to run on the 64,but I changed the offending line in the Salamander program, as shown below, and it now works perfectly.

I changed PCOPY N+4 TO N+16 [into] PCOPY N+1 to N+4.

I hope that this may be of some assistance to others, although it still won't be any use for M/C programs like "Junior" etc.


As promised in issue three of the newsletter this is the sequel to the earlier articles describing the interfacing of a Dragon to en ex GPO teleprinter. For new reeders, the previous articles described a method that involved rather complicated and expensive hardware in addition to the software.

The latest software (which is fully re-locatable) does all the conversion work except the final transition from 5 to 80 volts. When PRINT#-2, or LLIST is used the Dragon sends its output to the printer port but the format is now serial, the Ascii has become Baudot end the speed is 20m.secs per bit (50 baud).

Another feature of the software is a text screen dump which is activated by the down-arrow key in immediate mode or PRINT CHR$(10) in a Basic programme. This is very useful when running programmes such as disassemblers which do not have a built-in hard copy option.

The only hardware needed now is an opto-darlington to protect the Dragon and trigger a high speed relay. The relay contacts switch +80 or -80 volts as required to the Receive terminal of the teleprinter. Only 3 connections are used at the printer port..... a 5v supply for the relay,the 0v line and the strobe pin which is used for the data.

The system needs no major modifications to the standard telex terminal. It is only necessary to remove one diode and in practice this has usually been removed already by Telecoms so that the machine will no longer function as a telex unit.

The latest version of the software and hardware is being marketed by COMPUTIL of 22 Grove Park, Burbage, Hinckley, Leics. LE10 2BJ.


This contains most of the special offers that are available to members, I hope that you will avail yourselves of them as they are great value.


These are top quality 5.25" discs supplied by SBS Data Services. Individual orders are accepted at the price below for a box of ten, but if we get enough orders together at any one time to order 5 boxes we get a further reduction of £1.00 per box.

SS/DD soft sector normal price £22.00 reduced price £14.50.
SS/DD hard sector              £22.00               £14.50.
DS/DD soft sector              £27.00               £15.50.
DS/DD hard sector              £27.00               £15.50.

All prices are PLUS 15% VAT. With a little cutting on the cover a Dragon can take DS/DD's -a great saving. All orders to Paul, cheques payable to the group.


C5 - 2.5 mins per side leaderless computer tapes are available for £1.25 for 5 from Taurus Electrical Services, 26/28 Nottingham Road, Loughborough, Leics. LE1l 1EU.


Cable are offering their range at twenty per cent discount -see their ad in Dragon User for what's on offer. Place your orders through the editor.

Double Value Dragon -how to get maximum use of your D64s memory, by Bob Hall.

As everyone knows, the Dragon 64 has 64k of RAM,16k of BASIC in ROM, and room for another l6k (nearly) of goodies such as DragonDos in the cartridge port - that's 96k altogether!. Unfortunately, all the standard ways of using the system (except perhaps the Andtek 'P1us' add-on) require you to throw part of it away - in '32k' mode, you leave the other 32k of RAM idling in the background - in '64k' mode, using Flex or OS9, you lose the ROM routines, though you may gain a rather better version of BASIC (BASIC09).

What can be done to make better use of the Dragon's resources? For the '64 in 32k mode, there appear to be two possibilities: - Firstly, we could hide machine-code routines in the upper 32k (accessing them in Map Mode 1 with the interrupts off). We could also put a high-resolution graphics screen in 'high' memory, which is easy to implement, because the SAM chip ALWAYS gets information for the Video Display Generator from RAM, never ROM, and so will correct1y display our graphics in high memory, whilst we continue in BASIC in 32k mode.(A useful combination of these two ideas is a high-res text-generator & its screen- I've used the one in Flex to run with Editext; however, more of this, hopefully, another day.)

The secondway to use all the memory efficiently in 32k mode, is to use the SAM's Page-switching capabil1ity and have two independent programs in memory at the same time: one of these programs lives as usual between 0 & 32k (Page 0): the second is stored between 32 & 64k (Page 1)- but when we 'flip the page' the SAM will automatically add 32k to all the memory addresses from the cpu, before it sends them to the RAM, so that we can then address 'Page 1' as if it were at 0 to 32k. (However, it doesn't automaticaly do the same for the VDG addresses - see below).

The BASIC program which follows loads the necessary machine-code to do page-switching: it's configured to work with DragonDos, and by default goes into the cassette buffer at &H200. To use it without a disk, change the instructions at line 140 (JMP $D917) to read "140 DATA 39,12,12" (ie RTS,NOP,NOP), and allocate a specific address for BA when prompted in line 430. The machine-code comprises 3 sections: SWOPIT, which dumps the stack- pointer in "HOLE", switches pages, and reloads the SP from the corresponding location in the other page; VDG, which keeps the Video Display looking at the right text-screen; and MOVIT, which sets up Page 1 initially, by copying page 0 into it and then altering a few 1ocations. After the BASIC has run, it can be deleted (but the machine-code must be kept intact) - if Reset is pressed, SWOPIT will not in general work correctly (a bit more code, pointed to by the Reset vector, is needed). After the Basic has run, typing 'EXEC' (or executing it in a BASIC statement) will take you from one field to the other, and pick up any program from where it was interrupted; (however, SWOPIT could be linked into the 'End-of-Line' hook at &H19A-&H19C - or even into FIRQ). The routine is believed to work correctly for all BASIC programs (and many m/c ones), which use the text-screen only. It will also generate graphics correctly, but in Page 1 will not display them unless the statement 'SCREEN a,b' is expanded to 'SCREEN a,b: POKE &HFFD3,0'.

Thats it - it's all quite easy really - give it a try!.

                                                     Bob Hall.
                                ÚÄÄÄÄÄASSEMBLY LANGUAGEÄÄÄÄÄÄÄÄÄÄÄÄ¿
                                ³                                  ³
                                TTL PAGE SWOP ROUTINE PIC
³                           ³
20 DATA 0,0                     HOLE FDB 0 STACK STORED HERE
40 DATA 34,7F                   SWOPIT PSHS A,B,X,Y,U,DP,CC
50 DATA 1A,50                   ORCC œ$50 I0F
60 DATA 10,EF,8C,F6             STS HOLE,PCR
70 DATA 32,8C,75                LEAS SWOPIT+$80,PCR IN CASE OF NMI?
80 DATA B7,FF,D4                LS1 STA $FFD4 FLIP PAGE
90 DATA 10,EE,8C,EC             LDS HOLE,PCR
100 DATA 35,FF                  PULS PC,A,B,X,Y,U,DP,CC
120 DATA 7D,00,6F               VDG TST $6F FIND IF O/P TO SCREEN
130 DATA 27,03                  BEQ LV2
l40 DATA 7E,D9,17               JMP $D917 DRAGONDOS HOOK
150 DATA BD,8O,0C               LV2 JSR $800C PUT CHAR ON SCREEN
160 DATA 32,62                  LEAS 2,S DROP OLD RETURN ADDRESS OFF STACK
l70 DATA 34,16                  PSHS X,B,A
180 DATA 8E,FF,C8               LDX œ$FFC8 SAM VDG BITS START
190 DATA A7,0A                  LV1 STA $A,X
200 DATA 7E,A9,41               JMP $A941 NOW REJOIN ROM RESET ROUTINE
220 DATA 34,7F                  STTL COPY PAGE 0 TO PAGE 1 AND SETUP
230 DATA 1A,50                  MOVIT PSHS A,B,X,Y,U,DP,CC
240 DATA 8E,00,00               ORCC œ$5O
250 DATA 10,8E,80,00            LDX œ$0000
260 DATA B7,FF,DF               LDY œ$8000
270 DATA A6,80                  STA $FFDF MAPMODE 1
280 DATA A7,A0                  LM1 LDA ,X+
290 DATA 8C,7E,FF               STA ,Y+
300 DATA 2F,F7                  CMPX œ$7EFF
310 DATA 86,D5                  BLE LM1
320 DATA A7,8C,C6               LDA œ$D5
330 DATA 4A                     STA LS1+2,PCR
340 DATA A7,8D,7F,C1            DEC A
350 DATA 86,0A                  STA LS1+$8002,PCR
360 DATA A7,8C,D6               LDA œ$0A
370 DATA 4C                     STA LV1+1,PCR
380 DATA A7,8D,7F,D1            INC A
390 DATA B7,FF,DE               STA LV1+$8001,PCR
400 DATA 35,FF                  STA $FFDE MAPMODE 0
410 '                           PULS PC,X,Y,A,B,U,DP,CC
420 CLEAR 500
440 IF BA<300 THEN BA=512
460 FOR I=BA TO BA+92
470 READ V$:V=VAL("&H"+V$)
480 POKE I,V
490 NEXT I
510 X=VDG:Y=INT(X/256):Z=X-256*Y
520 POKE &H169,Z
530 POKE &H168,Y
540 POKE &H167,&H7E
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      ____     The Dragon Programmer             £5.95
      ____     Anatomy of the Dragon             £6.95
      ____     Language of the Dragon            £6.95
      ____     Artificial Intelligence in BASIC  £6.95
      ____     The Complete Programmer           £5.95
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                    *** GAMES TAPE - SPECIAL OFFER ***

The tape containing the 21 games from "THE DRAGON BOOK OF GAMES normally costs £5.95. Order both the book and the tape from us and pay just £3.95

Order any other book as well and the tape can be yours for just œ2.95!

Send your cheque or postal order payable to Ramsoft (UK orders only).
Outside UK please write for details.

We will try to despatch your order as soon as possible, but please allow 21 days for delivery.

The Dragon Library..........RAMSOFT.

lf you are a beginner or advanced programmer and you want to have fun or tackle a serious application we have the book that will help you use your Dragon.

THE DRAGON BOOK OF GAMES...by Mike James, SM.Gee and Kay Ewbank. (Granada.5.95).

A collection of 21 games written in Dragon BASIC that illustrate how the Dragon can be used to create a wide range of effects. If you are learning BASIC then typing in these programs is an excellent way to become familiar with programming. If you already know BASIC then you will still pick up a great many programming techniques.

If you'd rather save yourself the effort of typing these games in from the Iistings, you'll be glad to know that you can purchase a cassette tape containing all 21 games. This tape normally costs 5.95 but you can order it from us at a special discount....for dteails see our order form.

THE DRAGON PROGRAMMER...by S.M.Gee..(Granada.5.95).

This book is not only an introduction to Dragon BASIC, it also explains some of the pitfalls in using Dragon graphics and sound. Starting off from fundamentals, It explains how to write BASIC programs using the natural structure of BASIC. This encourages a good BASIC style without laying down strict do's and don'ts that often take the fun out of programming. Later chapters concentrate on using the Dragon's extensive sound and graphics facilities from BASIC. The emphasis here falls on understanding how things work and on avoiding any problems before they arise. For example; if you have ever used a DRAW command to produce a small shape only to discover that the actuaI shape it draws depends on its position on the screen then you need to read Chapter 10 in this book!.

ANATOMY OF THE DRAGON...by Mike James..(Sigma).6.95.

Dragon Data Approved.

This book is for anyone wanting to know how their Dragon works and how to control it from BASIC. It describes the Dragon's hardware and software from the point of view of a BASIC programmer. It introduces a number of new graphics modes, and explains how GET and PUT can be used to create user- defined graphics, shows how to disable the BREAK key and a great deal more.

LANGUAGE OF THE DRAGON...by Mike James....(Sigma).6.95.

This is an introduction to 6809 assembly language that also includes a complete assembler in BASIC. Assembler is much easier to learn if each of the registers, instructions, etc, are introduced as a way of doing something. In this book each of the 6809's features is introduced in a practical and logical way, building up a complete picture of assembly language programming on the Dragon. A key feature is the way the idea of a bit pattern is used to unify all of the confusing types of data encountered by an assembler language programmer.

ARTIFICIAL INTELLIGENCE IN BASIC...by Mike James....(Newnes).6.95.

Although not Dragon-specific this book contains many programs that will run on the Dragon without modification. Artificial intelligence is certainly where the future of computing lies and this book contains explanations and practical examples of most of the current A.I. techniques. Rather than abstract theory each chapter explains the ideas involved by way of writing working programs, making the book suitable for all BASIC programmers.

THE COMPLETE PROGRAMMER...by Mike James...(Granada).5.95.

This is another book which is not specific to any machine but, being written with the Dragon in mind, is therefore directly useful to it. IC and who want to increase their knowledge of programming and to improve their programming style.

THE 6809 COMPANION...by Mike James....(Babani).1.95.

This slim volume is an ideal reference book for every 6809 assembly language programmer. It includes the complete 6809 instruction set together with information about interupt handling and programming style.