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TIHOME Tidings - Volume 3, Number 1. March 21, 1983 Part 4

Afterthoughts
by Roger Culshaw

>nn mmmow Way, wwwwon Stone, Staffs. 0995-89999n
RPGs I was so glad to receive my first copy of Tidings. I am not the only person in the UK who has been silly enough to buy this TI computer made by such an obscure company. I've read it cover to cover about three times now. Having played Dungeons and Dragons for nearly 4 years now, your magazine seems somewhat similar to the early pioneering spirit in the fist role-playing 'zines.

My basic interest in computing stems from work where for my sins I now tell other people what to do rather than get my fingers onto a keyboard. So I filled this serious gap in my life by getting my own machine. I selected the TI for several reasons, it was available, cheap (I got the -50 handback), its color and sound were far superior to others (Dragon and Spectrum) and more importantly my financial manager (the wife) thought that the version of "Pacman" was good and gave me permission to buy it.

As I mentioned before my other passion is for role-playing games and I am now actively combining the two. This gave me the germ of an idea for a series of articles where I might outline the various game structures involved in role-playing games and discuss the computing problems they pose. I must confess that my programming background is in ALGOL, PL1 and Z80-based machine code so I do not profess to be an expert in Basic. But as far as D& D is concerned then I think I could hold up my own in a learned discussion about the merits of a "throwing star" or a "sleep spell"!

I hope to explore the basic fundamental structure of role-playing games and present some ideas on how to translate these onto the computer. Perhaps those of you with an interest in adventure games might also write in especially if you disagree with anything.

In this article I will outline the basic idea of role-playing games and try to describe the essence of some of the more commonly played games.

Role Playing Games: A Basic Description The first requirement of a role-playing game is a setting. Be it in fantasy with magic and mayhem or in science fiction with computers and mayhem. (Mayhem seems to be an important component). The next component are some imaginary characters controlled by the players and finally a referee/ games master/ dungeon master to design a scenario based in the setting and control the game.

The characters normally have randomly determined attributes such as strength, intelligence, dexterity, charisma etc. Their subsequent skills in the game are then dependent on these characteristics. For example characters with above average strength fight well whereas characters with good dexterity are better at activities needing stealth (like picking pockets). The players must first determine the attributes of their characters and equip them for an adventure. They then play through a scenario designed by the referee using rules laid down for combat, magic, movement etc.

Many people ask me how do you win? Well in a well designed role-playing game you don't actually win, nor do you really finish a game. In essence your characters live and exist in another world and life goes on for them as it does for you. Most games have a system of character improvement where the gaining of experience leads to the improvement in character abilities.

Typical Role-Playing Games Dungeons and Dragons The father of role-playing games and still regarded by many as the best. Set in a "Lord of the Rings" type world complete with magic monsters and of course mayhem. However it is quite expensive to buy all the books and supplements. If you just want an idea about role-playing games for the computer and don't want to actually play then; this may be the wrong one to buy.

Runequest Similar setting to D& D but with different philosophy of combat and character class. In Runequest a character has the ability to fight, cast magic or a whole host of other skills. As the game develops the player may well specialize on a few. In D& D the characters become specialists from the start. The Runequest combat system is also quite realistic but involved. The basic Runequest rule book will cost you -5.95.

Traveler Again a bit expensive to buy all the material but unlike the others detailed here this is the land of the future with laser pistols, spaceships and computers (Oh yes, mayhem as well).

Tunnels and Trolls Probably the best buy just to see the basic game mechanics of a role-playing game. The rule-book is only -3. 95 and I found it fairly easy to follow. This game also has the advantage of something like 15 solo adventures for you to try your hand at. I don't think it is the best game to play but to get ideas for a computer type adventure game its ideal.

Others Those of you who watched Shogun might like Bushido or you can get a game based on the wild west or even based on Dallas (No, you don't get a real live Victoria Principal). There is a legion of games to suit all tastes.

Problems of Computerization It is first of all important to establish that a solo role-playing game moderated by a computer will be a game of a different nature to a multi-player game with a human being as a moderator. Much of the fun in the "live" situation is the social interaction between players and of course the arguments with the Dungeon Master. "Of course my Dwarf can hit a Goblin with a Flail when he is 7' away." (This little discussion resulted in an enactment of the situation to resolve the issue) The computer will not respond to impassioned cries or threats. So from the start we will establish the principle that our computer moderated game is different and our aim should not be to mimic the "live" games.

Having said that, we don't want to lose all the components of these games. Somehow we must still capture the player's imagination and develop his attachment to his character. Our problem therefore is to design the framework for the game based on "live" role playing rules and provide a substitute for the lack of other human players.

Text and Graphics on the computer seems to be the solution adopted by most adventure program writers to convey the world and environment that a character exists in. One thing we know about Text and Graphics is that they gobble up memory and with our 16K machine needing a second mortgage to extend its memory this is a very important consideration.

To be fair to our machine, memory usage is a generally recognized problem of adventure programs. In most cases some compromise is achieved and in my mind the end results often leave a lot to be desired.

The next problem to be faced, is the problem of giving the player enough flexibility of action, so that he does not feel that he is being constrained into a course of action not of his choosing. More options mean more program and even more important more and more checks to ensure that the program will not allow inconsistencies to happen such as going through a door that does not exist or fighting a dead wolf etc. Simplicity is the key to success in avoiding these problems but at the same time it leads to restrictions that can detract from the game. (Why can't I pick up the chair and bash the sleeping Giant over the head with it? . . . Because my program sees a chair as an object not as a weapon!)

OK what else? Well the base data for our adventure setting will change as our player works through it. Monsters will be killed, objects taken, secret doors found etc. The program must be able to update the current status of the "Dungeon" so that a previously killed wolf isn't suddenly alive again when we re-enter the room we killed it in. This problem is normally solved by creating arrays which hold all the information about the dungeon and updating these as the character interacts with the situation. Once again arrays use memory especially on our machine that has this obsessive desire to please us with its 14-digit accuracy.

Next . . . How does the player communicate with the machine to control his character. The most common method used is the two-word instruction e. g. OPEN DOOR, DROP CHEST, FIGHT WOLF, etc. This can be elaborated to the sentence input where the program looks for key words to interpret your instructions. In both cases the player can get frustrated when the computer fails to recognize a command.

All in all adventure/ role playing programs are not easy to write. My own experiences have shown that much thought and flow charting is needed to achieve the best compromise between playability and memory usage. I hope to discuss these problems in more depth in later articles together with such topics as character generation, handling magic, traps and combat etc. I don't promise to solve all the problems but I think I've a few novel ideas.

In the next article I will look at the sort of data we need to hold the status of the dungeon and discuss ways of optimizing the use of arrays. In the meantime, see if you can get hold of any of the rule books mentioned or better still play a "live" game.

Program Hints
Memory Left . . .
As you can gather from the above I have quite an interest in how much memory my program has used. I believe that in Extended Basic there is a command that allows you to do this but I've not saved enough money yet. One way round this is to find the largest array size that the TI will allow you to dimension and still run the program. The largest array size with no program seems to be 1812. e. g.

10 DIM M( 1812) 

will run, but

10 DIM M(1812) 
20 PRINT "I LOVE TEXAS" 

will not. As your program grows in length then the maximum array size will decrease. I find that on average a line of Basic program reduces the array size by 3- 3. 5 depending on the type of program.

Assuming that we have 14K available to us this indicates that a numerical array element uses roughly 8 bytes. This seems about right to me as it means 7 bytes to store a 14 digit number (e. g. using 4 bits per digit) and one byte for sign and exponent (max 127).

Anyway the technicalities don't matter since to use this method all you have to do is find the largest array you can dimension subtract this from 1812 and divide the answer by 3.5. This is approximately how many more lines you can add to your program.

Example

10 DIM M( 900) 
REST OF THE PROGRAM 

Runs OK Memory left = 1812-900 = 912 Lines left = 912/ 3.5= 260.

Reviews Reviews
Winging-it
(From Stephen Shaw).
A great game which has kept me occupied for hours. Your task is to fly a monoplane by instruments. You have air-speed, altitude, revs, course ground map and bad weather indicators to help you. Very well presented graphics and the sound of the engines changes tone to meet the situation. More importantly once you have mastered basic flying then there are three games to play involving hunting a meteorite, chasing a flying saucer and running from an enemy plane. The instructions with the game are very good. Highly addictive and frustrating (Thank goodness it's not for real).

Forbidden City (APEX Trading).
So far the one and only firm I have seen selling TI games and advertising in the "big" mags. A fairly standard adventure game set in a futuristic city. On the whole I found it enjoyable and free from bugs. A little too much on the side of POW! you're dead, but fun. The input uses the standard two-word command and the game is a text only presentation. I would suggest that you try to map as you go on a piece of paper so you can avoid the death traps next time! One final comment: If the brains behind Apex Trading reads Tidings. Then there is something really special I would like to do with your "GREEN MIST'! Are you that sadistic in real life?

Comments, Conclusions and a Cry for Help Printers . . . Would it be possible for TIHOME to approach someone like Amber printers to see if they could provide an interface to our machine. From the copy of Tidings I have just read it would seem that some of our members could supply the technical details. Machine-code . . . Is anyone interested in writing some articles on 9900 machine code. I was going to buy the Mini Memory until I found that it did not explain the machine code commands. Is there a book available or do you have to buy the Editor/ Assembler to find out.

New Software Companies

. . . I must agree with the comments made by others about the lack of enthusiasm by some dealers over the TI. One of the problems seems to be an apparent lack of cassette based software. A prospective buyer gets his copy of "Your Computer" and finds it full of software for Spectrum, BBC, etc., but no TI. Talking to my local dealer this seems to be the biggest put-off.

Anyway . . . I thought if no-one else is doing it why shouldn't I. This saw the birth of "Time Travels Inc" and eventually the first game (see below). My cry for help is for a small number of TI users to play test future games. Your fee will be a free game and a view of some of the rubbish I don't end up selling. If you fancy the game described below and would also like to play/ test future games write me a small note when you send off for "Squadron Leader". I would like to know what tape recorder you use and a little about your interest in computing so that I can select a broad spectrum of users. If I choose you I will return your money together with a free copy of the game and a short questionnaire to complete when you have played it. (Needless to say the next game will be an adventure game once I've fitted it into my Memory) . . . Bye.


Time Travels Inc proudly presents its first games tape for the TI-99/ 4A SQUADRON LEADER Can you save your country and destroy the secret enemy laboratory. You must select the bombers to form your squadron . . . arm them with the right bombs . . . judge the wind speed . . . conserve your fuel . . . and if you get through, land your planes. (Combines arcade action with skill in selection of inputs.) Complete with instruction booklet . . . full use of color graphics and sound.

To Tidings readers a 25% discount if you order now . . . Normal price -6, but at the moment it will only cost you -4-50 inc p& p. Send to: Time Travels Inc, nn mmmmow Way, wwwwwn STOKE Staffs xx15 0zz


Bits and Bytes and Bits and Bytes and Bits and Bytes

The past few months have been good ones for the publication of programs for our computer - so I thought a quick run-down of all recent listings would be useful . . .

Computer and Video Games October Issue:
Hungarian Squares Puzzle by Stephen Shaw
November Issue: Space Lasar by GM Programs
December Issue: Hungarian Hex by Stephen Shaw
January Issue: Target by R. Matthews

Personal Computing Today
October Issue: Blind Maze by Mike O'Regan
January Issue: Earth Attack by Peter Clisby

Personal Computer World December Issue:
Teepee Textpro by Mike O'Regan
All the listings are games programs with the exception of Teepee Textpro which is a word processor which works with the TI Thermal Printer, but can be adapted for use with other printers.

All the programs are in TI Basic needing only the standard console with the exception of Target which is in Extended Basic.

As you can see, the pace of publication of new programs is sure hotting up, and I am reliably informed that in February's issue of C & VG there are going to be more programs for the 99/ 4A including one about Manchester's sewers?!

Of course the publication of these programs depends on YOU - so all you budding programmers get out there and get published!

### It might not have escaped the attention of many new owners that there is a sorry lack of software floating around for our machine in comparison to some others like the Spectrum, VIC, etc. Well, now good news!

For some time now Stephen Shaw, one of our longest standing members, has been encouraging people to write programs for him to distribute as well as importing some very good examples of what is available in the U. S. Stephen now has numerous programs on offer, so write to him for a list at NN Alsrryy Road, Stockport, Cheshire SK4 Z11.

Thankfully a few other software houses are now marketing programs for our machine and three that have recently come to my attention are: TX Software of Harlow, Essex; Apex Trading of Brighton; and Titan Programs of Corsham, Wiltshire. Also Gemini Marketing of Exmouth, Devon do an excellent range of software for businesses and are promising to expand into educational software.

[1999 update: Gemini and Titan never produced anything for the TI. Apex produced some simple programs but did not last too long. TX suffered the unfortunate loss of its owner before the programs were issued, although Mr Mathews widow did manage to get some copies out.]

Meanwhile, back in Texas, TI have brought out three new command modules Parsec, Chisholm Trail and Alpiner, all priced around $30 in the States but not yet available over here. They all sound pretty exciting, particularly Parsec which I understand has digitized speech (whatever that is!). TI say that they don't know when these will be available over here or what the price will be - so I have ordered Parsec from a dealer in the States - my first attempt at a personal import!

You have to watch TI very closely at times . . . at least in this country. Available now is the Logo language which is a beautiful, child appropriate computer language which is soon going to take over as the major computer language in our schools . . . BUT . . . over in the U. S. Logo 2 has come out which is a HUGE improvement on the original, but TI in this country are keeping quiet about it. When I enquired about Logo 2, TI told me that this was still being tested out in the States - come off it!

Don't try to unload your obsolete Logos on us - we weren't born yesterday! Give us the REAL THING! Fanfare of trumpets: . . . 99'er Magazine have at last gone monthly! The latest edition I have (November 1982) is up to the usual high standard with good programs for you to type into your machine together with helpful tips and news. One particularly fascinating article was how TI Extended Basic handles subprograms - that's right, not subroutines, but actually subprograms within a program together with some entertaining examples. It is pointed out that this is a unique system which is not available on other micros - and apparently the next cheapest system that uses subprograms is one that costs -40,000!

For all those of you who have not yet bought the Extended Basic command module, this is the most highly recommended expansion of your system. The price has dropped from GBP 100 in the summer to GBP 69 which is the price advertised by AB & C Computers in Tidings' last edition - by this edition it might even have come down further!

Software Reviews

1. PS Pesteroids, (PS Software) 2. Outland, (Roach Software)

Both programs available from Stephen Shaw, 10 Alstone Road, Stockport, Cheshire, SH4 5AH. Both these games are the familiar "asteroids" type games - but there the similarity ends. "Pesteroids" is written in Extended Basic whilst "Outland" is written in assembly code for the new Mini Memory Module.

Pesteroids This is graphically a very exciting game with excellent use of sprites and color. At first rather boring rocks come hurtling at you - but these are easy to dispose of and once you do, you meet some familiar shapes which are not very friendly! It was, nevertheless a brilliant idea of the programmer to give the TI user the opportunity of shooting up other computer companies' logos - grinning Apples, menacing IBMs are all trying to crash into your ship - and when you shoot them up they turn into attacking Ataris and even vicious VICs! Although the action does not seem to get any faster with each successive screen, the objects appear to get bigger and more deadly each time.

You fight back with your ship's lasers - but their range is limited, so be careful. If you do seem in danger of colliding then you have one of two possible courses which you have already chosen before the game started. The first are your shields (which gives you temporary protection) and the hyperspace option which moves your ship randomly to another place on the screen (rather hazardous)!

Your score is continuously displayed and when the game is over you can select either REDO or BACK which will give you the opportunity to re-select your options. In either case the best score is retained and displayed. Oh - I nearly forgot - there is the chance to score extra points in between screens, again with nice use of graphics and sounds - but I will let you find out for yourself. (There has to be some surprises left!)

Conclusion: At -9 this has got to be one of the best programs around!

Outland This is the first program that has become available in this country for the new Mini Memory Module and is written entirely in assembly code which accounts for its relatively high price of -10. The graphics are poor and look like a very childish drawing of a triangular ship and distorted asteroids (but then again, I don't suppose that asteroids are REALLY shaped like Apples, etc!!) Nevertheless, this program does have some saving graces, mainly the speed of action which is vastly superior to Pesteroids.

You have only one defense option (besides your laser, that is) which is your shields - which are not of a temporary nature but last until you release your shields to take some other action. If you are hit by an asteroid while your shields are up you go shooting around the screen like a billiard ball and the only way to slow down is to use your thrust option - but beware of letting your shields down at the wrong moment. An interesting effect of your ship being hurtled around the screen is if you try to fire your laser, your laser beam seems to bend back on itself and it appears as though you have just shot yourself . . . but this cannot happen! Score is continuously displayed, but there is no facility for "highest score to date".

I must add that despite the superior graphics of Pesteroids my five-year-old son prefers Outland every time!

Conclusion: Poor graphic quality adequately made up for in speed and excitement.

Happy computing, Arieh Yacobi.



Letters

Dear Pete (Brooks),
I have recently become a TI-99/ 4A user and must say how pleased I am with the computer. However I am more than a little disappointed with the after-sales organization, software availability and 99'er Magazine problems (I am still trying to get one from the U. S. A.) On the positive side, things can only improve!

A couple of observations which may help other users: When using Number Scramble (Oldies But Goodies by Texas Instruments) on my 4A, I found that the X key did not move the numbers as it should have done. It now works OK after changing:

3200 IF KEY= 3 THEN 3270 
3210 MROW=-1 
3270 MCOL=-1 

A very cheap cassette recorder which works well with the 99/ 4A is the Jones CT 5101. I use the Sanyo Slim 3G which I am very pleased with, but I know some recorders (regardless of price/ quality) just refuse to work with the computer. I believe it has a lot to do with the response time of the Auto Level Control.

Help please - I have just received my first batch of programs from the software library (Paul Dicks must spend most of his spare time copying programs!). I have some problems which others may have solved:

015 STARFIGHTER - No control 009 LUNAR LANDER - Metering doesn't seem to do anything 058 BOMB RUN - Doesn't run, Extended Basic? Not indicated on software library list as E/ B, so beware.

Finally, I am willing to help any beginners in my area (Swindon) if I can but would add that I still have my "L" [Learner] plates up myself! Anyway, if you can't seem to get off the ground, ring me on Swindon 822639.

Bruce Merrett.


Dear Paul,
First of all, congratulations on Tidings. I have found all of them interesting. I have only had a 99/ 4a since October and have not been able to spend much time using it. I note that there is some uncertainty in the nature of the 99/ 4A hardware. Whilst not having taken my 99/ 4A to pieces yet, to sort it all out, I may be able to offer some interesting information on the TMS9900, as I have been designing hardware and writing software for it for the past 5 years.

The TMS9900 is a 64-pin integrated circuit. It has 16 data input and output lines and 15 address lines. There are also memory control and interrupt lines. The address range available is 32K words, limited by the 15 address lines. The processor always generates word addresses, bytes are selected internally. There are no general purpose registers in the micro-processor.

It has only three registers. These are: 1. Program counter (PC) - Used to address the program instruction. The PC is incremented each time an instruction is executed, to the next instruction. An instruction may occupy 1 , 2 or 3 words of memory, the processor always steps on the correct amount.

2. Status register (ST) - This carries the results of arithmetic and logical operations. Bits in this register are set or reset to indicated arithmetic or logical comparisons. This register also carries the interrupt priority. If an interrupt of lower priority than set occurs, it is ignored. If an interrupt of higher priority occurs, it is serviced and the interrupt mask priority is set equal to this higher value.

3. Workspace pointer (WP) - As the chip has no general purpose registers, a block of 16 words in memory is pointed to by the workspace pointer. These 16 words are then treated as 16 registers.

Example. If workspace pointer = >F800 (> means hexadecimal) and instruction MOV R0,R1 was executed, then this would write the contents of address >F800 into >F802. (Note all addresses are word addresses and thus even). The most significant byte of a word lives at the even address, the least significant byte lives at an odd address. So R0 is the byte at >F800 and the byte at >F801 , making R1 carry on at >F802.

This WP system means that a new set of 16 registers can be obtained at any time by changing the workspace pointer. If an interrupt occurs, then there is no need to save any registers. The PC, WP and ST are stored in registers 13, 14, and 15 of the new workspace, so that they can be restored at the end of the interrupt.

The 9900 has all it's 16 interrupt vectors (WP + PC addresses) stored in memory, locations 0000 -> 003E. After that come the 16 software interrupt XOP (Ext. Operations) resides at >FFFC, >FFFE. Thus it is normal to place ROM in locations 0-> 3E, so that RESET (level 0 interrupt, usually derived from power up) causes a trap to locations 0000 (for WP) and 0002 (for PC). The other way of getting the processor running is to put ROM at the top of memory and use the LOAD signal (RESET inhibited). The program can then set up the interrupt vectors in RAM at the bottom of memory.

So, the 99/ 4A must have ROM in main memory to enable the system to run from cold. I assume the Basic interpreter also lives there. There must also be some RAM for workspace use (the 1/ 4K I suppose). The 16K RAM is said to be connected to the VDP. I don't have a full data sheet on the 9918 so do not know much about it.

The next question is how the CPU communicates with the VDP. It could be that the VDP is mapped into main memory or it could be done through the CRU. The CRU is the Communications Register Unit. This grand sounding facility is actually a bit serial I/ O method. It works by setting an address on the address lines A4 to A14. The address is obtained from Register 12 of the current workspace. To do an input, the CPU samples the CRUIN line.

For an output, the CRUOUT line is set to 0 or 1, and required, followed by a pulse on the CRUCLK line. This can be done for single bit inputs and outputs or multiple (1-16) inputs and outputs. For multiple bit transfers, the address is changed for each bit. This system allows the micro to address 4096 input and output bits.

This system need not be used only for I/ O. RAM can be connected to the CRU address space and then written and read via CRU instructions. The advantage of CRU I/ O is the simplicity of the hardware. The disadvantage is the speed. An output of 16 bits (LDCR R1,0) takes 52 clock cycles (17.3ms at 3MHz clock). An input of 16 bits (STCR R1,0) takes 60 clock cycles (20ms). So if the VDP is CRU addressed, transfers to the RAM will be slow. (A memory mapped I/ 0, MOV R1,@ PORT is 22 clock cycles - 7ms).

Well, that's a brief tour of the TMS9900. In the TI-99/ 4A free glossy, under specifications it says "System memory and address signals available at peripheral connector". They may be, but if TI don't say what is on which pin, what use is it? Even if it cannot be included in the price, a hardware manual for a few pounds would be useful.

Best wishes,
Chris Johnson.
P. S. I don't have Mini Memory but if anyone has a question on 9900 assembly language, drop me a line.


A-Rating
by Cyril D. Blount

I think it is a real break-through. I want to report an objective method of evaluating games for micros. Something that Software Houses all over the world have been looking for. Yet, like most scientific discoveries, my discovery was accidental, so I claim no credit for it.

Imagine! You wake at 7 a. m. one morning. There is a dull ache in your chest, your arms feel heavy as lead, your hands are tingling. You know you have a digestion like a horse, you've never had indigestion before, but the ache goes on and on and you cannot get back to sleep. You take a deep breath but the ache gets neither better nor worse. You feel as if you will never move again, heavy, washed out.

Suddenly you realize what is happening to you. All the lectures you have attended, all the folks you have talked to in hospital, all the books you have read come flooding back to you.

It is a heart attack! "Jen? You awake?" She turns over and groans. "I'm having a heart attack." She wakes up. Now there are advantages and disadvantages in having a nurse as a wife. They have a way of dismissing aches and paints as malingering. But this time in one minute flat she had run through the traditional list of symptoms. In one minute ten seconds you are sitting up at a forty five degree angle supported by pillows. One minute twenty and she is on the telephone to the G. P. (General Practitioner = doctor). Two minutes and she is packing "a few things" into a case ready for when the ambulance comes after her diagnosis has been confirmed by the doctor.

That is how my break through started. A few weeks in hospital which were busy and interesting and then home. Then I began to realize just how long a day really was. And the days stretched away in one long unbroken chain. What was I going to do with all that time?

I had been enjoying a full and satisfying life style. I had been a Methodist Minister for 26 years. I was looking after five churches with all the fun and sadness that goes with being involved in the devotional and social life of so many people. I had been doing a bit of teaching, just Psychology and Religious Studies at the local District College. I was Free Church Chaplain to a local Psychiatric Hospital. I was studying part time for a Masters degree with Sheffield University, and keeping up with my favorite hobby of astronomy.

How long before I could begin picking up my life again? Six months, they said, at least. Nothing intellectually demanding, they said. You'll have to give something up, they said, and get some weight off.

About this time, among the other magazines, someone sent me a copy of Printout. It was full of a jargon I didn't understand, though I'd done a bit of computing with an Open University course back in 1973. I found I only understood one word in ten. So I got them to bring me more computing magazines and soon

I had decided I was going to buy a micro. I listed all the attributes of my ideal micro. The two real one's which came anywhere near my ideal were the BBC 'B' and the TI-99/ 4A. But I found I would have to wait at least six months for a BBC so I ordered a Texas from Computer Supermarket in Corby with an Extended Basic module. Within a week it came.

Up till now I have spent my days reading. I'd always intended to read the vet books by James Herriott, now I read them one a day. I discovered the Covenant books by Stephen Donaldson: they took a little longer to read. I read the only one of Richard Adam's books I hadn't already read, Plague Dogs but suddenly I had no time for reading, the days sped by. I had found a new type of therapy.

My wife named it Texas Therapy. A new way to recover from a coronary. But there is still my break-through to tell you about.

One of the after effects of my heart attack is a new kind of pain in my chest. I get it under two sets of conditions (i) when I get excited (ii) when the wind blows in my face. The pain is called angina.

I can play a lot of TI Invaders before the excitement brings on my chest pain. But I first noticed that computer games do bring on angina after buying Octal from Stephen Shaw. Then I found that when I reached the third floor of Keys To The Castle (also obtainable from Stephen) I began to suffer. But the game which has given me the worst bout of angina is The Attack. After about one minute at level two I feel the ache begin and after five minutes I can stand it no longer and have to give up.

They say Parsec is even more exciting. Well, I will tell you. I have ordered it and we will see how it does on my new rating scale, how long it takes to give me angina.

These are my ratings so far:

TI Invaders 20+ 
Keys to the Castle 15 
Octal 10 
Cross Country Car Rally 7 
Winging it 4 (lt comes on as a crash, and I always do). 
The Attack 1 

The smaller the number, the quicker my angina starts and therefore the more exciting the game is. And that gives me an idea. There might be a way of raising enough money to buy myself a disk system in this heart of mine.

So Software House please note: If you want an independent objective assessment of how exciting your new game is why not try it out on my heart? Say GBP 5 a time? Let me see . . . that will be about 100 evaluations! I wonder if my heart will stand it?

Hold
by Cyril D. Blount.
Workspace 1.

Does your micro produce numbers which are consistently random when you call RND and tell it to RANDOMIZE or does it give you numbers whose distribution contain an inherent pattern? Why not check it out? Let us set our computer to generate pairs of digits in the range 0 to 9. If the two numbers generated are the same we score a "hit". In a run of 10,000 pairs we would expect a random number generator to produce 1,000 hits in theory, but on my 99/ 4A I scored 113 hits too many.

Superficially this shows that the TI Pseudo Random Number Generator does not produce random numbers, but if such results are obtained consistently with different computers using different methods of random number generation, and also when using such random natural events as radioactive decay to generate random numbers, then you need to ask what randomness is.

So I recommend a book to set you thinking and to stimulate you to perform experiments in randomness on your TI-99/ 4A. On Time by Michael Shallis (sub-titled, "An Investigation into Scientific Knowledge and Human Experience"). Published by Burnett Books Ltd., 1982.

Workspace 2.

I too wasted my day by going to the Northern Computer Fair at Belle Vue last December. Why doesn't TI exhibit at these do's? However I came away with one thing worth passing on. I had always kept my console covered with a piece of cloth thinking to keep dust and dog's hairs out of it. But while I was at the Fair I ordered a cover for my console. It cost me -4 and I am very satisfied with it. It fits very neatly and is well finished. I got it from Micro Aids, 2 Boston Close, Culcheth, Warrington, WA3 4LW. Their telephone number is 092 576 2804.

Workspace 3.
I have just received the newsletter of the International 99/ 4 Users-Group dated November 15, 1982. For those who have bought themselves a Mini Memory module there is an excellent article in it on the Assembly Language blues, and a report promising TI's version of Forth in the first quarter of 1983. Some time ago I bought an assembly source listing for Fig Forth 9900 from Microprocessor Engineering Ltd. of Southampton with the thought I would adapt it for the 99/ 4A. But it was beyond me, so I look forward to TI's own module. The annual subscription for the International Users-Group newsletter is $12 and membership offers a number of discounts on TI products. The address of the group is PO Box nn, Bethany, OK 73nnn, USA.

Workspace 4.
Oaktree Systems of 3922 Valentine Road, Whitmore Lake, MI 48189, USA have a package on offer for $24.95 for display enhancement. They offer a 40-character wide display mode instead of the 28-character standard display, plus forward and backward scrolling of 96 lines and the ability to split the screen into two parts so that one is scrolled while the other is stationary. However you will need Memory Expansion, Extended BASIC and Disk Drive to run it. It works by using 6 by 8 pixels to define the characters instead of 8 by 8 pixels and it occupies 3842 bytes of memory space.

Workspace 5.
If you are a Minister or Member of a Church you may be thinking about how you can use your micro for the benefit of your parish or circuit. You are not alone. The CCUG (Church Computer User's Group) has been set up by a group of enthusiasts to "gather and share ideas and information about the use of Computers in Church".

The Rev. R. S. Wilson of Ggggnside Vicarage, Rrron, Tyne and Wear is the editor of the magazine Church Computer and the Rev. Nigel Hardcastle of nnn Rrrrrrfield Road, Ggggetts Green, Birmingham deals with everything else.

In the December edition of the magazine there are articles on filing, computers and privacy, finance, religious education, computerization of diocesan offices and a report of the Church of England working party on computers.

Workspace 6.
Finally a little program for you to play with. It uses a simple FOR-NEXT loop as a clock.

100 INPUT "WHAT IS THE PRESENT TIME, IN HOURS, 
MINUTES?": Z, Y 
110 X= 0 
120 FOR TIME= 1 TO 309 
130 NEXT TIME 
140 X= X+ 1 
150 IF X< 60 THEN 120 
160 Y= Y+ 1 
170 CALL CLEAR 
180 PRINT Z;" HOURS", Y;" MINUTES" 
190 IF Y= 60 THEN 200 ELSE 230 
200 Y= 0 
210 Z= Z+ 1 
220 IF Z= 24 THEN Z= 0 
230 IF X= 60 THEN 110 

If you are using Extended BASIC then the loop runs at a different rate and line 120 needs to be changed to:

120 FOR TIME= 1 TO 227 

HOLD over: resume processing.


Letters
from Margaret Nobbs, Coatbridge Child Guidance Centre

Dear Paul, I would be very pleased to have my name published in Tidings for anyone who is interested in educational software for Primary Remedial or Special Education.

I am still pursuing my research into the possibility of acquiring LOGO without an exorbitant expenditure. I was discouraged at one point, by a contact who told me that it would be very difficult and would require a lot of effort on my part without any backup available. At that point I almost decided to trade in my TI for a micro with a cheaper expansion system. However, a fortnight ago in The Times Educational Supplement (12. 11. 82) there was an article giving a reference to a Rhys Gwyn in Didsbury School of Education, Manchester Polytechnic who has been experimenting with TI Logo in Primary Schools. I phoned him, and he reassured me about the possibility of using the module without difficulty. He is also going to send me details of a summer school on Logo, which I may decide to attend. So, with new enthusiasm I may indeed acquire the expansion system, 32K card and module, all to be able to key in

TELL SPRITE 
CARRY: TRUCK 
SET COLOR :RED 
SET HEADING :EAST 
SETSPEED 100 

and see a little truck dash. across the monitor, on which I will previously have drawn a suitable background.

If it ever comes about, I will write you an article for Tidings! Many thanks for all the effort you put into TIHOME, and happy computing.

Margaret.


Part 3 |   Part 5

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