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This web page contains the text of articles for owners of the TI-99/4a including a series called Rambles, taken from Issue 3 of TI*MES dated Winter 1984, published January 1984 by Clive Scally. It is of use to users of the TI-99/4a emulators and of historic interest regarding home computer use in the UK in 1984. This issue is important as it was the first publication following the announcement by TI in November 1983 that they were withdrawing from the market.
I have included excerpts from an article by Howard Greenberg of Arcade Hardware, of historic importance to TI users for the history of the Thorn-EMI modules which starts here (more excerpts regarding these will follow from later issues of TI*MES when I get to them). Also a rare article by Ian Godman of Christine Computing - in 2011 Ian and his son were working together on web sites, but alas without Christine, who had been suddenly taken from them by a car driver whilst she was crossing a road. She was a lovely lady.
Excerpts from an article by Howard Greenberg of Arcade Hardware
From conception, through development to production. The Arcade Hardware 32k RAM.
By May 1983 I had come to the conclusion that if I wanted a 32k RAM expansion for my TI99/4A that was cheaper than the official unit and didn't require the peripheral expansion box, then the only way to have one was to either import one from the states, which by the time it arrived here would have cost more due to customs duty, V.A.T. postage or to make one for myself.
Due to my work in the amusement industry I had a limited knowledge of electronics and I had already had some commercial experience adapting arcade joysticks for use with my TI99/4A. I knew that my electronics know-how wasn't enough to design a memory expansion board, so I turned to a friend who runs his own design consultancy.
Bob took my TI99/4A apart and studied all the documents available for it. It was then that I received my first shock. There was no way that a memory expansion could be made let alone sold for the same price as those sold for say, the Vic-20. Under those circumstances did I still want to go ahead ? I gave it some thought and decided yes. Bob made a wire-wrap prototype which after some modification worked fine. The next step was to design a printed circuit board, which would do away with the messy system that wire wrapping entails.
I 'phoned Stephen Shaw to see if he would try out the boards on his machine. As Stephen doesn't live too far from me and has all the software that uses a 32k RAM it seemed easier to try it out on his software rather than try to write a program to utilise the expansion memory.
Carefully plugging in the card into his Peripheral Box, I soon had an answer. Every time a program was loaded from disc using the Minimemory it crashed. The same program was then loaded using Editor/assembler and it worked. It was then tried again with Extended Basic and again it worked. At least all wasn't wrong, but it was a mystery as to why the Expansion memory should fail with the Minimemory.
A panic stricken 'phone call to Bob and we agreed to meet at Stephens house the following Thursday. It took Bob all of 10 minutes to find the problem and to affect a permanent cure. The problem was merely two tracks on the PCB being so close to each other that data was being transferred from one to the other, thus corrupting itself. Scraping away the offending area provided the solution.
Ultimately too, the plastic cases arrived, and very handsome they were too. All that was now to be done was to fit the boards into the cases and all was done. The unit worked, it looked good and it fulfilled all the requirements. From start to finish, the project took seven months. That it was finished at all is a tribute to those people who gave help and assistance when I was stuck, often they were laymen with no interest in computing. Because of the following people, you now have a choice as to whether you wish to expand your TI99/4A without buying the Peripheral Expansion Box.
Bob : Who designed the unit and gave encouragement and advice way beyond the
requirements of a normal customer/client relationship.
Stephen Shaw : Whose enthusiasm for the TI99/4A is boundless. Without his help, the flaw using the Minimemory would have gone unnoticed. He gave advice and help to a virtual stranger, just because I too was interested in the TI99/4A.
Gary Harding, Peter Brooks and Richard Blanden : Three people who I've never met, but were still prepared to offer advice and assistance, either by post or by 'phone, just because they too are TI99/4A enthusiasts.
Life after November 1983
So what is available, not counting official T.I. lines left in shops ?
Starting with software, there are now many vendors selling varying quality lines from the mundane through to excellent.
Of these vendors the most prominent is Stainless Software. This is run by Stephen Shaw, in a profesional manner. Stephen has probably the largest collection of software I've ever seen, and much of it is truly excellent. In particular is an imported program requiring all the expensive hardware, called Display Enhancement Package. This lets you do things with the TI99/4A that even T.I. didn't think of. The makers have threatened to make a version for the Mini-Memory that didn't require the Disk system but to date that hasn't been forthcoming. I long for the day I either get a disc drive and controller or Oak tree software make the Minimemory version. Stainless Software don't only stock applications programs, but games and utilities as well, and for every configuration, from the bare console in TI-Basic through Extended Basic to the above mentioned package, which requires Peripheral box, Expansion memory, Disc Controller and disc drive.
There are other software vendors of course. Amongst them Lantern Software and Christine Computing are the most prominent.
It is customary after even your worst enemy has died to stand around the grave muttering about how he was such a fine fellow. Well in this case, the person concerned certainly isn't dead and he's not my worst enemy.
In the last edition of Ti-mes, Clive mentioned that there wasn't much that
Stephen Shaw didn't know about the TI99/4A. I'd like to back that up. In
all probability Stephen knows more about the machine than those who are
supposed to. i.e. Texas Instruments. Since I first read Stephen's articles in
Tidings ( now sadly defunct ) I have learned a little and enjoyed a lot.
I'd have probably have learned a lot but for my being bone idle. Where he gets the time to write for Ti-mes I don't know. In between writing his new book, writing programs for the likes of HCW and Computer and Video Games, and a very informative set of articles for the excellent Popular Computing News on the baffling Mini- memory not to mention running Stainless Software, keeping up to date on all that's new in the USA, he also has time to go to work for a bank.
If you ever wonder what exactly Ideal Home are on about when they say so and so has a busy lifestyle, then perhaps they are talking about Stephen. I've met Stephen a couple of times and I've always been impressed with his grasp of the TI99/4(A). I've asked many stupid questions which have always been answered. In addition Stephen was invaluable when testing my 32k Ram expansion. Without his help, a last minute problem would not have been discovered, or put right.
So, Stephen please keep writing. I hope I haven't embarrassed you.
Monday 19th December 1983.
Ian Godman (Christine Computing) and I have just finished work at the Your Computer Christmas fair at Wembley Conference Centre. Although the show was disapointing commercially,(too many screaming kids treating the place as though it was some free amusement arcade) we did get to meet some very nice people. Some were already familiar with the TI99/4A, others contemplating buying one. To those of you who we managed to stand and talk with sensibly, thank you, you made the show worthwhile.
Amongst the people met for the first time were our editors,Clive and Audrey. It may seem odd to be writing this for unknown people, but they too are Texas owners, and that was enough to prompt not only myself but others such as Stephen Shaw to share trials and tribulations, pleasure and pitfalls re the TI99 with fellow owners. Now I've met Clive and Audrey, I know that my efforts aren't in vain, and that writing for this magazine is worthwhile.
Amongst the titbits of news learnt from C and A was that we shall have a new writer in TI*MES, Peter Brooks. Peter was one of the very first people in this country to own a TI99/4 (not 4A) and has accumulated a vast store of know how about the machine which in the pages of Tidings he passed on regularly. All we need now is one more writer formerly with Tidings(Gary Harding) and this magazine will deserve to be sold in WH Smiths. Gary Harding is a Computer programmer by profession and knows as much as is needed to know about programming in machine code. Gary, if you're reading this, please join us.
Dirty tricks division : Prize stinker this month must go to Thorn-EMI. In February 1983 I received their catalogue with the announcement that Submarine Commander and River Rescue would be released in cartridge format for the TI99/4A in Spring. Quoting the catalogue numbers I promptly ordered the modules. Back came two modules for the Atari.
They're very helpful at EMI ordering department. If they think you've made a mistake, they correct it for you and send the item they know you really meant to order. I explained to them that I really wanted what I'd ordered not what they thought I wanted. Oh, said the order desk, we have no record of those items in the computer. Hmm. I then phoned Thorn EMI video who are the administration for the Video and home computer software.
God forbid it should all be in the same building. Speaking to a very pleasant lady she informed me that she had only had the job a week, and that she wasn't really sure of the position. Neither had her boss, who realising that Thorn EMI weren't for him had disapeared in the direction of Virgin who were setting up their own home computer software division.
If I were to telephone later, she'd get hold of the new supremo, one Mr. Mike Dixon, and find out what wasn't going on. I duly 'phoned, and the story was that the launch was postponed until Summer.
Phoning in Summer produced 0 results. I was beginning to get a little fed up with all this inactivity. However in the October release sheet came the news I was waiting for. Not only would Submarine Commander and River rescue be released - but a new addition 'Computer Games' based on the film War Games was also due out.
I duly placed my order quoted my catalogue numbers and waited. And waited. On the grapevine came the news that the launch was now postponed until Nov 11th. On November the 11th I phoned the Administration office to ask why no delivery. It seems that Mike Dixon had left the company (popular job that) and after checking with the latest supremo I received this statement.
There are not, nor will there be any software from Thorn EMI for the TI99/4A.'
Just goes to show, you can still fool a lot of the people for a long time.
(This is NOT the end of this tale....)
This article is an attempt at presenting a technique for structured programming in a manner that is both understandable and usable.
However it may not be clear initially what advantages this technique has to offer other than making an understanding of the examples given in later articles easier.
what is presented here are the bare bones upon which some flesh will be put by me, but mostly by you.
Before starting to program there are two rules to remember:
1. Think - don't rush.
2. Switch the computer OFF.
Rule 1 will save a lot of problems later as an early mistake can carry on to the end. Rule 2 will save you many a headache and a great deal of agro.
PART 1 SPECIFICATION.
STEP 1:- A program is a series of instructions that perform a task. Therefore the first step is to define the task to be performed eg 'Play space invaders'.
STEP 2:- Analysis. This is the hard think stage. At this point it must be decided what is going to happen during 'space invaders' eg move laserbase across bottom of screen, fire at base, base fire at invader etc.
SUMMARY:- In step one you decide what you want to do and in step two how you expect to do it.
PART 2 PLANNING.
Make out a 'program map' on a sheet of paper by drawing boxes-
'program segments',and in each box write a part of the program.
Then join each box with an arrow showing the direction of flow.:
It may require several attempts before you succeed.It may even be necessary to return to your analysis.
SUMMARY: You should now have a pictorial representation of the components and their relationships that will make up the finished program.
STEP 1:- This is a return to part 1 but in greater detail. This time each box in the program may is given the analysis treatment,ie 'move base' would become 'delete old base, draw base in new position etc'
STEP 2:- Draw a map of each segment as you did for the program map This is called the flow chart and should look something like this:
PART 4 FINAL SYSTEMS PLANNING
STEP 1:- You now have a master program map and many program segment flow charts. You must now decide how each segment communicates necessary information and indeed what information needs to be communicated to other segments. ie space invader hit and type of invader needs to be communicated to score section. Make note of these inputs and outputs on both the program map and the program segment flow charts as this will enable later cross reference.
STEP 2:- Now look at the program map. Are there any segments duplicated? If so are they suitable for subroutines. eg print score. Now look at the program segments flow charts and ask are there any parts that could be subroutines such as key input before validation.
SUMMARY:- So far you will have most probably thrown away 5 times as much paper as you now have in front of you, but what you have is more than likely 10 times as good as anything you could have written in twice the time on the computer!
PART 5 CODING
This is the actual writing of the program which is undertaken using the segment flow charts plus 3 pieces of paper. One to write the program code on, one to write name,purpose and lines affecting variables, and one on which to write the name start and stop line numbers of each segment.
Write the program as the flow chart, a box at a time and test each box when written. Make sure that the segment under test does what you want it to and that any incorrect input is dealt with eg. giving a column address of O to a Call Hchar command will result in an error and program execution terminated.
PART 6 ENTERING-TESTING-DEBUGGlNG.
STEP 1:- Enter all the program segments making sure that you koep note of the start and stop line numbers of each segment, and the lines affecting all variable values and the lines those variables are used on.
do not resequence as this will invalidate your lists.
STEP 2:- Run the program and enter all types of data to check that only correct values are accepted and a correct response achieved. If an error occurs check the values of the variables by stopping the program and printing then in immediate mode, using your list to find out what variables are used. If a variable value is changed often and the error does not stop program execution then enter a break point so that when the program stops at the appropriate line the values can be printed and the program execution can be resumed with continue, thus avoiding resetting all variables to zero.
Once the culprit has been found using your lists go to the lines that effect its value and try to work out how it managed to achieve an incorrect value.
In the next issue I will demonstrate the working of the techniques outlined here with the development of a useful subroutine for creating display windows and simulating the "display at" instruction of extended basic.
Welcome to another issue of Rambles. No requests for specific items so it is the mixture as before!
Since the last issue of TI*MES we have had the appalling news of TI's withdrawal from the home computer market, and even worse for those of us in the UK, the decision by TI to employ (illegal) resale price fixing, at ninety pounds, while over in the USA the State Troopers had to be called in to handle the riots caused by the severe discounting over there!!!
The peripherals were dropped slightly and modules had some nice price cuts. Despite the low discounting, there was still a very significant drop in 3rd party cassette sales for a while, quite destroying the expected Christmas market.
At the time of writing, the end of December 83, almost all of the modules and peripherals were available from Parco in Honiton, but with nothing manufactured since the end of October, supplies will of course be limited.
Galaxy in Maidstone had a few TI modules in, and a small stock of some ATARISOFT modu1es...that is, modules for the TI99/4A made by Atari. There are about ten modules launched, and Galaxy had four titles in when I phoned them recently. The selling price is thirty pounds or less, and the titles launched include Pac Man, Donkey Kong, Dig Dug, Centipede, Defender, and a couple of titles licenced to Atari by Synapse, Protector and Picnic Paranoia.
I am going to buy some of these and maybe review them in the next issue. The UK supply may not be too reliable.
The FUNWARE modules do not have a UK source at present.
Thorne EMI have stated they will not now be launching the 99/4A modules first advertised by them 12 months ago (not the end of the story, Howard Greenberg got the modules from Thorn and licensed them, after many months of work).
As IMAGIC have themselves gone out of business, it seems we will not be seeing their modules, although a small number of Demon Attack and Microsurgeon have been sold in the USA.
Small quantities of the Spinnaker modules FACE MAKER and STORY MACHINE have also been sold in the USA, but distribution was by TI. The same applies to Jawbreaker by Sierra. The Broderbund and Sega modules do not seem to have made it.
Some new TI modules just made it into the States before they pulled out, including a fascinating title SLYMOIDS.
I shall be spending some time seeking these modules out and try to review them...it seems likely that small quantities will make there way here, possibly even 2nd hand modules, and it is as well for you to know what they are - just in case
As already announced. I shall continue (as Stainless Software) to supply cassette software as long as anyone wishes to buy it.
There are many other cassette suppliers...I count over two dozen...so any claims of a shortage of software indicate someone is buying the wrong magazines
TI Owners who do not wish to purchase by mail order WILL find it difficult to obtain supplies. Look into Home Computing Weekly for reviews of cassette games ,and of course TI*MES!!
Purchasing by mail order does of course require a certain care...the following
are some of the things you can do wrong, and result in disappointment or loss:
when writing an enquiry:
Send an SAE to ensure a reply.
Make sure the SAE does have your ADDRESS on it
...and a STAMP.
Make sure your letter and the SAE have adequate postage...few suppliers will accept a surcharged letter.
DO NOT pay postage on the SAE with a franking machine: a franked impression is of value only to the licensee, and cannot be posted elsewhere.
when writing overseas, do not send UK stamps...they are also of no value. Send one or two International Reply Coupons, available from your Post Office.
Ensure you have quoted your address, and that it is legible
when ordering goods:
DO NOT pay by means of a franked impression: it has no value.
Try not to send coin: it is easily lost. Also PO regulations forbid sending coin other than by registered post - your letter may be surcharged and refused.
QUOTE YOUR ADDRESS CLEARLY
Ensure you have the equipment needed to use the advertised product.
Leave adequate time for delivery: 28 days is normally considered a maximum, and 'by return' is rarely available. If you state an unreasonable required by date, your order may just be thrown away!
Tape software is hardly ever offered on approval, due to the ease of copying and the large number of unethical computer owners.
Try not to use Recorded Delivery: it stands a better chance of loss through theft, and as it has to be receipted could be undeliverable if no-one is in when the first and only delivery attempt is made.
And do write to the correct address of the supplier (and for that matter, ensure you write to the correct supplier!).
with care, mail order can run smoothly. A little carelessness could however cause much distress and possible loss. The above is obvious - but in the last month I have encountered all these things!
A recent issue of PUNCH had an ad by VAN HEUSEN (shirts), which had a TI99/4A in the picture. Anybody spotted any other guest appearances?
(Obtainable for GBP 7.95 from TIMELESS SOFTWARE,
3 Bcderend, Fderfhouse, West Lothian, EHNN 9YY)
Old readers of TIdings may recall a previous review of this program, then for Extended Basic plus 32k ram, and selling for US$35.00 !!
This review is of a rewritten version for Mini Memory, now available in the U.K. at the much lower price indicated above.
GAME: In this game you control an animated figure who must avoid being caught by any of six monsters, and 'poof' them back to their cages...after all the monsters are dealt with, its on to the next round!
The animation of the monsters is superb! Points are gained by lighting up dots in the play area (these also act as barriers to the monsters, but do not last for long!), by the length of time you survive, by placing one of your six 'poofers' in the play area, and by 'poofing' a monster.
You have only 6 'poofers'. When you place these in the main playing area, they count downwards, and if they reach zero without a monster having been lured into them, you lose the poofer! When a monster is poofed the used poof is added back to your arsenal.
Sound complex? Actually its a fast and fun game to play!
The main documentation is for the original game, with an insert for the revised version. Read both carefully!
Some points are not however covered:
The area of the playing field which you (as Kippy) can cover slowly reduces as time goes on...this adds a whole new dimension to the game: if you have unused poofs outside the reduced area, it can be impossible to lure a monster into them!
The poofers can in fact poof more than one monster. At times I managed to poof four monsters with one poofer...and each monster poofed added to the arsenal...so you can gain more than six poofers! This again adds to the strategy
As the game progressed, black squares appeared. These did not affect play, but no dot could be lit in them, therefore reducing your opportunity for scoring in this manner.
All these amendments to the original game actually add to the fun, as the game becomes increasingly difficult, and also allow more strategic play.
TECHNICAL: This game is way over 4K and is entirely in machine code. It appears
to exceed the 13k the usual tape load can handle ....
Hows it done?
First you use Easy Bug to load another tape loader. This loads the program at 1200 Baud (eg faster than usual). Then this loader loads the actual game...and most of the game seems to reside in the VDP area!!!
Loading at this speed is a trifle more sensitive, and you will need to ensure your cassette is clean and demagnetised. Finding the right level may take a little longer than normal: and the usual load error messages do not work!!
The author has given you another load indicator...and then failed to document its use! As the fast load is progressing, first the top third of the screen should fill with letters, then an announcement appears in the middle. If the middle announcement is corrupted, switch off, adjust volume levels and start again!
FINAL VIEW: If you have MINI MEM, this game is a MUST. 100% for value for money~ and for playability. Recommended. Stephen Shaw
TI supplied most dealers by distributor...Robox in Scotland and Lightning in England. Both pulled out quickly after TI's announcement, leaving dealers with an immediate loss of supply. Partly as a result stocks of modules in the UK are higher than might have been expected...there were only a handful of sources left!
LOGO 2 contains a new tiny bug...the primitive MS (makeshape) which works in a defined procedure in LOGO 1 can only be used in direct mode in LOGO2. Thus one of the sample procedures supplied will not run.
An new addition to the range of FUNWARE modules is DRIVING DEMON, a creditable car racing game for one player. JOYSTICK REQUIRED. Although no UK supplier known at present. I am sure someone somewhere will bring these modules in...keep watching the ads. Driving Demon is very similar to GRAND PRIX arcade game from Sega, but involves only one scenario. The joysticks used to change gear (fire button), accelerate and brake, and move left and right to avoid the other cars. There is also a time clock. Challenging.
The code on the back of your module says where and when it was made...I have a LOGO quoting ATA3783. made in week 37 of 1983 at Austin (Texas). My Mini Memory is LTAl582...made in week 15 of 1982 in Lubbock (and needing a new battery soon'!).
Two books on Assembly Language programming have been announced in the USA, and I shall be sending for these, and reporting to you in due course. One is by Steve Davis Publishing, and the other by John T Dow.
GRAPHICS are a subject producing some interest...
Your TI99/4A has four graphics modes...only one of which is available if you
have only the console!
This is the 32x24 graphics screen, allowing you to place a character on any of 32 columns of 24 rows.
There is also a graphics mode in which you can set each of the 32x24 character positions to any of four colours. setting one quarter of a character position at a time. This mode does not seem to be used!
The so called text mode is 24x40 but is otherwise similar to the main mode: the biggest limitation is that you may have only two colours on screen at a time. I have an assembly language program which allows you to use this mode in Basic, using 32k ram and the Assembly modules: MiniMem, Ed/As or ExtBasic.
In order to address individual pixels on the screen, and emulate the DRAW or CIRCLE commands on other computers, you must use the pixel graphic mode, which cannot (apparently) be used with Basic. It can only be used in a pure machine code program. The only examples known to me are the LINES program sold with the Mini Memory Module, and Parsec.
It IS possible to simulate pixel graphics in Basic by continually redefining characters on the screen. You are of course limited by the number of characters which can be defined, and very limited by the speed available (V E R Y slow!). I do have a couple of programs which use this method. The same thing can be done using a machine code utility, but it is still not very successful.
The LOGO turtle does the same thing...a bit faster admittedly and it has MORE characters available, but still manages to run out of 'ink'.
Defining sprites or characters is not too difficult and there are several utility programs on the market to assist with the sometimes arduous task of calculating the right hex code.
GETTING STARTED WITH THE TI99/4A went into its 2nd print within a month: many thanks to everyone who bought a copy. If you purchased the first print, it is possible your bookseller neglected to insert the Errata sheet which contained the Joystick program (p.90) omitted in error. I think the program was printed at the back of the 2nd print run. One or two errors were also corrected in the errata. If you don't have a copy and would like one, please send me an SAE.
Or download a couple of big pdf files: Side One errata || Side Two errata
EXTENDED BASIC PECULIARITIES:
There are one or two strange things you may meet up with when dealing with sprites, especially sprites off the bottom of the screen (pixel rows 192 to 256).
Try these two:
100 CALL CLEAR
110 FOR T=1 TD 24
120 CALL SPRITE(#T,63+T,2,T*
130 NEXT T
140 DISPLAY AT(24,1)BEEP:"NO
W WATCH .... "
150 FDR T=1 TD 50 :: NEXT T
160 CALL SPRlTE(#1,42,2,208,
170 DISPLAY AT(24,1)BEEP:"HH
HH ..... "
180 FDR T=1 TO 900 :: NEXT T
Look through your manual and decide what this program is meant to do...concentrate especially on what line 160 is going to do. Now enter the program and RUN it. Notice anything? Run it again... any change?
In direct command mode, enter CALL DELSPRITE(ALL) and RUN the program again...
Where should the * appear? Should it be moving? (Read the manual).
Here is another little puzzle:
100 CALL CLEAR
110 CALL SPRITE(#1,66,2,208,
120 CALL LOCATE(#1,208,57) :: CALL MOTION(#1,-l,-7)
130 FOR T=1 TO 70 :: NEXT T
140 CALL SOUND(-10,600,0) :: GOTO 110
Now, in every cycle between BEEPs, the same thing should happen...right?
Where should the B be?
Run the program and watch the screen carefully for some minutes. Interesting?
Try the first list with:
160 CALL SPRITE(#1,42,2,208,
20,0,-10) .... ANY CHANGE?
and the second with:
120 CALL LOCATE(#1,180,57) :: CALL MOTION(#1,-1,-7)
Any difference? A couple more listings follow...
100 CALL CLEAR
Run this program: the two values shown should coincide...do they?
110 R=INT(195+40*RND) :: C=lNT(RND*240+1)
120 CALL SPRlTE(#1,42,2,R,Cl :: CALL POSlTION(#1,A,B)
130 DISPLAY AT(24,1)BEEP:R;A
140 FOR T=1 TO 600 :: NEXT T :: GOTO 100
120 CALL SPRITE(#1,42,2,R,C,0,0) :: CALL POSlTlON(#1,A,B)
now RUN the program...any greater accuracy?
or how about:
120 CALL SPRITE(#1,42,2,R,C) :: Z=2*2 :: CALL POSITlON(1,A,B)
does that give greater accuracy?
When using sprites off screen you cannot apparently rely on Extended Basic doing what it should.
Here is another...four sprites should appear, two in each of two columns, and each pair should be the same distance apart:
10 CALL CLEAR :: CALL CHAR(4
50 GOTO 50
20 CALL SPRITE(#1,40,2,200,1
30 CALL SPRlTE(#3,40,2,100,1
40 CALL HOTION(#l,l,0,#2,1,0
Enter and RUN this one!
If you have the 32k RAM, add:
15 CALL INIT :: CALL LOAD(-31878,4)
and RUN...any difference?
This seems to indicate that Extended Basic is having trouble keeping the CPU informed of the number of sprites moving.
You can also advise the CPU of 4 sprites if you do not have the 32k ram by placing 4 invisible sprites with zero velocities (IMPORTANT!)on screen, moving them to the pif screen position and then making them visible and moving them ....
this is called fooling the cpu...
10 CALL CLEAR :: CALL CHAR(40,RPT$("F",16))
20 CALL SPRITE(#1,40,1,1,1,0
30 CALL LOCATE(#2,200,100,#1
40 CALL COLOR(#1,2,#2,2,#3,2,#4,2)
50 CALL MOTION(#1,1,0,#2,1,0
60 GOTO 60
Any improvement? Try some experiments of your own.
BRAINTEASERS FOR BASIC COMPUTERS.
Gordon Lee. SHIVA. GBP 4.95
PBK 123pp ISBN 0 906B12 36 4
This is a collection of fifty puzzles...you could work them out with a pencil and paper, but the idea is that you are to write a computer program to solve them. Once you have solved them with a program, you can then improve the time your program takes by rewriting it in a different manner (a digital stopwatch is handy). Thus even experienced programmers can improve their programming! Sample listings are given at the 'back' for each puzzle...these will find the solution, but they may not be the best program.
Notes for TI owners:
In TI BASIC you do not have OR or AND available.
You use the following:
ORIGINAL: IF U=T OR U=H THEN IF U=T AND A=B THEN
In an IF THEN line in TIBASIC, do not use GOTO,just the line number.
TI99/4A: IF (U=T)+(U=H) THEN IF (U=T)*(A=B) THEN
For STR$,use brackets: A$=STR$(A)
For LEN, use brackets: IF LEN(A$)<>3 THEN...
For concatenation use &: C$=A$&B$
For B$=A$(2 TO 5) use: B$=SEG$(A$,2,5-2)
For B$=A$(TO 5) use: B$=SEG$(A$,1,5)
I For B$=A$(3 TO) use: B$=SEG$(A$,3,LEN(A$)-3+1)
For PRINT 3**3 use: PRINT 3*3*3
For SCROLL use PRINT
Some multi statement lines in the examples also require splitting...this minor conversion is all good work!
This book is very useful in making you think HOW to put a problem into a form your computer can solve.
TIM HARTNELLS GIANT BOOK OF COMPUTER GAMES
Fontana PBR 386pp GBP 3.95 ISBN O 00 636743 7
This is a book of over 40 programs written in fairly simple BASIC suitable for conversion. Such conversions can also assist you to get to know your computer, and having dealt with simple conversion, you can go on to use the sound and graphics of your computer, and generally tidy and improve the program.
The Chess program in this book is quite abysmal, but still a worthwhile practise! Converting to TI BASIC,you have the usual task of splitting multi statement lines...and for some of these programs that can be quite complex! Extended Basic owners will find conversion very much easier!
For TI owners:
For MID$(...) use SEG$(...) .
Put all DIMs at the beginning of your TI program!
For CLS use CALL CLEAR
For A$=INKEY$ use the little routine following...
for A$=INKEY$ ....
The 99/4A does not have TIMES. It can usually be omitted completely.
1 CALL KEY(3,A,B)
2 IF B<1 THEN 1 .
3 INKEY$=CHR$(A) and only then...
The 99/4A does not have INSTR...it is probably easier to avoid any program with this in it!
For RIGHT$(C$,2) use SEG$(C$,LEN(C$)-2+1,2)
For LEFT$(C$,5) use SEG$(C$,1,5)
Those little hints should help you with the conversions
The games in this book are very simple, but the object is to familiarise yourself with your computer, with conversions, and then of course to improve the programs.
There are two similar books from Creative Computing, costing more, and with perhaps a more restricted range of programs, even if there are more programs in them.
Hartnells book is perhaps closer to EXTENDED BASIC than the Creative Computing book. Even if you only have TI BASIC, it is still worth while getting your teeth into conversion work of this kind: there are no difficult pokes or peeks, no strange abbreviated commands, and only minimal changes are required to fit the programs onto the 28 column wide print screen you have.
..... Apologies in advance to anyone writing to me or ordering programs from me in May/June, for any delays. We are expecting a little peripheral in the family and it could get a little hectic at that time.