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Greetings,

As everyone here knows, at both this site and at TI's web site anyone can submit a program that they have written and if accepted it will be made available to anyone, anywhere in the world. This is a great resource.

What most of you may not be aware of is that this idea of writing a program for a TI programable calculator and being able to make it available to anyone in the world is not a recent idea in this age of the internet. TI has been doing this since the invention of the programmable calculator way back in the early 1980's. TI called it PPX Exchange.

TI's first programmable calculators were the TI-58C and the TI-59. I originally had a TI-58C but soon upgraaded to a TI-59 around 1981. The main difference between the two was that the TI-58C had only half the memory of the TI-59. The other difference was that there was no way to save programs written for the TI-58C so you had to hand enter them each time you wanted to use them whereas the TI-59 had a card reader so you could save your programs onto magnetic cards.

The maximum number of program steps that a program on a TI-59 could have was 960 steps (a step was one key-press) with zero space for memory storage. You could partition the TI's program space between program and memory in chunks of 10 memorys which took away 80 program steps. In order to do anything useful on the TI-59 you would partition it to have 880 steps and 10 memorys.

In some ways it is a shame that some of you here were not able to experience programming this calculator. I think you would have really enjoyed the challenge of trying to squeeze down a rather complex program down to only 880 key presses and use only 10 memories. You had to really give some thought to the order in which the program ran so as to make the best use of data stored in memory. After all, with only 10 memories, you would not want to store data at the very beginning of your program that wasn't used until the end of your program, thus tying up that memory for the whole program.

Having only 880 steps to work with caused me to learn a bunch of math relationships that I could use to squeeze steps out of a program while maintaining the accuracy for the most part. These are concepts that I still use today when writing a program. For example, say you have something like this: +cos(? + 272į.34). This would take about 12 key presses; assuming two key presses to recall ? and one for cos(. First you should realize that +cos(? + 270į) will give you almost exactly the same answer. So you have reduced this to 9 key presses. But you can reduce this even further. If you look up trigonometry reduction formulas, you will find out that +cos(? + 270į) = +sin(?). You have just reduced this down to 5 key presses. As another example, rather then enter the number pi I would use 4*atan(1) (in radian mode); 5 key presses. I also would use logarithms if I wanted to round a number to say 5 significant digits. I'll let you figure out how this is done if you don't know how. I was forever on the hunt in math books for things I could use like this.

In order to share programs you had written with other people TI administered a group called PPX Exchange. After writing a program I could submit it to TI and if they accepted it, they would publish it in their catalog and something in their newsletter where anyone else in the world who was interested could request copies. This was a wonderful experience for it motivated me to try to squeeze down fairly lengthy calculations to fit inside a program having only 880 steps.

For anyone interested check out this .pdf
http://www.datamath.net/Manuals/PPX-V6N6_US.pdf
Scroll down to Page 9 (which is on the 13th page) and check out program 7880691 Astronomical Data for the Sun. It took everything I knew to fit this program into that space.

I know that this post has nothing to do with current programmable calculators, but having used programmable calculators since their inception I thought I might be allowed to muse a bit on them and how much they have improved over the years.

I find my new TI-84 Plus CE to be a great improvement over that 59. The amount of memory I have available to me I find to be luxurious. And you may be surprised to find out that programming the 84 isn't that much different then programming the 59. The only thing different is that the 84 has a screen that displays text, where as the 59 only displayed the numeric key code, one step at a time. However, unlike the 84, the 59 did have a printer that you could plug it into (yes I do mean you plugged the 59 into the printer) and print out a hardcopy of you program.

Thanks for reading my musings.

S. Thomas Bradley
stbradley You said the first TI programmable calculators were the TI 58C and TI 59. The TI SR 56 came out a year before them and had 100 program steps. I still have mine and it still works. Thatís what I used to learn how to program. I since went on to programming professionally and retired 8 years ago. Since the SR 56 didnít have any way to save the program, you had to key it in each time you wanted to use the program. Programs were 100 steps or less, so it didnít take too long but was still a pain. I picked up 2 TI 59 calculators awhile ago just to add to my TI collection. Both work, but saving the programs to the magnetic strip doesnít always work. Probably needs a good cleaning, but I donít mess with them anymore. I still do a lot of programming on a daily basis, but now itís on an iPad using Lua just for fun.

PS Thanks for the link to that one issue. I looked at it and it looked interesting. Hereís a link to all the issues.

http://www.rskey.org/CMS/index.php/the-library/15
Hey that's pretty cool! Thanks for sharing your experience, we all love hearing stories about old calculators. Congratulations on getting featured in TI's PPX! I suppose TI beat TIcalc.org at program sharing by about 10 to 20 years. Razz

Please share any programs you make on your shiny new TI 84 Plus CE!
Jeez, I wonder what TI calculators will look like in another 30 years...
TheLastMillennial wrote:
Hey that's pretty cool! Thanks for sharing your experience, we all love hearing stories about old calculators. Congratulations on getting featured in TI's PPX! I suppose TI beat TIcalc.org at program sharing by about 10 to 20 years. Razz

Please share any programs you make on your shiny new TI 84 Plus CE!
Jeez, I wonder what TI calculators will look like in another 30 years...



Sadly, most likely like the HP Prime or Casio Prizm of today. My best guess is that it may not change much (Its TI) so dont expect anything great.
TheLastMillennial wrote:
Jeez, I wonder what TI calculators will look like in another 30 years...


I wrote:
TI calcs in 30 years will look like what iPhones from 2008 look like now. Crappy, but "revolutionary"


Anywho, I read your musings, and they are pretty interesting. I learned a lot of nice history, so thanks!

Edit: I'm interested in seeing more of what you have to share- this is really cool.

Optimizing is still something TI-84+CE programmers have to do. On one of my recent projects (Procrastinate, for Cemetech Contest 21), I spent a ton of the development time squeezing bytes out of my program. That particular program didn't use any trigonometric identities, but I did use a bunch of tricks to store colors (which are just numbers) and compress algorithms.

Sure, we have relatively unbelievable amounts of storage, but it's good to keep program size down because of execution speed.

I think it's really cool how the earliest calculators just stored keypresses and executed those. That's a really clever workaround by TI, presumably they didn't have the storage and processing power for all of those tokens like the current models. It also takes some ingenuity on the part of the programmer to only have 10 digits of display. Really, really cool stuff.
dave1707 wrote:
stbradley You said the first TI programmable calculators were the TI 58C and TI 59. The TI SR 56 came out a year before them and had 100 program steps. I still have mine and it still works. Thatís what I used to learn how to program. I since went on to programming professionally and retired 8 years ago. Since the SR 56 didnít have any way to save the program, you had to key it in each time you wanted to use the program. Programs were 100 steps or less, so it didnít take too long but was still a pain. I picked up 2 TI 59 calculators awhile ago just to add to my TI collection. Both work, but saving the programs to the magnetic strip doesnít always work. Probably needs a good cleaning, but I donít mess with them anymore. I still do a lot of programming on a daily basis, but now itís on an iPad using Lua just for fun.

PS Thanks for the link to that one issue. I looked at it and it looked interesting. Hereís a link to all the issues.

http://www.rskey.org/CMS/index.php/the-library/15


Thanks for the correction. I was unaware that the SR-56 was programmable. Prior to getting the TI-58C I had a TI SR-50. The SR-50 died a horrible dead when it accidently was jarred from my hands and fell 3 stories to it's death. I no longer have the 59, it had the same problem with the card reader. Over the years I sent it in to TI several times for card reader repairs until one time when TI sent it back and said they don't repair them anymore. I bought another TI programmable calculator but I don't recall what it's designation was; that one got stolen.

Finding that PPX newsletter made me wonder where I got the time to write programs for the 59. The date of the newsletter I referenced was Nov/Dec 1982. In 1982 I was a junior at University and I was also working full time during the "graveyard shift" (10:30 pm - 7am) and was at school at 8 am to around 4pm most days. I slept on the weekends.

Thanks for the link to all the PPX newsletters. I lost all my copies a long time ago. I'll wander through those newsletters; as I recall they had a lot of interesting stuff in them. I'll bet that they might have some tips and tricks that would be useful even today.
stbradley I read your write up, but where can I find the actual program. I didnít see it in the list of programs in the link I showed, so is there another place where the programs might be and are they accessible. I thought I would convert it to Lua and run it on my iPad. If I remember correctly, I wrote a little program on my SR56 to solver the Kepler equation given an input angle. Also a little lunar lander game along with a lot of other programs. I might still have the programming sheets with the steps on them, but I havenít the slightest idea where. That was a fun little calculator for small programs.

PS. If I canít convert it straight from a listing, I could always key it in on one of the TI 59ís I have and see what it does and convert it from the calculator.
dave1707 wrote:
stbradley I read your write up, but where can I find the actual program. I didnít see it in the list of programs in the link I showed, so is there another place where the programs might be and are they accessible. I thought I would convert it to Lua and run it on my iPad. If I remember correctly, I wrote a little program on my SR56 to solver the Kepler equation given an input angle. Also a little lunar lander game along with a lot of other programs. I might still have the programming sheets with the steps on them, but I havenít the slightest idea where. That was a fun little calculator for small programs.

PS. If I canít convert it straight from a listing, I could always key it in on one of the TI 59ís I have and see what it does and convert it from the calculator.


Thanks for the interest. The listed programs at that site are only a small fraction of the programs that PPX had available I used to get a catalog from them once or twice a year and it was at least an inch thick so I would guess that at one time they had tens of thousands of programs. I recall that in their astronomy section they had several hundred programs. I was a little disappointed not to see mine listed as one of the available programs.

Unfortunately I lost all my TI-59 listing, cards, calculators, books, magazines printer, etc. years ago during one of several moves I've made over the years.

It's unfortunate, for I would have liked to share it with you. However, I still have the reference books that I used to create that original program so this might motivate me to try to recreate it on my TI-84 Plus CE. I do have a program that will solve Kepler's equation on my TI-83 Plus if you would like a copy. I have not had a chance to import it over to my 84 yet, I doubt I'll have to change anything.

I'm currently working on merging/upgrading several interpolation programs I have on my 83 into a single program. And then I plan on adding some new abilities to it.
stbradley You donít have to go through any trouble with your programs. I have or can get various programs off the internet. It just if they were available I would try playing with them.
  
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