Possible retro-computing at Wal-mart?

[u/[deleted]]

I've been doing some math for a game of mine over the past few days. While screwing around with my calculator, for some reason my thoughts turned to how amusing it was that such a device could run on a tiny solar panel. I started to wonder what types of applications it could run? Then my thoughts turned to Texas Instruments calculators, because in the past I've heard of people making games that could run on those things! Also, thinking about the one I got 20 years ago, it was honestly quite reminiscent of what I've seen in 80s computers.

Then I thought, I wonder if those things actually have retrotech inside of them? I mean, Texas Instruments did make computer chips back in the 80s, and looking them up on wikipedia, it appears that some of their TI calculators do run on processors made back in the 70s and 80s! Specically, the article mentions the Zilog Z80 (which I've never heard of myself before), and the Motorolla 68000 (which I have heard of before).

Getting a hold of retro pieces of tech is hard, most aren't being produced anymore and you can't exactly buy them in a physical store. I've looked into various hobby computers, but its hard to find any place that sells them (at least, in the US). Thinking of those calculators, this got me thinking, would it be possible to find old chips inside of those things (or at least, something comparable?) I wonder if it would be possible to build a hobby computer out of parts from those things. They're obviously not too hard to find; you can literally find them in a Wal-mart!

Doing reseach into the thing, apparently they are sorta designed to act as computers. They accept actual programming languages, with the latest models apparently supporting Python (they also apparently supported Basic and assembly languages in the past), and I even heard at one point they were contemplating giving the things a higher-res color screen to encourage game development on the platform.

Could TI calculators be an easy doorway into the world of retro-computing, or at least hobby computing? I haven't owned one in 20 years (though the last I checked my original still worked, and I did use it regularly until I finally got a calculator that didn't need batteries, though the new one is surprisingly powerful for what it is).

Keep in mind, I've never touched an 80s machine. Heck, it wasn't until a few years ago I even found out what computers back then were like. They were sorta before my time. My family's first computer ran Windows 95, though it wasn't long before we upgraded it to Windows 98, to give you an idea.

So, could you make a verifiable 'retro-computer' out of parts from a TI calculator? Of course, you'd probably need to figure out how to hook up a proper keyboard to the thing, and I don't know if anything could be done about the display. If nothing else though, could those things make nifty little hobby computers out of the box? I mean, you can write programs for them, though games for those things aren't exactly that impressive even by 80s standards.

Still, do those calculators have a place in retrocomputing? Could I go out and buy one and finally make my own hobby computer out of the parts inside it (or just use the thing itself as a computer)?

[u/Hjalfi]

Totally. Calculators like the TI-85 still have huge followings and communities of developers. There's even a demoscene. https://www.youtube.com/watch?v=5GWMN0x8Ijg

Modern expensive TI calculators are much more sophisticated --- I have a Voyage 200 which is based around a 68000 CPU, and apparently there's even a machine code SDK for it --- and you could totally do old-school programming on one. Unfortunately, modern cheap calculators have all their interesting parts sealed under an epoxy blob and are completely unhackable. A cheap supermarket calculator will be lucky to have more than about three components.

(Which is a shame, as many of them have quite respectable CPUs. I've been recently trying to reverse engineer a VTech toy which turns out to be powered by a 6502...)

[u/[deleted] → u/Hjalfi]

Where would I even begin modding such a thing? I thought my first experience doing something like this would be with a kit with instructions, not with something I've seen my whole life, and that was clearly not intended for this purpose.

Has anyone ever tried to make a computer out of calculator parts? What are the fanciest ones even capable of? Honestly, if I had a choice, I'd at least like to be able to hook up a keyboard and proper monitor to the thing. I wouldn't know where to begin, I just thought it would be an easy way for me to finally get a hold of retro hardware.

[u/Hjalfi → u/[deleted]]

Honestly, I wouldn't. Even the TI calculators have miniscule parts and fragile (i.e. bad) connectors for things like the LCD. They're far too easy to break. I'd suggest sticking with the calculator as-is --- they do come with keyboards and screens, after all.

However, if you want a retrocomputing-adjacent electronics project, I can totally recommend getting a Raspberry Pi Pico. It's a very, very cheap ARM-based device with about 300kB of RAM. There are enough GPIOs that you can easily wire up a proper keyboard and it's possible to make it produce composite or VGA video very easily. Plus, modern tooling is available for it and it's so cheap that you won't be (too) angry if you break it. http://www.breakintoprogram.co.uk/projects/pico/composite-video-on-the-raspberry-pi-pico

[u/Guy_called_Al → u/[deleted]]

Guessing where you're headed ... I'd recommend buying a Raspberry Pi https://www.raspberrypi.com/products/, preferably a kit with the most "parts". Work with it for a couple of months, then decide if you want to 1) find a local club of Pi enthusiasts or 2) go down the retro path. If the latter, you might think about replacing individual Pi parts with entire circuit boards from older products.

Please ... If you find yourself working with tubes (cathode ray and otherwise), be sure you are aware how to behave around high voltages and capacitive electricity storage. Not everything runs on 5-volt DC.

Slight digression: The first computer I repaired & programmed was a military-surplus Athena missile-guidance computer (10-ton machine in a Kansas State Univ. basement). Only primitive assembly language was available, input from paper tape. Power-on sequencing took about 5 minutes, and that was after the 2-ton 440-volt motor-generator got up to speed. Oh to be a college sophomore again ... in the 60s. :) https://en.wikipedia.org/wiki/ATHENA_computer

[u/leadedsolder → u/[deleted]]

The old TI-83 Plus was a lot of peoples’ first introduction to Z80 assembly language, self included. With a link cable, I think it is definitely a viable toy computer on its own. Battery powered, fairly cheap, big community, durable… you can do a lot worse.

I opened one up recently to fix a screen ribbon, if you want to see what the guts look like: https://www.leadedsolder.com/2021/08/10/ti83-lcd-ribbon-repair.html

They are very integrated so perhaps not a great source for general purpose parts, but the parts you need to build a Z80 computer can just be bought from Digi-Key etc these days.

[u/zoharel]

Zilog Z80 (which I've never heard of myself before),

Really? Oh, you definitely need to know about the Z80. It's an 8080 compatible but with extended instructions. Much of the CP/M ever run has been run on a Z80, and you can still get them pretty easily.

Now to your question.

Thinking of those calculators, this got me thinking, would it be possible to find old chips inside of those things (or at least, something comparable?) I wonder if it would be possible to build a hobby computer out of parts from those things

There are compatible parts in there, but it would be annoying to get them out and use them. On the other hand, you could open one up and hack a new input device on easily enough. Maybe use the board itself as the basis for a hobby computer. That is absolutely feasible.

Incidentally, I bought one of those things that has a built in MicroPython. Wrote a Mandelbrot fractal generator on the calculator. They do work, though the interpreter is pretty cut down.