[jeffchien]

Now I want a scavengers' guide to identify machines that might have a compatible microprocessor within them, because I haven't seen a Commodore or Apple II in a long time. Arcades with older cabinets obviously have them, but if most post-apocalyptic media are prophetic, they'll probably be occupied by a gang of young ne'er-do-wells. I suppose, thanks to the College Board, Ti-83s (Z80) are still quite common in the US. Are there toys, medical equipment, or vending machines that still use these chips?

I wonder if ESP32s and Arduinos might be more commonly found, though I could see the argument that places with those newfangled chips may be more likely to become radioactive craters in some scenarios.

[nkali]

I tried to do something like that in my free time. ARMs are everywhere, PICs are very common as well: https://github.com/ninakali/chip_scavenger/tree/main/src

[kragen]

Hey, this is fantastic, thanks!

[thesuitonym]

The Z80 is still an insanely popular microcontroller, that can be found it so, so many devices. Head down to your local Walmart's toy aisle open some of the electronics there (Post-collapse, of course) and you'll certainly find a few.

That's not as easy as just dropping a full computer on your desk, but having a low power processor that's easy to find replacements for would be useful. That is, of course, if you spent the time pre-collapse to learn how to make a useful system out of those components, which I suspect is the real goal of Collapse OS.

[kragen]

Can you name two such devices? Because the only thing I've ever found a Z80 in is an S1 MP3 player. I've found ARMs, 8051s, and weird Epson microcontrollers they seem to have never published the instruction set for, but never a Z80.

[zimpenfish]

According to [0], TI were launching new graphic calculators with Z80s as late as 2016 - the TI-84 Plus CE-T Python edition (which is still available on Amazon UK[1][2]!)

Not a hugely compelling argument for "the z80 is still a popular microcontroller", mind.

[0] https://en.wikipedia.org/wiki/Comparison_of_Texas_Instrument...

[1] https://www.amazon.co.uk/Texas-Instruments-TI-84-CE-T-Python...

[2] Mild cheating going on though because it runs the Python on an ARM copro.

[kragen]

Well, Z80-compatible but more efficient processors, sure. That pretty well counts because you can still run your own software on them, such as KnightOS, but KnightOS can't compile itself, and I don't think CollapseOS will run on a TI-84.

[vdupras]

Collapse OS runs on the TI-84+ but doesn't implement mass storage on its flash yet, so it's not self-hosting on that target.

[kragen]

Thank you for the correction!

[kjs3]

They only stopped making them last year. Someone was buying them, enough to keep the production lines going, and not to run CP/M.

TI uses them in one of their calculator lines. I've seen gobs of them as embedded controllers in invarious industrial systems (I have family in manufacturing). I understand a lot of coin-op games (think pinball or pachinko) use them. I've seen them in appliance controller boards (don't recall the brand).

[kragen]

Thanks! That sounds pretty plausible, except that the chips in TI's calculators were low-power Z80 clones, of which there are plenty still in production. Still, "various industrial control systems" is a far cry from "Head down to your local Walmart's toy aisle (...) and you'll certainly find a few."

[kjs3]

except that the chips in TI's calculators were low-power Z80 clones

So? That's like saying "there are no 8051s because Intel doesn't make them", even tho there are millions if not billions of clones made every year (since you'll undoubtedly say "well I haven't seen one", if your car tells you when your tire pressure is low, there's 4 8051s).

[kragen]

If we're talking about the ability to repurpose salvaged chips for new purposes, it barely matters what the instruction set is. What matters enormously about the 8051 in particular is that (1) by default it runs code from mask ROM you can't change, unlike the 8751, and (2) it has a pin called "external access" which lets you force it to run code from external SRAM or EPROM. Neither (1) nor (2) is generally true of the clones. What matters most then is whether you can figure out how to get it to run your code and toggle its pins. Can you load code via JTAG? UPDI? Changing an external ROM chip? Maybe it boots from an SPI Flash? That's what matters most.

(It also matters whether you need things like an external crystal or three power rails.)

I mean, it's convenient when you can use an existing compiler, or at least can find documentation for the instruction set; and 8-bit instruction sets and address buses are constraining enough that they can really make it hard to do things. But these are not nearly as important as being able to get your code running on the chip at all.

So, no, instruction-set-compatible clones (like the ones I mentioned I found in https://news.ycombinator.com/item?id=43488079, the day before your comment) are not interchangeable with Intel 8051s in the context of improvising computational capabilities out of garbage. Pinouts matter. Programming waveforms matter.

With respect to the Z80-clone TI calculators, in https://news.ycombinator.com/item?id=43488344 Virgil explained that they can in fact run CollapseOS, but can't yet self-host because CollapseOS can't yet access their Flash. If you want to use them to control motors or solenoids or something, you still need some pinout information, which I'm not sure we have.