Comment on The Computer We All Wish We’d Had In The 8-Bit Era

mozz@mbin.grits.dev ⁨2⁩ ⁨months⁩ ago

• thingsiplay@beehaw.org ⁨2⁩ ⁨months⁩ ago

  In context to 80s 8-bit era. There was no HDMI or USB yet.

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  • PenguinTD@lemmy.ca ⁨2⁩ ⁨months⁩ ago

    From look at the board, basically it looks like they did the “hardware” emu approach. But people I know that enjoy retro stuff they either want the look(original or replica case/keyboard, but internal is more modern that runs software emu) or they want the antique(functional original). It’s pretty rare to see these kinda of hardware emu where they bundle chips as close to old ones while trying to replicate how the old hardware work and then drive with another modern board for the input/output.

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    • thingsiplay@beehaw.org ⁨2⁩ ⁨months⁩ ago

      Sounds a bit like a repogrammable ROM (which is no longer ROM in that case, ROM=Read Only Memory). Kinda what FPGA does, if I’m not mistaken (and what you were referring to, right?).

      If you take a look at the die you’ll find what is in effect a ROM on board, a look-up table defining what each instruction does. A machine with said capability can change this ROM, and not merely emulate a different instruction set, but be that instruction set.

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      • barsoap@lemm.ee ⁨2⁩ ⁨months⁩ ago

        It’s an legit 8-bit microprocessor implemented as TTL chips, what makes it a different beast than what they did back in the days that its microcoding isn’t kneecapped. It would absolutely have been possible back in the days to build exactly such a thing, even from precisely those components. At least the TTL part, that is, I bet there’s wibbles around VGA etc. And because I already hear the detractors yes, 8-bit CPUs were microcoded. They decoded multiple external instructions into a stream of “load from memory, fetch from register so and so, switch on the ALU, put what’s in the ALU output somewhere”. They kept it as simple as possible and it wasn’t reprogrammable but that stuff there, that’s microcode.

        Implementing CPUs in TTL chips also isn’t a new idea, that’s how early minicomputers were made (later on they got some specialised chips). And those things also used ROMs for their microcode. So you could say that this is a minicomputer capable of pretending to be different 8-bit microcomputers.

        FPGAs are a completely different technology, those allow you to arrange logic in a (more or less) arbitrary topology. That is, looking at that board with all those TTL chips, it’d be the equivalent of being able to re-route all the board traces as you please.

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      • PenguinTD@lemmy.ca ⁨2⁩ ⁨months⁩ ago

        not necessary FPGA but can be re-writable: see

        …stackexchange.com/…/eeprom-is-a-read-only-memory…

        I am not good in that hardware emu branch but my guess is that they pick something that can drive and matches original clock speed as the old programmable rom was no longer produced. (the antique people would buy old broken ones and rip parts off them or try to restore them.)

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