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I'm building a hobby computer from scratch with a modern 80s era CPU. Anyone doing this kind of thing as a hobby has to decide what kind of project it is, what

I'm building a hobby computer from scratch with a modern 80s era CPU. Anyone doing this kind of thing as a hobby has to decide what kind of project it is, what you want to get out of it, and where you draw the line between modern and old. For me, I had never done electronics before so actually wiring up the components and doing logic at a electrical level was interesting in itself. But also I'm interested applying my programming knowledge to the limitations of that era. It's sort of an art project. No matter what, a computer today with an 8Bit CPU isn't practical. I'm going to have a 6502 CPU, I'm going to try for 1MB of RAM banked, SD card for storage, and I'm thinking of using a Pi Pico as a VGA graphics card. Obviously using a Pi Pico in a project with an 8bit CPU is "silly" but that still satisfies my own goal. Other people working on these types of computers tracking down chips from that era or are building their own TTL-logic basic graphics cards because they have different goals.

hakfoo 5y ago
Why not a 65816? That gives you the 6502 compatibility and a larger address space mode when you want it. In a way, an anemic CPU makes sense if you go back to the old Commodore model of smart peripherlas. You don't need a lot of CPU horsepower, for example, if you can communicate with the mass storage/network card/etc at a high level and it just DMAs into place.
- cmrdporcupine 5y ago
  The bus de-multiplexing with the 65816 is a pain for amateur hobby stuff. A W65C265S is worth looking at, tho it has some annoying masked ROM shipped on it you have to work around. It's basically an 65816 + UARTs + PIA + other stuff all packaged together. It has a boatload of pins which can be programmed to be either GPIO or the full address bus of the 65816 (instead of having demultiplex them like on the real 816). Comes in PLCC format, which is relatively hobbyist friendly as you can get adapters for breadboard, and it can be done thru-hole. Only downsides I found are the onboard ROM (which you can shortcircuit around I believe) and its maximum bus speed is 8mhz, lower than the 14mhz of the 65816.

hakfoo 5y ago

Why not a 65816? That gives you the 6502 compatibility and a larger address space mode when you want it. In a way, an anemic CPU makes sense if you go back to the old Commodore model of smart peripherlas. You don't need a lot of CPU horsepower, for example, if you can communicate with the mass storage/network card/etc at a high level and it just DMAs into place.

cmrdporcupine 5y ago
The bus de-multiplexing with the 65816 is a pain for amateur hobby stuff. A W65C265S is worth looking at, tho it has some annoying masked ROM shipped on it you have to work around. It's basically an 65816 + UARTs + PIA + other stuff all packaged together. It has a boatload of pins which can be programmed to be either GPIO or the full address bus of the 65816 (instead of having demultiplex them like on the real 816). Comes in PLCC format, which is relatively hobbyist friendly as you can get adapters for breadboard, and it can be done thru-hole. Only downsides I found are the onboard ROM (which you can shortcircuit around I believe) and its maximum bus speed is 8mhz, lower than the 14mhz of the 65816.