DIY 8bit computer

I’ve had a couple of 680x PIA chips laying around. Every now and then I come across a DIY retro 8bit computer project and makes me want to build one. So I went ahead and bought a 6800 CPU and a couple of 74s189 SRAM chips.

A while back I had sent off for some TerminalScope PCBs and they have been sitting collecting dust in a box somewhere. I guess I can toss one together for the 8bit computer.

While I was shopping for the SRAM chips I came across some z80 compatible PIA chips. It was 15 bucks but it comes with ten ICs. So maybe down the road I can build a Z80 based system with CP/M

In all I got a lot of info from Grant Searle’s website. He has a few small chip count mini 8bit computers that can be built on bread boards.

Right now im awaiting parts so I can start. In the meantime I am researching and thinking of a few things such as power supply and storage. I am thinking of a simple linear supply and making sure I have filter caps at every chip’s V+ and ground pins. Also im leaning towards Compact Flash for storage since it is a Parallel device. Doubt I could get Ethernet with a TCP/IP stack on it so simple direct connection via Serial should be plenty. I think I have a MAX232 chip in my junk box. If not I could use a 7404 Hex Inverter for it or for fun use some switching transistors and resistors. It would be fun to have an array of switches to control functions kinda like the Altair 8080. I’ll just add some LEDs to the inputs and outputs for some blinken lights.

If anything on the final build I can add the TerminalScope circuit to the mainboard. It’s a dirty way but the easiest without using too much system resources.


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