I'm in the mood for a homebrew computer. I've been ruminating on the idea of making a cheap 8-bit computer for a while. Something like Z80 + AY-3-8910 + TMS9918.

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Anyway, here they are:
3x TI TMS9929A (TMS9918 but YPrPb @ 50 Hz instead of NTSC)
5x Zilog Z84C0020 (Z80 @ 20 MHz)
5x Zilog Z84C0008 (Z80 @ 8 MHz)
4x GI AY-3-8910
4x UM61512AK (64 KiB SRAM)

This is going to be a very ambitious project that I most likely won't be able to accomplish, especially considering how inexperienced I am with hardware, but here are some notes. If anyone has any suggestions or ideas to share, hit me up.

TMS9918 expects 8x 4 KiB TMS4116 as external VRAM, which is DRAM with negative voltage bias rail, but there's a neat hack I found to make it use a generic 32 KiB SRAM with some register chips. I might try to convert the YPbPr component video output to RGB VGA at some point.

I'll need to manually implement I/O logic for stuff like bank switching to let Z80 efficiently use the whole RAM whilst being able to access the ROM.
Also TMS9918 and AY-3-8910 naturally have much lower clock speeds, so I'll need to learn to do clock stretching.

@erkin There are several ZX-80 kits and a ZX Spectrum kit (Harlequin) still offered, and then at least you have available software. Not as nice as an assembled SpecNext, but it'd be your own work. i've gotten cling wrapped stacks like this before, but packed inside antistatic bags lol

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