MiSTer FPGA Forum

If any of you are interested, this guy has recreated a ZX Spectrum from scratch, replacing the ULA with lookup ROM and using all standard logic. He's made a few changes to allow VGA output too!

This is the final video, his channel goes into how he engineered his solution and well worth it.
https://youtu.be/N36iWYcXBAE

Thank you, interesting but he is not the first one doing this. A few years ago Chris Smith reverse engineered the ULA and wrote a book about it. This was the first 100% compatible reverse engineering of the ULA making it possible to replicate the ULA with standard components.
Back in the 1980s many clones from eastern europe also attempted this, but their results never were exactly the same as the Sinclair ULA even if most software worked and what not worked was patched to make it run with the different timings of the replicated circuits.
If you are interested in this, there is also the Harlequin board. a clone board of the ZX Spectrum that uses Smiths' reverse engineered ULA and that can be purchased as a DIY kit.

cursedverses wrote: ↑Mon Aug 26, 2024 5:32 pm

If any of you are interested, this guy has recreated a ZX Spectrum from scratch, replacing the ULA with lookup ROM and using all standard logic. He's made a few changes to allow VGA output too!

This is the final video, his channel goes into how he engineered his solution and well worth it.
https://youtu.be/N36iWYcXBAE

Must admit, I didn't know about Dr R, and his channel, so many thanks for that.

If you're into the Spectrum, and/electronics, it's fascinating stuff.

Thanks again!