Sinclair ZX80 / ZX81 / Z88 Forums

I would be interested to know how many have been sold so far. Nice to know how wide-spread it is.

I am doing a demo residing in an 8k EPROM that replaces the ordinary ROM. I have a framebuffer in ROM, which is larger than the screen, that is shown. Will be released in the near future, I still have some graphics work to do. The code has worked on real HW for a long time, but EightyOne showed garb...

In the recent updates it is possible to have a video framebuffer in ROM, just like on the real thing. This has greatly simplified my coding endeavour. So a big thanks to those involved!

Good looking, some serious work. Well done!

Looking very good! Nice to get it to fit in 1k

Thank you all for your help! I had hoped this would be a quick port, but have now realized that it is fruitless for me to work any more on this project without a proper ZX80, so I will just leave the code in my repository. If I ever fall on a ZX80 I will try again, but it is not something I will sea...

I've had a good look at the ZX80 schematic and understood more about its operation. Since it does not have a 207-counter, the hsync is not self-generated, but must be done in SW. My code does not do that, I assumed the hsync worked like on the ZX81. So: I will try to do a SW-generated hsync and see ...

I found some encouraging artcles regarding downgrading a zx81 to something that is zx80-compatible, so that is my next step. That should help me debug what is going on.

A thought: a zx80 rom and disabling nmi on a zx81, would that be 100% compatible? Or just a bit?

Hm, I re-read some docs and found a possible error. I was using OUT ($FE),A, which I changed to OUT ($FF),A to end VSync. I hope it helps.
It would be helpful with a screenshot (camera?) to see what is going on if it fails.

[edit]: removed the file, it does not work on real HW