Sinclair ZX80 / ZX81 / Z88 Forums

Hi,
I have a working issue 3 48k board and a non-working issue 2 board. Is it ok to test the issue 2 ULA 5C112E in the issue 3 board to check it is working. I have a dandanator to run the zx diagnostics

Yes.

But note that ULAs are backwards compatible, not forwards compatible. Putting an earlier ULA in a later board may result in the board not working perfectly.

Mark

Thanks Mark