I use it through the ZXULA-2, an ULA replacement made by Andy Rea some time ago:claudineskiles wrote: ↑Wed Apr 01, 2020 5:57 am Has anyone built or used one of the ZX81 clock doublers ? If so where there any gotyas or was it difficult to get working ?
Here it running the CLCKFREQ test, with ZXpand patched with ZX81X2 ROM:
https://youtu.be/6Py3NUiEoDs
I swapped the original 4Mhz Z80 for another of 20Mhz that I had available, but an 8 Mhz Z80 is sufficient.
Please provide more details of the implementation you are using so that someone can help you.