I'm currently designing a ZXBus addon for Compact 256 Turbo clones and stumbled upon some questions regarding the ZXBus found on a number of ZX compatible computers.
https://zx-pk.ru/threads/28650-novod...05#post1192805
One of the most prominent questions is:
are there any expansions which use pins A4 (RB/BLK), A5 (Turbo), B5 (F), B16 (RS)?
I've checked a few schematics (ZXM-GS, ZX Multisound, SMUC 2.0, NemoIDE, ZX Multicard, ZXNetUSB) and couldn't find any to use them.
Another thing would be pin B8 which slightly differs in function between Scorpion (RAS) and Nemo (CPUCLK) ... any cards using that?
EDIT: Looks like F and RS are at least used on the Nemo FDC card to generate the clock for VG93 and adressing.