the boards arrived today just in time for some Easter weekend fun! 

I’ve assembled one and after some slightly tricky messes with the CPLD (firstly I forgot to configure the pin mappings when loading the completely untested VHDL file, secondly some pins got slightly bent on the socket so didn’t make contact) it generally seems to work as intended! 

I haven’t tried actually programming the Z80 yet but the AVR is working as expected and the Z80 seems to be doing something in its unprogrammed state.

I’ve already decided the chip select lines need pull-ups - the issues with the cpld meant sometimes multiple chips were trying to drive the data bus which isn’t good (I first noticed when power consumption was slightly higher than expected!)

Next step I guess is to write some Z80 code! Or maybe procrastinate on that by working on the AVR uploaded more!

The only other issue I need to think about right now is that CPLD - it’s actually an end of life part, which means I’m having to use some programming software from 2013 and also of course it may be hard to get in future.

It’s not a huge issue for now but I will probably be looking for alternatives - there’s a Microchip part that might be suitable so I guess we’ll see. Part of me is tempted to make a partial address decoder out of discrete logic but that’s quite inflexible and would probably make this already relatively large circuit board even larger!