The 6522... f*u
Wednesday nights are Creative Club for my friends and I, a night where we get on zoom and hold each other accountable for persuing goals outside of work or gaming.
Since I've been working on my 6502 computer, this was my creative club project for tonight (that and it was still a bit chilly for working in the wood shop.)
I spent the entire night trying to build and diagnose why my connection between the 6502 CPU and the 6522 Interface Adaptor were having problems.
Eventually, after the third time I ripped it apart and started over, I started adding one connection at a time and restarting the processor to see what would happen.
I got each of the glue logic connections in, no problem. Attached the 4 address bus lines to the register selection pins, no problem. Clock, reset, read/write pin... Still works perfect.
Data line 0.... Fail. Disconnected
Data line 7... Fail. Disconnected
Any data line caused data corruption. I'm at a loss. I posted up to the /r/BenEater subreddit to see if anyone has any ideas. Otherwise I'm stuck half way through video #2 for now.
Best I can tell, the 6522 is trying to assert something on the data lines rather than be in a high impendence state? I don't really know. I'm going to bed with the data sheet to see what I can figure out.
I knew this wasn't going to be as easy as I wanted it to be, but to be stopped by something that seems as simple as wiring seems.... wrong.