i was wondering if there's any test rom for the GB-Z80 processor, just like "nestest" (with the golden log) but for GameBoy. i couldn't find anything searching the forum, so that's why i'm asking...
When I was working on my GB emu all I could find as far as test roms were the ones Blargg wrote here:
http://blargg.parodius.com/gb-tests/, cpu_instrs.zip is the most like nestest but is a bit more complicated and can't be run in the basic mode that nestest supports, however it doesn't require LCD support and you can read the output from the gameboy's link port which is really easy to handle.