I do a lot of repair on 1980s era game boards (Atari/midway/etc). There are some nice tools if you can find them that connect in place of the cpu and can do rom/ram/io/bus testing. Reading and writing to specific addresses and such. Tools like the fluke 9010 and Atari cat box are getting very expensive to find, and then you need all the accessories. Im hoping to recreate something similar to this using a Mega. I started with an uno, and a bunch of 74ls373s to handle the address and bus data, but with the expanded capability of the mega, Im thinking I don't need all of the registers.
I need 16 address lines, 8 bi data lines (or 8 read and 8 write), some strobe lines for read/write/io/mem, and maybe some inputs to detect clock, interrupts, and reset lines. I don't plan on cpu emulation or anything like that, more like reading roms, testing ram, checking watchdogs.
It seems fairly straight forward, but Im sure there are some gotchas.
Does anyone have any experiences with something like this?