What chip should I use to read it? I'm using a Top3000.yes, you'd just want to double the ROM file before programming.
however, I'd suspect that the issue is either a cold solder joint, bad projection chip, or a bad C-ROM before the M-ROM is bad.
if you do desolder the M-ROM dump it and verify that's good before replacing it.
27020/27c2001 just read as if the rom is empty.