< old Altair hackers, so.... How hard would it be (for a software guy) to < replace the ROM with something else, say, a parallel cable from a PC that < fed data through the ROM socket? not easy at all. You really need to make or buy an eprom emulator that can do 6830 (an oddball pinout). < The clock is already very slow, 500KHz, I think, but I could slow it to < 1HZ if it would help. Could I software decode the address, do whatever < handshaking I need to do from the TTL-levels on LPT1, and emulate a ROM < without buying a ROM emulator? Not possible, there is a minimum clock spec as the internal registers are dynamic and would forget. Allison