This board is one of the first boards I’ve done for the monsputer. It has only TTL logic on it. I’ve probably made it about 25 years ago (or more!).
The chips came from a bunch of PCBs that I bought for $10 (Canadian). These were quite old and came from a 8-bit computer. The CPU was implemented with TTL logic. The ALU was made with 4 74S181.
The GPIO/Interrupts board has:
- 8 x 8-bit inputs
- 8 x 8-bit outputs
- 8 vectored interrupt inputs