I gave up on the MSDOS board/8086 CPU for a while and assembled the Serial IO board (V2) that I had in stock and tried to get it working with the Z80 board (V1) and the SMB (V1) that I have using the standard-issue monitor program (v4.8). I don’t usually use the SMB but it seems to be needed for the IOBYTE to force console I/O to the SCC. Like with the problems I had with the MSDOS board, this configuration also exhibits “input anomalies”. In this case, I see only output — no input. I can definitely “see” characters coming through the interface (using my protocol analyzer), but nothing on the screen.
I wrote a small loop-back program to run under my alternative monitor program (one based on Dave Dunfield’s MON85) with the Z80 board and the Serial I/O board. The SIO board passes the loopback.
So, there must be a configuration or other issue with the v4.8 monitor that I’m not seeing. Does anyone have a working combination of boards using the SIO and N8-S100 Monitor and can tell me how to force the console input and output to the SIO without needing the SMB? Maybe I’m missing a compilation switch somewhere.