I’m getting close! I had a “you idiot” moment at work today and realized that I was burning the EEPROM wrong. I forgot that the 8088 board really requires a 27C512 EPROM but if you use a 28C256, you needed to adjust some things, including how you burn the EEPROM. The file size was 64k but the programmer was only burning the first 32k of it (all 0’s) since that’s the target device size. Duh!
Once I fixed that, I’m now at least seeing some activity. The only issue is that serial output doesn’t work right. I see garbage on the screen, but clearly it’s accepting some sort of commands because I see activity. Baud rate is fixed at 9600 by the old serial board.
I wonder if it has to do with how the 8088 board interfaces with old 8-bit peripheral cards. Is there a way to force the input/output to the Serial I/O Board? I tried using the IOBYTE but I don’t think it has an option for this in the 8086 monitor.