The Cromemco Single Card Computer (SCC) design dates back to 1978 and this particular unit appears to have been made in 1978 or early 1979.
It has a Z80 processor running at 4MHz, 1kB of RAM, space for 8k of 2716 ROM, three parallel ports and one serial port.
The board was ROM-less but the binaries for the usual ROM set, MCB-216 were available online. These ROMs provide a monitor and 3k basic.
This means that with the addition of a terminal it’s possible to have a single card capable of executing programs that can exercise the S-100 bus.
I burnt the code into a couple of EPROMs, hooked up a terminal, and gave it a whirl. It fired up as if 45 years meant nothing. It starts up basic to start with but QUIT sends it to the monitor and B in the monitor sends it back to basic.
Programs can be saved to memory including to EPROM on particular Cromemco boards. They can also be saved to or read from the serial port.
The Monitor includes a memory test. I used it to check out a number of memory cards, with some success.
The Cromemco 64KZ appeared to be working fine. One board didn’t work because it expected pSTVAL to be driven and the SCC does not drive it. This was when i started to understand that the S-100 bus was not as “standard” as i had thought.
The main outcome was that i had a Cromemco memory card that was likely to be functional.