Cromemco OCTART
In the earliest days for Cromemco a computer might run a single user single tasking Operating System like Cromemco CDOS. Here one would need at a minimum a single serial port interface to connect an ASCII terminal to a Cromemco computer.
Since it was necessary to have a Cromemco floppy disk controller to use CDOS, and since these disk controllers had an on card serial port such a system would have no need of an Octart style board.