One of the first boards, it aimed to provide a full CP/M development system.
It was found that customers would develop programs on bigger machines, and wanted very simple Z80 boards for putting into control systems.
I'm not sure where I want to go with this. Floppy disks are pretty much dead, and the 64K DRAM and controller chip can be replaced by a simple 32K SRAM chip.
The SCPUB has the obsolete stuff thrown off already, and is easier to modify to run CP/M, because it has four JEDEC memory sockets.