This is a dual floppy z80 based CP/M system.
After extensive investigation, and parts replacement it is now operational, although the two Teac FD-55 floppy drives need some more attention.
Initially the problem appeared to be memory, but after removing and testing the soldered in chips, they proved to be reliable.
The problem was actually a corrupt eprom, and the FD1793 floppy disk controller as well, and luckily I was able to rob one from another board. The display issue was the SY6545 CRT Controller, which I managed to order from eBay.
It has been booted successfully from a GoTek floppy emulator, and once the drives are working correctly, and I find some good meda, it will be fully functional.