Epson HX20 Interface
As a more permanent solution I routed a PCB.
I then used an old PC HDD cable to attach to the HX20 which helpfully uses a standard 0.1" pitch IDC connector. Unhelpfully they have used a different numbering scheme to the rest of the world which means the pin numbers are all jumbled, but that's not and unsolvable problem, just an irritation.
The output port can be used to drive other hardware, I'm going to use this one to drive a relay module:
The bottom two bits of the data bus are wired up on this PCB, so you write to address &H5000 and D0 and D1 will end up latched in the output port. To read inputs you read the same memory location, again D0 and D1 are the data bits that are wired up.