RC2014
BusRaider With RC2014 Pro
https://youtube.com/watch?v=woY76BLfCcY [Embed]
"Using BusRaider to create a 3 board CP/M serial system with an RC2014 Pro Backplane."

More details are available here:
https://robdobson.com/2018/09/raid-the-bus-and-the-speccy-lives/
And open source hardware and software here:
https://github.com/robdobsn/PiBusRaider
https://www.tindie.com/products/robdobson/ramraider-1mb-linearpaged-ramrom-kit-for-rc2014/