[crb3]

A quick search on 'Ampro' turned up https://www.elite.parts/ampro/little%20board$z80 which might do.

My first CP/M computer was an Ampro Little Board 1A, sold along with a floppy carrying CP/M-2.2 + ZCPR3. I got a lot done on that machine, including a text-mode MIDI editor-sequencer -- the Z80 DART as set up could run the second serial channel (the first was CON to the terminal) at the MIDI baudrate and slave-interrupt to derive its MIDI Clocks from a sync-track recorded/played on a 4-track cassette machine through a Kansas City tape-modem.

[kjs3]

Yeah, but Ampro hasn't made a Little Board in decades; I've been crusing eBay for a reasonably priced Little Board for a while. There are, however, a lot of 'modern' Z-80 (and better, Z-180) SBCs running around that would be cheaper and easier to find. As another commenter pointed out, check out Tindie or google for "RC2014", for example.