Are there older implementations of the improved CP/M 2.2 for the ZX Spectrum and compatibles?
Such as the Z-System, https://www.cpcwiki.eu/index.php/Z-System.
Nihirash is working on a version for the ZX-Uno: https://github.com/nihirash/cpm-uno
Also is being prepared ZCPR + ZSDOS for the eLeMeNt ZX.
Z-System CP/M
Re: Z-System CP/M
Back then I had the CPM/3 By Locomotive for +3 patched to use ZPM3 and ZCCP, it worked great - but the disc are nowhere to be found these days. Can't remember how I did it - but it worked
https://api.zxinfo.dk/v3/ - ZXDB API for developers
zxinfo-file-browser - Cross platform app to manage your files
https://zxinfo.dk - another ZXDB frontend
zxinfo-file-browser - Cross platform app to manage your files
https://zxinfo.dk - another ZXDB frontend