Vortex implemented their own version of CP/M for the CPC and also provided patches for Amstrad's CP/M to use their memory expansion.
There were also third party implementations which supported the Vortex RAM Expansion such as RCPM.
Vortex's patch for CP/M 2.2 to use Vortex RAM Expansion
Vortex provided a disc with a PATCH.COM on it which patched Amstrad's CP/M 2.2, which came with the CPC664, so that CPM could use their RAM expansion to get 63KB TPA.
Vortex's implementation of CP/M on Floppy
To boot C/PM you need:
- a CPC464
- VDOS 1.0 on ROM and a Vortex disc interface.
- a 80 track double sided drive A.
- a Vortex 512KB RAM Expansion.