CP/M 2.2 was distributed with the DDI-1 disc interface, the CPC664, and on side 1 of the CPC6128 system discs. It provided 41K TPA.
Details of the implementation are in the [[Soft158A:_DDI-1_Firmware_-_The_Complete_CPC_464_DOS_ROM_Specification|DDI-1 Firmware SOFT158A]]. The following attempts to give more detail than described there.
==== Serial number ====
The CPM2.2 serial number appears to be stored on the disc. This is the number that is in the box on the label. Not the one with "serial number" next to it.
It's a 6 byte number stored after 'USER' on the disc. D0 seems to be Amstrad's manufacturer code.
==== MOVCPM ====