CP/M 2.2 was distributed with the DDI-1 disc interface, the CPC464, and on side 1 of the CPC6128 system discs. It provided 43K TPA.
CP/M 2.2 uses the firmware, and the CPM BIOS calls into it through a special "ENTER FIRMWARE" function in the disc ROM. 43K is the max useable ram when the firmware is active and the screen is at &c000-&ffff.
* Amstrad CPM2.2 uses Amstrad's "System" format. This is 40 tracks, 1 side, 9 sectors per track numbered &41-&49. Each sector holds 512Bytes. There are two reserved tracks, then the directory which has 64 entries, and then the data area.
* CP/M is booted by a RSX command "|CPM" which is implemented by the AMSDOS ROM (the standard disc ROM in the DDI-1, CPC664, CPC6128 and 6128Plus).