* Accessing a 64K expansion (or the first 64K of a bigger expansion) is compatible to the 128K in the CPC6128
* For full CPC6128 compatibility one may need some patches (eg. CP/M Plus will stiff still refuse to work; because it "detects" the 128K by checking the BASIC ROMs version number)
Expansions bigger than 64K combine the CPC6128-style mapping with some formerly unused chips in the fourth Gate Array register: