The standard expansions are based on the RAM banking logic from the CPC6128, ie. equivalent to the fourth [[Gate Array]] register in the CPC6128 (or more precisely, the PAL that assists its Gate Array chip).
* Accessing a 64K expansion (or the first 64K of a bigger expansion) is compatible to the 128K in the CPC6128
* Although, for real CPC6128 compatibility one may need some patches (eg. CP/M Plus refuses to work without the 6128s BASIC version) (it "detects" the 128K by checking the BASIC version)
Expansions bigger than 64K combine the CPC6128-style mapping with some formerly unused chips in the fourth Gate Array register:
== Capacity ==