* LK1-4 are links on the mainboard ("0" bits are wired to GND). On CPC464,CPC664,CPC6128 and GX4000 they are labeled LK1-LK4, on the CPC464+ and CPC6128+ they are labeled LK101-LK103 (and LK104, presumably?).
* Bit5 (/EXP) can be used by a expansion device to report it's presence. "1" = device connected, "0" = device not connected. This is not always used by all expansion devices. ''is it used by any expansions?''[in the DDI-1 disc interface, /EXP connects to the ROM bank selection, bank 0 or bank 7] * For more info see [[LK Links]]
Table showing manufacturer name on power-up (CPC and CPC+ only):