* LK1-LK4 - same as CPC, though not being actually used, due to absent BIOS
* LK5 - none such (corresponding PPI input is floating, neither having a LOW level, nor a stable HIGH level) (meaning the ROM Bank0=BASIC and Bank7=AMSDOS are unstable on GX4000, this seems to be the reason for the CPC+ System Cartridge not booting properly on the GX4000)
* LK6 - unknown (same as LK106 on CPC+) (usually LK6 is not installed, neither in GX4000 nor CPC+)
* LK7 - shortcut +5V with +5VMOD (installed in french version, which has no TV modulator)