Same as DDI-1:LK1 (see there).
== GX4000:LKs ==
* LK1-LK4 - same as CPC, though being not actually used by (absent) BIOS
* LK5 - none such...?
* LK6 - purpose unknown...? (related to /IORQ, A13, /WAIT, /RESET)
* LK7 - shortcut +5V with +5VMOD (use same supply for computer and modulator)
== CPC Plus:LK105 - Autoboot CP/M ==