In the DDI-1, LK1 connects '''both''' to the Expansion Port /EXP pin (which goes to [[8255|PPI]] Port B, Bit5, '''and''' to the AMSDOS ROM bank number selection logic. The latter one allow to map AMSDOS to bank 7 (default), or bank 0. If AMSDOS sees itself mapped to bank 0, then it does automatically load & start the boot sector from drive A (equivalent as when typing |CPM after power-up).
== DDI-1:LK2,LK3 - Disc Low-Level Stuff or so Write Precomp ==
In DDI-1, LK2-LK3 connect to the P1/P0 pins of the FDC9229BT Disc Data Separator(P0=LK3, P1=LK2, and fixed: P2=GND). PurposeAccording to FDC9229BT datasheet: ''P2-P0 select the amount of precompensation applied to the write data''...?
== CPC6128:LK7 - Autoboot CP/M ==