Writing to Port DFxxh selects the Upper ROM Bank Number (in range of 00h..FFh) to be mapped to memory at C000h..FFFFh. Whether or not the ROM is enabled (or if RAM is mapped to that region) is controlled by the [[Gate Array]].
== Technical ==
== Common ROM Bank Numbers ==
00h BASIC (or AMSDOS, depending on LK1on the DDI-1 board) 07h AMSDOS (or BASIC, depending on LK1on the DDI-1 board)
00h..07h Bootable ROMs on CPC 464/664/6128 (KL_ROM_WALK)
08h..0Fh Bootable ROMs on CPC 664/6128 (KL_ROM_WALK)
10h..FFh Non-bootable ROMs (or secondary banks of Bootable ROMs)
FCh..FFh Can be used, but aren't accessible by BIOS functions
FFh BASIC (or ROM with similar ID; for the crude 128K RAM-size detection in CP/M+) FFh BASIC (or ROM with similar ID; for the BIOS key scan detection in AMSDOS+)
== Other Bank Numbers ==
* You may want to add a list of devices with ROM here, please also include their fixed bank number(s), or selectable range of bank number(s))
* Not sure if there are devices with incompletely decoded bank numbers? Eg. a ROM mapped to bank 06h, but also mirrored to 16h, 26h, 36h, etc. If so, these addresses should be listed here, too.
[[Category:Programming]][[Category:Memory expansions]][[Category:Peripherals]][[Category:CPC Internal Components]]