NES 2.0 Mapper 554
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NES 2.0 Mapper 554 denotes the Kaiser KS-7010 circuit board, used for one of several cartridge conversions of the FDS version of 悪魔城 Dracula, the Japanese version of Castlevania. Bankswitching is unusual in being triggered entirely through reads from "magic" addresses. The board mounts 128 KiB PRG-ROM, 128 KiB CHR-ROM, a KS-201 ASIC and a 74'32.
- CPU $6000-$7FFF: Switchable 8 KiB PRG-ROM bank
- CPU $8000-$9FFF: Fixed 8 KiB PRG-ROM bank #10
- CPU $A000-$BFFF: Fixed 8 KiB PRG-ROM bank #11
- CPU $C000-$DFFF: Fixed 8 KiB PRG-ROM bank #6
- CPU $E000-$FFFF: Fixed 8 KiB PRG-ROM bank #7
- PPU $0000-$1FFF: Switchable 8 KiB CHR-ROM bank
- Nametable mirroring: hard-wired (to vertical)
The 8 KiB PRG-ROM bank at $6000, and the 8 KiB CHR-ROM bank, are both switched to the same bank number whenever certain addresses are read from.
A~FEDC BA98 7654 3210 ------------------- .??? ???? ??DC BA1. ++-++--- PRG/CHR A16..13
The exact address mask is not known; the following addresses have been verified to trigger a bankswitch, and are used by the game:
- EBE2, EE32
See: KS-201 pinout