iNES Mapper 043 is used for the TONY-I and YS-612 circuit boards, both containing conversions of Super Mario Brothers 2 (Japanese) from Famicom Disk System to ROM cartridge. There are two 32 KiB, one 2 KiB and one 8 KiB PRG-ROM chip. iNES-format ROM images first include the data of both 32 KiB ROM chips, then the data of the 2 KiB chip repeated four times, then the data of the 8 KiB ROM chip, for a total of 80 KiB of PRG-ROM.
Mask: $71FF
Bit 7654 3210
---------
.... .CCC
+++- Select 8 KiB PRG-ROM bank at CPU $C000-$DFFF.
The actual bank number is:
Value Bank# ------------ 0 4 1 3 2 4 3 4 4 4 5 7 6 5 7 6
Mask: $71FF?
Bit 7654 3210
---------
.... ...I
+- 0: Acknowledge and disable IRQ, reset counter
1: Enable IRQ
When enabled, the 12-bit IRQ counter increases on every M2 cycle until it overflows, upon which an IRQ is fired.
Categories: Mappers with fixed-timing cycle IRQs, FDS conversion mappers, INES Mappers