INES Mapper 087
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Here are Disch's original notes: ======================== = Mapper 087 = ======================== Example Games: -------------------------- Argus (J) City Connection (J) Ninja Jajamaru Kun Notes: --------------------------- Regs are at $6000-7FFF, so these games have no SRAM. Registers: -------------------------- $6000-7FFF: [.... ..LH] H = High CHR Bit L = Low CHR Bit This reg selects 8k CHR @ $0000. Note the reversed bit orders. Most games using this mapper only have 16k CHR, so the 'H' bit is usually unused.
iNES Mapper 101 is the same but with the bits in order. CNROM (which postdates mapper 87) is the same but with the bits in order and bus conflicts. New development should use mapper 101; those who wish to use a mapper 87 donor board can swap banks 1 and 2 of the CHR ROM.