INES Mapper 034
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iNES Mapper 034 is used to designate both the BNROM and NINA-001 boards.
Emulator authors are suggested to distinguish between these two by checking the number of CHR banks present - BNROM should be used when there is 0 to 8 KiB of CHR, and NINA-001 should be used otherwise.
Here are Disch's original notes: ======================== = Mapper 034 = ======================== aka -------------------------- BxROM NINA-001 Example Games: -------------------------- Darkseed (BxROM) Mashou (BxROM) Impossible Mission 2 (NINA-001) Notes: -------------------------- How these two seperate and completely imcompatible mappers got assigned the same mapper number is a mystery. BxROM and NINA-001 are both assigned mapper 034, however they both work totally differently. There is no reliable way to tell the difference between the two apart from a CRC or Hash check. ================================= BxROM ================================= BxROM has bus conflicts... however this mapper also covers some BxROM compatible boards that do not suffer from bus conflicts. Registers (**BUS CONFLICTS** sometimes): -------------------------- $8000-FFFF: Select 32k PRG @ $8000 Note on a real BxROM, only the low 2 bits are used (PRG capped at 128k). But since this is BxROM and compatible, emus should use all 8 bits PRG Setup: -------------------------- $8000 $A000 $C000 $E000 +-------------------------------+ | $8000 | +-------------------------------+ ================================= NINA-001 ================================= Registers: -------------------------- $7FFD: Select 32k PRG @ $8000 $7FFE: Select 4k CHR @ $0000 $7FFF: Select 4k CHR @ $1000 I'm not sure whether or not WRAM can also exist at $6000-7FFF PRG Setup: -------------------------- $8000 $A000 $C000 $E000 +-------------------------------+ | $7FFD | +-------------------------------+ CHR Setup: -------------------------- $0000 $0400 $0800 $0C00 $1000 $1400 $1800 $1C00 +-------------------------------+-------------------------------+ | $7FFE | $7FFF | +-------------------------------+-------------------------------+