INES Mapper 148

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Revision as of 21:06, 30 November 2019 by NewRisingSun (talk | contribs) (The "lack of bus prevention circuitry" part was highly misleading, as bus prevention circuity more commonly refers to PRG-ROM /OE being connected to inverted CPU /WR, when we're actually talking about a different address range.)
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iNES Mapper 148 denotes the Sachen SA-008-A and Tengen 800008 circuit boards, which switch up to 64 KiB of PRG-ROM in 32 KiB amounts and up to 64 KiB of CHR-ROM in 8 KiB amounts using a data latch. The bit assignment of the data latch is the same as INES Mapper 079's, but unlike mapper 79, the latch register is in the CPU $8000-$FFFF range instead of $4100-$5FFF, introducing bus conflicts.

Data Latch

 Mask: $8000
 Bus conflicts:
 $8000: [.... PCCC] - Select 32 KiB PRG bank and 8 KiB CHR bank

References