INES Mapper 148: Difference between revisions
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(it's not really bizarre... just obnoxiously pedantic.) |
(someone bothered to trace the photos in the flickr link and found that CPU A13 and A14 are also ORed into the bits that must not be set for a mapper write) |
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{{DEFAULTSORT:148}}[[Category:iNES Mappers]][[Category:GNROM-like mappers]] | {{DEFAULTSORT:148}}[[Category:iNES Mappers]][[Category:GNROM-like mappers]] | ||
'''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 | Mask: $8000 | ||
Bus conflicts: | Bus conflicts: | ||
$8000: [.... PCCC] | $8000: [.... PCCC] - Select 32 KiB PRG bank and 8 KiB CHR bank | ||
Sachen's SA-008-A board uses a mask of $E000 but is otherwise the same. | |||
== References == | == References == | ||
* http://cah4e3.shedevr.org.ru/%5Blst%5D-sachen-mappers.txt | * http://cah4e3.shedevr.org.ru/%5Blst%5D-sachen-mappers.txt | ||
* [http://kevtris.org/mappers/tengen/800008.html Kev's analysis of Tengen 800008] | * [http://kevtris.org/mappers/tengen/800008.html Kev's analysis of Tengen 800008] | ||
* [https://www.flickr.com/photos/153392699@N08/sets/72157680729618601 Box, cart, and PCB pictures] | |||
Latest revision as of 16:44, 18 June 2024
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
Sachen's SA-008-A board uses a mask of $E000 but is otherwise the same.
