INES Mapper 224: Difference between revisions
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NewRisingSun (talk | contribs) (Created page with "Category:MMC3-like mappersCategory:Mappers with scanline IRQs iNES Mapper 224 is used for a number of Waixing and Nanjing games with 1024 KiB of PRG-ROM and no CHR-ROM...") |
NewRisingSun (talk | contribs) (I misunderstood Cah4e3's original post on the subject (http://cah4e3.shedevr.org.ru/dumping_2014.php).) |
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[[Category:MMC3-like mappers]][[Category:Mappers with scanline IRQs]] | [[Category:MMC3-like mappers]][[Category:Mappers with scanline IRQs]] | ||
iNES Mapper 224 is used for | iNES Mapper 224 is used for the 晶科泰 (Jncota) KT-008 PCB. It's an MMC3 clone that supports 1024 KiB of PRG-ROM through an additional outer bank register at $5000. | ||
=Registers= | |||
==MMC3-compatible Registers== | |||
Mask: $E001 | |||
$8000, $8001, $A000, $A001, $C000, $C001, $E000, $E001: As normal MMC3. | |||
==Outer Bank Register ($5000)== | |||
Mask: unknown, but probably $F003. | |||
7654 3210 | |||
--------- | |||
.... .P.. | |||
+-- Select outer 512 KiB PRG-ROM bank | |||
==Other registers ($5001-$5003)== | |||
Mask: unknown, but probably $F003. | |||
Meaning unknown; games just write $00 to them. | |||
=Note= | |||
* Because the outer bank register is initialized to $00 at power-on, these games boot with the $E000 bank from the ''first'' 512 KiB half. | |||
* Most of these ROM images are incorrectly set to Mapper 4, thus sharing a mapper number with oversize [[TxROM|TNROM]] images having 1024 KiB of PRG-ROM. Oversize TNROM switches 512 KiB banks through bits 6-7 of MMC3 bank registers 6 and 7 and initializes them to $FE and $FF, causing these games to boot with the $E000 bank from the ''second'' 512 KiB half. | |||
Revision as of 09:54, 2 April 2018
iNES Mapper 224 is used for the 晶科泰 (Jncota) KT-008 PCB. It's an MMC3 clone that supports 1024 KiB of PRG-ROM through an additional outer bank register at $5000.
Registers
MMC3-compatible Registers
Mask: $E001
$8000, $8001, $A000, $A001, $C000, $C001, $E000, $E001: As normal MMC3.
Outer Bank Register ($5000)
Mask: unknown, but probably $F003.
7654 3210
---------
.... .P..
+-- Select outer 512 KiB PRG-ROM bank
Other registers ($5001-$5003)
Mask: unknown, but probably $F003.
Meaning unknown; games just write $00 to them.
Note
- Because the outer bank register is initialized to $00 at power-on, these games boot with the $E000 bank from the first 512 KiB half.
- Most of these ROM images are incorrectly set to Mapper 4, thus sharing a mapper number with oversize TNROM images having 1024 KiB of PRG-ROM. Oversize TNROM switches 512 KiB banks through bits 6-7 of MMC3 bank registers 6 and 7 and initializes them to $FE and $FF, causing these games to boot with the $E000 bank from the second 512 KiB half.
