INES Mapper 224: Difference between revisions
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Meaning unknown; games just write $00 to them. | Meaning unknown; games just write $00 to them. | ||
= | =Notes= | ||
* 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. | * 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 | * 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 them to boot with the $E000 bank from the ''second'' 512 KiB half. | ||
Revision as of 10:16, 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.
Notes
- 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 them to boot with the $E000 bank from the second 512 KiB half.
