INES Mapper 100: Difference between revisions
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[[Category:Bad iNES Mappers | {{DEFAULTSORT:100}}[[Category:Bad iNES Mappers]][[Category:INES Mappers]][[Category:MMC3-like mappers]][[Category:Mappers with scanline IRQs]] | ||
iNES Mapper 100 was assigned by fwNES<ref>FWNES98E.TXT, fwNES 0.302b, 1998/11/16, by FanWen Yang</ref> to denote [[Mapper hack|mapper hacks]] for the [[INES Mapper 004|MMC3]] emulation of Nesticle, an influential NES emulator for MS-DOS in the late 1990s. Nesticle did not directly support many of the custom ASICs by Irem, Konami and Namco, but did incorrectly emulate the MMC3 in a way that made it useful to run modified ROM images. Most of them use 512-byte trainers that must be loaded to CPU address $7000. | |||
iNES Mapper 100 | |||
Nestopia uses iNES mapper 100 as a magic number for UNIF-only boards. Nintendulator uses this as a general-purpose debugging mapper, allowing PRG/CHR banks to be selected arbitrarily using a control dialog. | |||
==Bankswitch Index Register ($8000)/Data Register ($8001)== | ==Bankswitch Index Register ($8000)/Data Register ($8001)== | ||
Mask: $E001 (nominally) | Mask: $E001 (nominally) | ||
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$85: 1 KiB CHR-ROM bank at PPU $0C00-$0FFF := Value | $85: 1 KiB CHR-ROM bank at PPU $0C00-$0FFF := Value | ||
On an actual MMC3, changing bits 6 and 7 in the index register would immediately apply the current content of all seven bank registers to their flipped meaning. Nesticle applies these bits only on the next $8001 write, which makes eight independent 1 KiB CHR-ROM banks available: Registers $82-$85 to set four 1 KiB banks at CPU $0000-$0FFF, and registers $02-$05 to set four more 1 KiB banks at CPU $1000-$1FFF. | |||
Nesticle | |||
Latest revision as of 19:00, 24 April 2019
iNES Mapper 100 was assigned by fwNES[1] to denote mapper hacks for the MMC3 emulation of Nesticle, an influential NES emulator for MS-DOS in the late 1990s. Nesticle did not directly support many of the custom ASICs by Irem, Konami and Namco, but did incorrectly emulate the MMC3 in a way that made it useful to run modified ROM images. Most of them use 512-byte trainers that must be loaded to CPU address $7000.
Nestopia uses iNES mapper 100 as a magic number for UNIF-only boards. Nintendulator uses this as a general-purpose debugging mapper, allowing PRG/CHR banks to be selected arbitrarily using a control dialog.
Bankswitch Index Register ($8000)/Data Register ($8001)
Mask: $E001 (nominally)
$00: 1 KiB CHR-ROM bank at PPU $0000-$03FF := Value AND $FE
1 KiB CHR-ROM bank at PPU $0400-$07FF := Value OR $01
$01: 1 KiB CHR-ROM bank at PPU $0800-$0BFF := Value AND $FE
1 KiB CHR-ROM bank at PPU $0C00-$0FFF := Value OR $01
$02: 1 KiB CHR-ROM bank at PPU $1000-$13FF := Value
$03: 1 KiB CHR-ROM bank at PPU $1400-$17FF := Value
$04: 1 KiB CHR-ROM bank at PPU $1800-$1BFF := Value
$05: 1 KiB CHR-ROM bank at PPU $1C00-$1FFF := Value
$06: 8 KiB PRG-ROM bank at CPU $8000-$9FFF := Value
$07: 8 KiB PRG-ROM bank at CPU $A000-$BFFF := Value
$46: 8 KiB PRG-ROM bank at CPU $C000-$DFFF := Value
$47: 8 KiB PRG-ROM bank at CPU $A000-$BFFF := Value
$80: 1 KiB CHR-ROM bank at PPU $1000-$13FF := Value AND $FE
1 KiB CHR-ROM bank at PPU $1400-$17FF := Value OR $01
$81: 1 KiB CHR-ROM bank at PPU $1800-$1BFF := Value AND $FE
1 KiB CHR-ROM bank at PPU $1C00-$1FFF := Value OR $01
$82: 1 KiB CHR-ROM bank at PPU $0000-$03FF := Value
$83: 1 KiB CHR-ROM bank at PPU $0400-$07FF := Value
$84: 1 KiB CHR-ROM bank at PPU $0800-$0BFF := Value
$85: 1 KiB CHR-ROM bank at PPU $0C00-$0FFF := Value
On an actual MMC3, changing bits 6 and 7 in the index register would immediately apply the current content of all seven bank registers to their flipped meaning. Nesticle applies these bits only on the next $8001 write, which makes eight independent 1 KiB CHR-ROM banks available: Registers $82-$85 to set four 1 KiB banks at CPU $0000-$0FFF, and registers $02-$05 to set four more 1 KiB banks at CPU $1000-$1FFF.
- ↑ FWNES98E.TXT, fwNES 0.302b, 1998/11/16, by FanWen Yang
