View source for VRC1

{{Infobox_iNES_mapper
|name=VRC1
|company=Konami
|mapper=75
|nescartdbgames=6
|complexity=ASIC
|boards=JF-20, JF-22, 4036, 302114A, 350459
|pinout=VRC1 pinout
|prgmax=128K
|prgpage=8K
|wrammax=none
|wrampage=n/a
|chrmax=128K
|chrpage=4K
|mirroring=H or V, switchable
|busconflicts=No
|irq=No
}}
[[Category:ASIC mappers]][[Category:in NesCartDB]]
The Konami VRC1 is an [[:Category:ASIC mappers|ASIC]] [[MMC|mapper]]. The [[iNES]] format assigns '''mapper 75''' to VRC1.

The VRC1 was used in several Famicom games released by Konami and Jaleco:
* ''Exciting Boxing''
* ''Ganbare Goemon! Karakuri Douchuu''
* ''Jajamaru Ninpouchou''
* ''King Kong 2: Ikari no Megaton Punch''
* ''Moero!! Junior Basket: Two on Two''
* ''Tetsuwan Atom''

__TOC__


== Banks ==
* CPU $8000-$9FFF: 8 KiB switchable PRG ROM bank
* CPU $A000-$BFFF: 8 KiB switchable PRG ROM bank
* CPU $C000-$DFFF: 8 KiB switchable PRG ROM bank
* CPU $E000-$FFFF: 8 KiB PRG ROM bank, fixed to the last bank
* PPU $0000-$0FFF: 4 KiB switchable CHR bank
* PPU $1000-$1FFF: 4 KiB switchable CHR bank

== Registers ==

=== PRG Select 0 ($8000-$8FFF) ===

 7  bit  0
 ---------
 .... PPPP
      ||||
      ++++- Select 8 KB PRG ROM at $8000

=== PRG Select 1 ($A000-$AFFF) ===

 7  bit  0
 ---------
 .... PPPP
      ||||
      ++++- Select 8 KB PRG ROM at $A000


=== PRG Select 2 ($C000-$CFFF) ===

 7  bit  0
 ---------
 .... PPPP
      ||||
      ++++- Select 8 KB PRG ROM at $C000


=== Mirroring Control, CHR bits ($9000-$9FFF) ===

 7  bit  0
 ---------
 .... .BAM
       |||
       ||+- [[Mirroring]]  (0: Vertical; 1: Horizontal)
       |+-- High Bit of 4 KB CHR bank at PPU $0000
       +--- High Bit of 4 KB CHR bank at PPU $1000

The mirroring bit is ignored if the cartridge is wired for 4-screen VRAM, as is typical for [[Vs. System]] games using the VRC1.

=== CHR Select 0 ($E000-$EFFF) ===

 7  bit  0
 ---------
 .... CCCC
      ||||
      ++++- Low 4 bits of 4 KB CHR bank at PPU $0000

These bits combined with bit 1 of $9000 make a 5-bit CHR selection.


=== CHR Select 1 ($F000-$FFFF) ===

 7  bit  0
 ---------
 .... CCCC
      ||||
      ++++- Low 4 bits of 4 KB CHR bank at PPU $1000

These bits combined with bit 2 of $9000 make a 5-bit CHR selection.

==References==
* [http://www.romhacking.net/documents/362/ Disch's Mapper Notes]