VRC7

From Nesdev wiki
Jump to: navigation, search

The Konami VRC7 is an ASIC mapper. In the iNES format, it's #85.

Contents


Overview

  • Manufacturer: Konami
  • PRG ROM size: Up to 512 KB
  • PRG ROM bank size: 8 KB at $8000, $A000, and $C000
  • PRG RAM: Up to 8 KB
  • CHR capacity: Up to 256 KB (only two games released: one has 128 KB ROM, the other has 8 KB RAM)
  • CHR bank size: 1 KB - swappable even when RAM instead of ROM
  • Nametable mirroring: Controlled by mapper
  • Subject to bus conflicts: No

See VRC7 pinout for chip pinout.

Registers

One wiring variant of the VRC7 uses A4 for registers ($x010), the other uses A3 ($x008). Although A5 is wired for sound registers on both ($x030, $x028), in the latter board the ceramic resonator believed necessary for the sound hardware to work is missing.

PRG Select 0 ($8000)

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


PRG Select 1 ($8010, $8008)

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

PRG Select 2 ($9000)

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

CHR Select 0…7 ($A000…$DFFF)

Write to CPU address 1KB CHR bank affected
$A000 $0000-$03FF
$A008 or $A010 $0400-$07FF
$B000 $0800-$0BFF
$B008 or $B010 $0C00-$0FFF
$C000 $1000-$13FF
$C008 or $C010 $1400-$17FF
$D000 $1800-$1BFF
$D008 or $D010 $1C00-$1FFF

Mirroring Control ($E000)

7  bit  0
---------
RS.. ..MM
||     ||
||     ++- Mirroring (0: vertical; 1: horizontal;
||                        2: one-screen, lower bank; 3: one-screen, upper bank)
|+-------- Silence expansion sound if set
+--------- WRAM enable (1: enable WRAM, 0: protect)

IRQ Control ($E008 - $F010)

$E008, $E010:  IRQ Latch
       $F000:  IRQ Control
$F008, $F010:  IRQ Acknowledge

Many VRC mappers use the same IRQ system. For details on IRQ operation, see VRC IRQs.

Sound ($9010, $9030)

For details on sound information, see VRC7 Audio.

Personal tools