VRC7: Difference between revisions
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m (→Overview: Enough pins for the entire 256kB of CHR address space.) |
m (→Registers: There aren't enough pins for more than 6 bits of PRG bank select, don't claim they exist. Talk about Lagrange Point vs Tiny Toon Adventures 2.) |
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| Line 18: | Line 18: | ||
== Registers == | == Registers == | ||
One variant of the VRC7 uses A4 for registers ($x010), | One wiring variant of the VRC7 uses A4 for registers ($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) === | === PRG Select 0 ($8000) === | ||
| Line 24: | Line 24: | ||
7 bit 0 | 7 bit 0 | ||
--------- | --------- | ||
..PP PPPP | |||
|| |||| | |||
++-++++- Select 8 KB PRG ROM at $8000 | |||
| Line 33: | Line 33: | ||
7 bit 0 | 7 bit 0 | ||
--------- | --------- | ||
..PP PPPP | |||
|| |||| | |||
++-++++- Select 8 KB PRG ROM at $A000 | |||
| Line 42: | Line 42: | ||
7 bit 0 | 7 bit 0 | ||
--------- | --------- | ||
..PP PPPP | |||
|| |||| | |||
++-++++- Select 8 KB PRG ROM at $C000 | |||
| Line 122: | Line 122: | ||
|| | || | ||
++- [[Mirroring]] (0: vertical; 1: horizontal; | ++- [[Mirroring]] (0: vertical; 1: horizontal; | ||
2: one-screen, lower bank; 3: one-screen, upper bank | 2: one-screen, lower bank; 3: one-screen, upper bank) | ||
Revision as of 09:22, 31 January 2012
The Konami VRC7 is an ASIC mapper.
Overview
- Manufacturer: Konami
- PRG ROM size: Up to 512 KB
- PRG ROM bank size: 8 KB at $8000, $A000, and $C000
- PRG RAM: Up to 8 KB
- CHR capacity: Up to 256 KB (only two games released: one has 128 KB ROM, the other has 8 KB RAM)
- CHR bank size: 1 KB - swappable even when RAM instead of ROM
- Nametable mirroring: Controlled by mapper
- Subject to bus conflicts: No
Registers
One wiring variant of the VRC7 uses A4 for registers ($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 $C000
CHR Select 0 ($A000)
7 bit 0 --------- CCCC CCCC |||| |||| ++++-++++- Select 1 KB CHR ROM/RAM at PPU $0000
CHR Select 1 ($A010, $A008)
7 bit 0 --------- CCCC CCCC |||| |||| ++++-++++- Select 1 KB CHR ROM/RAM at PPU $0400
CHR Select 2 ($B000)
7 bit 0 --------- CCCC CCCC |||| |||| ++++-++++- Select 1 KB CHR ROM/RAM at PPU $0800
CHR Select 3 ($B010, $B008)
7 bit 0 --------- CCCC CCCC |||| |||| ++++-++++- Select 1 KB CHR ROM/RAM at PPU $0C00
CHR Select 4 ($C000)
7 bit 0 --------- CCCC CCCC |||| |||| ++++-++++- Select 1 KB CHR ROM/RAM at PPU $1000
CHR Select 5 ($C010, $C008)
7 bit 0 --------- CCCC CCCC |||| |||| ++++-++++- Select 1 KB CHR ROM/RAM at PPU $1400
CHR Select 6 ($D000)
7 bit 0 --------- CCCC CCCC |||| |||| ++++-++++- Select 1 KB CHR ROM/RAM at PPU $1800
CHR Select 7 ($D010, $D008)
7 bit 0 --------- CCCC CCCC |||| |||| ++++-++++- Select 1 KB CHR ROM/RAM at PPU $1C00
Mirroring Control ($E000)
7 bit 0
---------
.... ..MM
||
++- Mirroring (0: vertical; 1: horizontal;
2: one-screen, lower bank; 3: one-screen, upper bank)
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.
