Namco 163
The Namco 106 and Namco 163 (which adds expansion sound to the 106) are ASIC mappers, assigned to iNES mapper 19. A variant of this mapper with hardwired mirroring is assigned to iNES mapper 210.
Overview
- PRG ROM size: Up to 512 KB
- PRG ROM bank size: 8 KB
- PRG RAM: Up to 8 KB
- CHR capacity: Up to 256 KB ROM and/or 32 KB RAM simultaneously
- CHR bank size: 1 KB
- Nametable mirroring: Controlled by mapper (Mapper 19), hardwired (Mapper 210)
- Subject to bus conflicts: No
Banks
- CPU $6000-$7FFF: 8 KB PRG RAM bank
- CPU $8000-$9FFF: 8 KB switchable PRG ROM bank
- CPU $A000-$BFFF: 8 KB switchable PRG ROM bank
- CPU $C000-$DFFF: 8 KB switchable PRG ROM bank
- CPU $E000-$FFFF: 8 KB PRG ROM bank, fixed to the last bank
- PPU $0000-$03FF: 1 KB switchable CHR bank
- PPU $0400-$07FF: 1 KB switchable CHR bank
- PPU $0800-$0BFF: 1 KB switchable CHR bank
- PPU $0C00-$0FFF: 1 KB switchable CHR bank
- PPU $1000-$13FF: 1 KB switchable CHR bank
- PPU $1400-$17FF: 1 KB switchable CHR bank
- PPU $1800-$1BFF: 1 KB switchable CHR bank
- PPU $1C00-$1FFF: 1 KB switchable CHR bank
Registers
The n106 has 19 registers within $4800-$FFFF, except $6000-$7FFF which is WRAM. Each register occupies a range of $800 bytes, so $4800-$4FFF all refers to one register, $5000-$57FF all refers to another register, and so on.
Sound Data Port ($4800-$4FFF) r/w
See Namco 163 audio.
IRQ Counter (low) ($5000-$57FF) r/w
7 bit 0 ---- ---- IIII IIII |||| |||| ++++-++++- Low 8 bits of IRQ counter
IRQ Counter (high) / IRQ Enable ($5800-$5FFF) r/w
7 bit 0 ---- ---- EIII IIII |||| |||| |+++-++++- High 7 bits of IRQ counter +--------- IRQ Enable: (0: disabled; 1: enabled)
CHR Select 1 ($8000-$87FF) w
7 bit 0 ---- ---- CCCC CCCC |||| |||| ++++-++++- Select 1KB page of CHR-ROM or CHR-RAM at $0000
Note: Pages $E0-$FF are CHR-RAM, as long as $E800.6 is set to 0. If $E800.6 is set to 1, then pages $E0-$FF refer to the last $20 pages of CHR-ROM as you'd expect.
CHR Select 2 ($8800-$88FF) w
7 bit 0 ---- ---- CCCC CCCC |||| |||| ++++-++++- Select 1KB page of CHR-ROM or CHR-RAM at $0400
Note: Pages $E0-$FF are CHR-RAM, as long as $E800.6 is set to 0. If $E800.6 is set to 1, then pages $E0-$FF refer to the last $20 pages of CHR-ROM as you'd expect.
CHR Select 3 ($9000-$97FF) w
7 bit 0 ---- ---- CCCC CCCC |||| |||| ++++-++++- Select 1KB page of CHR-ROM or CHR-RAM at $0800
Note: Pages $E0-$FF are CHR-RAM, as long as $E800.6 is set to 0. If $E800.6 is set to 1, then pages $E0-$FF refer to the last $20 pages of CHR-ROM as you'd expect.
CHR Select 4 ($9800-$9FFF) w
7 bit 0 ---- ---- CCCC CCCC |||| |||| ++++-++++- Select 1KB page of CHR-ROM or CHR-RAM at $0C00
Note: Pages $E0-$FF are CHR-RAM, as long as $E800.6 is set to 0. If $E800.6 is set to 1, then pages $E0-$FF refer to the last $20 pages of CHR-ROM as you'd expect.
CHR Select 5 ($A000-$A7FF) w
7 bit 0 ---- ---- CCCC CCCC |||| |||| ++++-++++- Select 1KB page of CHR-ROM or CHR-RAM at $1000
Note: Pages $E0-$FF are CHR-RAM, as long as $E800.7 is set to 0. If $E800.7 is set to 1, then pages $E0-$FF refer to the last $20 pages of CHR-ROM as you'd expect.
CHR Select 6 ($A800-$AFFF) w
7 bit 0 ---- ---- CCCC CCCC |||| |||| ++++-++++- Select 1KB page of CHR-ROM or CHR-RAM at $1400
Note: Pages $E0-$FF are CHR-RAM, as long as $E800.7 is set to 0. If $E800.7 is set to 1, then pages $E0-$FF refer to the last $20 pages of CHR-ROM as you'd expect.
CHR Select 7 ($B000-$B7FF) w
7 bit 0 ---- ---- CCCC CCCC |||| |||| ++++-++++- Select 1KB page of CHR-ROM or CHR-RAM at $1800
Note: Pages $E0-$FF are CHR-RAM, as long as $E800.7 is set to 0. If $E800.7 is set to 1, then pages $E0-$FF refer to the last $20 pages of CHR-ROM as you'd expect.
CHR Select 8 ($B800-$BFFF) w
7 bit 0 ---- ---- CCCC CCCC |||| |||| ++++-++++- Select 1KB page of CHR-ROM or CHR-RAM at $1C00
Note: Pages $E0-$FF are CHR-RAM, as long as $E800.7 is set to 0. If $E800.7 is set to 1, then pages $E0-$FF refer to the last $20 pages of CHR-ROM as you'd expect.
Nametable Select 1 ($C000-$C7FF) w
7 bit 0
---- ----
NNNN NNNN
|||| ||||
++++-++++- Select nametable at $2000:
$00-$DF: Use a 1KB page of CHR-ROM as a nametable
$E0-$FF: Use the NES's internal nametables (even values for A, odd values for B)
Note: On mapper 210, this register has no effect.
Nametable Select 2 ($C800-$CFFF) w
7 bit 0
---- ----
NNNN NNNN
|||| ||||
++++-++++- Select nametable at $2400:
$00-$DF: Use a 1KB page of CHR-ROM as a nametable
$E0-$FF: Use the NES's internal nametables (even values for A, odd values for B)
Note: On mapper 210, this register has no effect.
Nametable Select 3 ($D000-$D7FF) w
7 bit 0
---- ----
NNNN NNNN
|||| ||||
++++-++++- Select nametable at $2800:
$00-$DF: Use a 1KB page of CHR-ROM as a nametable
$E0-$FF: Use the NES's internal nametables (even values for A, odd values for B)
Note: On mapper 210, this register has no effect.
Nametable Select 4 ($D800-$DFFF) w
7 bit 0
---- ----
NNNN NNNN
|||| ||||
++++-++++- Select nametable at $2C00:
$00-$DF: Use a 1KB page of CHR-ROM as a nametable
$E0-$FF: Use the NES's internal nametables (even values for A, odd values for B)
Note: On mapper 210, this register has no effect.
PRG Select 1 ($E000-$E7FF) w
7 bit 0 ---- ---- ..PP PPPP || |||| ++-++++- Select 8KB page of PRG-ROM at $8000
PRG Select 2 / CHR-RAM Enable ($E800-$EFFF) w
7 bit 0
---- ----
HLPP PPPP
|||| ||||
||++-++++- Select 8KB page of PRG-ROM at $A000
|+-------- Disable CHR-RAM at $0000-$0FFF
| 0: Pages $E0-$FF are CHR-RAM
| 1: Pages $E0-$FF are the last $20 banks of CHR-ROM)
+--------- Disable CHR-RAM at $1000-$1FFF
0: Pages $E0-$FF are CHR-RAM
1: Pages $E0-$FF are the last $20 banks of CHR-ROM)
PRG Select 3 ($F000-$F7FF) w
7 bit 0 ---- ---- ..PP PPPP || |||| ++-++++- Select 8KB page of PRG-ROM at $C000
Sound Address Port ($F800-$FFFF) w
See Namco 163 audio.
IRQ Operation
The IRQ is a 15-bit CPU cycle up-counter. $5000 and $5800 provide direct access to the counter itself (i.e., this isn't a reload value). Games can read and write to these registers in realtime.
The IRQ counter increments on each CPU cycle. Upon reaching $7FFF, an IRQ is fired. However, it is unknown if the counter wraps to $0000 afterwards. Reading/Writing to $5000 or $5800 will acknowledge any pending IRQs.
