Namco 163

Namco 129/163

Company	Namco
Games	20 in NesCartDB
Complexity	ASIC
Boards	11xF0, 111F0S
PRG ROM capacity	512K
PRG ROM window	8Kx3 + 8K fixed
PRG RAM capacity	8K
PRG RAM window	8K
CHR capacity	256K
CHR window	1Kx8 (PT) + 1Kx4 (NT)
Nametable mirroring	arbitrary, up to 226 source nametables
Bus conflicts	No
IRQ	CPU cycle counter
Audio	Yes
iNES mappers	019

Namco 175

Company	Namco
Games	4 in NesCartDB
Complexity	ASIC
Boards	110F0B
PRG ROM capacity	512K
PRG ROM window	8Kx3 + 8K fixed
PRG RAM capacity	8K
PRG RAM window	8K
CHR capacity	256K
CHR window	1Kx8
Nametable mirroring	H or V fixed
Bus conflicts	No
IRQ	No
Audio	No
iNES mappers	210

Namco 340

Company	Namco
Games	8 in NesCartDB
Complexity	ASIC
Boards	CS000x
PRG ROM capacity	512K
PRG ROM window	8Kx3 + 8K fixed
PRG RAM capacity	none
PRG RAM window	none
CHR capacity	256K
CHR window	1Kx8
Nametable mirroring	H, V, or 1 switchable
Bus conflicts	No
IRQ	No
Audio	No
iNES mappers	210

The Namco 163 with expansion sound (and its predecessor 129 which has some mistake in the audio hardware) are assigned to iNES Mapper 19, while simpler variants are assigned to iNES Mapper 210: those using the Namco 175 ICs have hard-wired mirroring and those using the Namco 340 support mapper-switchable mirroring. All four were packaged in 48-pin TQFPs (see: Namcot 163 family pinout).

Many older programs incorrectly identify this mapper by the name Namco 106. Some sources use the name Namcot instead of Namco, as some games and PCBs use this variation on the company name.

In addition to the 8 KB of PRG RAM that may be available, the Namco 163 has an additional 128 bytes of internal memory intended for expansion audio. Any of that memory that is not used to specify sound could be used as RAM by the game.

Example games: (Mapper 019)

• Digital Devil Story - Megami Tensei II
• Erika to Satoru no Yume Bouken
• Famista '90
• Final Lap
• King of Kings (Namco)
• Rolling Thunder (J)
• Sangokushi I, II (Namco)
• Star Wars (Namco)
• Mappy Kids
• Namco Classic I, II

Example games: (Mapper 210)

• Dream Master
• Famista '91 - '94
• Splatter House
• Wagyan Land 2, 3

Banks

• CPU $6000-$7FFF: 8 KB PRG RAM bank (Namco 129, 163, and 175)
• 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
• PPU $2000-$23FF: 1 KB switchable CHR bank (Namco 129/163 only)
• PPU $2400-$27FF: 1 KB switchable CHR bank (Namco 129/163 only)
• PPU $2800-$2BFF: 1 KB switchable CHR bank (Namco 129/163 only)
• PPU $2C00-$2FFF: 1 KB switchable CHR bank (Namco 129/163 only)

The Namco 129 and 163 have the unusual ability to select the internal 2 KB nametable RAM as a CHR bank page, allowing it to be used as CHR RAM in combination with the existing CHR ROM.

Registers

The 163 has 19 registers within $4800-$5FFF and $8000-$FFFF, while the the 175 and 340 only have 12. 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 (Namco 129,163 only)

See Namco 163 audio. Note that the 129's audio doesn't work correctly.

IRQ Counter (low) ($5000-$57FF) r/w (Namco 129,163 only)

7  bit  0
---- ----
IIII IIII
|||| ||||
++++-++++- Low 8 bits of IRQ counter

IRQ Counter (high) / IRQ Enable ($5800-$5FFF) r/w (Namco 129,163 only)

7  bit  0
---- ----
EIII IIII
|||| ||||
|+++-++++- High 7 bits of IRQ counter
+--------- IRQ Enable: (0: disabled; 1: enabled)

CHR and NT Select ($8000-$DFFF) w

Note: The Namco 175 and 340 do not support using nametable RAM as CHR-RAM, and the nametable selection registers have no effect.

Value CPU writes	Behavior
$00-$DF	Always selects 1KB page of CHR-ROM
$E0-$FF	If enabled by bit in $E800 and using a N163 or N129, use the NES's internal nametables (even values for A, odd values for B)

Write to CPU address	1KB CHR bank affected	Values ≥ $E0 denote NES NTRAM if
$8000-$87FF	$0000-$03FF	$E800.6 = 0
$8800-$8FFF	$0400-$07FF	$E800.6 = 0
$9000-$97FF	$0800-$0BFF	$E800.6 = 0
$9800-$9FFF	$0C00-$0FFF	$E800.6 = 0
$A000-$A7FF	$1000-$13FF	$E800.7 = 0
$A800-$AFFF	$1400-$17FF	$E800.7 = 0
$B000-$B7FF	$1800-$1BFF	$E800.7 = 0
$B800-$BFFF	$1C00-$1FFF	$E800.7 = 0
$C000-$C7FF	$2000-$23FF	always
$C800-$CFFF	$2400-$27FF	always
$D000-$D7FF	$2800-$2BFF	always
$D800-$DFFF	$2C00-$2FFF	always

It is believed, but untested, that a game could add a normal SRAM and use it in lieu of the nametable RAM; if so, a game would be able to get 4-screen mirroring and many more pages of CHR-RAM.

External PRG RAM enable ($C000-$C7FF) w (Namco 175 only)

7  bit  0
---- ----
.... ...E
        |
        +- 1: Enable PRG RAM

PRG Select 1 ($E000-$E7FF) w

7  bit  0
---- ----
MMPP PPPP
|||| ||||
||++-++++- Select 8KB page of PRG-ROM at $8000
|+-------- Namco 129, 163 only: Disable sound if set
++-------- Namco 340 only: Select mirroring
             0: One-screen A
             1: Vertical
             2: Horizontal
             3: One-screen B

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 (Namco 129, 163 only)
|            0: Pages $E0-$FF use NT RAM as CHR-RAM
|            1: Pages $E0-$FF are the last $20 banks of CHR-ROM
+--------- Disable CHR-RAM at $1000-$1FFF (Namco 129, 163 only)
             0: Pages $E0-$FF use NT RAM as 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

Write Protect for External RAM AND Sound Address Port ($F800-$FFFF) w (Namco 129, 163 only)

7  bit  0
---- ----
KKKK DCBA
|||| ||||
|||| |||+- 1: Write-protect 2kB window of external RAM from $6000-$67FF (0: write enable)
|||| ||+-- 1: Write-protect 2kB window of external RAM from $6800-$6FFF (0: write enable)
|||| |+--- 1: Write-protect 2kB window of external RAM from $7000-$77FF (0: write enable)
|||| +---- 1: Write-protect 2kB window of external RAM from $7800-$7FFF (0: write enable)
++++------ Additionally the upper nybble must be equal to b0100 to enable writes

Any value outside of the range $40-$4E will cause all PRG RAM to be read-only.

Also 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, and it stops counting. Writing to $5000 or $5800 will acknowledge any pending IRQs.

See also

• Namcot 106 by goroh, fix by ZW4 and nori, english translation by nori.
• Comprehensive NES Mapper Document by \Firebug\, information about mapper's initial state is inaccurate.

All of the below are in Japanese:

• Namco mapper by goroh
• Naruko's post to the forum
• Wiki on same
• Naruko's blog's post on mirroring on the 340
• Naruko's blog's post on the write protect register at $F800