iNES Mapper 210 is used to denote Famicom boards bearing either the Namco 175 (Submapper 1) or Namco 340 (Submapper 2) ASIC. Both can be thought of as cost-reduced versions of the Namco 163:
Function
N163
N175
N340
IRQ counter
Yes
No
No
ROM nametables
Yes
No
No
Optional WRAM
Yes
Yes
No
Expansion audio
Yes
No
No
ASIC-internal RAM
Yes
No
No
Mirroring
Selectable (extended)
Hardwired H/V
Selectable H/V/0/1
Game list
Namco 175 (Submapper 1)
Name
Battery
WRAM
Mirroring
Chibi Maruko-chan: Uki Uki Shopping
No
No
V
Family Circuit ‘91
Yes
2 KiB
V
Famista ‘91
No
No
V
Heisei Tensai Bakabon
No
No
V
Splatterworld: Rick to Kyoufu no Daiou (unreleased)
Yes
8 KiB
V
Namco 340 (Submapper 2)
Dream Master
Famista ‘92
Famista ‘93
Famista ‘94
Splatterhouse: Wanpaku Graffiti
Top Striker
Wagyan Land 2
Wagyan Land 3
Banks
CPU $6000-$7FFF: PRG RAM bank, mirrored if smaller than 8 KB (Namco 175 only)
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 175 and 340 have 12 registers within $8000-$FFFF. Each register occupies a range of $800 bytes, so $8000-$87FF all refers to one register, $8800-$8FFF all refers to another register, and so on.
CHR Select ($8000-$BFFF) w
Value CPU writes
Behavior
$00-$FF
Selects 1KB page of CHR-ROM
Write to CPU address
1KB CHR bank affected
$8000-$87FF
$0000-$03FF
$8800-$8FFF
$0400-$07FF
$9000-$97FF
$0800-$0BFF
$9800-$9FFF
$0C00-$0FFF
$A000-$A7FF
$1000-$13FF
$A800-$AFFF
$1400-$17FF
$B000-$B7FF
$1800-$1BFF
$B800-$BFFF
$1C00-$1FFF
External PRG RAM enable ($C000-$C7FF) w (Namco 175 only)
7 bit 0
---- ----
MMPP PPPP
|||| ||||
||++-++++- Select 8KB page of PRG-ROM at $8000
++-------- Namco 340 only: Select mirroring
0: One-screen A
1: Vertical
2: One-screen B
3: Horizontal
PRG Select 2 ($E800-$EFFF) w
7 bit 0
---- ----
..PP PPPP
|| ||||
++-++++- Select 8KB page of PRG-ROM at $A000
PRG Select 3 ($F000-$F7FF) w
7 bit 0
---- ----
..PP PPPP
|| ||||
++-++++- Select 8KB page of PRG-ROM at $C000
Notes
Family Circuit ‘91 relies on its 2 KiB of PRG-RAM being correctly mirrored throughout the $6000-$7FFF address range, while Splatterworld relies on having a full 8 KiB in the same range.
Both of these games contain a hidden test activated by shorting expansion port pins, which only passes or reinitializes PRG-RAM contents correctly with the aforementioned PRG-RAM sizes.
Many INES Mapper 210 games are incorrectly set to INES Mapper 019.
All the commercial Namco 175 games (including the unreleased Splatterworld) set the upper bits of $E000 to match their respective hardwired nametable mirroring. Thus, in the absence of a NES 2.0 header, emulating this mapper as a 175 if the header battery bit is set and a 340 otherwise will work with all commercial games.
Splatterhouse and Famista ‘91 both perform a complete Namco 163 initialization on reset, writing to various registers that do not exist on the 175 or 340. Splatterhouse additionally writes to the 163 nametable select registers ($C000-$DFFF) every frame.
