NES 2.0 Mapper 558
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NES 2.0 Mapper 558 denotes the 燕城 (Yànchéng) YC-03-09 circuit board, used for the following games:
- 口袋精靈: 水晶 (Pokémon: Crystal Edition)
- 大話三國 (Dàhuà Sānguó)
A compatible circuit board with an unknown PCB code is used for the original editions of a few games from 外星 (Wàixīng):
- Pet Family - 宠物大家族: 部落纷争 (ES-1081)
- Pet Evolve - 宠物进化史 (ES-1085)
- 口袋妖怪꞉ 鑽石版 (Pokémon: Diamond Edition, ES-1090)
- 口袋精靈: 紅 and its title screen hack 宠物: 红 (Pokémon: Red Edition, ES-1088)
- 数码暴龙 4: 水晶版 and its title screen hack 数码宝贝 (Digimon 4: Crystal Edition)
- 盟军敢死队 - Commandos
The Yànchéng games save the game state to a 93C66 512-byte serial EEPROM, while the Wàixīng games save to 8 KiB battery-backed WRAM. The NES 2.0 Header's PRG-NVRAM field distinguishes between the two board variants.
Banks
- CPU $6000-$7FFF: up to 8 KiB unbanked PRG-RAM, can be battery-backed
- CPU $8000-$FFFF: 32 KiB switchable PRG-ROM bank
- PPU $0000-$1FFF: 8 KiB unbanked CHR-RAM bank
- Nametable mirroring: hard-wired
Registers
All registers are initialized to $00 on reset.
PRG-ROM Bank Low ($5000, write)
Mask: $FF00 D~7654 3210 --------- .... PPPP ++++- PRG A18..A15
- Note that if $5300.0 is 0, the two lowest bits are swapped during writing.
PRG-ROM Bank High ($5100, write)
Mask: $FB00 D~7654 3210 --------- .... ..PP ++- PRG A20..A19
- Note that if $5300.0 is 0, the two lowest bits are swapped during writing.
Microwire Interface ($5200, write)
Mask: $FF00 D~7654 3210 --------- .... .SDC ||+- 93C66 EEPROM CLK ($5300.0=0)/DAT ($5300.0=1) output |+-- 93C66 EEPROM DAT ($5300.0=0)/CLK ($5300.0=1) output +--- 93C66 EEPROM CS output
Mode ($5300, write)
Mask: $FF00 D~7654 3210 --------- .... .AB. |+- 0: Swap D0,D1 on all register writes to $5000-$5200. | 1: Leave D0,D1 unmodified on register writes to $5000-$5200. +--- 0: PRG A15/A16=1 1: PRG A15/A16 from $5000
- Writes to this register are not subject to D0/D1 bit-swapping, i.e. the register is not affected by its own bit 0.
- Because this register is initialized to $00 on reset, thus clearing bit 2 which causes PRG A15/A16 to be held high, the game will boot in 32 KiB PRG-ROM bank #3.
- Changing the value of $5300.0 without writing to $5000-$5200 afterwards does not change the latched bits.
Microwire Interface ($5500, read)
Mask: $FF00 D~7654 3210 --------- .... .A.. | | +--- 93C66 EEPROM DAT input
Unlike INES Mapper 164, the EEPROM input is not inverted.
Notes
- CPU D0 and D1 are connected in reverse to the mapper blob compared to other circuit boards using this ASIC. This means that setting $5300.0 to 0, not to 1, will effectively swap PRG A15/A16 and PRG A19/A20. Cartridges using this mapper must be dumped with $5300=$07 during dumping to obtain a readout that matches that of a desoldered ROM chip.
- The Wàixīng games using this mapper were previously set to 162/163 or 164, resulting in incompatibility either because of the different address of the PRG-ROM Bank High register (mapper 162/163) or the different startup bank (164).
See also
- INES Mapper 162/163 swap the effective meaning of registers $5100 and $5200, the meaning of the D0/D1 bit swap, and use the microwire interface only for protection purposes.
- INES Mapper 164 is an earlier implementation without D0/D1 swapping, optional UNROM-like bankswitching, and a 1 bpp CHR mode.
- PCB images and analysis