iNES Mapper 164 denotes the 燕城 (Yànchéng) cy2000-3 circuit board, used for the following games:
The chipset is also used in the Dongda PEC-9588 Pyramid Educational Computer.
The circuit board has address lines for 8 KiB of PRG-RAM, though all known carts mount either no or a 2 KiB RAM chip which is then mirrored three times across the respective address range. PRG-RAM is never battery-backed; all games save the game state to a 93C66 512-byte serial EEPROM.
All registers are initialized to $00 on reset.
Mask: $FF00 D~7654 3210 --------- CSQM PPPp ||+|-++++- PRG A18..A14 if M=0 || | ++++- PRG A18..A15 if M=1 || +------ PRG banking mode || 0: PRG A14..A18=QPPPp when CPU A14=0 (UxROM, 16 KiB switchable bank) || PRG A14..A18=11111 when CPU A14=1 and S=0 (fixed bank=1F) || PRG A14..A18=111p0 when CPU A14=1 and S=1 (fixed bank=1C or 1E) || 1: PRG A14=CPU A14, PRG A15..A18=PPPp (BxROM, 32 KiB switchable bank) |+-------- See 'M' bit description +--------- 1 bpp video mode: when PPU A13=0 (pattern table) ... 0: CHR A3=PPU A3, CHR A12=PPU A12 (disable 1 bpp mode) 1: CHR A3=PPU A0, CHR A12=PPU A9, both latched on last rise of PPU A13 (enable 1 bpp mode)
Mask: $FF00 D~7654 3210 --------- .... ..PP ++- PRG A20..A19
Mask: $FF00 D~7654 3210 --------- ...S .C.D | | +- 93C66 EEPROM DAT output | +--- 93C66 EEPROM CLK output +------ 93C66 EEPROM CS output
Mask: $FF00
All games just write $00 to this register. Its meaning is certainly not the one seen in INES Mapper 162/163.
Mask: $FF00 D~7654 3210 --------- .... .A.. | | +--- 93C66 EEPROM DAT input (inverted)
Categories: Mappers using $4020-$5FFF, Mappers with CHR RAM, INES Mappers