NES 2.0 Mapper 359

NES 2.0 Mapper 359 is used for at least two multicarts using the SB-5013 PCB. Its UNIF board name is BMC-SB-5013.

• Super Boy 6-in-1
• Super Boy Top 5-in-1 特輯

Banks

• CPU $6000-$7FFF: 8 KiB switchable inner PRG-ROM bank
• CPU $8000-$9FFF: 8 KiB switchable inner PRG-ROM bank
• CPU $A000-$BFFF: 8 KiB switchable inner PRG-ROM bank
• CPU $C000-$DFFF: 8 KiB switchable inner PRG-ROM bank
• CPU $E000-$FFFF: 8 KiB inner PRG-ROM bank, fixed to last bank (within outer bank)
• PPU $0000-$1FFF: 8 KiB unbanked CHR-RAM

Registers

PRG Bank Select ($8000-$8003, write)

Mask: $F003

• $8000: Select 8 KiB PRG-ROM bank at CPU $8000-$9FFF
• $8001: Select 8 KiB PRG-ROM bank at CPU $A000-$BFFF
• $8002: Select 8 KiB PRG-ROM bank at CPU $C000-$DFFF
• $8003: Select 8 KiB PRG-ROM bank at CPU $6000-$7FFF

PRG Base Select ($9000, write)

Mask: $F003

D~7654 3210
  ---------
  ..PP P...
    ++-+---- Select 128 KiB outer PRG-ROM bank

Outer Bank Size Select ($9001, write)

Mask: $F003

D~7654 3210
  ---------
  .... ..SS
         ++- Select size of outer PRG-ROM bank
              0: 512 KiB (8 KiB inner PRG-ROM bank ANDed with $3F)
              1: 256 KiB (8 KiB inner PRG-ROM bank ANDed with $1F)
              2: Unused (8 KiB inner PRG-ROM bank ANDed with $2F?)
              3: 128 KiB (8 KiB inner PRG-ROM bank ANDed with $0F)

Nametable Mirroring Type Select ($9002, write)

Mask: $F003

D~7654 3210
  ---------
  .... ..MM
         ++- Select nametable mirroring type
              0: Vertical
              1: Horizontal
              2: One-screen, page 0
              3: One-screen, page 1

Unknown register ($9003, write)

Mask: $F003

Because both available cartridges always write $00 to this register; its function, if any, is unknown.

IRQ Counter Low/Reload ($C000, write)

Mask: $F003

• In M2 mode, directly sets the low eight bits of the 16-bit M2 cycle counter.
• In PA12 mode, writing sets the Reload flag, just as writing to register $C001 does on the MMC3.
• In either mode, if the Auto-Enable/Disable Flag is set, disables counting (M2) or just IRQ generation (PA12).

IRQ Counter High/Load Latch ($C001, write)

Mask: $F003

• In M2 mode, directly sets the high eight bits of the 16-bit M2 cycle counter.
• In PA12 mode, reloads the latch, just as writing to register $C000 does on the MMC3.
• In either mode, if the Auto-Enable/Disable Flag is set, enables counting (M2) or just IRQ generation (PA12).

IRQ Mode ($C002, write)

Mask: $F003

D~7654 3210
  ---------
  .... .AME
        ||+- IRQ Disable/Enable
        ||    0=M2 Mode: Disable counting, PA12 Mode: Disable IRQ generation
        ||    1=M2 Mode: Enable counting, PA12 Mode: Enable IRQ generation
        |+-- Select IRQ source
        |     0=CPU Cycles (M2)
        |     1=Filtered PPU A12 rises (PA12)
        +--- Auto-Enable/Disable Flag
              0=IRQ is not disabled/enabled by writing $C000/$C001, only by writing to $C002/$C003
              1=IRQ is disabled by writing to $C000 and enabled by writing to $C001, $C003 has no effect

IRQ Disable/Enable ($C003, write)

Mask: $F003

D~7654 3210
  ---------
  .... ...E
          +- IRQ Disable/Enable
              0=M2 Mode: Disable counting, PA12 Mode: Disable IRQ generation
              1=M2 Mode: Enable counting, PA12 Mode: Enable IRQ generation

Writing to $C003 has no effect if Auto-Enable/Disable flag is set.

IRQ Operation

• In M2 mode: If IRQ is enabled, counts down on every M2 cycle until counter is zero, then generates an IRQ.
• In PA12 mode: Just like the MMC3's scanline counter.