NES 2.0 Mapper 439: Difference between revisions

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==Latch Register ($8000-$FFFF, write)==
==Latch Register ($8000-$FFFF, write)==
  D~[M..PP PPPP]
  D~[M..PP PPPP] Address mask: $8000
     |  ++-++++- PRG A19..A14 when CPU A14=0,
     |  ++-++++- PRG A19..A14 when CPU A14=0,
     |          $3F when CPU A14=1
     |          $3F when CPU A14=1
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==Outer Bank Register ($6000, write)==
==Outer Bank Register ($6000, write)==
  D~[.PPP ....]
  D~[.PPP ....] Address mask: $E001
     +++------ PRG A19..A17 if enabled via $6001
     +++------ PRG A19..A17 if enabled via $6001


==Mask Register ($6001, write)==
==Mask Register ($6001, write)==
  D*[MPPP ....]
  D~[MPPP ....] Address mask: $E001
     |||+------- 0: PRG A17 from Latch, 1: PRG A17 from $6000
     |||+------- 0: PRG A17 from Latch, 1: PRG A17 from $6000
     ||+-------- 0: PRG A18 from Latch, 1: PRG A18 from $6000
     ||+-------- 0: PRG A18 from Latch, 1: PRG A18 from $6000
     |+--------- 0: PRG A19 from Latch, 1: PRG A19 from $6000
     |+--------- 0: PRG A19 from Latch, 1: PRG A19 from $6000
     +---------- 1: Protect Mirroring bit in Latch from being changed
     +---------- 1: Protect Mirroring bit in Latch from being changed

Latest revision as of 19:25, 21 June 2023

NES 2.0 Mapper 439 denotes the YS2309 UxROM-like multicart PCB. Its UNIF MAPRs are BMC-DS-07 and BMC-K86B. All registers set to $00 on reset.

Latch Register ($8000-$FFFF, write)

D~[M..PP PPPP]  Address mask: $8000
   |  ++-++++- PRG A19..A14 when CPU A14=0,
   |           $3F when CPU A14=1
   +---------- Nametable mirroring, 0=Vertical, 1=Horizontal

This is basically an UxROM-like latch register for up to 1 MiB of PRG ROM, plus software-switchable mirroring.

Outer Bank Register ($6000, write)

D~[.PPP ....]  Address mask: $E001
    +++------ PRG A19..A17 if enabled via $6001

Mask Register ($6001, write)

D~[MPPP ....]  Address mask: $E001
   |||+------- 0: PRG A17 from Latch, 1: PRG A17 from $6000
   ||+-------- 0: PRG A18 from Latch, 1: PRG A18 from $6000
   |+--------- 0: PRG A19 from Latch, 1: PRG A19 from $6000
   +---------- 1: Protect Mirroring bit in Latch from being changed