NES 2.0 Mapper 324: Difference between revisions

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m (No WRAM here.)
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NES 2.0 Mapper 324 is used for Farid's homebrew 8-in-1 UNROM multicart board. It consists of an UNROM latch with an additional outer bank register. Mirroring is hard-wired. Its UNIF board name is '''FARID_UNROM_8-IN-1'''.
NES 2.0 Mapper 324 is used for Farid's homebrew 8-in-1 UNROM multicart board. It consists of an UNROM latch with an additional outer bank register. Mirroring is hard-wired. Its UNIF board name is '''FARID_UNROM_8-IN-1'''.


==Outer Bank Register ($F000-$FFF7, write)==
==Bank Register ($8000-$FFFF, write)==
  Mask: $8000?
  Mask: $8000
   
   
  D~7654 3210
  D~7654 3210
   ---------
   ---------
   1OOO L...
   Cooo kIII
  |||| ||||
  |||| |+++- Standard UNROM inner bank (select 16K at $8000-$BFFF)
   |||| +---- 1=Lock Outer Bank
   |||| +---- 1=Lock Outer Bank
   |+++------ Select 128 KiB outer PRG-ROM bank
   |+++------ Select 128 KiB outer PRG-ROM bank
   +--------- Clock Generator (must be 1)
   +--------- Clock Generator ("oook" bits latched only when this changes from 0 to 1)
 
The middle four bits ($78, lowercase) are one 74'161; their contents are explicitly zeroed on power-up or reset.
The outer four bits ($87, uppercase) are the other 74'161; their contents are NOT.


==UNROM latch ($8000-$FFFF)==
==UNROM latch ($8000-$FFFF)==

Revision as of 19:30, 31 May 2018

NES 2.0 Mapper 324 is used for Farid's homebrew 8-in-1 UNROM multicart board. It consists of an UNROM latch with an additional outer bank register. Mirroring is hard-wired. Its UNIF board name is FARID_UNROM_8-IN-1.

Bank Register ($8000-$FFFF, write)

Mask: $8000

D~7654 3210
  ---------
  Cooo kIII
  |||| ||||
  |||| |+++- Standard UNROM inner bank (select 16K at $8000-$BFFF)
  |||| +---- 1=Lock Outer Bank
  |+++------ Select 128 KiB outer PRG-ROM bank
  +--------- Clock Generator ("oook" bits latched only when this changes from 0 to 1)

The middle four bits ($78, lowercase) are one 74'161; their contents are explicitly zeroed on power-up or reset. The outer four bits ($87, uppercase) are the other 74'161; their contents are NOT.

UNROM latch ($8000-$FFFF)

See INES Mapper 002.

See also

NesDev discussion