INES Mapper 031: Difference between revisions

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'''iNES Mapper 031''' represents ''2A03 Puritans'', a cartridge implementing a variant of the [[NSF]] mapper.
'''iNES Mapper 031''' represents ''2A03 Puritans'', a cartridge implementing a variant of the [[NSF]] mapper.


$5FF8 switches $8000-$8FFF, $5FF9 switches $9000-$9FFF, ..., $5FFF switches $F000-$FFFF, in 4096 bytes out of a PRG ROM up to 1 MiB.
PRG-ROM is bankswitched in 8 x 4 kB banks from $8000-FFFF. These are controlled by registers at $5FF8-$5FFF like the NSF mapper. The high bank at $F000-FFFF is initialized to the last bank at power-on.
At power-on, $F000 is the last bank ($5FFF contains $FF), and nothing changes at reset.
These registers are [[mirroring|mirrored]] throughout $5000-$5FFF with no bus conflicts.


As with [[BNROM]] and [[UxROM]], there is no mirroring, CHR bank, or IRQ control; this mapper is intended for use with an 8 KiB CHR RAM or ROM and hardwired H or V mirroring.
CHR-RAM is provided, but there is no CHR bankswitching.
 
As with [[BNROM]] and [[UxROM]], there is no mirroring, CHR bank, or IRQ control; this mapper is intended for use with an 8 kB CHR-RAM and hardwired H or V mirroring.
 
== Overview ==
* PRG ROM size: Up to 1024 KB
* PRG ROM bank size: 4 kB
* PRG RAM: None
* CHR capacity: 8 KB RAM
* CHR bank size: Not bankswitched
* Nametable [[mirroring]]: horizontal or vertical, hard wired.
* Subject to [[bus conflict]]s: No
 
== Registers ==
 
=== PRG bank select $5000-$5FFF ===
 
address              data
15      bit      0  7  bit  0
-------------------  ---------
0101 .... .... .AAA  PPPP PPPP
                |||  |||| ||||
                |||  ++++-++++- Select 4 kB PRG ROM bank at slot specified by write address.
                +++------------ Specify 4 kB bank slot at: $8000 + (AAA * $1000)
 
The canonical write position for these registers is $5FF8-$5FFF, as used in [[NSF]]s.
 
At power on, the register at $5FFF is set to $FF. Startup code should be placed in the last bank. There is no change to this register on reset.


== References ==
== References ==

Revision as of 22:35, 24 January 2015

iNES Mapper 031 represents 2A03 Puritans, a cartridge implementing a variant of the NSF mapper.

PRG-ROM is bankswitched in 8 x 4 kB banks from $8000-FFFF. These are controlled by registers at $5FF8-$5FFF like the NSF mapper. The high bank at $F000-FFFF is initialized to the last bank at power-on.

CHR-RAM is provided, but there is no CHR bankswitching.

As with BNROM and UxROM, there is no mirroring, CHR bank, or IRQ control; this mapper is intended for use with an 8 kB CHR-RAM and hardwired H or V mirroring.

Overview

  • PRG ROM size: Up to 1024 KB
  • PRG ROM bank size: 4 kB
  • PRG RAM: None
  • CHR capacity: 8 KB RAM
  • CHR bank size: Not bankswitched
  • Nametable mirroring: horizontal or vertical, hard wired.
  • Subject to bus conflicts: No

Registers

PRG bank select $5000-$5FFF

address              data
15      bit       0  7  bit  0
-------------------  ---------
0101 .... .... .AAA  PPPP PPPP
                |||  |||| ||||
                |||  ++++-++++- Select 4 kB PRG ROM bank at slot specified by write address.
                +++------------ Specify 4 kB bank slot at: $8000 + (AAA * $1000)

The canonical write position for these registers is $5FF8-$5FFF, as used in NSFs.

At power on, the register at $5FFF is set to $FF. Startup code should be placed in the last bank. There is no change to this register on reset.

References

Emulator support

  • BizHawk r6492
  • MESS r30137
  • puNES 0.84
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