NES 2.0 Mapper 429: Difference between revisions

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[[NES 2.0 Mapper 429]] has been earmarked for a project by Milowork on 2021-11-10. If no updates are present within three years, it should be assumed to be available for other purposes.
[[NES 2.0 Mapper 429]] is for Milowork FCFC1 flash cartridge (in A mode). There is some doujin game in progress using this mapper.
 
== Overview ==
* PRG ROM size: 512 KB (or 1024 KB, FCFC1 DIY)
* PRG ROM bank size: 32 KB
* PRG RAM: None
* CHR capacity: 32 KB RAM, optional battery-backup or FeRAM
* CHR bank size: 8 KB
* Nametable [[mirroring]]: vertical or horizontal selected by switch, or fixed (or Single-screen, FCFC1 DIY)
* Subject to [[bus conflict]]s: No
 
== Registers ==
=== Bank select ($8000-$FFFF) ===
==== Regular ====
7  bit  0
---- ----
xpPP PPCC
  ||| ||||
  ||| ||++- Select 8 KB CHR RAM bank for PPU $0000-$1FFF, initial bank 0
  +++-++--- Select 32 KB PRG ROM bank for CPU $8000-$FFFF, initial bank 1
==== Submapper #1 ====
7  bit  0
---- ----
MpPP PPCC
|||| ||||
|||| ||++- Select 8 KB CHR RAM bank for PPU $0000-$1FFF, initial bank 0
|+++-++--- Select 32 KB PRG ROM bank for CPU $8000-$FFFF, initial bank 1
+--------- Same as [[AxROM]]
 
== FCFC1 Details ==
 
* The A mode of FCFC1 has compatibility with [[CNROM]]/[[GxROM]], but the compatibility is fragile, some games will switch back to the page where the firmware is located, causing problems such as crashes.
 
* The B mode of FCFC1 is a [[BNROM]]/[[AxROM]] with initial bank 4 and no [[bus conflict]], and has compatibility with [[NROM]]/[[UNROM]].
 
* To simplify the circuit implementation, the actual location of the page in ROM is shuffled.
 
* It is recommended to save the preserved data to a page other than 0 of CHR RAM, as this avoids being overwritten by the kazzo programming process, and it can also make the bank selection play a role similar to the WRAM lock bit.
 
* Some FCFC1 sold as game carriers do not have switches, or the switches do not have the W position. These FCFC1 are not compatible with kazzo.
 
{| class="wikitable"
! Register value causes error !! CNROM (A) !! GxROM (A) !! NROM (B) (Except using CHR RAM)
|-
| Firmware 2.1 and before    || xxx1xx    || xxx1xx    || xxx1xx
|-
| Firmware 2.2 and after      || xx01xx    || xx01xx    || xx01xx
|}

Latest revision as of 02:32, 21 January 2023

NES 2.0 Mapper 429 is for Milowork FCFC1 flash cartridge (in A mode). There is some doujin game in progress using this mapper.

Overview

  • PRG ROM size: 512 KB (or 1024 KB, FCFC1 DIY)
  • PRG ROM bank size: 32 KB
  • PRG RAM: None
  • CHR capacity: 32 KB RAM, optional battery-backup or FeRAM
  • CHR bank size: 8 KB
  • Nametable mirroring: vertical or horizontal selected by switch, or fixed (or Single-screen, FCFC1 DIY)
  • Subject to bus conflicts: No

Registers

Bank select ($8000-$FFFF)

Regular

7  bit  0
---- ----
xpPP PPCC
 ||| ||||
 ||| ||++- Select 8 KB CHR RAM bank for PPU $0000-$1FFF, initial bank 0
 +++-++--- Select 32 KB PRG ROM bank for CPU $8000-$FFFF, initial bank 1

Submapper #1

7  bit  0
---- ----
MpPP PPCC
|||| ||||
|||| ||++- Select 8 KB CHR RAM bank for PPU $0000-$1FFF, initial bank 0
|+++-++--- Select 32 KB PRG ROM bank for CPU $8000-$FFFF, initial bank 1
+--------- Same as AxROM

FCFC1 Details

  • The A mode of FCFC1 has compatibility with CNROM/GxROM, but the compatibility is fragile, some games will switch back to the page where the firmware is located, causing problems such as crashes.
  • To simplify the circuit implementation, the actual location of the page in ROM is shuffled.
  • It is recommended to save the preserved data to a page other than 0 of CHR RAM, as this avoids being overwritten by the kazzo programming process, and it can also make the bank selection play a role similar to the WRAM lock bit.
  • Some FCFC1 sold as game carriers do not have switches, or the switches do not have the W position. These FCFC1 are not compatible with kazzo.
Register value causes error CNROM (A) GxROM (A) NROM (B) (Except using CHR RAM)
Firmware 2.1 and before xxx1xx xxx1xx xxx1xx
Firmware 2.2 and after xx01xx xx01xx xx01xx
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