Nintendo header: Difference between revisions
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m (moved Nintendo+header to Nintendo header: I guess the + sign was created by mistake when someone was attempting to type in a URL to create the page.) |
m (did you really mean almost 4 KiB back?) |
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* '''$ffe0-$ffef''' : Name of the game, in ASCII, zero terminated (sometimes the name is abbreviated or replaced by Nintendo's code). | * '''$ffe0-$ffef''' : Name of the game, in ASCII, zero terminated (sometimes the name is abbreviated or replaced by Nintendo's code). | ||
* '''$ | * '''$fff0-$fff1''' : PRG Checksum (either the last 16k bank, or the whole PRG-ROM). Clamped sum of all bytes, excluding the two checksum bytes. | ||
* '''$ | * '''$fff2-$fff3''' : CHR Checksum. | ||
* '''$ | * '''$fff4''' : High nybble = prg size (0=64kb, 2=32kb, 3=128kb, 4=256kb 5=512kb) | ||
* '''$ | * '''$fff4''' Low nybble = chr size (0 or 8 = 8kb of RAM, 1=16kb, 2=32kb 3=128kb, 4=256kb) | ||
* '''$fff5''' : Mirroring. ($04 = mapper controlled, $02 = hardwired to vertical, $81 or $82 = harwired to horizontal | * '''$fff5''' : Mirroring. ($04 = mapper controlled, $02 = hardwired to vertical, $81 or $82 = harwired to horizontal | ||
* '''$fff6''' : Version ($01 by default, incrementing on revisions) | * '''$fff6''' : Version ($01 by default, incrementing on revisions) |
Revision as of 22:26, 11 January 2011
About 33% of licensed Nintendo NES games have an header present at their last bank, at adresses $ffe0-$fff9, right before the interrupt vectors.
The info in them is frequently incomplete and/or inaccurate. When info on a particular filed is not present, a byte $00 or $ff is used for padding
- $ffe0-$ffef : Name of the game, in ASCII, zero terminated (sometimes the name is abbreviated or replaced by Nintendo's code).
- $fff0-$fff1 : PRG Checksum (either the last 16k bank, or the whole PRG-ROM). Clamped sum of all bytes, excluding the two checksum bytes.
- $fff2-$fff3 : CHR Checksum.
- $fff4 : High nybble = prg size (0=64kb, 2=32kb, 3=128kb, 4=256kb 5=512kb)
- $fff4 Low nybble = chr size (0 or 8 = 8kb of RAM, 1=16kb, 2=32kb 3=128kb, 4=256kb)
- $fff5 : Mirroring. ($04 = mapper controlled, $02 = hardwired to vertical, $81 or $82 = harwired to horizontal
- $fff6 : Version ($01 by default, incrementing on revisions)
- $fff7 : Unknown
- $fff8 : maker's code, the same used for the FDS, GB, GBC and SNES headers. $01 = Nintendo, $08 = Capcom, etc...
- $fff9 : Unknown