rgbfix —
Game Boy checksum fixer
rgbfix |
[-CcjsVv] [-f
fix_spec] [-i
game_id] [-k
licensee_str] [-l
licensee_id] [-m
mbc_type] [-n
rom_version] [-p
pad_value] [-r
ram_size] [-t
title_str] file |
The rgbfix program changes headers of Game Boy ROM
images. It also performs other filetype operations, such as truncation. The
arguments are as follows:
-C- Set the Game Boy Color–only flag: 0x143 =
0xC0. If both this and the
-c flag are set, this
takes precedence.
-c- Set the Game Boy Color–compatible flag:
0x143 = 0x80. If both this and the
-C flag are set, -C takes
precedence.
-f
fix_spec- Fix certain header values that the Game Boy checks for correctness.
Alternatively, intentionally trash these values by writing their binary
inverse instead. fix_spec is a string containing any
combination of the following characters:
l- Fix the Nintendo logo
(0x104–0x133).
L- Trash the Nintendo logo.
h- Fix the header checksum (0x14D).
H- Trash the header checksum.
g- Fix the global checksum
(0x14E–0x14F).
G- Trash the global checksum.
-i
game_id- Set the game ID string
(0x13F–0x142) to a
given string of exactly 4 characters. If both this and the title are set,
the game ID will overwrite the overlapping portion of the title.
-j- Set the non-Japanese region flag: 0x14A = 1.
-k
licensee_str- Set the new licensee string
(0x144–0x145) to a
given string, truncated to at most two characters.
-l
licensee_id- Set the old licensee code, 0x14B, to a given value
from 0 to 0xFF. This value is deprecated and should be set to 0x33 in all
new software.
-m
mbc_type- Set the MBC type, 0x147, to a given value from 0
to 0xFF.
-n
rom_version- Set the ROM version, 0x14C, to a given value from
0 to 0xFF.
-p
pad_value- Pad the image to a valid size with a given pad value from 0 to 0xFF.
rgbfix will automatically pick a size from 32KiB,
64KiB, 128KiB, ..., 8192KiB and give a warning thereafter. The cartridge
size byte (0x148) will be changed to reflect this
new size.
-r
ram_size- Set the RAM size, 0x149, to a given value from 0
to 0xFF.
-s- Set the SGB flag: 0x146 = 3.
-t
title- Set the title string
(0x134–0x143) to a
given string, truncated to at most 16 characters. It is recommended to use
15 characters instead, to avoid clashing with the CGB flag
(
-c or -C). If both this
and the game ID are set, the game ID will overwrite the overlapping
portion of the title.
-V- Print the version of the program and exit.
-v- Equivalent to
-f lhg.
Most values in the ROM header are only cosmetic. The bare minimum requirements
for a workable image are checksums, the Nintendo logo, and (if needed) the
CGB/SGB flags. It is a good idea to pad the image to a valid size as well
(“valid” meaning a multiple of 32KiB).
The following will make a plain, no-color Game Boy game without
checking for a valid size:
$ rgbfix -v foo.gb
The following will make a SGB-enabled, color-enabled game with a
title of “foobar”, and pad it to a multiple of 32KiB. (The
Game Boy itself does not use the title, but some emulators or ROM managers
might.)
$ rgbfix -vcs -l 0x33 -p 0 -t foobar baz.gb
The following will duplicate the header (sans global checksum) of
the game “Survival Kids”:
$ rgbfix -cjsv -k A4 -l 0x33 -m 0x1B -p 0xFF -r 3 -t
SURVIVALKIDAVKE SurvivalKids.gbc
rgbfix was originally released by Carsten
Sørensen as a standalone program called gbfix, and was later packaged
in RGBDS by Justin Lloyd. It is now maintained by a number of contributors at
https://github.com/rednex/rgbds.