From WikiTemp, the GBAtemp wiki


GCM is a command-line tool for Gamecube game image files. It can view information such as the Game ID, Region, Maker ID, the filesystem, calculate the CRC32 checksum, and shrink images just like GCMUtility.


From a command prompt:

  • gcm [-fs|-sh|-crc] <filename>
-fs: Display the filesystem of the image.
-sh: Shrink the image.
-crc: calculate the CRC32 of the image.


Archive contains Windows exe and C source code. The source code can be compiled for Linux and Mac.


  • Gamecube ISO files work just fine.
  • Since Wii ISOs have a similar format, it can get some information from those as well (game and maker codes, region, game name). Do not use the -fs nor -sh options on Wii images.
  • Shrinking compatibility
It has been discovered that some games are shrunk differently with GCMUtility. This has caused some instability in the images created with this utility. Listed are ones that have become known to have issues while shrunk:
  • Super Monkey Ball - Freezes after the first couple intro screens.


  • Dec 16, 2007 - v0.1 - first public release.
  • Dec 16, 2007 - v0.2 - added -fs and -sh options.
  • Jan 01, 2008 - v0.3 - -fs displays the shrunken size, much improved the speed of shrinking an image, added -crc.
  • Jan 10, 2008 - v0.4 - fix bootfile bug when shrinking.






  • File browsing, extracting, etc.
  • Send suggestions to the discussion page.