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NHL96 to 97 have a slightly longer routine which isn't as friendly to being moved to a different address offset.

NHL91 to 95 appears to use a simpler routine which does allow being moved. The length of the checksum routine in bytes (starting with 700091C8, ending with 60FE) will also depend on the ROM you are editing. It typically exists at either Hex 302, Hex 692 or Hex 768. Save the file and you are basically done.ĭepending on the year the rom was published will depend on where you should find the referenced address location to the beginning of the checksum routine. Replace all the following bytes up to and including the last 60FE with FFFF. Replace the 7000 with 60FE, bytes seemingly used to signify "End of File/Data". While not required (though recommended) go back to ROM offset 000FFAC0 by using the search or goto function. This basically disables the checksum routine, allowing the game to load successfully even if hacked. Also change the referenced address location that follows, 000FFAC0 to 4E714E71. In this example, the data resides at Hex 302.Īt Hex 300, you should find the value 4EB9. Again you should find 1 instance, and it should exist towards the very top of the ROM. If you find more than one, use the last instance found as the checksum routine typically exists at the end of the ROM game data. Open the ROM in your Hex Editor of choice. The example/screen shots attached are based on the NHL94 ROM. This is the method used within the upcoming NHL editor. Noting the differences, a little bit of trial and error has allowed me to find a generic way you can disable the checksum routines for Genesis ROMs published by EA.

I found this method by comparing NHL98 which has no checksum routine, to all the other ROMs in the series. The following is a quick guide to completely remove the EA checksum routine used within EA Genesis games.