The notes below are specific to the Mac SE/30, which has gestalt ID 0009. For System 7.5 or later to function correctly with an alternate ROM, you must find the gestalt ID for your Macintosh model, and change the corresponding boot method to 0005.

The boot method is 0003 for each of the gestalt IDs 0007, 0008, and 0009. These are pairs of gestalt IDs followed by boot methods. Gamba’s instructions below will direct you to find sections of the System file with this general form: Mac IIcx and IIcx Note: It was originally believed these patches were only necessary for the Mac SE/30, but we’ve since learned they’re also relevant to the Mac IIx and IIcx, and possibly others too. The information below was taken from Gamba’s Macintosh web page and is preserved here to help ensure it doesn’t disappear from the web. These patches are required when using System 7.5 – 8.1 on certain Macintosh models with an upgraded ROM, such as a Mac ROM-inator II or a borrowed IIsi or IIfx ROM SIMM. This page describes a small set of patches to Mac OS System 7.5 or later.