OS X Hackers has been the forefront of the Unsupported Mac Community. We are collection of developers that regularly communicate, collaborate, and congregate online in various forums, social networks, and chat rooms. There is no leadership or registration involved because we believe that everyone can contribute and help the community grow under the shared love for our legacy Macs.
OS X 10.6 Snow Leopard was the first OS X version with optional support for a 64-bit kernel, allowing booting either with a 32-bit or 64-bit kernel. However, Apple did not support booting the 64-bit kernel in Macs that shipped with EFI32 firmware, even if they had 64-bit processors capable of running the 64-bit kernel. When Apple dropped the 32-bit kernel entirely from OS X, starting with OS X 10.8 Mountain Lion, EFI32 Macs no longer had an Apple-supported mechanism to boot newer OS X versions.
OS X 10.11 El Capitan includes System Integrity Protection (Rootless security). It makes sure that System file permissions are automatically protected, and updated during Software Updates. The Repair Permissions function is no longer available and access to system files that we need to use in this thread may be locked.
Older Macs that lost support in macOS Sierra have an USB related issue that prevents the built-in USB as well as the thereon connected Input Devices and Bluetooth from working.