Booting to EFI
While you might think booting to EFI on an Intel-based Macintosh is the same as booting to Open Firmware on a Power PC–based Macintosh, there are some critical differences.
On a Power PC–based Macintosh, booting into Open Firmware yielded a shell command prompt where a savvy troubleshooter could do many useful things, such as reset the nonvolatile memory (NVRAM), eject a CD, set up Open Firmware password protection, and even disable one of the processors in a multiple-processor Macintosh for testing purposes.
The firmware in an Intel-based computer uses EFI technology. When Apple introduced the earliest Intel Macintosh models, they did not have a shell. All the diagnostics and key commands at startup functioned as they did for Open Firmware, but without a shell. Enterprising, if uninformed, users could irreparably damage the logic board.
Since those earliest Intel-based Macintosh models were introduced, Apple has made available a few key tools:
- Boot Camp, so you can boot Macintosh computers into Windows
- A firmware restoration utility, available through the Downloads section of the Apple Support page (www.apple.com/support/downloads)
Depending on what you’re trying to achieve, use one of these two tools, or the diagnostic and key commands; do not boot into EFI.