Where's the BIOS on an Intel Mac?

There is no BIOS on a Mac. It uses EFI, which can be configured from within OS X e.g. using bless from the command line.

You are able to boot from external USB drives that satisfy some requirements.

There are some key combinations that change the boot sequence, but there is no real boot menu.

Change the permanent preferred boot device in System Preferences on OS X or Boot Camp settings on Windows.

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If you want more than what's available out of the box, you need to e.g. use rEFIt.

Daniel Beck

Posted 2011-12-30T21:45:54.460

Reputation: 98 421

Could we update this answer from rEFIt to rEFInd?

– CaldeiraG – 2019-11-22T12:08:06.333

@grawity What exactly was your edit referring to? Partially reverted because unclear (did you mean bless?), and conflict with an edit of mine. – Daniel Beck – 2011-12-30T22:01:52.563

I was adding a note about the ability to reconfigure EFI from the booted operating system ("EFI variables" on standard UEFI, although Apple obviously chose its own path), as opposed to BIOS which has to be managed through a pre-boot settings screen. This could be why Apple left out the pre-boot settings completely; it's all integrated. – user1686 – 2011-12-30T22:09:04.543

1Actually newer Macs which can run windows do have BIOS. It's just that it's there only for compatibility with older windows versions that don't support UEFI and if I remember correctly, there's no way to access it. – AndrejaKo – 2011-12-31T00:04:11.213

3@AndrejaKo AFAIK, BIOS is only emulated on top of EFI in a minimal way to support Windows. – Daniel Beck – 2011-12-31T00:46:19.963

Where's the BIOS on an Intel Mac?

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