The Apple–Intel architecture, or Mactel, is an unofficial name used for Macintosh personal computers developed and manufactured by Apple Inc. that use Intel x86 processors, rather than the PowerPC and Motorola 68000 ("68k") series processors used in their predecessors or the ARM-based Apple silicon SoCs used in their successors. As Apple changed the architecture of its products, they changed the firmware from the Open Firmware used on PowerPC-based Macs to the Intel-designed Extensible Firmware Interface (EFI). With the change in processor architecture to x86, Macs gained the ability to boot into x86-native operating systems (such as Microsoft Windows), while Intel VT-x brought near-native virtualization with macOS as the host OS.
Technologies
Background
Apple uses a subset of the standard PC architecture, which provides support for Mac OS X and support for other operating systems. Hardware and firmware components that must be supported to run an operating system on Apple-Intel hardware include the Extensible Firmware Interface.
The EFI and GUID Partition Table
With the change in architecture, a change in firmware became necessary. Extensible Firmware Interface (EFI) is the firmware-based replacement for the PC BIOS from Intel. Designed by Intel, it was chosen by Apple to replace Open Firmware, used on PowerPC architectures. Since many operating systems, such as Windows XP and many versions of Windows Vista, are incompatible with EFI, Apple released a firmware upgrade with a Compatibility Support Module that provides a subset of traditional BIOS support with its Boot Camp product.
GUID Partition Table (GPT) is a standard for the layout of the partition table on a physical hard disk. It is a part of the Extensible Firmware Interface (EFI) standard proposed by Intel as a substitute for the earlier PC BIOS. The GPT replaces the Master Boot Record (MBR) used with BIOS.
Booting
To Mac operating systems
Intel Macs can boot in two ways: directly via EFI, or in a "legacy" BIOS compatibility mode. For multibooting, holding down "Option" gives a choice of bootable devices, while the rEFInd bootloader is commonly used for added configurability.
Legacy Live USBs cannot be used on Intel Macs; the EFI firmware can recognize and boot from USB drives, but it can only do this in EFI mode–when the firmware switches to BIOS mode, it no longer recognizes USB drives, due to lack of a BIOS-mode USB driver. Many operating systems, such as earlier versions of Windows and Linux, could only be booted in BIOS mode, or were more easily booted or perform better when booted in BIOS mode, and thus USB booting on Intel-based Macs was for a time largely limited to Mac OS X, which can easily be booted via EFI.
To non-Mac operating systems
On April 5, 2006, Apple made available for download a public beta version of Boot Camp, a collection of technologies that allows users of Intel-based Macs to boot Windows XP Service Pack 2. The first non-beta version of Boot Camp is included in Mac OS X v10.5, "Leopard." Before the introduction of Boot Camp, which provides most hardware drivers for Windows XP, drivers for XP were difficult to find.
Linux can also be booted with Boot Camp.