Apple–Intel architecture

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.^[1] 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.

This article is about the architecture of Intel-based Apple computers. For information about the transition to this architecture, see Mac transition to Intel processors.

Booting[edit]

To Mac operating systems[edit]

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,^[4] 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.

is a custom Apple chip that controls various functions of the computer related to power management, including handling the power button, management of battery and thermal sensors, among others.^[7] It also plays a part in the protection scheme deployed to restrict booting macOS to Apple hardware (see Digital Rights Management below). Intel-based Mac doesn't implement TPM.

System Management Controller

Laptop input devices. Early and MacBook Pro computers used an internal variant of USB as a keyboard and trackpad interconnect.^[8] Since the 2013 revision of MacBook Air, Apple started to use a custom Serial Peripheral Interface controller instead.^[9] The 2016 MacBook Pro additionally uses a custom internal USB device dubbed "iBridge" as an interface to the Touch Bar and Touch ID components, as well as the FaceTime Camera.^[10] PC laptops generally use internal variant of the legacy PS/2 keyboard interconnect. PS/2 also used to be the standard for PC laptop pointing devices, although a variety of other interfaces, including USB,^[11] SMBus, and I2C,^[12] may also be used.

MacBook

Additional custom hardware may include a GMUX chip that controls ,^[13] non-compliant implementations of solid-state storage^[14] and non-standard configurations of HD Audio subsystem.^[15]

GPU switching

has significant differences between Apple and IBM PC keyboards. While PC keyboards can be used in macOS, as well as Mac keyboards in Microsoft Windows, some functional differences occur. For example, the Alt (PC) and ⌥ Option (Mac) keys function equivalently; the same is true for ⊞ Win (PC) and ⌘ Command (Mac) – however, the physical location of those keys is reversed. There are also keys exclusive for each platform (e.g. Prt Sc), some of which may require software remapping to achieve the desired function.^[16] Compact and laptop keyboards from Apple also lack some keys considered essential on PCs, such as the forward Delete key, although some of them are accessible through the Fn key.^[17]

Keyboard layout

[18]

Intel-based Mac computers use very similar hardware to PCs from other manufacturers that ship with Microsoft Windows or Linux operating systems. In particular, CPUs, chipsets, and GPUs are entirely compatible. However, Apple computers also include some custom hardware and design choices not found in competing systems:

Some of these differences can pose as obstacles both to running macOS on non-Apple hardware and booting alternative operating systems on Mac computers – Apple only provides drivers for its custom hardware for macOS and Microsoft Windows (as part of Boot Camp); drivers for other operating systems such as Linux need to be written by third parties, usually volunteer free software enthusiasts.

Digital rights management[edit]

Digital rights management in the Apple–Intel architecture is accomplished via the "Dont Steal Mac OS X.kext," sometimes referred to as DSMOS or DSMOSX, a file present in Intel-capable versions of the Mac OS X operating system. Its presence enforces a form of digital rights management, preventing Mac OS X being installed on stock PCs. The name of the kext is a reference to the Mac OS X license conditions, which allow installation on Apple hardware only. According to Apple, anything else is stealing Mac OS X. The kext is located at /System/Library/Extensions on the volume containing the operating system.^[23] The extension contains a kernel function called page_transform() that performs AES decryption of "apple-protected" programs. A system lacking a proper key will not be able to run the Apple-restricted binaries, which include Dock, Finder, loginwindow, SystemUIServer, mds, ATSServer, backupd, fontd, translate, or translated.^[24] If the check fails, a short poem is displayed, reading "Your karma check for today: There once was a user that whined, his existing OS was so blind, he'd do better to pirate an OS that ran great, but found his hardware declined. Please don't steal Mac OS! Really, that's way uncool. (C) Apple Computer, Inc."

After the initial announcement of first Intel-based Mac hardware configurations, reporting a Trusted Platform Module among system components, it was believed that the TPM is responsible for handling the DRM protection. It was later proven to not be the case. The keys are actually contained within the System Management Controller, a component exclusive to Apple computers, and can be easily retrieved from it.^[25] These two 32-byte keys form a human-readable ASCII string copyrighted by Apple,^[26] establishing another possible line of legal defence against prospective clone makers.

Virtualization[edit]

The processors found in Intel Macs support Intel VT-x, which allows for high performance (near-native) virtualization that gives the user the ability to run and switch between two or more operating systems simultaneously, rather than having to dual-boot and run only one operating system at a time.

The first virtualization software for Intel Macs was Parallels Desktop for Mac, released in June 2006.^[27] The Parallels virtualization products allow users to use installations of Windows XP and later in a virtualized mode while running macOS. VirtualBox is another piece of virtualization software originally from Innotek (now Oracle Corporation), which had a first public beta release for Mac OS X in April 2007.^[28] It supports VT-x and can run multiple other guest operating systems, including Windows XP and later. It is available free of charge under either a proprietary license or the GPL.^[29]

VMware also offers a Mac virtualization product competing with Parallels called Fusion, released August 2007.^[30] VMware's virtualization product also allows users to use installations of Windows XP and later under macOS.

Regardless of the product used, there are inherent limitations and performance penalties in using a virtualized guest OS versus the native macOS or booting an alternative OS solution offered via Boot Camp.