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. Differences from standard PCs 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: System Management Controller 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. 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. Laptop input devices. Early MacBook and MacBook Pro computers used an internal variant of USB as a keyboard and trackpad interconnect. Since the 2013 revision of MacBook Air, Apple started to use a custom Serial Peripheral Interface controller instead. 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. 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, SMBus, and I2C, may also be used. Additional custom hardware may include a GMUX chip that controls GPU switching, non-compliant implementations of solid-state storage and non-standard configurations of HD Audio subsystem. Keyboard layout has significant differences between Apple and IBM PC keyboards. While PC keyboards can be used in macOS, as well