as Mac keyboards in Microsoft Windows, some functional differences occur. For example, the (PC) and (Mac) keys function equivalently; the same is true for (PC) and (Mac) – however, the physical location of those keys is reversed. There are also keys exclusive for each platform (e.g. ), some of which may require software remapping to achieve the desired function. Compact and laptop keyboards from Apple also lack some keys considered essential on PCs, such as the forward key, although some of them are accessible through the key. Boot process. All Intel-based Macs have been using some version of EFI as the boot firmware. At the time the platform debuted in 2006, it was in a stark contrast to PCs, which almost universally employed legacy BIOS, and Apple's implementation of EFI did not initially implement the Compatibility Support Module that would allow booting contemporary standard PC operating systems. Apple updated the firmware with CSM support with the release of Boot Camp in April 2006, and since the release of Windows 8 in 2012, Microsoft has required its OEM partners to use UEFI boot process on PCs, which made the differences smaller. However, Apple's version of EFI also includes some custom extensions that are utilized during regular macOS boot process, which include the following: Drivers for the HFS Plus and APFS file systems with support locating the bootloader based on the "blessed directory" and "blessed file" properties of HFS+ and APFS volumes. The EFI System Partition is thus not used or necessary for regular macOS boot process. Rudimentary pre-boot GUI framework, including support for image drawing, mouse cursor and events. This is used by FileVault 2 to present the login screen before loading the operating system. Other non-standard EFI services for managing various firmware features such as the computer's NVRAM and boot arguments. 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 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