In computing, BIOS is firmware used to provide runtime services for operating systems and programs and to perform hardware initialization during the booting process. The BIOS firmware comes pre-installed on an IBM PC or IBM PC compatible's system board and exists in UEFI-based systems too. The name originates from the Basic Input/Output System used in the CP/M operating system in 1975. The BIOS originally proprietary to the IBM PC has been reverse engineered by some companies looking to create compatible systems. The interface of that original system serves as a de facto standard.
In computing, booting is the process of starting a computer as initiated via hardware such as a button or by a software command. After it is switched on, a computer's central processing unit (CPU) has no software in its main memory, so some process must load software into memory before it can be executed. This may be done by hardware or firmware in the CPU, or by a separate processor in the computer system.
Disk partitioning or disk slicing is the creation of one or more regions on secondary storage, so that each region can be managed separately. These regions are called partitions. It is typically the first step of preparing a newly installed disk, before any file system is created. The disk stores the information about the partitions' locations and sizes in an area known as the partition table that the operating system reads before any other part of the disk. Each partition then appears to the operating system as a distinct "logical" disk that uses part of the actual disk. System administrators use a program called a partition editor to create, resize, delete, and manipulate the partitions. Partitioning allows the use of different filesystems to be installed for different kinds of files. Separating user data from system data can prevent the system partition from becoming full and rendering the system unusable. Partitioning can also make backing up easier. A disadvantage is that it can be difficult to properly size partitions, resulting in having one partition with too much free space and another nearly totally allocated.
LILO is a boot loader for Linux and was the default boot loader for most Linux distributions in the years after the popularity of loadlin. Today, many distributions use GRUB as the default boot loader, but LILO and its variant ELILO are still in wide use. Further development of LILO was discontinued in December 2015 along with a request by Joachim Wiedorn for potential developers.
GNU GRUB is a boot loader package from the GNU Project. GRUB is the reference implementation of the Free Software Foundation's Multiboot Specification, which provides a user the choice to boot one of multiple operating systems installed on a computer or select a specific kernel configuration available on a particular operating system's partitions.
In computing, the Preboot eXecution Environment, PXE specification describes a standardized client–server environment that boots a software assembly, retrieved from a network, on PXE-enabled clients. On the client side it requires only a PXE-capable network interface controller (NIC), and uses a small set of industry-standard network protocols such as DHCP and TFTP.
The Unified Extensible Firmware Interface (UEFI) is a publicly available specification that defines a software interface between an operating system and platform firmware. UEFI replaces the legacy Basic Input/Output System (BIOS) firmware interface originally present in all IBM PC-compatible personal computers, with most UEFI firmware implementations providing support for legacy BIOS services. UEFI can support remote diagnostics and repair of computers, even with no operating system installed.
TrueOS is a discontinued Unix-like, server-oriented operating system built upon the most recent releases of FreeBSD-CURRENT.
A Hackintosh is a computer that runs Apple's Macintosh operating system macOS on computer hardware not authorized for the purpose by Apple. "Hackintoshing" began as a result of Apple's 2005 transition to Intel processors, away from PowerPC. Since 2005, Mac computers use the same x86-64 computer architecture as many other desktop PCs, laptops, and servers, meaning that in principle, the code making up macOS systems and software can be run on alternative platforms with minimal compatibility issues. Benefits cited for "Hackintoshing" can include cost, ease of repair and piecemeal upgrade, and freedom to use customized choices of components that are not available in the branded Apple products. macOS can also be run on several non-Apple virtualization platforms, although such systems are not usually described as Hackintoshes. Hackintosh laptops are sometimes referred to as "Hackbooks".
The GUID Partition Table (GPT) is a standard for the layout of partition tables of a physical computer storage device, such as a hard disk drive or solid-state drive, using universally unique identifiers, which are also known as globally unique identifiers (GUIDs). Forming a part of the Unified Extensible Firmware Interface (UEFI) standard, it is nevertheless also used for some BIOS systems, because of the limitations of master boot record (MBR) partition tables, which use 32 bits for logical block addressing (LBA) of traditional 512-byte disk sectors.
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. With the change in architecture, a change in firmware became necessary; Apple selected the Intel-designed Extensible Firmware Interface (EFI) as its comparable component to the Open Firmware used on its PowerPC architectures, and as the firmware-based replacement for the PC BIOS from Intel. With the change in processor architecture to x86, Macs gained the ability to boot into x86-native operating systems, while Intel VT-x brought near-native virtualization with macOS as the host OS.
Boot Camp Assistant is a multi boot utility included with Apple Inc.'s macOS that assists users in installing Microsoft Windows operating systems on Intel-based Macintosh computers. The utility guides users through non-destructive disk partitioning of their hard disk drive or solid state drive and installation of Windows device drivers for the Apple hardware. The utility also installs a Windows Control Panel applet for selecting the default boot operating system.
A live USB is a portable USB-attached external data storage device containing a full operating system that can be booted from. The term is reminiscent of USB flash drives but may encompass an external hard disk drive or solid-state drive, though they may be referred to as "live HDD" and "live SSD" respectively. They are the evolutionary next step after live CDs, but with the added benefit of writable storage, allowing customizations to the booted operating system. Live USBs can be used in embedded systems for system administration, data recovery, or test driving, and can persistently save settings and install software packages on the USB device.
The EFIsystem partition or ESP is a partition on a data storage device that is used by computers having the Unified Extensible Firmware Interface (UEFI). When a computer is booted, UEFI firmware loads files stored on the ESP to start installed operating systems and various utilities.
The startup process of Windows NT 6 differ from the startup process part of previous versions of Windows.
The following tables compare general and technical information for a number of available boot loaders.
Linux startup process is the multi-stage initialization process performed during booting a Linux installation. It is in many ways similar to the BSD and other Unix-style boot processes, from which it derives.
systemd-boot, formerly known as gummiboot, is a free and open-source boot manager. It was created when gummiboot was merged into systemd and renamed to "systemd-boot" in May 2015.
rEFInd is a boot manager for UEFI and EFI-based machines. It can be used to boot multiple operating systems that are installed on a single non-volatile device. It also provides a way to launch UEFI applications.
iBoot is the stage 2 bootloader for all Apple products. It replaces the old bootloader, BootX. Compared with its predecessor, iBoot improves authentication performed in the boot chain.
