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In computing, booting is a bootstrapping process that starts operating systems when the user turns on a computer system. A boot sequence is the set of operations the computer performs when it is switched on which load an operating system. Originally, the word computing was synonymous with counting and calculating, and a computer was a person who computes. ...
Bootstrapping alludes to a German legend about a Baron Münchhausen, who was able to lift himself out of a swamp by pulling himself up by his own hair. ...
In computing, an operating system (OS) is the system software responsible for the direct control and management of hardware and basic system operations. ...
A computer system is a set of hardware and software which processes data in a meaningful way. ...
Boot loader Most computer systems can only execute code found in the memory (ROM or RAM); modern operating systems are mostly stored on hard disks, LiveCDs and USB flash drives. Just after a computer has been turned on, it doesn't have an operating system in memory. The computer's hardware alone cannot perform complicated actions of the operating system, such as loading a program from disk; so a seemingly irresolvable paradox is created: to load the operating system into memory, one appears to need to have an operating system already installed. The tower of a personal computer (specifically a Power Mac G5). ...
Rom is also the name of a toy and comic book character Rom (Spaceknight). ...
Different types of RAM. From top to bottom: DIP, SIPP, SIMM 30 pin, SIMM 72 pin, DIMM, RIMM RAM redirects here. ...
Typical hard drives of the mid-1990s. ...
A LiveCD is an operating system (usually containing other software as well) stored on a bootable CD-ROM that can be executed from it, without installation on a hard drive. ...
A USB keydrive, shown with a US quarter coin for scale. ...
Hardware comprises all of the physical parts of a computer, as distinguished from the data it contains or operates on, and the software that provides instructions for the hardware to accomplish tasks. ...
Robert Boyles self-flowing flask fills itself in this diagram, but perpetual motion machines do not exist. ...
The solution to the paradox involves using a special small program, called a bootstrap loader or boot loader. This program doesn't have the full functionality of an operating system, but is tailor-made to load enough other software for the operating system to start. Often, multiple-stage boot loaders are used, in which several small programs summon each other, until the last of them loads the operating system. The name bootstrap loader comes from the image of one pulling oneself up by one's bootstraps (see bootstrapping). Program or Programme can refer to: a computer program a radio program, a television program a collection of managed projects a 12-step program one of the short films in The Animatrix series. ...
Bootstrapping alludes to a German legend about a Baron Münchhausen, who was able to lift himself out of a swamp by pulling himself up by his own hair. ...
Early programmable computers had toggle switches on the front panel to allow the operator to place the bootloader into the program store before starting the CPU. This would then read the operating system in from an outside storage medium such as paper tape or an old fixed head disk drive. Electrical switches. ...
CPU can stand for: in computing: Central processing unit in journalism: Commonwealth Press Union in law enforcement: Crime prevention unit in software: Critical patch update, a type of software patch distributed by Oracle Corporation CPU is a TLA, a type of acronym. ...
A roll of punched tape Punched tape is an old-fashioned form of data storage, consisting of a long strip of paper in which holes are punched to store data. ...
Disk Drive is the afternoon show on CBC Radio Two. ...
Pseudo-assembly code for the bootloader might be as simple as the following eight instructions: Pseudo is a prefix of Greek origin. ...
Assembly language or simply assembly is a human-readable notation for the machine language that a specific computer architecture uses. ...
0: set the P register to 8 1: check paper tape reader ready 2: if not ready, jump to 1 3: read a byte from paper tape reader to accumulator 4: if end of tape, jump to 8 5: store accumulator to address in P register 6: increment the P register 7: jump to 1 In modern computers the bootstrapping process begins with the CPU executing software contained in ROM (for example, the BIOS of an IBM PC) at a predefined address (the CPU is programmed to execute this software after reset without outside help). This software contains rudimentary functionality to search for devices eligible to participate in booting, and load a small program from a special section (most commonly the boot sector) of the most promising device. The central processing unit (CPU) is the part of a computer that interprets and carries out the instructions contained in the software. ...
In computing, the Basic Input-Output System or BIOS is primitive software code embedded within a computer hardware system whose main functions are: to provide a visual display of the system to a monitor on startup of the system, have basic key access to a keyboard and provide low-level...
IBM PC (IBM 5150) with keyboard and green screen monochrome monitor (IBM 5151), running MS-DOS 5. ...
The boot sector is a region of a hard disk, floppy disk, or similar data storage device. ...
Boot loaders may face peculiar constraints, especially in size; for instance, on the IBM PC and compatibles, the first stage of boot loaders is always 512 bytes in length and ends with the AA55h value (which the BIOS looks at to ensure that it is a proper boot loader). This article refers to the unit of binary information. ...
Second-stage boot loader The small program is most often not itself an operating system, but only a second-stage boot loader, such as NTLDR, LILO or GRUB. It will then be able to load the operating system proper, and finally transfer execution to it. The system will initialize itself, and may load device drivers and other programs that are needed for the normal operation of the OS. NTLDR (abbreviation for NT Loader) is the boot loader for Windows NT, including its later versions (2000/XP/Longhorn). ...
LILO (LInux LOader) is a boot loader for Linux. ...
This article refers to the bootloader, for other uses of the term see Grub. ...
A device driver, often called a driver for short, is a computer program that enables another program (typically, an operating system) to interact with a hardware device. ...
The boot process is considered complete when the computer is ready to interact with the user or the operating system is capable of running ordinary applications. Typical modern PCs boot in about a minute (of which about 15 seconds are taken by the preliminary boot loaders, and the rest by loading the operating system), while large servers may take several minutes to boot and to start all services - to ensure high availability, they bring up some services before others. In computing, an operating system (OS) is the system software responsible for the direct control and management of hardware and basic system operations. ...
The tower of a personal computer. ...
Most embedded systems must boot almost instantly -- for instance, waiting a minute for the television to come up is not acceptable. Therefore they have their whole operating system in ROM or flash memory, so it can be executed directly. An embedded system is a special-purpose computer system, which is completely encapsulated by the device it controls. ...
Flash memory is a form of EEPROM that allows multiple memory locations to be erased or written in one programming operation. ...
BIOS boot devices A boot device is any device that must be initialized prior to loading the operating system. This includes the primary input device (keyboard), the primary output device (display), and the initial program load device (floppy drive, hard drive, CD-ROM, keydrive, etc.). (An IPL device is any device in the system that can boot and load an operating system, a stand alone utility (i.e. memtest86+) or even a boot loader; in old AT machines, this is the floppy drive or hard drive.) A boot device makes a computer work. ...
Any of a number of devices used for inputing information into a machine, typically a computer. ...
QWERTY computer keyboard A computer keyboard is a peripheral modelled after the typewriter keyboard. ...
Only meanings of encyclopedic scope are listed here for disambiguation purposes. ...
A floppy disk is a data storage device that comprises a circular piece of thin, flexible (hence floppy) magnetic storage medium encased in a square or rectangular plastic wallet. ...
Typical hard drives of the mid-1990s. ...
The CD-ROM (an abbreviation for Compact Disc Read-Only Memory (ROM)) is a non-volatile optical data storage medium using the same physical format as audio compact discs, readable by a computer with a CD-ROM drive. ...
A USB keydrive, shown with a US quarter coin for scale. ...
In computing, an operating system (OS) is the system software responsible for the direct control and management of hardware and basic system operations. ...
In computing, booting is a bootstrapping process that starts operating systems when the user turns on a computer system. ...
In a modern BIOS, the user can select one of several devices from which to boot, for example hard disk, floppy, SCSI, CDROM, ZIP, LS-120 or USB (USB-FDD, USB-ZIP, USB-CDROM, USB-HDD). In computing, the Basic Input-Output System or BIOS is primitive software code embedded within a computer hardware system whose main functions are: to provide a visual display of the system to a monitor on startup of the system, have basic key access to a keyboard and provide low-level...
Typical hard drives of the mid-1990s. ...
A floppy disk is a data storage device that comprises a circular piece of thin, flexible (hence floppy) magnetic storage medium encased in a square or rectangular plastic wallet. ...
SCSI stands for Small Computer System Interface, and is a standard interface for transferring data between devices on a computer bus. ...
The CD-ROM (an abbreviation for Compact Disc Read-Only Memory (ROM)) is a non-volatile optical data storage medium using the same physical format as audio compact discs, readable by a computer with a CD-ROM drive. ...
Later (USB, left) and earlier (parallel, right) Zip drives (media in foreground). ...
Also known as the LS-120 and the later variant LS-240, the SuperDisk was introduced by 3Ms storage products group (later known as Imation) circa 1997 as a high-speed, high-capacity alternative to the 3. ...
Type A USB connector USB 2. ...
For example, one can install Microsoft Windows on the first hard disk and Linux on the second. By changing the BIOS boot device, the user can select the operating system to load. Microsoft Windows is a range of commercial operating environments for personal computers. ...
Tux, a lovable and cuddly penguin sitting down after having gorged itself on herring, is the official Linux mascot. ...
In computing, an operating system (OS) is the system software responsible for the direct control and management of hardware and basic system operations. ...
Boot sequence on standard PC (IBM-PC compatible)
 A PC going through its boot sequence Upon starting, a personal computer's CPU runs the instruction located at the memory register FFFF0h of the BIOS. This memory register location is close to the end of system memory. It contains a jump instruction that transfers execution to the location of the BIOS start-up program. This program runs a Power-On Self Test (POST), which is a test to check that devices the computer will rely on are functioning; it also initializes these devices. Then, the BIOS goes through a preconfigured list of devices until it finds one that is bootable. If it finds no such device, an error is given and the boot process stops. If the BIOS finds a bootable device, it loads and executes its boot sector, called a master boot record (MBR) and is often not operating system specific. Usually, the MBR code checks the partition table for an active partition. If one is found, the MBR code loads that partition's boot sector and executes it. The boot sector is often operating system specific, however in most operating systems its main function is to load and execute a kernel, which continues startup. If there is no active partition or the active partition's boot sector is invalid, the MBR may load a secondary boot loader and pass control to it and this secondary boot loader will select a partition (often via user input) and load its boot sector, which usually loads the corresponding operating system kernel. Wikipedia does not have an article with this exact name. ...
Wikipedia does not have an article with this exact name. ...
The central processing unit (CPU) is the part of a computer that interprets and carries out the instructions contained in the software. ...
In computing, the Basic Input-Output System or BIOS is primitive software code embedded within a computer hardware system whose main functions are: to provide a visual display of the system to a monitor on startup of the system, have basic key access to a keyboard and provide low-level...
Power-on Self Test (POST) is the common term for a computers pre-boot sequence. ...
The boot sector is a region of a hard disk, floppy disk, or similar data storage device. ...
The master boot record (MBR), also the partition sector, in IBM PC architecture, is the 512-byte (½ kilobyte) boot sector, i. ...
In computing, an operating system (OS) is the system software responsible for the direct control and management of hardware and basic system operations. ...
A partition in the IBM PC architecture, is a part of a hard disk that can have an independent file system. ...
The boot sector is a region of a hard disk, floppy disk, or similar data storage device. ...
In computing, an operating system (OS) is the system software responsible for the direct control and management of hardware and basic system operations. ...
In computer science, the kernel is the fundamental part of an operating system. ...
In computing, an operating system (OS) is the system software responsible for the direct control and management of hardware and basic system operations. ...
Other kinds of boot sequence Some other processors have other kinds of boot modes; most digital signal processors have the following boot modes: A digital signal processor (DSP) is a specialized microprocessor designed specifically for digital signal processing, generally in real-time. ...
- Serial mode boot
- Parallel mode boot
- HPI boot
- Warm boot or soft reboot (as opposed to hard reboot) refers to an abridged start up which does not require that power be removed and reapplied.
A soft reboot (also known as a warm reboot, in contrast to a cold reboot) is restarting a computer under software control, without removing power or (directly) triggering a reset line. ...
Computing A hard reboot (also known as a cold reboot) is when power to a computer is cycled (turned on and off) or a special reset signal to the processor is triggered (from a front panel switch of some sort). ...
Related articles A boot disk is a removable media, normally read-only, that can boot an operating system or utility. ...
A LiveCD is an operating system (usually containing other software as well) stored on a bootable CD-ROM that can be executed from it, without installation on a hard drive. ...
Microreboot is a technique used to recover from failures in software systems. ...
Crash-only software refers to a computer program that adheres to crash-only principles that are applied recursively to all components. ...
Grub or GRUB can mean: a slang term for food a beetle larva that resembles a worm the GNU projects Grand Unified Bootloader software: see GRUB a distributed commercial search engine: see Grub distributed web-crawling project a number of places in Switzerland, Austria and Germany, such as: Grub...
LILO (LInux LOader) is a boot loader for Linux. ...
NTLDR (abbreviation for NT Loader) is the boot loader for Windows NT, including its later versions (2000/XP/Longhorn). ...
External links
Booting is also a slang term referring to the disconnection or crashing of a remote computer system via a chat server, often involving malicious software. The process usually consists of sending a large volume of UDP packets to the target, which cause the target to reboot or be disconnected from the Internet. A computer system is a set of hardware and software which processes data in a meaningful way. ...
Computer software (or simply software) refers to one or more computer programs and data held in the storage of a computer for some purpose. ...
The abbreviation UDP can refer to: User Datagram Protocol Usenet Death Penalty Ulster Democratic Party Uridine-diphosphate, cf. ...
A packet is the fundamental unit of information carriage in all modern computer networks. ...
Reboot, in computing is either a hard reboot (cold boot) or soft reboot (warm boot) of a computer. ...
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