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Disk partitioning Multi-boot and mixed-boot systems
Multi-boot systems are computers where the user can boot into one of two or more distinct operating systems (OS) stored in separate storage devices or in separate partitions of the same storage device. In such systems a menu at startup gives a choice of which OS to boot/start (and only one OS at a time is loaded).

Disk partitioning Multi-boot and mixed-boot systems
This is distinct from virtual operating systems, in which one operating system is run as a self-contained virtual "program" within another already-running operating system. (An example is a Windows OS "virtual machine" running from within a Linux OS.)

Some entertainment software contained custom bootblocks
AmigaOS Bootblock Some entertainment software contained custom bootblocks

AmigaOS Bootblock Unfortunately these could not be used on disks that already relied on a custom bootblock, but did alert users of potential trouble

Apple DOS Boot loader When the Monitor or BASIC issued the next prompt character, it would call the ROM routines on the disk card, which would then proceed with the boot sequence

Apple DOS Boot loader When the Apple II Plus was introduced, it included the ability to scan each expansion slot (working downward from slot 7 to slot 1) for an expansion card ROM with additional boot code, and automatically call it.

Apple DOS Boot loader The expansion card ROM boot code attemptted to boot from drive 1 of the controller, by moving the read/write arm to track zero and attempting to read 256 bytes from sector zero of that track. (If no readable disk was present, the drive spun indefinitely until a readable disk was provided and the drive door was closed.)

Apple DOS Boot loader Sector zero contained a small program which instructed the computer how to read sectors 0 to 9 of track zero (re-reading sector 0 in the process).

Apple DOS Boot loader The program in sectors 1-9 of track 0, including the complete RWTS code, then proceeded to load tracks 1 and 2, which contained the rest of DOS. On a "system master" disk, code was also included to relocate DOS as high into system memory as possible, up to the 48 kB limit of the Apple II's main memory ($BFFF16).

Apple DOS Boot loader Once DOS was loaded into memory, it attempted to load and execute a startup program as indicated in the DOS program code

The startup program would then begin executing.
Apple DOS Boot loader The startup program would then begin executing.

DOS Boot sequence The bootstrap loader on PC-compatible computers (MBR or boot sector) is located at track zero, the first sector on a disk. The ROM BIOS will load this sector into memory at address 0000h:7C00h, and typically check for a signature "55h AAh" at offset +1FEh. If the sector is not considered to be valid, the ROM BIOS will try the next physical disk in the row, otherwise it will jump to the load address with certain registers set up.

DOS Boot sequence The MBR code will scan the partition table, which is located within this sector, for an active partition (modern MBRs check if bit 7 is set at offset +1BEh+10h*n, whereas old MBRs simply check for a value of 80h), and, if found, load the first sector of the corresponding partition, which holds the Volume Boot Record (VBR) of that volume, into memory at 0000h:7C00h in the similar fashion as it had been loaded by the ROM BIOS itself

DOS Boot sequence In later issues, it would locate and store the contents of the first two entries in the root directory at 0000h:0500h and if they happen to reflect the correct boot files as recorded in the VBR, the VBR would load the first 3 consecutive sectors of the IO.SYS/IBMBIO.COM file into memory at 0070h:0000h

DOS Boot sequence In modern DOS versions, where the VBR has loaded only the first 3 sectors of the IO.SYS/IBMBIO.COM file into memory, the loaded portion contains another boot loader, which will then load the remainder of itself into memory, using the root directory information stored at 0000h:0500h. For most versions, the file contents still need to be stored in consecutive order on disk. In older versions of DOS, which were still loaded as a whole, this step is skipped.

DOS Boot sequence The DOS system initialization code will initial its builtin device drivers and then load the DOS kernel, located in MSDOS.SYS on MS-DOS systems, into memory as well. In Windows 9x, the DOS system initialization code and builtin device drivers and the DOS kernel are combined into a single IO.SYS file while MSDOS.SYS is used as a text configuration file.

DOS Boot sequence The CONFIG.SYS file is then read to parse configuration parameters. The SHELL variable specifies the location of the shell which defaults to COMMAND.COM.

The shell is loaded and executed.
DOS Boot sequence The shell is loaded and executed.

The startup batch file AUTOEXEC.BAT is then run by the shell.
DOS Boot sequence The startup batch file AUTOEXEC.BAT is then run by the shell.

DOS Boot sequence Therefore, system files can be simply copied to a disk provided that the boot sector is DR DOS compatible already.

DOS Boot sequence In PC DOS and DR DOS 5.0 and above, the DOS system files are named IBMBIO.COM instead of IO.SYS and IBMDOS.COM instead of MSDOS.SYS. Older versions of DR DOS used DRBIOS.SYS and DRBDOS.SYS instead.

BIOS - The BIOS boot process
If the reset button was pressed ("warm boot"), a special flag value is detected in Nonvolatile memory (NVRAM) and the BIOS does not run the POST

BIOS - The BIOS boot process
This process is known as booting, or booting up, which is short for "bootstrapping".

BIOS - Boot devices The BIOS proceeds to test each device sequentially until a bootable device is found, at which time the BIOS transfers control to the loaded sector with a jump instruction to its first byte at address 0x007C00 (1 KiB below the 32 KiB mark).

BIOS - Boot devices Later computers would display a message like "No bootable disk found." Modern BIOSes may display nothing or may automatically enter the BIOS configuration utility when the boot process fails.

BIOS - Boot devices Therefore, CD-ROM drives boot as emulated floppy disk drives; the bootable virtual floppy disk can then contain software that provides access to the optical medium in its native format.

BIOS - Boot devices A little-known feature of the original IBM BIOS versions is that before beginning the normal boot process they would attempt to load a program through the keyboard port. This was intended for factory test or diagnostic purposes. This was of limited utility outside of factory or repair facilities.

BIOS - Boot environment
All memory at and above address 0x can be used by the boot program; it may even overwrite itself

BIOS - BIOS Boot Specification
The official title is BIOS Boot Specification (Version 1.01, 11 January 1996) and is available here:

Linux startup process - Boot loader phase
The boot loader phase varies by platform. Since the earlier phases are not specific to the OS, the boot process is considered to start, for x86 or x86-64, when the partition boot sector code is executed in real mode and loads the first stage boot loader (typically a part of LILO or ). From that point, the boot process continues as follows:

The first stage boot loader (in the MBR or the volume boot record) loads the remainder of the boot loader, which typically gives a prompt asking which Operating System (or type of session) the user wishes to initialize. LILO and differ in some ways:

Boot time LILO logic loads the menu code, and then, depending on the lilo.conf directives used to make the map file, along with any user interaction, loads either the boot sector for another system such as Microsoft Windows, or the kernel image for Linux.

by contrast does have understanding of the common ext2, ext3 and ext4 file systems. Because stores its data in a configuration file rather than the MBR and contains a command-line interface, it is often easier to rectify or modify if misconfigured or corrupt.

FreeDOS - Booting FreeDOS can be booted from a Hard Drive, live CD, USB flash drive or floppy disk. It can also be run using virtualization software like Virtual PC and VirtualBox or emulation software like Bochs and QEMU. To use the Windows Boot Menu the following line can be added to 2K/XP's C:\BOOT.INI:

FreeDOS - Booting To boot using GRUB something similar to the following can be added to menu.lst(the following only applies to GRUB4DOS):

title FreeDOS # Anything you want
FreeDOS - Booting title FreeDOS # Anything you want

FreeDOS - Booting To use it under GRUB2, a different solution is needed which involves device mappings.

GNU GRUB - Booting When a computer is turned on, the computer's BIOS finds the configured primary bootable device (usually the computer's hard disk) and loads and executes the initial bootstrap program from the master boot record (MBR)

GNU GRUB - Booting Boot loaders with bigger footprints are thus split into pieces, where the smallest piece fits into and resides within the MBR, while larger piece(s) are stored in another locations (for example, into empty sectors between the MBR and the first partition) and invoked by the boot loader's MBR code.

GNU GRUB - Booting Operating system kernel images are in most cases files residing on appropriate file systems, but the concept of a file system is unknown to the BIOS. Thus, in BIOS-based systems, the duty of a boot loader is to access content of those files, so it can be read from the hard disk, loaded into the RAM and executed.

GNU GRUB - Booting Also, in case of the maps changing their physical location, their locations need to be updated within the boot loader's MBR code, so the sectors indirection mechanism continues to work

GNU GRUB - Booting As a downside, such boot loaders have increased internal complexity and even bigger footprints.

GNU GRUB - Booting GNU GRUB utilizes the second approach, by understanding the underlying file systems. The boot loader itself is split into multiple stages, allowing for itself to fit within the MBR boot scheme.

GNU GRUB - Booting Two major versions of GRUB are in common use. GRUB version 2, called GRUB 2, was written from scratch and intended to replace its predecessor GRUB version 1, and it is now used by a majority of Linux distributions. GRUB version 1, called GRUB legacy, is only prevalent in older releases of Linux distributions, among which some are still in use and supported, for example in Ubuntu or CentOS 5.

Hardware restriction - Verified/trusted/secure boot
Some devices implement a feature called "verified boot", "trusted boot" or "secure boot", which will only allow signed software to run on the device, usually from the device manufacturer. This is considered a restriction unless users either have the ability to disable it or have the ability to sign the software.

Hardware restriction - Secure boot
In January 2012, Microsoft confirmed it would require hardware manufacturers to enable secure boot on Windows 8 devices, and that x86/64 devices must provide the option to turn it off while ARM-based devices must not provide the option to turn it off

Knoppix - Boot options If the user does not enter a cheat code, or does not press any key before the timeout, Knoppix will boot with its default options

LILO (boot loader) - Overview
LILO does not depend on a specific file system, and can boot an operating system (e.g., Linux kernel images) from floppy disks and hard disks. One of up to sixteen different images can be selected at boot time. Various parameters, such as the root device, can be set independently for each kernel. LILO can be placed in the master boot record (MBR) or the boot sector of a partition. In the latter case, the MBR must contain code to load LILO.

At system start, only the BIOS drivers are available for LILO to access hard disks. For this reason, a very old BIOS access area is limited to cylinders 0 to 1023 of the first two hard disks. For a later BIOS, LILO can use 32-bit "logical block addressing" (LBA) to access the entire capacity of the hard disks the BIOS has access to.

LILO (boot loader) - lilo.conf
The lilo.conf file is typically located at /etc/lilo.conf. Within lilo.conf there are typically two section types. The first section, which defines the global options, contains parameters which specify boot location attributes. The second section(s) contain parameters associated with the operating system images to be loaded. The section type can be repeated for up to 16 different boot selections.

Remember to run the /sbin/lilo command after editing the /etc/lilo.conf file so that your changes take effect.

Definition information can be found in the LILO Manpage.

Note: Here LILO offers after correct installation a menu with Linux and FreeBSD.

LILO (boot loader) - /boot/
LILO stores a number of files in the /boot/ – see /boot/: LILO.

LILO (boot loader) - Output
When LILO loads itself it displays the word “LILO”. Each letter is printed before or after some specific action. If LILO fails at some point, the letters printed so far can be used to identify the problem.

No part of LILO has been loaded. LILO either isn't installed or the partition on which its boot sector is located isn't active. The boot media is incorrect or faulty.

The first stage boot loader has been loaded and started, but it can't load the second stage boot loader. The two-digit indicate the type of problem. This condition usually indicates a media failure or bad disk parameters in the BIOS.

The first stage boot loader was able to load the second stage boot loader, but has failed to execute it. This can be caused by bad disk parameters in the BIOS.

The second stage boot loader has been started, but it can't load the descriptor table from the map file. This is typically caused by a media failure or by bad disk parameters in the BIOS.

The second stage boot loader has been loaded at an incorrect address. This is typically caused by bad disk parameters in the BIOS.

The descriptor table is corrupt. This can be caused by bad disk parameters in the BIOS.

All parts of LILO have been successfully loaded.

LILO (boot loader) - Error codes
0x00 Internal Error This code is generated by the sector read routine of the LILO boot loader whenever an internal inconsistency is detected. This might be caused by corrupt files. Try re-building the map file. Another possible cause for this error are attempts to access cylinders beyond 1024 while using the LINEAR option.

0x01 Illegal Command This shouldn't happen, but if it does, it may indicate an attempt to access a disk which is not supported by the BIOS. Definitely check to see if the disk is seen by the BIOS first (and that the BIOS detail is complete).

0x02 Address mark not found This usually indicates a media problem. Try again several times.

0x03 Write-protected disk This should only occur on write operations.

0x04 Sector not found This typically indicates a geometry mismatch. If you're booting a raw-written disk image, verify whether it was created for disks with the same geometry as the one you're using. If you're booting from a SCSI disk or a large IDE disk, you should check, whether LILO has obtained correct geometry data from the kernel or whether the geometry definition corresponds to the real disk geometry. Removing COMPACT may help too. So may adding LBA32 or LINEAR.

0x06 Change line active This should be a transient error. Try booting a second time.

0x07 Invalid initialization The BIOS failed to properly initialize the disk controller. You should control the BIOS setup parameters. A warm boot might help too. (Boot a rescue disc and rerun LILO.)

0x08 DMA overrun This shouldn't happen. Try booting again.

0x09 DMA attempt across 64k boundary This shouldn't happen, but may indicate a disk geometry mis-match. Try omitting the COMPACT option. You may need to specify the disk geometry yourself.

0x0C Invalid media This shouldn't happen and might be caused by a media error. Try booting again.

0x10 CRC error A media error has been detected. Try booting several times, running the map installer a second time (to put the map file at some other physical location or to write "good data" over the bad spot), mapping out the bad sectors/tracks and, if all else fails, replacing the media.

0x11 ECC correction successful A read error occurred, but was corrected. LILO does not recognize this condition and aborts the load process anyway. A second load attempt should succeed.

0x20 Controller error This shouldn't happen, then again, none of these errors should happen eh?

0x40 Seek failure This might be a media problem. Try booting again.

0x80 Disk timeout The disk or the drive isn't ready. Either the media is bad or the disk isn't spinning. If you're booting from a floppy, you might not have closed the drive door. Otherwise, trying to boot again might help.

0x9A Can't Find Second Stage Check to see if you have the correct device for boot, e.g. boot=/dev/hda1 when it should be in the MBR i.e. boot=/dev/hda.

0xBB BIOS error This shouldn't happen. Try booting again. If the problem persists, removing the COMPACT option or adding/removing LINEAR or LBA32 might help.

LILO (boot loader) - elilo
For EFI-based PC hardware the elilo boot loader was developed, originally by Hewlett Packard for IA-64 systems made, but later also for standard Intel IA-32 and x86-64 hardware with EFI support.

LILO (boot loader) - elilo
On any version of Linux running on Intel-based Apple Macintosh hardware, elilo is one of the available bootloaders.

LILO (boot loader) - Notes
LILO and GRUB: Boot Loaders Made Simple by Judith Myerson

Bonney, Laurence ( ). "Boot loader showdown: Getting to know LILO and GRUB: Contrast and compare these two contenders". IBM DeveloperWorks. Retrieved

lilo(8) – Linux Administration and Privileged Commands Manual

lilo.conf(5) – Linux File Formats Manual

Live CD - Boot code During live CD initialization, a user typically may resort to using one or more boot codes to change the booting behavior. These vary from distribution to distribution but can most often be accessed upon first boot screen by one of the function keys.

Linux Terminal Server Project - The LTSP client boot process
On the LTSP server, a chroot environment is set up with a minimal Linux Operating System and X environment.

Either a computer will boot from a local boot device (like a harddisk, CD-ROM or USB disk), where it loads a small Linux kernel from that device which initializes the system and all of the peripherals that it recognizes.

A PXE bootloader (PXElinux) is loaded which then retrieves a Linux kernel and initrd from a Trivial File Transfer Protocol (TFTP) service usually running on the LTSP server

The client then loads Linux from the NFS mounted root filesystem (or NBD filesystem image) and starts the X Window system. At this XDMCP login manager on the LTSP server. In case of the newer MueKow (LTSP v5.x) setup, the client first builds an SSH tunnel to the LTSP server's X environment, through which it will start the LDM (LTSP Display Manager) login manager locally. From this point forward, all programs are started on the LTSP server, but displayed and operated from the client.

Intregration method LTSP tarball Native as part of distribution

Motherboard - Bootstrapping using the BIOS
At power-up, the central processor would load its program counter with the address of the boot ROM and start executing instructions from the ROM

Non-operating system boot programs are still supported on modern IBM PC-descended machines, but nowadays it is assumed that the boot program will be a complex operating system such as MS Windows NT or Linux

Cards inserted into slots, such as conventional PCI

Temperatures, voltages, and fan speeds for hardware monitoring

CMOS used to store BIOS setup configuration

Security devices, such as a fingerprint reader or the state of a latch switch to detect intrusion

USB devices, such as a memory storage device

On recent motherboards, the BIOS may also patch the central processor microcode if the BIOS detects that the installed CPU is one for which errata have been published.

Entrepreneurship - Financial Bootstrapping
While bootstrapping involves a risk for the founders, the absence of any other stakeholder gives the founders more freedom to develop the company

Entrepreneurship - Financial Bootstrapping
Minimization of the accounts payable

File Allocation Table - Boot Sector
On non-partitioned devices, such as floppy disks, the Boot Sector (VBR) is the first sector (logical sector 0 with physical CHS address 0/0/1 or LBA address 0). For partitioned devices such as hard drives, the first sector is the Master Boot Record defining partitions, while the first sector of partitions formatted with a FAT file system is again the Boot Sector.

Common structure of the first 11 bytes used by most FAT versions for IBM compatible x86-machines since DOS 2.0 are:

0x000 3 Jump instruction. If the boot sector has a valid signature residing in the last two bytes of the boot sector (tested by most boot loaders residing in the System BIOS or the MBR) and this volume is booted from, the prior boot loader will pass execution to this entry point with certain register values, and the jump instruction will then skip past the rest of the (non-executable) header. See Volume Boot Record.

(See below for Atari ST compatibility.) The presence of one of these opstring patterns (in combination with a test for a valid media descriptor value at offset 0x015) serves as indicator to DOS 3.3 and higher that some kind of BPB is present (although the exact size should not be determined from the jump target since some boot sectors contain private boot loader data following the BPB), while for DOS 1.x (and some DOS 3.0) volumes, they will have to fall back to the DOS 1.x method to detect the format via the media byte in the FAT (in logical sector 1).

0x003 8 OEM Name (padded with spaces 0x20). This value determines in which system the disk was formatted.

Although officially documented as free for OEM use, MS-DOS/PC DOS (since 3.1), Windows 95/98/SE/ME and OS/2 check this field to determine which other parts of the boot record can be relied upon and how to interpret them. Therefore, setting the OEM label to arbitrary or bogus values may cause MS-DOS, PC DOS and OS/2 to not recognize the volume properly and cause data corruption on writes. Common examples are "IBM␠␠3.3", "MSDOS5.0", "MSWIN4.1", "IBM␠␠7.1", "mkdosfs␠", and "FreeDOS␠".

The Volume Tracker in Windows 95/98/SE/ME will overwrite the OEM label with "?????IHC" signatures (a left-over from "␠OGACIHC" for "Chicago") even on a seemingly read-only disk access (such as a DIR A:) if the medium is not write-protected

Some boot loaders make adjustments or refuse to pass control to a boot sector depending on certain values detected here (e.g., NEWLDR offset 0x018).

varies varies File system and operating system specific boot code; often starts immediately behind [E]BPB, but sometimes additional "private" boot loader data is stored between the end of the [E]BPB and the start of the boot code.

0x1FD 1 Physical drive number (only in DOS 3.2 to 3.31 boot sectors). With OS/2 1.0 and DOS 4.0, this entry moved to sector offset 0x024 (at offset 0x19 in the EBPB). Most Microsoft and IBM boot sectors maintain values of 0x00 at offset 0x1FC and 0x1FD ever since, although they are not part of the signature at 0x1FE.

If this belongs to a boot volume, the DR-DOS 7.07 enhanced MBR can be configured (see NEWLDR offset 0x014) to dynamically update this entry to the DL value provided at boot time or the value stored in the partition table. This enables booting off alternative drives, even when the VBR code ignores the DL value.

Formatting tools must not write this signature if the written boot sector does not contain at least an x86-compatible dummy boot loader stub; at minimum, it must halt the CPU in an endless loop (0xF4 0xEB 0xFD) or issue an INT 19h and RETF (0xCD 0x19 0xCB)

This signature must be located at fixed sector offset 0x1FE for sector sizes 512 or higher. If the physical sector size is larger, it may be repeated at the end of the physical sector.

Atari STs will assume a disk to be Atari bootable if the checksum over the 256 big-endian words of the boot sector equals 0x1234.[nb 9] If the boot loader code is IBM compatible, it is important to ensure that the checksum over the boot sector does not match this checksum by accident. If this would happen to be the case, changing an unused bit (e.g., before or after the boot code area) can be used to ensure this condition is not met.

In rare cases, a reversed signature 0xAA 0x55 has been observed on disk images

FAT-formatted Atari ST floppies have a very similar boot sector layout:

0x000 2 Jump instruction. Original Atari ST boot sectors start with a BRA.S instruction (0x60 0x??). For compatibility with PC operating systems, Atari ST formatted disks since TOS 1.4 start with 0xE9 0x?? instead.

0x002 6 OEM Name (padded with spaces 0x20), e.g., "Loader" (0x4C 0x6F 0x61 0x64 0x65 0x72) on volumes containing an Atari ST boot loader. See OEM Name precautions for PC formatted disks above. Note the different offset and length of this entry compared to the entry on PC formatted disks.

0x008 3 Disk serial number (default: 0x00 0x00 0x00), used by Atari ST to detect a disk change. (Windows 9x Volume Tracker will always store "IHC" here on non-write-protected floppy disks; see above.) This value must be changed if the disk content is externally changed, otherwise Atari STs may not recognize the change on re-insertion. This entry overlaps the OEM Name field on PC formatted disks. For maximum compatibility, it may be necessary to match certain patterns here; see above.

varies varies File system and operating system specific Atari ST boot code. No assumptions must be made in regard to the load position of the code, which must be relocatable. If loading an operating system fails, the code can return to the Atari ST BIOS with a RTS (opcode 0x4E75 with big-endian byte sequence 0x4E 0x75[nb 8]) instruction and all registers unaltered.

0x1FE 2 Checksum. The 16-bit checksum over the 256 big-endian words of the 512 bytes boot sector including this word must match the magic value 0x1234 in order to indicate an Atari ST executable boot sector code. This checksum entry can be used to align the checksum accordingly.[nb 9]

Since some PC operating systems erroneously do not accept FAT formatted floppies if the 0x55 0xAA[nb 8] signature is not present here, it is advisable to place the 0x55 0xAA in this place (and add an IBM compatible boot loader or stub) and use an unused word in the private data or the boot code area or the serial number in order to ensure that the checksum 0x1234[nb 9] is not matched (unless the shared fat code overlay would be both IBM PC and Atari ST executable at the same time).

FAT12-formatted MSX-DOS volumes have a very similar boot sector layout:

0x01E varies (2) MSX-DOS 1 code entry point for Z80 processors into MSX boot code. This is where MSX-DOS 1 machines jump to when passing control to the boot sector. This location overlaps with BPB formats since DOS 3.2 or the x86 compatible boot sector code of IBM PC compatible boot sectors and will lead to a crash on the MSX machine unless special precautions have been taken such as catching the CPU in a tight loop here (opstring 0x18 0xFE for JR 0x01E).

0x MSX-DOS 2 volume signature "VOL_ID".

0x026 1 MSX-DOS 2 undelete flag (default: 0x00. If the "VOL_ID" signature is present at sector offset 0x020, this flag indicates, if the volume holds deleted files which can be undeleted (see offset 0x0C in directory entries).

0x027 4 MSX-DOS 2 disk serial number (default: 0x ). If the "VOL_ID" signature is present at sector offset 0x020, MSX-DOS 2 stores a volume serial number here for media change detection.

0x030 varies (2) MSX-DOS 2 code entry point for Z80 processors into MSX boot code. This is where MSX-DOS 2 machines jump to when passing control to the boot sector. This location overlaps with EBPB formats since DOS 4.0 / OS/2 1.2 or the x86 compatible boot sector code of IBM PC compatible boot sectors and will lead to a crash on the MSX machine unless special precautions have been taken such as catching the CPU in a tight loop here (opstring 0x18 0xFE for JR 0x030).

Dave Winer - Rebooting the News
Since 2009, Winer has collaborated with New York University's associate professor of journalism Jay Rosen on Rebooting the News, a weekly podcast on technology and innovation in journalism. It was announced on July 1, 2011 that the show would be on break, as NYU itself was, from June to September. However, no new episodes have been released since, making show #94 released on May 23, 2011 the last.

Fantastic Four: Rise of the Silver Surfer - Reboot
The Fantastic Four reboot will be released on March 6, 2015.

Booting A boot loader is a computer program that loads the main operating system or runtime environment for the computer after completion of the self-tests.

Booting The computer term boot is short for bootstrap or bootstrap load and derives from the phrase to pull oneself up by one's bootstraps

Booting Some embedded systems do not require a noticeable boot sequence to begin functioning and when turned on may simply run operational programs that are stored in ROM.

Booting - History There are many different methods available to load a short initial program into a computer. These methods reach from simple, physical input to removable media that can hold more complex programs.

Booting - Early computers
Bootstrapping in a stored-program computer simply did not apply

Booting - First commercial computers
This booting concept was called a variety of names for IBM computers of the 1950s and early 1960s, but IBM used the term "Initial Program Load" starting with the System/360 in 1964.

The term "boot" has been used in this sense since at least 1958.

Other IBM computers of that era had similar features

Another example was the IBM 650 (1953), a decimal machine, which had a group of ten 10-position switches on its operator panel which were addressable as a memory word (address 8000) and could be executed as an instruction. Thus setting the switches to and pressing the appropriate button would read the first card in the card reader into memory (op code 70), starting at address 400 and then jump to 400 to begin executing the program on that card.

IBM's competitors also offered single button program load.

The CDC 6600 (c. 1964) had a dead start panel with 144 toggle switches; the dead start switch entered 12 words from the toggle switches to the memory of peripheral processor (PP) 0 and initiated the load sequence. PP 0 loaded the necessary code into its own memory and then initialized the other PPs.

The GE 645 (c. 1965) had a "SYSTEM BOOTLOAD" button that, when pressed, caused one of the I/O controllers to load a 64-word program into memory from a diode read-only memory and deliver an interrupt to cause that program to start running.

The first model of the PDP-10 had a "READ IN" button that, when pressed, reset the processor and started an I/O operation on a device specified by switches on the control panel, reading in a 36-bit word giving a target address and count for subsequent word reads; when the read completed, the processor started executing the code read in by jumping to the last word read in.

Instead, after the system is reset it reads and executes opcodes sequentially from a tape drive mounted on the front panel; this sets up a boot loader in RAM which is then executed

Booting - IBM System/360 and successors
In the IBM System/360 and its successors, including the current z/Architecture machines, the boot process is known as Initial Program Load (IPL).

This term was coined by IBM for the design of the System/360 (ca, 1965) and continues to be used in those environments today

The IPL function in the System/360 and its successors, and its compatibles such as Amdahl's, reads 24 bytes from an operator-specified device into main storage starting at real address zero

The disk, tape or card deck must contain a special program to load the actual operating system into main storage, and for this specific purpose "IPL Text" is placed on the disk by the stand-alone DASDI (Direct Access Storage Device Initialization) program or an equivalent program running under an operating system, e.g., ICKDSF, but IPL-able tapes and card decks are usually distributed with this "IPL Text" already present.

Booting - Minicomputers
Since the early minicomputers used magnetic core memory, which did not lose its information when power was off, these bootstrap loaders would remain in place unless they were erased

DEC later added an optional diode matrix read-only memory for the PDP-11 that stored a bootstrap program of up to 32 words (64 bytes)

Following the older approach, the earlier PDP-1 has a hardware loader, such that an operator need only push the "load" switch to instruct the paper tape reader to load a program directly into core memory.

Booting - Early minicomputer boot loader examples
In a minicomputer with a paper tape reader, the first program to run in the boot process, the boot loader, would read into core memory either the second-stage boot loader (often called a Binary Loader) that could read paper tape with checksum or the operating system from an outside storage medium. Pseudocode for the boot loader might be as simple as the following eight instructions:

If not ready, jump to 2

Store accumulator to address in P register

If end of tape, jump to 9

A related example is based on a loader for a Nicolet Instrument Corporation minicomputer of the 1970s, using a Teletype Model 33 ASR teleprinter as a paper tape reader. Note that the bytes of the second-stage loader are read from paper tape in reverse order.

The difference between the boot loader and second stage loader is the addition of checking code to trap paper tape read errors, a frequent occurrence with relatively low-cost, "part-time-duty" hardware such as the Teletype Model 33 ASR

Booting - Booting the first microcomputers
Once correctly loaded, the CPU was enabled to execute the bootstrapping code

Booting - Integrated circuit read-only memory era
The boot process was revolutionized by the introduction of integrated circuit read-only memory (ROM), with its many variants, including mask-programmed ROMs, programmable ROMs (PROM), erasable programmable ROMs (EPROM), and flash memory. These allowed firmware boot programs to be shipped installed on the computer.

Apple Inc.'s first computer, the Apple 1 introduced in 1976, featured PROM chips that eliminated the need for a front panel for the boot process. According to Apple's ad announcing it "No More Switches, No More Lights ... the firmware in PROMS enables you to enter, display and debug programs (all in hex) from the keyboard."

A common solution in such situations is to design a boot loader that works as a program belonging to the standard OS that hijacks the system and loads the alternative OS

The Atari ST hardware was also designed so the cartridge slot could provide native program execution for gaming purposes as a holdover from Atari's legacy making electronic games; by inserting the Spectre GCR cartridge with the Macintosh system ROM in the game slot and turning the Atari on, it could "natively boot" the Macintosh operating system rather than Atari's own TOS system.

The IBM Personal Computer included ROM-based firmware called the BIOS; one of the functions of that firmware was to perform a power-on self test when the machine was powered up, and then to read software from a boot device and execute it

Sun Microsystems later developed OpenBoot, later known as Open Firmware, which incorporated a Forth interpreter, with much of the firmware being written in Forth

Booting - Modern boot loaders
When a modern computer is turned off, software, including operating systems, application code, and data, is stored on nonvolatile data storage devices such as hard drives, CDs, DVDs, flash memory cards (like SD cards), USB flash drives, and floppy disks

The small program that starts this sequence is known as a bootstrap loader, bootstrap or boot loader. This small program's only job is to load other data and programs which are then executed from RAM. Often, multiple-stage boot loaders are used, during which several programs of increasing complexity load one after the other in a process of chain loading.

Other systems may send hardware commands directly to peripheral devices or I/O controllers that cause an extremely simple input operation (such as "read sector zero of the system device into memory starting at location 1000") to be carried out, effectively loading a small number of boot loader instructions into memory; a completion signal from the I/O device may then be used to start execution of the instructions by the CPU.

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.

For example, DR-DOS boot sectors are able to locate the boot file in the FAT12, FAT16 and FAT32 file system, and load it into memory as a whole via CHS or LBA, even if the file is not stored in a fixed location and in consecutive sectors.

Booting - Second-stage boot loader
Second-stage boot loaders, such as GNU GRUB, BOOTMGR, Syslinux, or NTLDR, are not themselves operating systems, but are able to load an operating system properly and transfer execution to it; the operating system subsequently initializes itself and may load extra device drivers.

Usually a default choice is preselected with a time delay during which a user can press a key to change the choice; after this delay, the default choice is automatically run so normal booting can occur without interaction.

Large servers may take several minutes to boot and start all their services.

Many embedded systems must boot immediately. For example, waiting a minute for a digital television or a GPS navigation device to start is generally unacceptable. Therefore such devices have software systems in ROM or flash memory so the device can begin functioning immediately; little or no loading is necessary, because the loading can be precomputed and stored on the ROM when the device is made.

Large and complex systems may have boot procedures that proceed in multiple phases until finally the operating system and other programs are loaded and ready to execute. Because operating systems are designed as if they never start or stop, a boot loader might load the operating system, configure itself as a mere process within that system, and then irrevocably transfer control to the operating system. The boot loader then terminates normally as any other process would.

Booting - Network booting
Most computers are also capable of booting over a computer network. In this scenario, the operating system is stored on the disk of a server, and certain parts of it are transferred to the client using a simple protocol such as the Trivial File Transfer Protocol. After these parts have been transferred, the operating system then takes over control of the booting process.

Booting - Boot devices (IBM PC)
Older, less common BIOS-bootable devices include floppy disk drives, SCSI devices, Zip drives, and LS-120 drives.

Typically, the BIOS will allow the user to configure a boot order. If the boot order is set to "first, the DVD drive; second, the hard disk drive", then the BIOS will try to boot from the DVD drive, and if this fails (e.g. because there is no DVD in the drive), it will try to boot from the local hard drive.

In this example of dual booting, the user chooses by inserting or removing the CD from the computer, but it is more common to choose which operating system to boot by selecting from a menu using the computer keyboard

Booting - Boot sequence of IBM-PC compatibles
Upon starting, an IBM-compatible personal computer's x86 CPU executes, in real mode, the instruction located at reset vector (the physical memory address FFFF0h on 16-bit x86 processors and FFFFFFF0h on 32-bit and 64-bit x86 processors), usually pointing to the BIOS entry point inside the ROM

After initializing required hardware, the BIOS goes through a pre-configured list of non-volatile storage devices ("boot device sequence") until it finds one that is bootable. A bootable device is defined as one that can be read from, and where the last two bytes of the first sector contain the little-endian word AA55h, found as byte sequence 55h, AAh on disk (also known as the MBR boot signature), or where it is otherwise established that the code inside the sector is executable on x86 PCs.

Coreboot splits the initialization and boot services into distinct parts, supporting "payloads" such as SeaBIOS, TianoCore, GRUB, and Linux directly (from flash).

If an active partition is found, the MBR code loads the boot sector code from that partition, known as Volume Boot Record (VBR), and executes it.

The VBR is often operating-system specific; however, in most operating systems its main function is to load and execute the operating system kernel, which continues startup.

If all else fails, it should issue an INT 18h BIOS interrupt call (followed by an INT 19h just in case INT 18h would return) in order to give back control to the BIOS, which would then attempt to boot off other devices, attempt a remote boot via network or invoke ROM BASIC.

Some systems (particularly newer Macintoshes and new editions of Microsoft Windows) use Intel's EFI. Also coreboot allows a computer to boot without having the firmware/BIOS constantly running in system management mode. 16-bit BIOS interfaces are required by certain x86 operating systems, such as DOS and Windows 3.1/95/98 (and all when not booted via UEFI). However, most boot loaders retain 16-bit BIOS call support.

Booting - Other kinds of boot sequences
There are alternative techniques for booting CPUs and microcontrollers:

This feature is often used for system recovery purposes when for some reasons usual boot software in non-volatile memory got erased

This allows, for example, the recovery of embedded systems where no software remains on any supported boot device, and where the processor does not have any integrated boot ROM

In other cases such interfaces could be created by software running in integrated on-chip boot ROM from GPIO pins.

Parallel mode boot, such as the host port interface (HPI boot)

The DSP often lacks its own boot memories and relies on the host processor to supply the required code instead

Many FPGA chips load their configuration from an external serial EEPROM ("configuration ROM") on power-up.

Booting - Quick boot Several devices are available that enable the user to "quick-boot" to a usually Linux-powered OS for various simple tasks such as Internet access (such as Splashtop and Latitude ON).

Booting - Further reading
Practical boot loader tutorial for ATmega microcontrollers

Booting with Grub at OSDEV Community

Tutorial on writing hello world boot loader

Jonathan de Boyne Pollard (2006). "The EFI boot process". Frequently Given Answers.

Jonathan de Boyne Pollard (2006). "The ARC boot process". Frequently Given Answers.

Jonathan de Boyne Pollard (1996). "The DOS and DOS/Windows boot processes". Frequently Given Answers.

Jonathan de Boyne Pollard (2006). "The Windows NT 6 boot process". Frequently Given Answers.

mdadm - Booting This will result in a catch-up, but /boot filesystems are usually small.

mdadm - Booting With more recent bootloaders it is possible to load the MD support as a kernel module through the initramfs mechanism, this approach allows you to let the /boot filesystem be inside any RAID system without the need of a complex manual configuration.

Nested RAID levels - Near versus far, advantages for bootable RAID
A nonstandard definition of "RAID 10" was created for the Linux MD driver; RAID 10 as recognized by the storage industry association and as generally implemented by RAID controllers is a RAID 0 array of mirrors (which may be two way or three way mirrors) and requires a minimum of 4 drives. Linux "RAID 10" can be implemented with as few as two disks. Implementations supporting two disks such as Linux RAID 10 offer a choice of layouts.

iSCSI - Network booting
For general data storage on an already-booted computer, any type of generic network interface may be used to access iSCSI devices. However, a generic consumer-grade network interface is not able to boot a diskless computer from a remote iSCSI data source. Instead, it is commonplace for a server to load its initial operating system from a TFTP server or local boot device, and then use iSCSI for data storage once booting from the local device has finished.

iSCSI - Network booting
The most popular free software to offer iSCSI boot support is iPXE.

Rootkit - Bootkits More recently, the Alureon rootkit has successfully subverted the requirement for 64-bit kernel-mode driver signing in Windows 7 by modifying the master boot record.

Rootkit - Bootkits The only known defenses against bootkit attacks are the prevention of unauthorized physical access to the system—a problem for portable computers—or the use of a Trusted Platform Module configured to protect the boot path.

Installation (computer programs) - Bootstrapper
During the installation of computer programs it is sometimes necessary to update the installer or package manager itself. To make this possible, a technique called bootstrapping is used. The common pattern for this is to use a small executable file..... which updates the installer and starts the real installation after the update. This small executable is called bootstrapper.Sometimes the bootstrapper installs other prerequisites for the software during the bootstrapping process too.

Bundling of Microsoft Windows - Boot locking concerns
Boot locking is now required for ARM devices.

IPhone 3GS - New Bootrom and 2011 Baseband Update
On September 9, 2009, Apple launched an updated model of the iPhone 3GS that patched a segment overflow in the SecureROM of the Device that had allowed loading an unsigned Bootloader|LLB.

IPhone 3GS - New Bootrom and 2011 Baseband Update
After the release of the iPhone 4S, Apple killed the unlock for the new iPhone 3GS devices that were produced after week 36 of 2011 by updating its baseband hardware from an Infineon Baseband chip to a Toshiba Baseband chip. Although the new chip uses the same modem firmware as the Infineon chip, it cannot be updated to iPad baseband that is still vulnerable to the exploit.

Droid Razr - Unlocked bootloader
There is a Droid Razr variant that features the same characteristics as the Droid Razr with the difference of having an unlockable bootloader. All Razrs now can be unlocked, provided they aren't the old OMAP processor. This device, the Motorola RAZR developer edition, is currently sold in Europe.

Droid Razr - Unlocked bootloader
The developer edition features the capability of unlocking its bootloader by a tool found in the Motorola Mobility website. The unlock bootloader gives developers the ability to flash custom Firmware|ROMs onto the phone without the need to use alternative bypasses such as Safestrap, it also provides easy Android rooting|root access without the need to use specific root exploits such as the Verizon variant (XT912) and the international variant(XT910).

Hardware restrictions - Verified/trusted/secure boot
Some devices implement a feature called verified boot, trusted boot or secure boot, which will only allow signed software to run on the device, usually from the device manufacturer. This is considered a restriction unless users either have the ability to disable it or have the ability to sign the software.

Hardware restrictions - Secure boot
Soon after the feature was announced, September 2011, it caused widespread fear it would lock-out alternative Operating Systems. In January 2012, Microsoft confirmed it would require hardware manufacturers to enable secure boot on Windows 8 devices, and that x86/x64|64 devices must provide the option to turn it off while ARM architecture|ARM-based devices must not provide the option to turn it off

Android Open Accessory Development Kit - Fastboot
Some of the most commonly used fastboot commands include:

* flash - Rewrites a partition with a binary image stored on the host computer.

* devices - Displays a list of all devices (with the serial number) connected to the host computer.

* format - Format a specific partition. The file system of the partition must be recognized by the device.

Asus Eee Pad Transformer - Random reboot issues
Beginning in February, multiple online Transformer communities, including Xda-developers, began to cite problems with random reboot loops on the TF101 caused by Kernel (computing)|Kernel issues with ASUS distributions. As of August 2012, ASUS has yet to formally recognise exact issues and provide fixes.

Fastboot 'Android software development' is the process by which new applications are created for the Android (Operating System)|Android Operating System

Fastboot - SDL The Simple DirectMedia Layer|SDL library offers also a development possibility beside Java, allowing the development with C and the simple porting of existing SDL and native C applications. By injection of a small Java shim (computing)|shim and JNI the usage of native SDL code is possible, allowing Android ports like e.g. the Jagged Alliance 2 Video Game. on the Bear's Pit Forum, October 3, 2011

Fastboot - The Simple project
The goal of Simple is to bring an easy-to-learn-and-use language to the Android platform. Simple is a BASIC dialect for developing Android applications. It targets professional and non-professional programmers alike in that it allows programmers to quickly write Android applications that use the Android runtime components.

Similar to Microsoft Visual Basic 6, Simple programs are form definitions (which contain components) and code (which contains the program logic). The interaction between the components and the program logic happens through events triggered by the components. The program logic consists of event handlers which contain code reacting to the events.

The Simple project is not very active, the last source code update being in August 2009.

Saphir is a fork of the open source Rebol 3 (R3) interpreter
Fastboot - Saphir Saphir is a fork of the open source Rebol 3 (R3) interpreter

Boot ROM A 'boot loader' is a computer program that loads the main Operating System or runtime environment for the computer after completion of the self-tests.

Boot ROM The computer term boot is short for bootstrapping|bootstrap or bootstrap load and derives from the phrase to Bootstrapping#Etymology|pull oneself up by one's bootstraps

Boot ROM Some embedded systems do not require a noticeable boot sequence to begin functioning and when turned on may simply run operational programs that are stored in ROM.

Boot ROM - First commercial computers
The term boot has been used in this sense since at least 1958.

* The CDC 6600 (c. 1964) had a dead start panel with 144 toggle switches; the dead start switch entered 12 words from the toggle switches to the memory of peripheral processor (PP) 0 and initiated the load sequence. PP 0 loaded the necessary code into its own memory and then initialized the other PPs.

* The GE-600 series|GE 645 (c. 1965) had a SYSTEM BOOTLOAD button that, when pressed, caused one of the I/O controllers to load a 64-word program into memory from a diode read-only memory and deliver an interrupt to cause that program to start running.

* The first model of the PDP-10 had a READ IN button that, when pressed, reset the processor and started an I/O operation on a device specified by switches on the control panel, reading in a 36-bit word giving a target address and count for subsequent word reads; when the read completed, the processor started executing the code read in by jumping to the last word read in.

Instead, after the system is reset it reads and executes opcodes sequentially from a tape drive mounted on the front panel; this sets up a boot loader in RAM which is then executed

Boot ROM - IBM System/360 and successors
This term was coined by IBM for the design of the System/360 (ca, 1965) and continues to be used in those environments today

The IPL function in the System/360 and its successors, and its compatibles such as Amdahl's, reads 24 bytes from an operator-specified device into main storage starting at real address zero

The disk, tape or card deck must contain a special program to load the actual Operating System into main storage, and for this specific purpose IPL Text is placed on the disk by the stand-alone DASDI (Direct Access Storage Device Initialization) program or an equivalent program running under an Operating System, e.g., ICKDSF, but IPL-able tapes and card decks are usually distributed with this IPL Text already present.

Boot ROM - Minicomputers
DEC later added an optional diode matrix read-only memory for the PDP-11 that stored a bootstrap program of up to 32 words (64 bytes)

Boot ROM - Early minicomputer boot loader examples
# If not ready, jump to 2

# Store accumulator to address in P register

# If end of tape, jump to 9

The difference between the boot loader and second stage loader is the addition of checking code to trap paper tape read errors, a frequent occurrence with relatively low-cost, part-time-duty hardware such as the Teletype Model 33 ASR

Boot ROM - Integrated circuit read-only memory era
The boot process was revolutionized by the introduction of integrated circuit read-only memory (ROM), with its many variants, including Mask ROM|mask-programmed ROMs, programmable read-only memory|programmable ROMs (PROM), EPROM|erasable programmable ROMs (EPROM), and flash memory. These allowed firmware boot programs to be shipped installed on the computer.

A common solution in such situations is to design a boot loader that works as a program belonging to the standard OS that hijacks the system and loads the alternative OS

The Atari ST hardware was also designed so the cartridge slot could provide native program execution for gaming purposes as a holdover from Atari's legacy making electronic games; by inserting the Spectre GCR cartridge with the Macintosh system ROM in the game slot and turning the Atari on, it could natively boot the Macintosh Operating System rather than Atari's own Atari TOS|TOS system.

The IBM Personal Computer included ROM-based firmware called the BIOS; one of the functions of that firmware was to perform a power-on self test when the machine was powered up, and then to read software from a boot device and execute it

Sun Microsystems later developed OpenBoot, later known as Open Firmware, which incorporated a Forth (programming language)|Forth interpreter, with much of the firmware being written in Forth

Boot ROM - Modern boot loaders
When a modern computer is turned off, software, including Operating Systems, application code, and data, is stored on nonvolatile data storage devices such as Hard Drives, CDs, DVDs, memory card|flash memory cards (like SD cards), USB flash drives, and floppy disks

Other systems may send hardware commands directly to peripheral devices or I/O controllers that cause an extremely simple input operation (such as read sector zero of the system device into memory starting at location 1000) to be carried out, effectively loading a small number of boot loader instructions into memory; a completion signal from the I/O device may then be used to start execution of the instructions by the CPU.

Boot ROM - Second-stage boot loader
Second-stage boot loaders, such as GNU GRUB, BOOTMGR, SYSLINUX|Syslinux, or NTLDR, are not themselves Operating Systems, but are able to load an Operating System properly and transfer execution to it; the Operating System subsequently initializes itself and may load extra device drivers.

Usually a default choice is preselected with a time delay during which a user can press a key to change the choice; after this delay, the default choice is automatically run so normal booting can occur without interaction.

Many embedded systems must boot immediately. For example, waiting a minute for a Television set|digital television or a GPS navigation device to start is generally unacceptable. Therefore such devices have software systems in ROM or flash memory so the device can begin functioning immediately; little or no loading is necessary, because the loading can be precomputed and stored on the ROM when the device is made.

Large and complex systems may have boot procedures that proceed in multiple phases until finally the Operating System and other programs are loaded and ready to execute. Because Operating Systems are designed as if they never start or stop, a boot loader might load the Operating System, configure itself as a mere process within that system, and then irrevocably transfer control to the Operating System. The boot loader then terminates normally as any other process would.

Boot ROM - Network booting
Most computers are also capable of booting over a computer network. In this scenario, the Operating System is stored on the disk of a server (computing)|server, and certain parts of it are transferred to the client using a simple protocol such as the Trivial File Transfer Protocol. After these parts have been transferred, the Operating System then takes over control of the booting process.

Boot ROM - Boot devices (IBM PC)
Older, less common BIOS-bootable devices include boot floppy|floppy disk drives, SCSI devices, Zip drives, and LS-120 drives.

Typically, the BIOS will allow the user to configure a boot order. If the boot order is set to first, the DVD drive; second, the hard disk drive, then the BIOS will try to boot from the DVD drive, and if this fails (e.g. because there is no DVD in the drive), it will try to boot from the local Hard Drive.

In this example of dual booting, the user chooses by inserting or removing the CD from the computer, but it is more common to choose which Operating System to boot by selecting from a BIOS or UEFI boot menu, by using the computer keyboard; the boot menu is typically entered by pressing or keys during the POST.

Boot ROM - Boot sequence of IBM-PC compatibles
A bootable device is defined as one that can be read from, and where the last two bytes of the first sector contain the little-endian Word (data type)|word AA55h, found as byte sequence 55h, AAh on disk (also known as the MBR boot signature), or where it is otherwise established that the code inside the sector is executable on x86 PCs.

Coreboot splits the initialization and boot services into distinct parts, supporting payloads such as SeaBIOS, TianoCore, GRUB, and Linux kernel|Linux directly (from flash).

If an active partition is found, the MBR code loads the boot sector code from that partition, known as Volume Boot Record (VBR), and executes it.

However, most boot loaders retain 16-bit BIOS call support.Intel Macintosh computers all have firmware with compatibility mode for legacy BIOS operations

Boot ROM - Other kinds of boot sequences
This feature is often used for system recovery purposes when for some reasons usual boot software in non-volatile memory got erased

This allows, for example, the recovery of embedded systems where no software remains on any supported boot device, and where the processor does not have any integrated boot ROM

In other cases such interfaces could be created by software running in integrated on-chip boot ROM from GPIO pins.

* Parallel mode boot, such as the host port interface (HPI boot)

Boot ROM - Quick boot Several devices are available that enable the user to quick-boot to a usually Linux-powered OS for various simple tasks such as Internet access (such as Splashtop and Latitude ON).

Photo Booth 'Photo Booth' is a small software application for taking photos and videos with an iSight webcam|camera by Apple Inc. for Mac OS X and IOS (Apple)|iOS (although only available on the iPad, starting with the iPad 2).

Photo Booth Photo Booth consists of a single window containing a large viewer which provides a preview when taking photo snapshots or video clips. Thumbnails of saved photos and videos are displayed along the bottom of the window. These can be shown or played by double clicking on the thumbnails. There are also backdrops to go along with the setting or video you are doing.

Photo Booth Clicking the large red button underneath the preview area starts a 3-second countdown, after which a photo is snapped or a video clip begins recording, depending on which setting is selected

Photo Booth - Mac Version
Photo Booth has two sets of image effects that can be applied when taking a picture. The first set may be described to contain photographic filters similar to those in Adobe Photoshop:

Photo Booth - Standard effects
Many more can be downloaded from websites, including apple|apple.com

Photo Booth - Backdrops
Photo Booth incorporates this technology by recognizing a still background, then replacing it with either a pre-set image or movie clip, or allowing the user to choose their own background

* Clouds (image)

Backgrounds are only available on Macs featuring an Intel processor. By default, Photo Booth's live preview and captured images are reversed horizontally, to simulate the user looking into a mirror; however, it can flip the image automatically or upon request to provide a true-to-life representation.

4FFF N Dual-boot The devices seem to contain a native dual-boot capability. When a device specific key combination is pressed during power-on any linux-kernel + ramdisk combination is booted from the sd-card.

A reboot is a type of sequel which technically is not a sequel
Sequel - Reboot A reboot is a type of sequel which technically is not a sequel

Motorola Droid - Locked bootloader
Unlike the DROID, the Milestone has a bootloader that only allows signed firmware to load. This creates difficulties for users who wish to boot custom ROM images not signed by Motorola that have become popular in the Droid modding community. This has caused discontent in the Droid community in markets foreign to the US, with numerous petitions being created. Whether the disabling of custom boot loaders is due to retailer, carrier, manufacturer, or legal restrictions is unknown.

Early in 2011 the community around Milestone ROM-Development and the Polish National BOINC Team initiated AndrOINC[ AndrOINC] to decipher the RSA 1024-bit signature and make customizing possible. The project has been down since April 2011 because the German police confiscated the server on suspicion it was involved with an illegal P2P service.

In June 2011, Motorola committed to delivering an unlockable/relockable bootloader solution for phones receiving updates later that year. This will likely not include the Milestone as Motorola has not indicated it will update the Milestone past Android 2.2/Froyo.

Douglas Engelbart - Bootstrap and the Doug Engelbart Institute
By the early 1990s there was sufficient interest among his seminar graduates to launch a collaborative implementation of his work, and the Bootstrapping|Bootstrap Alliance was formed as a non-profit home base for this effort

Douglas Engelbart - Bootstrap and the Doug Engelbart Institute
The Institute promotes Engelbart's philosophy for boosting Collective IQ—the concept of dramatically improving how we can solve important problems together—using a strategic bootstrapping approach for accelerating our progress toward that goal

Doom 4 - Production reboot and development hell
In April 2013, Kotaku published an article describing Doom 4 as trapped in development hell

Doom 4 - Production reboot and development hell
Tim Willits commented to IGN during Quakecon 2013, Every game has a soul

Entrepreneur - Financial Bootstrapping
* [ Owner financing]

Deicing boot A 'deicing boot' is a type of ice protection system installed on aircraft surfaces to permit a mechanical deicing in flight. Such boots are generally installed on the leading edges of wings and flight control surfaces|control surfaces (e.g. horizontal stabilizer|horizontal and vertical stabilizer) as these areas are most likely to accumulate ice and any contamination could severely affect the aircraft's performance.

Deicing boot - Design A deicing boot consists of a thick rubber membrane that is installed over the surface to be deiced. As atmospheric icing occurs and ice builds up, a pneumatic system inflates the boot with compressed air. This expansion in size cracks any ice that has accumulated, and this ice is blown away into the airflow. The boots are then deflated to return the wing or surface to its optimal shape.

Deicing boot - Design The use of deicing boots may enable some aircraft to be certified for flight into known icing conditions.

Deicing boot - Design Several disadvantages are associated with the use of deicing boots. Boots need to be replaced frequently (on the order of 2–3 years), and require proper care. Holes in the boot may create air leaks that will decrease the effectiveness of the boots. As such, boots must be carefully inspected before each flight and any holes or cuts must be patched.

Deicing boot - Design The use of boots may not be sufficient to handle extremely severe icing. In these cases, ice can accumulate faster than the boots can shed it, or ice can accumulate on non-booted surfaces to the point where it disrupts airflow enough to cause a dangerous loss of lift or control.

Deicing boot - Invention and use
[ Artificial Blizzards Help To Protect Planes, February 1931, Popular Mechanics] illustration of blizzard machine and how de-icing boots work [ Overshoes For Planes End Ice Danger, November 1931, Popular Science] bottom of page 28

Deicing boot - Invention and use
Deicing boots are most commonly seen on medium-sized airliners and utility aircraft. Larger airliners and military jets tend to use heating systems that are installed underneath the wing's leading edge, keeping it constantly warm and preventing ice from forming.

Deicing boot - Alternatives
Other deicing techniques for larger commercial aircraft include electrothermal systems and bleed air systems

Deicing boot - Alternatives
Boeing uses electrothermal ice protection on the wings of the Boeing 787 Dreamliner|787. Electrothermal ice protection systems are being considered more often than boots and bleed air systems on commercial aircraft. General aviation jet manufacturers also are studying the effect on thrust and fuel consumption of bleed air and additional benefits of its removal.paper AIAA by John Ensign and Dr. John Gallman from the Cessna Aircraft Company

Ice protection system - Pneumatic deicing boots
The deicing boot|pneumatic boot is a Synthetic rubber|rubber device attached to a wing's leading edge, invented by the Goodrich Corporation (previously known as B.F. Goodrich) in Portions of the boot are alternately inflated and deflated to break ice off the boot, de-icing the wing. Rubber boots are used on jets and propeller driven aircraft.

El Torito (CD-ROM standard) - Boot modes
This is useful for computers built before about 1999, which were designed to boot only from floppy drive

The BIOS will assign a BIOS drive number to the CD drive. The drive number (for INT 13H|INT 13h) assigned is any of 80 (hard disk emulation), 00 (floppy disk emulation) or an arbitrary number if the BIOS should not provide emulation.

Emulation allows older operating systems to be booted from a CD, by making it appear to them as if they were booted from a hard or floppy disk.

Earth: Final Conflict - Spin-Off and Possible Reboot
The series finale hinted that a new show would evolve wherein Renee Palmer would travel through space seeking out other species that Earth can befriend, essentially the basis of Gene Roddenberry's Star Trek. But the proposed series never materialized.

Earth: Final Conflict - Spin-Off and Possible Reboot
In 2009 there was talk that the Canadian Broadcasting Company|CBC network were interested in rebooting the show. So far there is no word if such a project will happen.

Ratchet and Clank - Ratchet Clank Future: Quest for Booty
Ratchet Clank Future: Quest for Booty is a short game developed by Insomniac Games and was released on August 21, 2008 for the PlayStation 3 PlayStation Network. It was later released as a Blu-ray disc in Europe and Asia, but not North America. It is also known as Ratchet Clank: Quest for Booty in most PAL regions and as Ratchet Clank Future Gaiden: Kaizoku Dark Water no Hihou in Japan.

Ratchet and Clank - Ratchet Clank Future: Quest for Booty
Taking place where Tools of Destruction left off, the game focuses on Ratchet and Talwyn's search for Clank

Alias (TV series) - Reboot
In May 2010, E! Online's Kristin Dos Santos reported that ABC was toying with the idea of rebooting Alias, but getting rid of the mythological Rambaldi elements to make the storylines more accessible for a mainstream audience. Subsequently, Entertainment Weekly columnist Michael Ausiello confirmed that ABC was in the early stages of developing a reboot, but that the potential series probably wouldn't make it beyond the development phase.

Bootstrapping 'Bootstrapping' or 'booting' refers to a group of metaphors which refer to a self-sustaining process that proceeds without external help.

Bootstrapping The phrase appears to have originated in the early 19th century United States (particularly in the sense pull oneself over a fence by one's bootstraps), to mean an absurdly impossible action, an adynaton.[ World Wide Words: Boot], Michael Quinion

Bootstrapping He founded an institute The Bootstrap Alliance,[ bootstrap.org] focused on getting better at getting better embodying the notion of the Bootstrap Circuit, taking in feedback from the output and feeding it back in to improve.

Bootstrapping - Etymology
Murphee will now be enabled to hand himself over the Cumberland river or a barn yard fence by the straps of his boots.Jan Freeman, [ Bootstraps and Baron Munchausen], Boston.com, January 27, 2009 In 1860 it appeared in a comment on metaphysical philosophy: The attempt of the mind to analyze itself [is] an effort analogous to one who would lift himself by his own bootstraps.Jan Freeman, [ The unkindliest cut], Boston.com, January 25, 2009 Bootstrap as a metaphor, meaning to better oneself by one's own unaided efforts, was in use in 1922.Ulysses (novel)|Ulysses cited in the Oxford English Dictionary This metaphor spawned additional metaphors for a series of self-sustaining processes that proceed without external help.[ Phrase Finder]

Bootstrapping - Etymology
The term is sometimes attributed to Rudolf Erich Raspe's story wikisource:The Surprising Adventures of Baron Munchausen|The Surprising Adventures of Baron Munchausen, where the main character pulls himself (and his horse) out of a swamp by his hair (specifically, his pigtail), but Baron Münchhausen (1720–1797), a recounter of tall tales, does not, in fact, pull himself out by his bootstraps – and there's no sign that anyone has found an explicit reference to bootstraps in the various versions of the Munchausen tales.

Bootstrapping - Software loading and execution
Booting often involves processes such as performing power-on self-test|self-tests, loading computer configuration|configuration settings, loading a BIOS, resident monitors, a hypervisor, an operating system, or utility software.

Bootstrapping - Software loading and execution
The computer term bootstrap began as a metaphor in the 1950s. In computers, pressing a bootstrap button caused a hardwired control|hardwired program to read a bootstrap program from an input unit. The computer would then execute the bootstrap program, which caused it to read more program instructions. It became a self-sustaining process that proceeded without external help from manually entered instructions. As a computing term, bootstrap has been used since at least 1953.

Bootstrapping - Software development
Bootstrapping can also refer to the development of successively more complex, faster programming environments

Compilers, linkers, loaders, and utilities were then coded in assembly language, further continuing the bootstrapping process of developing complex software systems by using simpler software.

The term was also championed by Doug Engelbart to refer to his belief that organizations could better evolve by improving the process they use for improvement (thus obtaining a compounding effect over time). His SRI International|SRI team that developed the NLS (computer system)|NLS hypertext system applied this strategy by using the tool they had developed to improve the tool.

Bootstrapping - Compilers
The development of compilers for new programming languages first developed in an existing language but then rewritten in the new language and compiled by itself, is another example of the bootstrapping notion. Using an existing language to bootstrap a new language is one way to solve the chicken or the egg causality dilemma.

Bootstrapping - Installers
During the installation of computer programs it is sometimes necessary to update the installer or package manager itself. The common pattern for this is to use a small executable bootstrapper file (e.g. setup.exe) which updates the installer and starts the real installation after the update. Sometimes the bootstrapper also installs other prerequisites for the software during the bootstrapping process.

Bootstrapping - Overlay networks
A bootstrapping node, also known as a rendezvous host, is a Node (networking)|node in an overlay network that provides initial configuration information to newly joining nodes so that they may successfully join the overlay network.

Bootstrapping - Discrete event simulation
A type of computer simulation called discrete event simulation represents the operation of a system as a chronological sequence of events. A technique called bootstrapping the simulation model is used, which bootstraps initial data points using a pseudorandom number generator to schedule an initial set of pending events, which schedule additional events, and with time, the distribution of event times approaches its steady state—the bootstrapping behavior is overwhelmed by steady-state behavior.

Bootstrapping - Artificial intelligence and machine learning
Bootstrapping is a technique used to iteratively improve a classifier (machine learning)|classifier's performance. Seed AI is a hypothesized type of strong Artificial Intelligence capable of recursion|recursive self-improvement. Having improved itself, it would become better at improving itself, potentially leading to an exponential increase in intelligence. No such AI is known to exist, but it remains an active field of research.

Bootstrapping - Artificial intelligence and machine learning
Seed AI is a significant part of some theories about the technological singularity: proponents believe that the development of seed AI will rapidly yield ever-smarter intelligence (via bootstrapping) and thus a new era.

Bootstrapping - Research
Bootstrapping is a database searching technique. One may perform an inexact search (using keywords, for instance) and retrieve numerous hits, some of which will be on-target. When the researcher looks at a relevant document that comes through in the mix, subject headings will be located within the document. The researcher can then execute a new search using authorized subject headings that will yield more focused, pinpointed results.

Bootstrapping - Statistics
Bootstrapping is a resampling (statistics)|resampling technique used to obtain estimates of summary statistics.

Bootstrapping - Business
Bootstrapping was also expanded upon in the book Bootstrap Business, by Richard J

* Startup company|Startups can grow by reinvesting profits in its own growth if bootstrapping costs are low and return on investment is high.

* Leveraged buyouts, or highly leveraged or bootstrap transactions, occur when an investor acquires a controlling interest in a company's equity and where a significant percentage of the purchase price is financed through leverage, i.e.,borrowing

* Bootstrapping (finance)|Bootstrapping in finance refers to the method to create the Spot contract|spot rate curve

* Operation Bootstrap (Operación Manos a la Obra) refers to the ambitious projects that industrialized Puerto Rico in the mid-20th century

Bootstrapping - Biology
Richard Dawkins in his book River Out of EdenRichard Dawkins, River Out of Eden, pages 23-25, 1995 (paper) ISBN used the computer bootstrapping concept to explain how biological cells differentiate: Different cells receive different combinations of chemicals, which switch on different combinations of genes, and some genes work to switch other genes on or off. And so the bootstrapping continues, until we have the full repertoire of different kinds of cells.

Bootstrapping - Phylogenetics
Bootstrapping analysis gives a way to judge the strength of support for clades on phylogenetic trees. A number is written by a node, which reflects the percentage of bootstrap trees which also resolve the clade at the endpoints of that branch.

Bootstrapping - Law Bootstrapping is a rule preventing the admission of hearsay evidence in conspiracy cases.

Bootstrapping - Linguistics
Bootstrapping is a theory of language acquisition.

Bootstrapping - Physics
Bootstrapping is using very general consistency criteria to determine the form of a quantum theory from some assumptions on the spectrum of particles.

Bootstrapping - Electronics
Bootstrapping is a form of positive feedback in analog circuit design.

Bootstrapping - Power stations
A black start is the process of restoring a power station to operation without relying on the external electric power transmission network. In the absence of grid power, a so-called black start needs to be performed to bootstrap the power grid into operation.

Bootstrapping - Cellular networks
A Bootstrapping Server Function (BSF) is an intermediary element in cellular networks which provides application independent functions for mutual authentication of user equipment and servers unknown to each other and for 'bootstrapping' the exchange of secret session keys afterwards. The term 'bootstrapping' is related to building a security relation with a previously unknown device first and to allow installing security elements (keys) in the device and the BSF afterwards.

Island Press - Conservation Finance Boot Camp
Island Press published three of the textbooks for this course, and in 2010 sponsored the first Western Conservation Finance Boot Camp at Stanford University

Inline skates - Boot For most skating a high boot is used, which provides more ankle support and is easier to skate in, particularly for beginners. Speed skaters often use a carbon fiber boot which provides greater support with a lower cut allowing more ankle flexion.

Inline skates - Boot For recreational skating a soft boot is used for greater comfort, but many other disciplines prefer a harder boot, either to protect the foot against impact or for better control of the skate. The boot may also contain shock absorbent padding for comfort. Downhill skaters often use boots that are heat-molded to the shape of the foot, with a foam liner.

Inline skates - Boot Most aggressive skates use a hard boot or a hard/soft boot for increased support.

Disk encryption - The boot key problem
This ensures that authentication can take place in a controlled environment without the possibility of a bootkit being used to subvert the pre-boot decryption.

With a Pre-Boot Authentication environment, the key used to encrypt the data is not decrypted until an external key is input into the system.

Solutions for storing the external key include:

* Using a biometric authentication method such as a fingerprint

* Using a dongle to store the key, assuming that the user will not allow the dongle to be stolen with the laptop or that the dongle is encrypted as well.

* Using a boot-time driver that can ask for a password from the user

* Using a network interchange to recover the key, for instance as part of a Preboot Execution Environment|PXE boot

* Using a Trusted Platform Module|TPM to store the decryption key, preventing unauthorized access of the decryption key or subversion of the boot loader.

* Use a combination of the above

All these possibilities have varying degrees of security, however most are better than an unencrypted disk.

Atmel AVR - Bootloader Most AVR models can reserve a bootloader region, 256B to 4KB, where re-programming code can reside. At reset, the bootloader runs first, and does some user-programmed determination whether to re-program, or jump to the main application. The code can re-program through any interface available, it could read an encrypted binary through an Ethernet adapter like Preboot Execution Environment|PXE. Atmel has application notes and code pertaining to many bus interfaces.

USB memory stick - Booting operating systems
!-- This image is of a drive not supported by Microsoft any longer, so it should be replaced by something supported

Most current PC firmware permits booting from a USB drive, allowing the launch of an Operating System from a bootable flash drive. Such a configuration is known as a Live USB.

Original flash memory designs had very limited estimated lifetimes

* Loading a minimal, hardened Kernel (computing)|kernel for embedded applications (e.g., network router, firewall).

* Maintenance tasks, such as virus scanning or low-level data repair, without the primary host Operating System loaded.

As of 2011, newer flash memory designs have much higher estimated lifetimes

The X Factor (UK) - Bootcamp and judges' houses
In early series this allocation took place after completion of the auditions and prior to bootcamp, but from series 4, all four judges work together at the bootcamp stage

In series 4 and 6, the judges found out which category they would be mentoring at the same time that the contestants found out their mentor, but in series 5 and 7 the contestants did not know who their mentor was until they revealed themselves at the house. The judges then disband for the judges' houses round, where they reduce their six acts to three for the live shows. In series 7 and 8, a total of 32 acts went through to judges' houses, giving each judge eight acts instead of six.

From series 10, the format to bootcamp changed: the judges found out their categories before bootcamp started

Boot Camp (software) The utility also installs a Windows Control Panel applet for selecting the boot operating system.

Boot Camp (software) However, with the release of Boot Camp 5.0 for OS X Mountain Lion version , only 64-bit computing|64-bit versions of Windows 7 and Windows 8 are officially supported

Boot Camp (software) - Overview
Holding down the option key (⌥) at startup brings up the boot manager, allowing the user to choose which operating system to start up. When using a non-Apple keyboard, the alt key usually performs the same action. The boot manager can also be launched by holding down the “menu” button on the Apple Remote at startup.

Boot Camp displaced the open source Xom Project for dual booting Mac OS X and Windows XP.

Its functionality relies on BIOS emulation through Extensible Firmware Interface|EFI and a partition table information synchronization mechanism between GUID Partition Table|GPT and GUID Partition Table#Legacy MBR (LBA 0)|MBR combined.

Boot Camp (software) - OS X Lion and Mountain Lion
Apple's Boot Camp system requirements lists the following requirements for Mac OS X Lion|OS X Lion and Mountain Lion:

* 8Gigabyte|GB USB storage device, or external drive formatted as MS-DOS (File Allocation Table|FAT) for installation of Windows drivers for Mac hardware

* 20GB free hard disk space for a first-time installation or 40GB for an upgrade from a previous version of Windows

* A full version of one of the following operating systems:

** Windows 7 Home Premium, Professional, or Ultimate

Boot Camp (software) - Mac OS X Leopard and Snow Leopard
Apple lists the following requirements for Mac OS X Leopard and Snow Leopard:

* An Intel-based Macintosh computer with the latest firmware (Early Intel-based Macintosh computers require an EFI firmware update for BIOS compatibility).

* A Mac OS X Leopard or Mac OS X Snow Leopard installation disc or Mac OS X Disc 1 included with Macs that have Leopard or Snow Leopard preinstalled; this disc is needed for installation of Windows drivers for Mac hardware

** Windows Vista Home Basic, Home Premium, Business, Enterprise or Ultimate (32-bit and 64-bit editions)

** Windows 7 Home Premium, Professional, Enterprise or Ultimate (32-bit and 64-bit editions)

Boot Camp (software) - Supported Macintosh computers with Windows 8
The earliest Macintosh models that support Windows 8 are the mid-2011 MacBook Air, 13-inch-mid-2011 or 15 and 17-inch-mid-2010 MacBook Pro, mid-2011 Mac Mini, 21-inch-mid-2011 or 27-inch-mid-2010 iMac, and early 2009 Mac Pro.

Boot Camp (software) - Limitations
Officially Boot Camp does not work on Mac OS X Lion and later releases if more than three primary OS X partitions exist on the target hard drive. Since on Mac OS X Lion, the Mac operating system itself consumes three partitions (EFI, Mac OS X, and Recovery), effectively there can only be one partition other than Boot Camp. Thus, for example, it is not officially possible to create a data partition.

Boot Camp (software) - Limitations
There are alternatives to Boot Camp like rEFIt which are not subject to these limitations. There is also a work around for Mac OSX Lion which involves interrupting the standard procedure after creating the Boot Camp partition, resizing the primary OS X partition and creating a third partition in the now available space, then continuing with the Windows install.

Bootstrap aggregating
'Bootstrap aggregating' ('bagging') is a Ensemble learning|machine learning ensemble meta-algorithm designed to improve the stability and accuracy of machine learning algorithms used in statistical classification and Regression analysis|regression

Bootstrap aggregating - Description of the technique
The m models are fitted using the above m bootstrap samples and combined by averaging the output (for regression) or voting (for classification).

Bootstrap aggregating - Description of the technique
Bagging leads to improvements for unstable procedures (Breiman, 1996), which include, for example, neural nets, classification and regression trees, and subset selection in linear regression (Breiman, 1994)

Bootstrap aggregating - Example: Ozone data
To illustrate the basic principles of bagging, below is an analysis on the relationship between ozone and temperature (data from Peter Rousseeuw|Rousseeuw and Leroy (1986), available at classic data sets, analysis done in R (programming language)|R).

The relationship between temperature and ozone in this data set is apparently non-linear, based on the scatter plot. To mathematically describe this relationship, local regression|LOESS smoothers (with span 0.5) are used.

For each bootstrap sample, a LOESS smoother was fit

But taking the average of 100 smoothers, each fitted to a subset of the original data set, we arrive at one bagged predictor (red line). Clearly, the mean is more stable and there is less overfitting|overfit.

Bootstrap aggregating - Bagging for nearest neighbour classifiers
It is well known that the Bayes classifier|risk of a 1 nearest neighbour (1NN) classifier is at most twice the risk of the Bayes classifier, but there are no guarantees that this classifier will be Bayes classifier|consistent

Bootstrap aggregating - Bagging for nearest neighbour classifiers
Under infinite simulation, the bagged nearest neighbour classifier can be viewed as a weighted nearest neighbour classifier. Suppose that the feature space is d dimensional and denote by C^_ the bagged nearest neighbour classifier based on a training set of size n, with resamples of size n'. In the infinite sampling case, under certain regularity conditions on the class distributions, the Bayes classifier|excess risk has the following asymptotic expansion

Gaston Means - Bootleggers' helper
Although the United States was officially dry during the Harding years as a result of Prohibition, illegal alcohol was common. In the late fall of 1922, Means began selling his services to local Washington Rum-running|bootleggers, with the offer that he could use his connections to fix their legal problems with the government. Some of these fixes were made, and the matter became an embarrassing scandal.

In 1924, following Harding’s death, Congress held hearings on the United States Department of Justice|Justice Department's role in failing to oversee their Prohibition duties under the Volstead Act

The congressional investigation also revealed evidence of Means' own role in the illegal issuance of Prohibition-era liquor permits

Ensemble learning - Bootstrap aggregating (bagging)
Bootstrap aggregating, often abbreviated as bagging, involves having each model in the ensemble vote with equal weight

Wisdom of the crowd - Dialectical Bootstrapping: Improving the estimates of the “crowd within”
Results of this study revealed that while dialectical bootstrapping did not out perform the wisdom of the crowd (averaging each participants’ first estimate with that of a random other participant), it did render better estimates than simply asking individuals to make two estimates.

Hirt and Markman (1995) found that participants need not be limited to a consider-the-opposite strategy in order to improve judgments

It should also be noted that not all studies have shown support for the “crowd within” improving judgments

Channel I/O - Booting with channel I/O
Even bootstrapping of the system, or Initial Program Loader|Initial Program Load (IPL) in IBM nomenclature, is carried out by channels: to load the system, a very small, simple channel program is loaded into memory and initiated, and this program causes the first portion of the system loading software to be loaded. The software is then executed once the I/O is completed, and an interrupt is signaled to the CPU.

Apple–Intel architecture - Booting
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 rEFIt bootloader is commonly used for added configurability.

Apple–Intel architecture - Booting
can only be booted in BIOS mode, or are more easily booted or perform better when booted in BIOS mode, and thus USB booting on IntelMacs is largely limited to Mac OS X, which can easily be booted via EFI

International CES - Booth babes controversy
Other publications, like PC Magazine, although aware of the controversy relished however in publishing galleries of booth babes without negative commentary. In 2013, CES organizers released statements in which they claimed that enforcing business casual attire for the exhibitor personnel would be impractical and would detract CES staff on the ground from their main focus of providing security.

International CES - Booth babes controversy
Greenfield notes that other electronics shows like Electronic Entertainment Expo|E3 have adopted a similar practice of encouraging booth babes in the late 1990s, but abandoned it in 2006 after outcry, with E3 organizers later threatening to fine any exhibitor for nudity, partial nudity, and bathing-suit bottoms.

Étoile Sportive du Sahel - Golden Boot
*Raouf Ben Aziza

TurboTax - Writing to the boot track
The 2003 version of the TurboTax software contained digital rights management that tracked whether it had previously been installed on a computer by writing to sector 33 on the hard drive. This allowed it to track if it was on a computer previously, even through reinstalling the operating system. This also caused it to conflict with some boot loaders that store data there, rendering those computers unbootable.

Motor Racing Network - Booth Announcers
*Joe Moore (booth announcer, 2001–present, host of Ned Jarrett's World of Racing.)

*Jeff Striegle (booth announcer, 2013–present, fill in turn announcer.)

*Kurt Becker (booth announcer for Trucks and standalone Nationwide races)

Omni (magazine) - Reboot
In August 2013 plans to launch a new online project, described as an 'Omni reboot' were reported by The Verge

George Gough Booth 'George Gough Booth' (September 24, 1864 – April 11, 1949) was the publisher of the privately held Evening News Association, a co-founder of Booth Newspapers, and a philanthropist.

George Gough Booth - Biography
During Booth's time, the ENA consisted of only the The Detroit News and WWJ (AM)|WWJ AM-FM-WWJ-TV|TV.

George Gough Booth - Biography
He died on April 11, 1949 in Detroit, Michigan. He was buried in Greenwood Cemetery (Birmingham, Michigan)|Greenwood Cemetery in Birmingham, Michigan.

George Gough Booth - Philanthropy
As their country estate grew both in purpose and in scale, Booth had both noted architect Eliel Saarinen and renowned sculptor Carl Milles in residence for many years at CEC.

George Gough Booth - Philanthropy
Booth was an avid student of the Arts and Crafts movement and, together, brothers Ralph and George Booth were major benefactors of the Detroit Institute of Arts.

George Gough Booth - Legacy
Booth newspapers|Booth Newspapers was sold to Advance Publications, a Samuel I. Newhouse property, in WWJ (AM)|WWJ AM-FM-WWJ-TV|TV was eventually sold to the Gannett Company in MediaNews Group owns The Detroit News.

NASCAR on Fox - Broadcast booth
For full races on Sunday, Waltrip is positioned initially in the studio for the show's pre-race segments.

NASCAR on NBC - Booth Announcers
*Rick Allen (television announcer)|Rick Allen (lead announcer)

*Allen Bestwick (lead announcer 1999–2004, Busch Series stand-alone events ; now at ESPN)

*Bill Weber (fill in announcer 2004; lead announcer )

*Benny Parsons (2000–2006, died January 2007)

Build-Operate-Transfer - BOOT (build–own–operate–transfer)
Some advantages of BOOT projects are:

*Encourage private investment

*Inject new foreign capital to the country

*Completing project within time frame and planned budget

*Providing additional financial source for other priority projects

*Releasing the burden on public budget for infrastructure development

AngularJS - The AngularJS Boot Strapper
There are three phases of the AngularJS boot strapper that occur after the DOM completes loading:

AngularJS - The AngularJS Boot Strapper
#Compile service - The Compile service is like compiling in C or C++. It walks the DOM and locates all the directives such as ng-app.

Huawei Ascend G600 - Rooting and Unlocking Bootloader
'csfrank271' published an in-depth article on XDA developers about unlocking the bootloader and gaining root access.

Huawei Ascend G600 - Rooting and Unlocking Bootloader
The article can be found here:

One Laptop per Child - Open source vs. dual-boot systems
OLPC released the first test firmware enabling XO-1 dual-boot on July 3, 2008.

This option did not prove popular. As of 2011, a few pilots had received a few thousand total dual-boot machines, and the new ARM-based machines do not support Windows XP. No significant deployment purchased Windows licenses.[ OLPC blog, September 1, 2011]. Retrieved November 23, 2011.

Negroponte and Charles Kane (business executive)|Charles Kane made statements explaining OLPC's decision to enable XO-1 laptops to dual-boot either open source Fedora or proprietary Microsoft Windows XP:

quote|[Nicholas] Negroponte says that within OLPC, the open-source scrap had become a distraction

JikesRVM - Bootstrap Being metacircular interpreter|meta-circular Jikes RVM requires a bootstrap JVM to run upon to create a boot image. The boot image is a view of the objects Jikes RVM requires to boot created using reflection in the bootstrap JVM. A small C (programming language)|C loader is responsible for loading the boot image at runtime.

Boot loader The computer term boot is short for bootstrapping|bootstrap or bootstrap load and derives from the phrase to Bootstrapping#Etymology|pull oneself up by one's bootstraps

Boot loader - Modern boot loaders

LILO (boot loader) 'LILO' ('LI'nux 'LO'ader) 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, most distributions use GNU GRUB|GRUB as the default boot loader.

LILO does not depend on a specific file system, and can boot an operating system (e.g., Linux kernel|Linux kernel (computer science)|kernel images) from floppy disks and hard disks. One of up to sixteen different images can be selected at boot time. Various parameters, such as the root device, can be set independently for each kernel. LILO can be placed in the master boot record (MBR) or the boot sector of a partition. In the latter case, the MBR must contain code to load LILO.

At system start, only the BIOS device driver|drivers are available for LILO to access hard disks. For this reason, a very old BIOS access area is limited to cylinder 1024|cylinders 0 to 1023 of the first two hard disks. For a later BIOS, LILO can use 32-bit logical block addressing (LBA) to access the entire capacity of the hard disks the BIOS has access to.

The lilo.conf file is typically located at /etc/lilo.conf. Within lilo.conf there are typically two section types. The first section, which defines the global options, contains parameters which specify boot location attributes. The second section(s) contain parameters associated with the operating system images to be loaded. The section type can be repeated for up to 16 different boot selections.

Definition information can be found in the [ LILO] Manpage.

image=/boot/vmlinuz

'Note:' Here LILO offers after correct installation a menu with Linux and FreeBSD.

; (nothing):No part of LILO has been loaded. LILO either isn't installed or the partition on which its boot sector is located isn't active. The boot media is incorrect or faulty.

; L:The first stage boot loader has been loaded and started, but it can't load the second stage boot loader. The two-digit error codes indicate the type of problem. This condition usually indicates a media failure or bad disk parameters in the BIOS.

; LI:The first stage boot loader was able to load the second stage boot loader, but has failed to execute it. This can be caused by bad disk parameters in the BIOS.

; LIL:The second stage boot loader has been started, but it can't load the descriptor table from the map file. This is typically caused by a media failure or by bad disk parameters in the BIOS.

; LIL?:The second stage boot loader has been loaded at an incorrect address. This is typically caused by bad disk parameters in the BIOS.

; LIL-:The descriptor table is corrupt. This can be caused by bad disk parameters in the BIOS.

; LILO:All parts of LILO have been successfully loaded.

VHD (file format) - Native VHD Boot
Native VHD Boot refers to the ability of a physical computer to mount (computing)|mount and boot from an operating system contained within a VHD. Windows 7 Enterprise and Ultimate editions support this ability, both with and without a host operating system present. Windows Server 2008 R2 is also compatible with this feature.

Edward Felten - Cold boot attack
In February 2008, Felten and his students were part of the team that discovered the cold boot attack, which allows someone with physical access to a computer to bypass operating system protections and extract the contents of its memory.

Features new to Windows 8 - Secure boot
Windows 8 supports the UEFI Secure Boot|secure boot mechanism on supported UEFI systems. It uses a public-key infrastructure process to verify the integrity of the Windows boot loaderpreventing malware from infecting the system before the operating system loads. Windows 8.1 displays an on-screen watermark on the desktop if the system supports secure boot but it is disabled, however a patch was later released to remove the watermark.

Apple SOS - Boot sequence
When powered on, the Apple III ran through system diagnostics, then read block number one (zero-indexed) from the built-in diskette drive into memory and executed it

Apple SOS - Boot sequence
Since Apple ProDOS uses the same file system as SOS, and since ProDOS stores its own boot code in block number zero rather than block number one, SOS and ProDOS can co-exist on the same medium. Some software, e.g. ADTPro, makes use of this to store Apple II and Apple III versions of a program on the same disk, which is then bootable on both systems.

NTLDR - boot.ini Though NTLDR can boot DOS and non-NT versions of Windows, boot.ini cannot configure their boot options.

NTLDR - boot.ini For NT-based OSs, the location of the operating system is written as an Advanced RISC Computing (ARC) path.

NTLDR - boot.ini boot.ini is protected from user configuration by having the following file attributes: system, hidden, read-only. To manually edit it, one would first have to remove these attributes.

NTLDR - boot.ini A more secure fashion to edit the file is to use the bootcfg command from a console. bootcfg will also relock the file (setting the file back to system, hidden, and read-only). Additionally, the file can be edited within Windows using a text editor if the folder view option Show hidden files and folders is selected, the folder view option Hide protected operating system files is unchecked, and the Read-only option is unchecked under file properties.

FAT12 - Boot Sector On non-partitioned devices, such as floppy disks, the Boot Sector (Volume Boot Record|VBR) is the first sector (logical sector 0 with physical CHS address 0/0/1 or LBA address 0). For partitioned devices such as hard drives, the first sector is the Master Boot Record defining partitions, while the first sector of partitions formatted with a FAT file system is again the Boot Sector.

Windows Vista startup process - Boot Configuration Data
'Boot Configuration Data' (BCD) is a firmware-independent database for booting|boot-time configuration data. It is used by Microsoft's new Windows Boot Manager and replaces the boot.ini that was used by NTLDR.

Boot Configuration Data are stored in a data file that has the same format as the Windows Registry hives and is eventually loaded at registry key [HKEY_LOCAL_MACHINE\BCD00000]. The file is located either on the EFI System Partition (on machines that use Extensible Firmware Interface firmware) or in \Boot\Bcd on the system partition and boot partition|system volume (on machines that use IBM PC compatible firmware).

Boot Configuration Data may be altered using a command-line tool (bcdedit.exe), using Registry Editor (regedit.exe), using Windows Management Instrumentation, or with third-party tools such as EasyBCD, BOOTICE. or Visual BCD Editor.

Boot Configuration Data contain the menu entries that are presented by the Windows Boot Manager, just as boot.ini contained the menu entries that were presented by NTLDR. These menu entries can include:

* Options to resume Windows Vista from hibernation by invoking winresume.exe.

* Options to load and to execute a volume boot record.

Boot Configuration Data allows for third-party integration, so anyone can implement tools like diagnostics or recovery options.

Windows Deployment Services - WDS automation and dual-boot systems
WDS automated capture and apply do not directly support dual-boot operating systems. Only one operating system at a time can be captured and deployed, and the automated capture process only deals with single partitions containing a sysprepped Windows OS installation. It will not capture data-only partitions.

Windows Deployment Services - WDS automation and dual-boot systems
However, WDS automated capture and apply can be used to duplicate and create dual-boot systems, if each OS is captured and applied separately. Generally, Windows XP and older operating systems need to be applied to the target system before Vista or Windows 7, due to the different boot loaders used by the newer operating systems.

Apple Remote - Boot Camp
Boot Camp 5, the latest version of the software, also includes drivers for the remote control.

Extensible Firmware Interface - UEFI booting
The UEFI specification defines a boot manager, a firmware policy engine that is in charge of loading the operating system loader and all necessary drivers. The boot configuration is controlled by a set of global NVRAM variables, including boot variables that indicate the paths to the loaders.

UEFI does not rely on a boot sector, although ESP provides space for it as part of the backwards compatibility.

UEFI booting from GPT disks is commonly called UEFI-GPT.

Boot loaders can also be automatically detected by the UEFI firmwares, to enable booting from removable devices. Auto-detection relies on a standardized file path to the operating system loader, depending on the actual architecture to boot. Format of the file path is defined as /BOOT/BOOT.EFI, e.g. /efi/BOOT/BOOTX64.EFI.

It is common for UEFI firmware to include a user interface to the boot manager, to allow the user to select and load the operating system among the possible options.

Extensible Firmware Interface - CSM booting
For backwards compatibility, most of the UEFI implementations on PC-class machines also support booting in legacy BIOS mode from MBR-partitioned disks, through the Compatibility Support Module (CSM) which provides legacy BIOS compatibility. In that scenario, booting is performed in the same way as on legacy BIOS-based systems, by ignoring the partition table and relying on the content of a boot sector.

BIOS booting from MBR-partitioned disks is commonly called BIOS-MBR, regardless of it being performed on UEFI or legacy BIOS-based systems. As a side note, booting legacy BIOS-based systems from GPT disks is also possible, and it is commonly called BIOS-GPT.

Despite the fact MBR partition tables are required to be fully supported within the UEFI specification, some UEFI firmwares immediately switch to the BIOS-based CSM booting depending on the type of boot disk's partition table, thus preventing UEFI booting to be performed from EFI System partitions on MBR-partitioned disks. Such a scheme is commonly called UEFI-MBR.

Extensible Firmware Interface - Network booting
UEFI specification includes support for booting over network through the Preboot Execution Environment|Preboot eXecution Environment (PXE). Underlying network protocols include Internet Protocol (IPv4 and IPv6), User Datagram Protocol (UDP), Dynamic Host Configuration Protocol (DHCP) and Trivial File Transfer Protocol (TFTP).

Extensible Firmware Interface - Network booting
Included is also support for boot images remotely stored on storage area networks (SANs), with iSCSI|Internet Small Computer System Interface (iSCSI) and Fibre Channel over Ethernet (FCoE) as supported protocols for accessing the SANs.

Extensible Firmware Interface - Secure boot
Secure boot can also be placed in Custom mode, where additional public keys can be added to the system that do not match the private key.

Secure boot is supported by Windows 8, Windows Server 2012, and selected Linux distributions.

Microsoft denied that the secure boot requirement was intended to serve as a form of lock-in, and clarified its requirements by stating that systems certified for Windows 8 must allow secure boot to enter custom mode or be disabled, but not on systems using the ARM architecture.

Former Red Hat developer Matthew Garrett noted that conditions in the GNU General Public License version 3 may prevent the use of the GNU GRUB|GRUB bootloader without a distribution's developer disclosing the private key (however, the Free Software Foundation has since clarified its position, assuring that the responsibility to make keys available was held by the hardware manufacturer), and that it would also be difficult for advanced users to build custom Linux kernel|kernels that could function with secure boot enabled without self-signing them

Canonical also maintains its own private key to sign installations of Ubuntu pre-loaded on certified OEM computers that run the operating system, and also plans to enforce a secure boot requirement as wellrequiring both a Canonical key and a Microsoft key (for compatibility reasons) to be included in their firmware

However, the proposal was criticized by Linux creator Linus Torvalds, who attacked Red Hat for supporting Microsoft's control over the secure boot infrastructure.

On March 26, 2013, the Spain|Spanish free software development group Hispalinux filed a formal complaint with the European Commission, contending that Microsoft's secure boot requirements on OEM systems were obstructive and anti-competitive practices|anti-competitive.

At the Black Hat Briefings|Black Hat conference in August 2013, a group of security researchers presented a series of exploits in specific vendor implementations of UEFI that could be used to exploit secure boot.

Preboot Execution Environment
The 'Preboot eXecution Environment' ('PXE', also known as 'Pre-Execution Environment'; sometimes pronounced pixie) is an environment to booting|boot computers using a network interface card|network interface independently of data storage devices (like hard disks) or installed operating systems.

Preboot Execution Environment - Overview
It makes use of several network protocols like Internet Protocol (IPv4), User Datagram Protocol (UDP), Dynamic Host Configuration Protocol (DHCP) and Trivial File Transfer Protocol (TFTP) and of concepts like globally unique identifier (GUID), universally unique identifier (UUID) and Universal Network Device Interface and extends the firmware of the PXE Client (Computing)|client (the computer to be Bootstrapping|bootstrapped via PXE) with a set of predefined application programming interfaces (APIs).

Preboot Execution Environment - Overview
The firmware on the client tries to locate a PXE redirection service on the network (Proxy DHCP) in order to receive information about available PXE boot servers. After parsing the answer, the firmware will ask an appropriate boot server for the Path (computing)|file path of a #Network bootstrap program|network bootstrap program (NBP), download it into the computer's random-access memory (RAM) using Trivial File Transfer Protocol|TFTP, possibly verify it, and finally execute it.

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