Boo from FOLDOC

There is a tradition in hackerdom of informally tagging important textbooks and standards documents with the dominant colour of their covers or with some other conspicuous feature of the cover. Many of these are described in this dictionary under their own entries. See Aluminum Book, Blue Book, Cinderella Book, Devil Book, Dragon Book, Green Book, Orange Book, Pink-Shirt Book, Purple Book, Red Book, Silver Book, White Book, Wizard Book, Yellow Book, bible, rainbow series.

[Jargon File]

Last updated: 1996-12-03

Bookviewer

A hypertext documentation system from Oracle based on Oracle Toolkit. It allows the user to create private links and bookmarks, and to make multimedia annotations.

bool

Boolean

<logic>

1. Boolean algebra.

<programming>

2. (bool) The type of an expression with two possible values, "true" and "false". Also, a variable of Boolean type or a function with Boolean arguments or result. The most common Boolean functions are AND, OR and NOT.

Last updated: 1997-12-01

Boolean algebra

<logic>

(After the logician George Boole)

1. Commonly, and especially in computer science and digital electronics, this term is used to mean two-valued logic.

2. This is in stark contrast with the definition used by pure mathematicians who in the 1960s introduced "Boolean-valued models" into logic precisely because a "Boolean-valued model" is an interpretation of a theory that allows more than two possible truth values!

Strangely, a Boolean algebra (in the mathematical sense) is not strictly an algebra, but is in fact a lattice. A Boolean algebra is sometimes defined as a "complemented distributive lattice".

Boole's work which inspired the mathematical definition concerned algebras of sets, involving the operations of intersection, union and complement on sets. Such algebras obey the following identities where the operators ^, V, - and constants 1 and 0 can be thought of either as set intersection, union, complement, universal, empty; or as two-valued logic AND, OR, NOT, TRUE, FALSE; or any other conforming system.

 a ^ b = b ^ a    a V b  =  b V a     (commutative laws)
 (a ^ b) ^ c  =  a ^ (b ^ c)
 (a V b) V c  =  a V (b V c)          (associative laws)
 a ^ (b V c)  =  (a ^ b) V (a ^ c)
 a V (b ^ c)  =  (a V b) ^ (a V c)    (distributive laws)
 a ^ a  =  a    a V a  =  a           (idempotence laws)
 --a  =  a
 -(a ^ b)  =  (-a) V (-b)
 -(a V b)  =  (-a) ^ (-b)             (de Morgan's laws)
 a ^ -a  =  0    a V -a  =  1
 a ^ 1  =  a    a V 0  =  a
 a ^ 0  =  0    a V 1  =  1
 -1  =  0    -0  =  1

There are several common alternative notations for the "-" or logical complement operator.

If a and b are elements of a Boolean algebra, we define a <= b to mean that a ^ b = a, or equivalently a V b = b. Thus, for example, if ^, V and - denote set intersection, union and complement then <= is the inclusive subset relation. The relation <= is a partial ordering, though it is not necessarily a linear ordering since some Boolean algebras contain incomparable values.

Note that these laws only refer explicitly to the two distinguished constants 1 and 0 (sometimes written as LaTeX \top and \bot), and in two-valued logic there are no others, but according to the more general mathematical definition, in some systems variables a, b and c may take on other values as well.

Last updated: 1997-02-27

Boolean logic

<logic>

A logic based on Boolean algebra.

Last updated: 1995-03-25

Boolean search

<information science>

(Or "Boolean query") A query using the Boolean operators, AND, OR, and NOT, and parentheses to construct a complex condition from simpler criteria. A typical example is searching for combinatons of keywords on a web search engine.

Examples:

 car or automobile

 "New York" and not "New York state"

The term is sometimes stretched to include searches using other operators, e.g. "near".

Not to be confused with binary search.

Boole, George

George Boole

Booster

A data-parallel language.

"The Booster Language", E. Paalvast, TR PL 89-ITI-B-18, Inst voor Toegepaste Informatica TNO, Delft, 1989.

boot

bootstrap

boot block

<operating system>

A program on a hard disk, floppy disk or other media, which is loaded when the computer is turned on or rebooted and which controls the next phase of loading the actual operating system. The loading and execution of the boot block is usually controlled by firmware in ROM or PROM. It may be at some fixed location possibly or may be pointed to by the master boot record.

Last updated: 2009-05-19

boot disk

<operating system>

The magnetic disk (usually a hard disk) from which an operating system kernel is loaded (or "bootstrapped"). This second phase in system start-up is performed by a simple bootstrap loader program held in ROM, possibly configured by data stored in some form of writable non-volatile storage.

MS-DOS and Microsoft Windows can be configured (in the BIOS) to try to boot off either floppy disk or hard disk, in either order. By default they first check for the presence of a floppy disk in the drive at start-up and try to use that as a boot disk if present. If no disk is in the drive they then try to boot off the hard disk.

Some operating systems, notably SunOS and Solaris, can be configured to boot from a network rather than from disk. Such a system can thus run as a diskless workstation.

Last updated: 1997-06-09

booting

bootstrap

BOOTP

The Bootstrap Protocol.

A protocol described in RFCs 951 and 1084 and used for booting diskless workstations.

Last updated: 1995-02-16

bootstrap

<operating system, compiler>

To load and initialise the operating system on a computer. Normally abbreviated to "boot". From the curious expression "to pull oneself up by one's bootstraps", one of the legendary feats of Baron von Munchhausen. The bootstrap loader is the program that runs on the computer before any (normal) program can run. Derived terms include reboot, cold boot, warm boot, soft boot and hard boot.

The term also applies to the use of a compiler to compile itself. The usual process is to write an interpreter for a language, L, in some other existing language. The compiler is then written in L and the interpreter is used to run it. This produces an executable for compiling programs in L from the source of the compiler in L. This technique is often used to verify the correctness of a compiler. It was first used in the LISP community.

bootstrap loader

<operating system>

A short program loaded from non-volatile storage and used to bootstrap a computer.

On early computers great efforts were expended on making the bootstrap loader short, in order to make it easy to toggle in via the front panel switches. It was just clever enough to read in a slightly more complex program (usually from punched cards or paper tape), to which it handed control. This program in turn read the application or operating system from a magnetic tape drive or disk drive. Thus, in successive steps, the computer "pulled itself up by its bootstraps" to a useful operating state.

Nowadays the bootstrap loader is usually found in ROM or EPROM, and reads the first stage in from a fixed location on the disk, called the "boot block". When this program gains control, it is powerful enough to load the actual OS and hand control over to it. A diskless workstation can use bootp to load its OS from the network.

Last updated: 2005-04-12

boot virus

An MS-DOS virus that infects the boot record program on hard disks and floppy disks or the master boot record on hard disks. The virus gets loaded into memory before MS-DOS and takes control of the computer, infecting any floppy disks subsequently accessed. An infected boot disk may stop the computer starting up at all.

Last updated: 1995-02-16

Nearby terms:

bondage-and-discipline language ♦ bonk/oif ♦ Booch method ♦ book ♦ bookmark

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