Bit Map-through-Boot Disk
A/B Switch box ~ America On-line AMI BIOS ~ Arithmetic Operation ARP ~ AVI Backbone ~ Bit Image Bit Map ~ Boot Disk Boot Drive ~ Bytes Per Inch C++ ~ Carrier Frequency carrier system ~ certification CGI ~ Chooser extension cipher ~ Clipper Chip clock ~ color color bits ~ communications satellite communications server ~ computer security CON ~ copy copy program ~ cycle time daemon ~ defragmentation demand paging ~ digitize DikuMUD ~ disk disk buffer ~ Document Style Semantics and Specification Language document window ~ dynamic Web page Easter egg ~ erase erase head ~ ezine F2F ~ finger2 firewall ~ font suitcase footer ~ FYI Game Control Adapter ~ GUI HAL ~ hot key1 hot key2 ~ Hz i486DX ~ internal modem internet ~ ISO 9660 ISO/OSI model ~ just-in-time K1 ~ knowledge base L1 cache ~ LU luggable computer ~ LZW compression MAC ~ MILNET mime ~ msec MTBF ~ MYOB named anchor ~ network drive Network File System ~ number crunching object ~ overwrite mode P5 ~ PC/XT keyboard PDA ~ pipeline processing piracy ~ preventive maintenance preview ~ pwd quasi-language ~ QWERTY keyboard R&D ~ registration marks Registry ~ RFI RF shielding ~ run-time library SAA ~ server error server push-pull ~ soft return software ~ style sheet stylus ~ System T1 ~ ToggleKeys token ~ typography UART ~ uupc V.120 ~ view2 viewer ~ VxD w3 ~ WinG WINS ~ WWW X.25 ~ X Windows Yahoo! ~ yotta- Z39.50 standard ~ Zulu time
bit map
or bitmap n. A data structure in memory that represents information in the form of a collection of individual bits. A bit map is used to represent a bit image. Another use of a bit map in some systems is the representation of the blocks of storage on a disk, indicating whether each block is free (0) or in use (1). See also bit image, pixel image.
bitmapped font
n. A set of characters in a particular size and style in which each character is described as a unique bit map (pattern of dots). Macintosh screen fonts are examples of bitmapped fonts. See also downloadable font, outline font, TrueType. Compare PostScript font, vector font.
bitmapped graphics
n. Computer graphics represented as arrays of bits in memory that represent the attributes of the individual pixels in an image (one bit per pixel in a black-and-white display, multiple bits per pixel in a color or gray-scale display). Bitmapped graphics are typical of paint programs, which treat images as collections of dots rather than as shapes. See also bit image, bit map, pixel image. Compare object-oriented graphics.
BITNET
n. Acronym for Because It's Time Network. A wide area network, founded in 1981 and operated by the Corporation for Research and Educational Networking (CREN) in Washington, D.C., used to provide e-mail and file transfer services between mainframe computers at educational and research institutions in North America, Europe, and Japan. BITNET uses the IBM Network Job Entry (NJE) protocol rather than TCP/IP, but it can exchange e-mail with the Internet. The listserv software for maintaining mailing lists was originated on BITNET.
bit. newsgroups
n. A hierarchy of Internet newsgroups that mirror the content of some BITNET mailing lists. See also BITNET.
bit pattern
n. 1. A combination of bits, often used to indicate the possible unique combinations of a specific number of bits. For example, a 3-bit pattern allows 8 possible combinations and an 8-bit pattern allows 256 combinations. 2. A pattern of black and white pixels in a computer system capable of supporting bitmapped graphics. See also pixel.
bits per inch
n. A measure of data storage capacity; the number of bits that fit into an inch of space on a disk or a tape. On a disk, bits per inch are measured based on inches of circumference of a given track. See also packing density. Acronym: BPI.
bit stream
n. 1. A series of binary digits representing a flow of information transferred through a given medium. 2. In synchronous communications, a continuous flow of data in which characters in the stream are separated from one another by the receiving station rather than by markers, such as start and stop bits, inserted into the data.
bit stuffing
n. The practice of inserting extra bits into a stream of transmitted data. Bit stuffing is used to ensure that a special sequence of bits appears only at desired locations. For example, in the HDLC, SDLC, and X.25 communications protocols, six 1 bits in a row can appear only at the beginning and end of a frame (block) of data, so bit stuffing is used to insert a 0 bit into the rest of the stream whenever five 1 bits appear in a row. The inserted 0 bits are removed by the receiving station to return the data to its original form. See also HDLC, SDLC, X.25.
BIX
n. Acronym for BYTE Information Exchange. An online service originated by BYTE magazine, now owned and operated by Delphi Internet Services Corporation. BIX offers e-mail, software downloads, and conferences relating to hardware and software.
black box
n. A unit of hardware or software whose internal structure is unknown but whose function is documented. The internal mechanics of the function do not matter to a designer who uses a black box to obtain that function. For example, a memory chip can be viewed as a black box. Many people use memory chips and design them into computers, but generally only memory chip designers need to understand their internal operation.
blackout
n. A condition in which the electricity level drops to zero; a complete loss of power. A number of factors cause a blackout, including natural disasters, such as a storm or an earthquake, or a failure in the power company's equipment, such as a transformer or a power line. A blackout might or might not damage a computer, depending on the state of the computer when the blackout occurs. As with switching a computer off before saving any data, a blackout will cause all unsaved data to be irretrievably lost. The most potentially damaging situation is one in which a blackout occurs while a disk drive is reading information from or writing information to a disk. The information being read or written will probably become corrupted, causing the loss of a small part of a file, an entire file, or the entire disk; the disk drive itself might suffer damage as a result of the sudden power loss. The only reliable means of preventing damage caused by a blackout is to use a battery-backed uninterruptible power supply (UPS). See also UPS. Compare brownout.
blank1
n. The character entered by pressing the spacebar. See also space character.
blank2
vb. To not show or not display an image on part or all of the screen.
bleed
n. In a printed document, any element that runs off the edge of the page or into the gutter. Bleeds are often used in books to mark important pages so they are easier to find. See also gutter.
blink
vb. To flash on and off. Cursors, insertion points, menu choices, warning messages, and other displays on a computer screen that are intended to catch the eye are often made to blink. The rate of blinking in a graphical user interface can sometimes be controlled by the user.
block1
n. 1. Generally, a contiguous collection of similar things that are handled together as a whole. 2. A section of random access memory temporarily assigned (allocated) to a program by the operating system. 3. A group of statements in a program that are treated as a unit. For example, if a stated condition is true, all of the statements in the block are executed, but none are executed if the condition is false. 4. A unit of transmitted information consisting of identification codes, data, and error-checking codes. 5. A collection of consecutive bytes of data that are read from or written to a device (such as a disk) as a group. 6. A rectangular grid of pixels that are handled as a unit. 7. A segment of text that can be selected and acted upon as a whole in an application.
block2
vb. 1. To distribute a file over fixed-size blocks in storage. 2. To prevent a signal from being transmitted. 3. To select a segment of text, by using a mouse, menu selection, or cursor key, to be acted upon in some way, such as to format or to delete the segment.
block cursor
n. An on-screen cursor that has the same width and height in pixels as a text-mode character cell. A block cursor is used in text-based applications, especially as the mouse pointer when a mouse is installed in the system. See also character cell, cursor (definition 1), mouse pointer.
block diagram
n. A chart of a computer or other system in which labeled blocks represent principal components and lines and arrows between the blocks show the pathways and relationships among the components. A block diagram is an overall view of what a system consists of and how it works. To show the various components of such a system in more detail, different types of diagrams, such as flowcharts or schematics, are used. Compare bubble chart, flowchart.
blue screen
n. A technique used in film matte special effects, in which one image is superimposed on another image. Action or objects are filmed against a blue screen. The desired background is filmed separately, and the shot containing the action or objects is superimposed onto the background. The result is one image where the blue screen disappears.
BNC connector
n. A connector for coaxial cables that locks when one connector is inserted into another and rotated 90 degrees. BNC connectors are often used with closed-circuit television. See also coaxial cable.
board
n. An electronic module consisting of chips and other electronic components mounted on a flat, rigid substrate on which conductive paths are laid between the components. A personal computer contains a main board, called the motherboard, which usually has the microprocessor on it and slots into which other, smaller boards, called cards or adapters, can be plugged to expand the functionality of the main system, such as to connect to monitors, disk drives, or a network. See also adapter, card (definition 1), motherboard.
body
n. In e-mail and Internet newsgroups, the content of a message. The body of a message follows the header, which contains information about the sender, origin, and destination of the message. See also header (definition 1).
body face
n. A typeface suitable for the main text in a document rather than for headings and titles. Because of their readability, fonts having serifs, such as Times and Palatino, are good body faces, although sans serif faces can also be used as body text. See also sans serif, serif. Compare display face.
boilerplate
n. Recyclable text; a piece of writing or code, such as an organization's mission statement or the graphics code that prints a software company's logo, which can be used over and over in many different documents. The size of boilerplate text can range from a paragraph or two to many pages. It is, essentially, generic composition that can be written once, saved on disk, and merged, either verbatim or with slight modification, into whatever documents or programs later require it.
boldface
n. A type style that makes the text to which it is applied appear darker and heavier than the surrounding text. Some applications allow the user to apply a "Bold" command to selected text; other programs require that special codes be embedded in the text before and after words that are to be printed in boldface. This sentence appears in boldface.
bomb1
n. A program planted surreptitiously, with intent to damage or destroy a system in some way--for example, to erase a hard disk or cause it to be unreadable to the operating system. See also Trojan horse, virus, worm.
bomb2
vb. To fail abruptly and completely, without giving the user a chance to recover from the problem short of restarting the program or system. See also abend, bug (definition 1), crash3 (definition 1), hang.
bookmark
n. 1. A marker inserted at a specific point in a document to which the user may wish to return for later reference. 2. In Netscape Navigator, a link to a Web page or other URL that a user has stored in a local file in order to return to it later. See also Favorites folder, hotlist, URL.
bookmark file
n. 1. A Netscape Navigator file containing the addresses of preferred Web sites. It is synonymous with the Favorites folder in Internet Explorer and the hotlist in Mosaic. See also Favorites folder, hotlist, Internet Explorer, Mosaic. 2. A rendering of such a file in HTML format, generally posted on a Web page for the benefit of other people. See also HTML.
Boolean
adj. Of, pertaining to, or characteristic of logical (true, false) values. Many languages directly support a Boolean data type, with predefined values for true and false; others use integer data types to implement Boolean values, usually (although not always) with 0 equaling false and "not 0" equaling true. See also Boolean algebra, Boolean operator.
Boolean search
n. A database search that uses Boolean operators. See also Boolean operator.
boot1
n. The process of starting or resetting a computer. When first turned on (cold boot) or reset (warm boot), the computer executes the software that loads and starts the computer's more complicated operating system and prepares it for use. Thus, the computer can be said to pull itself up by its own bootstraps. Also called bootstrap. See also BIOS, bootstrap loader, cold boot, warm boot.
boot2
vb. 1. To start or reset a computer by turning the power on, by pressing a reset button on the computer case, or by issuing a software command to restart. Also called bootstrap, boot up. See also reboot. 2. To execute the bootstrap loader program. Also called bootstrap. See also bootstrap loader.
bootable
adj. Containing the system files necessary for booting a PC and running it. See also boot2.
boot disk
n. A floppy disk that contains key system files from a PC-compatible operating system and that can boot, or start, the PC. A boot disk must be inserted in the primary floppy disk drive (usually drive A:) and is used when there is some problem with starting the PC from the hard disk, from which the computer generally boots. Also called bootable disk. See also A:, boot2, boot drive, hard disk.
A/B Switch box ~ America On-line AMI BIOS ~ Arithmetic Operation ARP ~ AVI Backbone ~ Bit Image Bit Map ~ Boot Disk Boot Drive ~ Bytes Per Inch C++ ~ Carrier Frequency carrier system ~ certification CGI ~ Chooser extension cipher ~ Clipper Chip clock ~ color color bits ~ communications satellite communications server ~ computer security CON ~ copy copy program ~ cycle time daemon ~ defragmentation demand paging ~ digitize DikuMUD ~ disk disk buffer ~ Document Style Semantics and Specification Language document window ~ dynamic Web page Easter egg ~ erase erase head ~ ezine F2F ~ finger2 firewall ~ font suitcase footer ~ FYI Game Control Adapter ~ GUI HAL ~ hot key1 hot key2 ~ Hz i486DX ~ internal modem internet ~ ISO 9660 ISO/OSI model ~ just-in-time K1 ~ knowledge base L1 cache ~ LU luggable computer ~ LZW compression MAC ~ MILNET mime ~ msec MTBF ~ MYOB named anchor ~ network drive Network File System ~ number crunching object ~ overwrite mode P5 ~ PC/XT keyboard PDA ~ pipeline processing piracy ~ preventive maintenance preview ~ pwd quasi-language ~ QWERTY keyboard R&D ~ registration marks Registry ~ RFI RF shielding ~ run-time library SAA ~ server error server push-pull ~ soft return software ~ style sheet stylus ~ System T1 ~ ToggleKeys token ~ typography UART ~ uupc V.120 ~ view2 viewer ~ VxD w3 ~ WinG WINS ~ WWW X.25 ~ X Windows Yahoo! ~ yotta- Z39.50 standard ~ Zulu time