K

K

K¹ n. Short for kilobyte.

K² prefix See kilo-.

K&R C n. Short for (Brian W.) Kernighan and (Dennis M.) Ritchie C. The version of the C programming language, defined by those two authors, that was the informal C standard until a more formal standard was developed by an ANSI committee. See also C.

Kalman filter n. An adaptive filter used to estimate the state of a system from measurements that contain random errors. This recursive adaptive filter determines the correct parameters of a process model. Each new measurement allows the parameters of a model to be predicted and adjusted, thus providing an estimate of error at each update. The Kalman filter s computational structure and its ability to incorporate the effects of noise (from both measurement and modeling) recommends itself for use in computer vision tracking applications. See also active vision, distortion, modeling, noise.

kamikaze packet n. See Chernobyl packet.

kashidas n. Special characters that are used to extend the joiner between two Arabic characters. Kashidas are used to improve the appearance of justified text by visually lengthening words rather than increasing the spacing between words. See the illustration.

Kashidas.

Kb n. See kilobit.

KB n. 1. See kilobyte. 2. Short for Knowledge Base. Primary source of product information for Microsoft support engineers and customers. This comprehensive collection of articles, updated daily, contains detailed how-to information, answers to technical-support questions, and known issues. Also called: Microsoft Knowledge Base.

Kbit n. See kilobit.

Kbps n. See kilobits per second.

Kbyte n. See kilobyte.

kc n. See kilocycle.

KDE n. Acronym for K Desktop Environment. A popular open-source desktop environment originally intended for UNIX workstations and now developed for the Linux operating system. KDE provides a graphical user interface (GUI) and basic applications that correspond to those found with Microsoft Windows or the Macintosh operating system. By providing a mainstream environment and familiar desktop appearance, KDE is intended to make Linux easier for users. KDE and GNOME are leading contenders for consideration as a Linux desktop standard. See also GNOME, GUI.

Kerberos n. A network authentication protocol developed by MIT. Kerberos authenticates the identity of users attempting to log on to a network and encrypts their communications through secret-key cryptography. A free implementation of Kerberos is available from MIT, although it is also available in many commercial products. Also called: Kerberos v5 authentication protocol. See also authentication, cryptography, IPSec.

Kermit n. A file transfer protocol used in asynchronous communications between computers. Kermit is a very flexible protocol used in many software packages designed for communications over telephone lines. Compare Xmodem, Ymodem, Zmodem.

kern vb. To alter selectively the distance between pairs of letters for readability and to make the type spacing more balanced and proportional. See the illustration.

Kern. The first three letters of the second example are kerned.

kernel n. The core of an operating system the portion of the system that manages memory, files, and peripheral devices; maintains the time and date; launches applications; and allocates system resources.

Kernel Extension n. See KEXT.

kernel panic n. In Mac OS X and UNIX-based systems, a type of error that occurs when the core level of the operating system is unable to properly handle an instruction. A kernel panic appears to the user as a text screen containing information about the nature of the error, which often can be corrected with a system reboot.

KEXT n. Acronym for Kernel Extension. In Mac OS X, an extension mechanism created to expand the functionality of the operating system kernel. KEXTs are modular and dynamic loading, and they may be created for any service that requires access to kernel internal interfaces. Creation of a KEXT allows the loading of pieces of code into the kernel without the need to recompile.

key n. 1. On a keyboard, the combination of a plastic keycap, a tension mechanism that suspends the keycap but allows it to be pressed down, and an electronic mechanism that records the key press and key release. 2. In database management, an identifier for a record or group of records in a datafile. See also B-tree, hash, index(definition 1), inverted list, key field. 3. In encryption and digital signatures, a string of bits used for encrypting and decrypting information to be transmitted. Encryption commonly relies on two different types of keys, a public key known to more than one person (say, both the sender and the receiver) and a private key known only to one person (typically, the sender). 4. A metal object used with a physical lock to disable a computer system.

key binary large object n. A key binary large object (BLOB) provides a way to store keys outside of the cryptographic service provider (CSP) and is used to transfer keys securely from one CSP to another. A key BLOB consists of a standard header followed by data representing the key. Acronym: key BLOB.

key BLOB n. See key binary large object.

keyboard n. A hardware unit with a set of switches that resembles a typewriter keyboard and that conveys information from a user to a computer or data communications circuit. See also Alt key, Apple key, arrow key, Backspace key, Break key, Caps Lock key, character code, Clear key, Command key, control character, Control key, Delete key, Dvorak keyboard, End key, enhanced keyboard, Enter key, ergonomic keyboard, Escape key, function key, Help key, Home key, Insert key, keyboard buffer, keyboard controller, keyboard enhancer, keycap, key code, numeric keypad, Num Lock key, Option key, original Macintosh keyboard, Page Down key, Page Up key, Pause key, PC/XT keyboard, Power-on key, Print Screen key, QWERTY keyboard, Return key, scan code, Scroll Lock key, Shift key, Sys Req key, Tab key.

keyboard buffer n. A small amount of system memory that stores the most recently typed characters. This buffer is used to store typed characters that have not yet been processed. Also called: type-ahead buffer.

keyboard controller n. A microprocessor installed in a keyboard whose primary function is to wait for and report on keystrokes.

keyboard enhancer n. A program that monitors keystrokes as they are typed and that can be used to redefine the meaning of certain keys or key combinations. Keyboard enhancers are used to create and store macros sets of keystrokes, mouse actions, menu selections, or other instructions that are then assigned to keys. Also called: macro program.

keyboard layout n. The key arrangement used for a particular keyboard, including such factors as the number of keys (101 is the current standard) and the configuration of the keys (QWERTY is the United States standard). Some proprietary systems use different layouts, and many allow you to map the keys to characters according to your preferences.

keyboard port n. The connector on a computer that receives data from the keyboard. See also port¹ (definition 1).

keyboard processor n. See keyboard controller.

keyboard repeat n. See typematic.

keyboard shortcut n. See application shortcut key.

keyboard template n. A piece of plastic or heavy paper that fits over or around part of the keyboard, such as the function keys, and has information printed on it about the meanings of the keys.

keycap n. The plastic piece identifying a key on a keyboard.

key code n. A unique code number assigned to a particular key on a computer keyboard, used to tell the computer which key has been pressed or released. A key code is a special identifier for the key itself and is always the same for a particular key, regardless of the letter, number, or symbol on the key or the character generated by the key. Compare character code, scan code.

key escrow n. An approach to key recovery in which an encryption key is provided to a third party approved by a government agency so that any encrypted message can, if necessary, be decrypted and read by the government. See also encryption, key recovery.

key field n. A field in a record structure or an attribute of a relational table that has been designated to be part of a key. Any field can be keyed, or indexed, to improve or simplify the performance of retrieval and/or update operations. See also attribute (definition 1), field (definition 1), primary key.

key-frame adj. Describing animation in which starting and ending positions of an object are given, and all frames in between are interpolated by a computer to produce smooth automated animation. Most ray-traced computer animation is created using this technique. See also ray tracing.

key in vb. To enter information into a computer by typing it on the computer s keyboard.

keymaster n. A common host name assigned by network administrators to a gateway or router. Popularized in part by the Keymaster character in the 1984 movie Ghostbusters. See also gatekeeper.

keypad n. See numeric keypad.

key pair n. A widely used encryption scheme that allows secure use of digital certificate identification. A key pair consists of a public key and a private key. The public key is shared with other individuals; the private key is known only to its owner. The public and private key form an asymmetric pair, meaning the keys on either end of a transmission are different. A message encrypted with the public key can be decrypted only with the private key, and a message encrypted with the private key can be decrypted only with the public key.

keypunch n. An archaic keyboard-activated device used to punch holes in predetermined locations on paper cards roughly the size of a business envelope. It was used to provide programs and data to early computing systems.

key recovery n. General term referring to the ability to retrieve a cryptographic key in order to decode encrypted information. Key recovery can be used to regain a lost key or, as has been publicized in recent years, can be used as a means of enabling government agencies to decode encrypted information. One method of providing for key recovery is known as key escrow. See also encryption, key escrow, private key.

key sort n. See tag sort.

keystroke n. The act of pressing a key on a keyboard to enter a character or initiate a command in a program. The efficiency and ease of use of certain applications is often measured in terms of how many keystrokes it takes to perform common operations. See also command, key (definition 1), keyboard.

keyword n. 1. A characteristic word, phrase, or code that is stored in a key field and is used to conduct sorting or searching operations on records in a database. See also key field. 2. Any of the set of words that composes a given programming language or set of operating-system routines. See also reserved word.

keyword density n. A measurement of the keywords on a Web page as a percentage of total text. High keyword density can increase a Web site s probability of being found by search engines, some of which use keyword density to rank a Web page s relevance to an Internet search. See also keyword (definition 1).

keyword-in-context n. An automatic search methodology that creates indexes of document text or titles. Each keyword is stored in the resulting index along with some surrounding text, usually the word or phrase that precedes or follows the keyword in the text or title. Acronym: KWIC.

keyword stuffing vb. See spamdexter.

Khornerstone n. A benchmark of floating-point calculation performance used to test UNIX workstations. See also benchmark¹, Dhrystone, floating-point operation, Whetstone.

kHz n. See kilohertz.

kiddie script n. A simple and easy-to-use executable script used to hack into a computer or network. Unlike the traditional hacker s techniques, which require detailed networking and programming knowledge, a kiddie script does not require any specialized skills or knowledge. See also script, script kiddie.

kill vb. 1. To stop or abort a process in a program or operating system. 2. In file management, to erase a file, often without hope of reversing the action.

killer app n. 1. An application of such popularity and widespread standardization that it fuels sales of the hardware platform or operating system for which it was written. See also application. 2. An application that supplants its competition. See also application.

kill file n. See bozo filter.

kilo- prefix 1. Metric prefix meaning 10³ (one thousand). 2. In computer-related terms, a prefix meaning 2¹⁰ (1024).

kilobaud n. A unit of measure of the transmission capacity of a communications channel, equal to 2¹⁰ (1024) baud. See also baud.

kilobit n. A data unit equal to 1024 bits. Abbreviated Kb or Kbit.

kilobits per second n. Data transfer speed, as through a modem or on a network, measured in multiples of 1024 bits per second. Abbreviated Kbps.

kilobyte n. A data unit of 1024 bytes. Abbreviated K, KB, or Kbyte. See also kilo-.

kilocycle n. A unit of measurement representing 1000 cycles, generally meaning 1000 cycles per second. Abbreviated kc. See also kilohertz.

kilohertz n. A measure of frequency equivalent to 1000 hertz, or 1000 cycles per second. Abbreviated kHz. See also hertz.

Kinesis ergonomic keyboard n. A keyboard designed ergonomically to eliminate repetitive strain injuries. See also ergonomic keyboard, repetitive strain injury.

kiosk n. A freestanding computer or terminal that provides information to the public, usually through a multimedia display.

kludge n. 1. A short-term or makeshift hardware construction. 2. A program characterized by a lack of design or forethought, as if written in a hurry to satisfy an immediate need. A kludge basically operates properly, but its construction or design is severely lacking in elegance or logical efficiency. See also braindamaged, hack¹ (definition 1), spaghetti code.

knockout n. 1. In multicolor printing, the process of removing from one image the overlapping parts of a graphic or text that are to be printed in a different color so that ink colors will not mix. See the illustration. See also spot color. Compare overprint. 2. In hardware, a section of a panel that can be removed to make space for a switch or other component.

Knockout. A knockout allows an overlapping image to print in the correct color.

knowbot n. Short for knowledge robot. An artificial-intelligence program that follows a set of predetermined rules to perform work, such as searching for files or looking for documents that contain specific pieces of information on a network, such as the Internet. See also bot (definition 2).

knowledge acquisition n. The process of translating knowledge from one or more human experts into a form of representation usable by a computer, for the purpose of developing an expert system. See also expert system.

knowledge base n. A form of database used in expert systems that contains the accumulated body of knowledge of human specialists in a particular field. The reasoning ability or problem-solving approach that a specialist would use is contained in the inference engine, which forms another crucial part of an expert system. See also expert system, inference engine.

knowledge-based system n. See expert system.

knowledge domain n. The specific area of expertise to which an expert system is devoted. See also expert system.

knowledge engineer n. A computer scientist who builds an expert system by acquiring the needed knowledge and translating it into a program. See also expert system.

knowledge representation n. The methodology that forms the basis for the decision-making structure in an expert system, usually taking the form of if-then rules. See also expert system.

knowledge worker n. Term invented by a management consultant, Peter Drucker, for an individual whose job centers on the collection, processing, and application of information, especially when meaningful value is added to purely factual information. A knowledge worker is someone with both formal education and the ability to apply that education knowledge in a work situation. See also information explosion.

Korn shell n. A command-line interface, available under UNIX, that combines features of the Bourne and C shells. The Korn shell is fully compatible with the Bourne shell but also offers the history and command-line editing capabilities of the C shell. See also command-line interface, shell¹, UNIX. Compare Bourne shell, C shell.

KSR terminal n. Short for keyboard send/receive terminal. A type of terminal that accepts input from a keyboard only and uses an internal printer rather than a screen to display the keyboard input and the output received from the sending terminal. See also TTY.

KWIC n. See keyword-in-context.