~H~
HAL ~ hot key1
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
HAL
n. See hardware abstraction layer.
half-duplex
adj. Of or pertaining to two-way communication that takes place in only one direction at a time. For example, communication between people is half-duplex when one person listens and waits to speak until the other has finished speaking. Compare duplex1.
half-duplex transmission
n. Two-way electronic communication that takes place in only one direction at a time. Compare duplex2, simplex transmission.
halftone
n. A printed reproduction of a photograph or other illustration, using evenly spaced spots of varying diameter to produce apparent shades of gray. The darker the shade at a particular point in the image, the larger the corresponding spot in the halftone. In traditional publishing, halftones are created by photographing an image through a screen. In desktop publishing, each halftone spot is represented by an area containing a number of dots printed by a laser printer or digital imagesetter. In both cases, the frequency of the halftone dots is measured in lines per inch. Higher printer resolution enables effective use of higher frequencies of halftone dots, enhancing image quality. See also dithering, gray scale, imagesetter, spot function.
handheld computer
n. A computer small enough to be held in one hand while being operated by the other hand. Handheld computers are commonly used in transportation and other field service industries. They are usually built to perform specific tasks. They often have restricted specialized keyboards rather than the standard QWERTY layout, smaller displays, input devices such as bar code readers, and communications devices for sending their data to a central computer; they rarely have disk drives. Their software is usually proprietary and stored in ROM. See also QWERTY keyboard, ROM. Compare handheld PC, PDA.
handheld PC
n. A computer that is small enough to fit in a jacket pocket and that can run, for example, Microsoft Windows CE (a scaled-down version of Windows 95) and applications made for that operating system. Compare handheld computer, PDA. Acronym: HPC.
handwriting recognition
n. 1. The ability of a computer to identify a user by recognizing features of handwriting, especially a signature. 2. The ability of a computer to translate handwritten text into character data for input. This technology is still under considerable development, and most handwriting recognition programs require users to form letters and words in a very consistent and clear manner to work adequately. The development of handwriting recognition programs has been spurred by PDAs, which frequently have keyboards that are too small for data entry, and software designed for Asian markets that have languages with numerous characters, which makes keyboards a cumbersome method for entering text. See also PDA. Compare optical character recognition.
hang
vb. To stop responding. A hung program or computer system does not respond to user input, but the screen looks as if everything is running normally. The program or system might be waiting for something, for example, information from a network, or it might have terminated abnormally. It might resume running normally on its own, or the user might need to terminate and restart the program or reboot the computer. A hung computer system is said to be locked up. See also crash2.
hanging indent
n. Placement of the beginning of the first line of a paragraph farther to the left than the subsequent lines. Also called outdent. Compare indent.
hard-coded
adj. 1. Designed to handle a specific situation only. 2. Depending on values embedded in the program code rather than on values that can be input and changed by the user.
hard disk
n. A device containing one or more inflexible platters coated with material in which data can be recorded magnetically, together with their read/write heads, the head-positioning mechanism, and the spindle motor in a sealed case that protects against outside contaminants. The protected environment allows the head to fly 10 to 25 millionths of an inch above the surface of a platter rotating typically at 3600 to 7200 rpm; therefore, much more data can be stored and accessed much more quickly than on a floppy disk. Most hard disks contain from two to eight platters. Also called hard disk drive. Compare floppy disk.
hard disk type
n. One or more numbers that inform a computer about the characteristics of a hard disk, such as the number of read/write heads and the number of cylinders the hard disk contains. The hard disk type numbers are usually marked on a label attached to the disk and must be input to the computer when the hard disk is installed, often by means of the computer's CMOS setup program. See also CMOS setup.
hard return
n. A character input by the user to indicate that the current line of text is to end and a new line is to begin. In word-processing programs that automatically break lines within the margins of a page, a hard return indicates the end of a paragraph. In text-entry programs that lack wordwrap, on the other hand, a hard return is required to end each line, and often two or more hard returns are needed to end a paragraph. See also wordwrap. Compare soft return.
hardware
n. The physical components of a computer system, including any peripheral equipment such as printers, modems, and mouse devices. Compare firmware, software.
hardware abstraction layer
n. In advanced operating systems such as Windows NT, a layer in which assembly language code is isolated. A hardware abstraction layer functions similarly to an application programming interface (API) and is used by programmers to write device-independent applications. See also application programing interface, device independence. Acronym: HAL.
hardware-dependent
adj. Of or pertaining to programs, languages, or computer components and devices that are tied to a particular computer system or configuration. Assembly language, for example, is hardware-dependent because it is created for and works only with a particular make or model of microprocessor.
hardware interrupt
n. A request for service from the central processing unit, generated either externally by a hardware device such as a disk drive or an input/output port or internally by the CPU itself. External hardware interrupts are used for such situations as a character received from a port and needing to be processed, a disk drive ready to transfer a block of data, or a tick of the system timer. Internal hardware interrupts occur when a program attempts an impossible action such as accessing an unavailable address or dividing by zero. Hardware interrupts are assigned levels of importance or priority. The highest priority is given to a type of interrupt called a nonmaskable interrupt--one that indicates a serious error, such as a memory failure, that must be serviced immediately. See also external interrupt, interrupt.
hardware profile
n. A set of data that describes the configuration and characteristics of a given piece of computer equipment. Such data is typically used to configure computers for use with peripheral devices.
hardwired
adj. 1. Built into a system using hardware such as logic circuits, rather than accomplished through programming. 2. Physically connected to a system or a network, as by means of a network connector board and cable.
hash1
n. In many FTP client programs, a command that instructs the FTP client to display a pound sign (#) each time it sends or receives a block of data. See also FTP client.
hash2
vb. To be mapped to a numerical value by a transformation known as a hashing function. Hashing is used to convert an identifier or key, meaningful to a user, into a value for the location of the corresponding data in a structure, such as a table. For example, given the key MOUSE and a hashing function that added up the ASCII values of the characters, divided the total by 127, and took the remainder, MOUSE would hash to 12, and the data identified by MOUSE would be found among the items in entry 12 in the table.
HDTV
n. Acronym for high-definition television. A method of transmitting and receiving television signals that produces a picture with much greater resolution and clarity than does standard television technology. International standards for HDTV are not yet established.
help
n. 1. The capability of many application programs to display advice or instructions for using their features when so requested by the user, as by a screen button or menu item or a function key. The user can access help without interrupting work in progress or leafing through a manual. Some help facilities are context-sensitive, meaning that the user receives information specific to the task or command being attempted. Although help facilities are not usually as extensive as manuals, they give the user a means of refreshing the memory and may also offer the more advanced user quick access to details on little-used program features. Also called online help. 2. In many applications, a command that displays an explanation of another command that follows it. For instance, in many FTP programs, the command help can be followed by other commands, such as cd (change directory) or ls (list files and directories), to discover the purpose of these other commands.
Help
n. An item on a menu bar in a graphical user interface that enables the user to access the help feature of the present application. See also graphical user interface, help (definition 1), menu bar.
help desk
n. 1. Technical support staff who help solve users' problems with hardware or software systems or refer such problems to those who can solve them. Help desks are typically run by larger organizations, such as corporations or universities, or vendors to corporations, to assist users in the organization. 2. A software application for tracking problems with hardware and software and their solutions.
helper application
n. An application intended to be launched by a Web browser when the browser downloads a file that it is not able to process itself. Examples of helper applications are sound and movie players. Helper applications generally must be obtained and installed by users; they usually are not included in the browser itself. Many current Web browsers no longer require helper applications for common multimedia file formats. Also called helper program. Compare ActiveX contrls, plug-in (definition 2).
Help key
n. A key on the keyboard that the user can press to request help. See also function key, help (definition 1).
help screen
n. A screen of information that is displayed when the user requests help. See also help (definition 1).
hertz
n. Abbreviated Hz. The unit of frequency measurement; one cycle (of a periodic event such as a waveform) per second. Frequencies of interest in computers and electronic devices are often measured in kilohertz (kHz = 1,000 Hz = 103 Hz), megahertz (MHz = 1,000 kHz = 106 Hz), gigahertz (GHz = 1,000 MHz = 109 Hz), or terahertz (THz = 1,000 GHz = 1012 Hz).
heterogeneous environment
n. A computing milieu, usually within an organization, in which hardware and software from two or more manufacturers are used. Compare homogeneous environment.
hidden file
n. A file that, in order to protect it from deletion or modification, is not shown in the normal listing of the files contained in a directory. Such a file is often used to store code or data critical to the operating system.
hierarchical
adj. Of, relating to, or organized as a hierarchy. See also hierarchy.
high-end
adj. A descriptive term for something that uses the latest technology to maximize performance. There is usually a direct correlation between high-end technology and higher prices.
high-level language
n. A computer language that provides a level of abstraction from the underlying machine language. Statements in a high-level language generally use keywords similar to English and translate into more than one machine-language instruction. In practice, every computer language above assembly language is a high-level language. Also called high-order language. Compare assembly language.
highlight
vb. To alter the appearance of displayed characters as a means of calling attention to them, as by displaying them in reverse video (light on dark rather than dark on light, and vice versa) or with greater intensity. Highlighting is used to indicate an item, such as an option on a menu or text in a word processor, that is to be acted on in some way.
high memory
n. 1. Memory locations addressed by the largest numbers. 2. In IBM PCs and compatibles, the range of addresses between 640 kilobytes and 1 megabyte, used primarily for the ROM BIOS and control hardware such as the video adapter and input/output ports. Compare low memory.
high memory area
n. In IBM PCs and compatibles, the 64-kilobyte range of addresses immediately above 1 megabyte. By means of the file HIMEM.SYS, MS-DOS (versions 5.0 and later) can move portions of itself into the high memory area, thereby increasing the amount of conventional memory available for applications. See also conventional memory, expanded memory. Acronym: HMA.
high tech
n. 1. Cutting-edge applied science and engineering, usually involving computers and electronics. 2. Sophisticated, often complex, specialized technical innovation.
HIPPI
n. Acronym for High-Performance Parallel Interface. An ANSI communications standard used with supercomputers.
histogram
n. A chart consisting of horizontal or vertical bars, the widths or heights of which represent the values of certain data.
history
n. A list of the user's actions within a program, such as commands entered in an operating system shell, menus passed through using Gopher, or links followed using a Web browser.
hit
n. 1. A successful retrieval of data from a cache rather than from the slower hard disk or RAM. See also cache, hard disk, RAM. 2. A successful retrieval of a record matching a query in a database. See also query (definition 1), record1. 3. Retrieval of a document, such as a home page, from a Web site.
HKEY
n. Short for handle key. In Windows 95, a handle to a Registry key in which configuration information is stored. Each key leads to subkeys containing configuration information that, in earlier versions of Windows, was stored in .ini files. For example, the handle key HKEY_CURRENT_USER\Control Panel leads to the subkey for the Windows Desktop. See also handle (definition 1).
HLS
n. Acronym for hue-lightness-saturation. See HSB.
home
n. A beginning position, such as the top left corner of a character-based display, the left end of a line of text, cell A1 of a spreadsheet, or the top of a document.
homebrew
n. Hardware or software developed by an individual at home or by a company for its own use rather than as a commercial product, such as hardware developed by electronics hobbyists when microcomputers first appeared in the 1970s.
Home key
n. A key, found on most keyboards, whose function usually involves sending the cursor to some type of home position in an application. See also home.
home page
n. 1. A document intended to serve as a starting point in a hypertext system, especially the World Wide Web. A home page is called a start page in Microsoft Internet Explorer. 2. An entry page for a set of Web pages and other files in a Web site.
homogeneous network
n. A network on which all the hosts are similar and only one protocol is used.
horizontal scrolling
n. A feature of programs such as word processors and spreadsheets that enables the user to scroll left and right to display information beyond the horizontal limits of the screen (or window, in a graphical user interface).
host
n. The main computer in a system of computers or terminals connected by communications links.
host adapter
n. A device for connecting a peripheral to the main computer, typically in the form of an expansion card. Also called controller, host bus adapter.
host name
n. The name of a specific server on a specific network within the Internet, leftmost in the complete host specification. For example, www.microsoft.com indicates the server called "www" within the network at Microsoft Corporation.
host not responding
n. An error message issued by an Internet client indicating that the computer to which a request has been sent is refusing the connection or is otherwise unavailable to respond to the request.
host timed out
n. An error message returned by a server when the host machine that contains the requested information fails to return a response within a set time limit. Some UNIX servers will close timed-out sessions to manage system resources.
host unreachable
n. An error message indicating that a server has failed to connect to the requested host. This may be because the server does not know the host's address, the host may be down, or the host is refusing the connection.
hot docking
n. The process of attaching a laptop computer to a docking station while the computer is running, and automatically activating the docking station's video display and other functions. See also docking station, laptop.
hot insertion
n. The insertion of a device or card while there is power to the system. Many newer laptops allow for hot insertion of PCMCIA cards. High-end servers may also allow hot insertion to reduce downtimes.
HotJava
n. A Web browser developed by Sun Microsystems that is optimized to run Java applications and applets embedded in Web pages. See also applet, Java, Java applet.
hot key1
n. A keystroke or combination of keystrokes that switches the user to a different program, often a terminate-and-stay-resident (TSR) program or the operating system user interface. See also TSR
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
