A device that connects a computer to the Internet via existing
broadband cable networks.
A special area of memory, managed by a cache controller, that improvers performance by storing the contents of frequently accessed memory locations and their addresses. When the processor references a memory address, the cache checks to see if it holds that address. If it does, the information is passed directly to the processor; if not, a normal memory access takes place instead. A cache can speed up operations in a computer whose RAM access is slow compared with its processor speed, because the cache memory is always faster than normal RAM.
A special-purpose processor, such as the Intel 82385, whose sole task is to manage cache memory. On newer processors, such as the Intel Pentium, cache management is integrated directly into the processor.
A relatively small section of very fast memory (often called static RAM) reserved for the temporary storage of the data or instructions likely to be needed next by the processor.
A feature found on many browsers that stores a copy of visited
Web pages on the user's hard disk. The next time you visit the
site, the page is retrieved from your computer rather than through
A version of QAM in which incoming data modulates a single carrier that is then transmitted down a telephone line. The carrier itself is suppressed before transmission ( it contains no information, and can be reconstructed at the receiver), hence the adjective "carrierless."
The NetWare command used to redirect printer output to a network printer. It is usually run in a batch file or login script.
A printed circuit board or adapter that you plug into your computer to add support for a specific piece of hardware not normally present on the computer.
Part of the software support needed for PCMCIA hardware devices in a portable computer, controlling the use of system interrupts, memory, or power management.
When an application wants to access a PC Card, it always goes through the card services software and never communicates directly with the underlying hardware.
Under Windows, a protected-mode system component that is a VxD linked with the PC Card bus driver. Card Services passes the event notification from socket services to the PC Card bus driver, provides information from the computer's cards to the PC Card bus driver, and sets up the configuration for cards in the adapter sockets.
Card Select Number
The handle created by the system BIOS or the operating system through the isolation process and assigned as a unique identifier to each Plug and Play card on the ISA bus.
In communications, a signal of chosen frequency generated to carry data, often used for long-distance transmissions. The data is added to this carrier signal modulation, and decoded on the receiving end by demodulation.
(Compatiblity Basic Input/Output System) Firmware service routines built into the IBM PS/2 series of computers with Micro Channel Architecture (MCA), generally considered to be a super-set of the original IBM PC BIOS.
(Comité Consultatif Internationale de Téléphonie et de Télégraphie.) An organization ,based in Geneva, that develops world-wide data communications standards. CCITT is part of the ITU (International Telecommunications Union).
Three main sets of standards have been established: CCITT Groups 1-4 standards apply to facsimile transmissions; the CCITT V series of standards apply to modems and error detection and correction methods; and the CCITT X series standards apply to local area networks.
CCITT Groups 1-4
A set of four CCITT recommended standards for facsimile transmissions.
Groups 1 and 2 defined analog facsimile transmissions, and are no longer used. Groups 3 and 4 describe digital systems, as follows:
Group 3specifies a 9600 bps modem to transmit standard images of 203 dots per inch (dpi) horizontally by 98 dpi vertically in standard mode, and 203 dpi by 198 dpi in fine mode.
Group 4supports images up to 400 dpi for high-speed transmission over a digital data network like ISDN, rather than a dial-up telephone line.
CCITT V Series
A set of recommended standards for data communications over a telephone line, including transmission speeds and operational modes,issued by CCITT.
CCITT X Series
A set of recommended standards issued by CCITT to standardize protocols and equipment used in public and private computer networks, including the transmission speeds, the interfaces to and between networks, and the operation of user hardware.
Acronym for Compact Disk-Interactive. A hardware and software standard disk format that encompasses data, text, audio, still video images, and animated graphics. The standard also defines methods of encoding and decoding compressed data, as well as displaying data.
Abbreviation for CD Recordable. A type of CD device that brings CD-ROM publishing into the realm of the small business or home office. From a functional point of view, a CD-R and a CD-ROM are identical; you can read CD-R disks using almost any CD-ROM drive, although the processes that create the disks are slightly different. Low-cost CD-R drives are available from many manufacturers, including Kao, Kodak, Mitsui, Phillips, Ricoh, Sony, TDK, 3M, and Verbatim.
Acronym for Compact Disk-Read-Only Memory. A high-capacity, optical storage device that uses compact disk technology to store large amounts of information, up to 650 MB ( the equivalent of approx. 300,000 pages of text), on a single 4.72" disk.
A CD-ROM uses the constant linear velocity encoding scheme to store information in a single, spiral track, divided into many equal length segments. To read data, the CD-ROM disk drive must increase the rotational speed as the read head gets closer to the center of the disk, and decrease as the head moves back out. Typical CD-ROM data access times are in the range of 0.3 to 1.5 seconds; much slower than a hard disk.
CD-ROM disk drive
A disk device that uses compact disk technology for information storage. They are available with several different data transfer rates--Single-speed, double-speed,etc. all the way up to 16x.
(CD-ROM/XA) An extension to the CD-ROM format, developed by Microsoft, Phillips and Sony, that allows for the storage of audio and visual information on compact disk, so that you can play the audio at the same time you view the visual data.
CD-ROM/XA is compatible with the High Sierra specification also known as ISO standard 9660.
Consumer Digital Subscriber Line (CDSL) is a proprietary technology
trademarked by Rockwell International.
EtherLoop is currently a proprietary technology from Nortel, short for Ethernet Local Loop. EtherLoop uses the advanced signal modulation techniques of DSL and combines them with the half-duplex "burst" packet nature of Ethernet. EtherLoop modems will only generate hi-frequency signals when there is something to send. The rest of the time, they will use only a low-frequency (ISDN-speed) management signal. EtherLoop can measure the ambient noise between packets. This will allow the ability to avoid interference on a packet-by-packet basis by shifting frequencies as necessary. Since EtherLoop will be half-duplex, it is capable of generating the same bandwidth rate in either the upstream or downstream direction, but not simultaneously. Nortel is initially planning for speeds ranging between 1.5Mbps and 10Mbps depending on line quality and distance limitations.
A circuit switch that terminates all the local access lines in a particular geographic servicing area; a physical building where the local switching equipment is found. xDSL lines running from a subscriber's home connect at their serving central office.
CPU. The computing and control part of the computer. The CPU in a mainframe computer may be contained on many printed circuit boards; the CPU in a mini computer may be contained on several boards; and the CPU in a PC is contained in a single extremely powerful microprocessor.
Centronics parallel interface
A standard 36-pin interface in the PC world for the exchange of information between the PC and a peripheral such as a printer, originally developed by the printer manufacturer Centronics,Inc. The standard defines 8 parallel data lines, plus additional lines for status and control information.
A video adapter introduced by IBM in 1981 that provided low-resolution text and graphics. CGA provided several different text and graphics modes, including 40- or 80-column by 25 line 16-color text mode, and graphics modes of 640 horizontal pixels by 200 vertical pixels with 2 colors, or 320 horizontal pixels by 200 vertical pixels with 4 colors. See also EGA , VGA, SuperVGA, and XGA.
(CCD) A special type of memory that can store patterns of changes in a sequential manner. The light-detecting circuitry contained in many still and video cameras is CCD.
A method of providing information for error detection, usually calculated by summing a set of values.
The checksum is usually appended to the end of the data that it is calculated from, so that data and checksum can be compared.
A DOS command that checks the record-keeping structures of a DOS disk for errors.
A communications channel or path between two devices capable of carrying electrical current. Also used to describe a set of components connected together to perform a specific task.
Refers to a characteristic common to most telephone networks
where a single path or line must remain open between sender and
receiver to enable transmission.
For hardware, the manner in which devices and buses are grouped for purposes of installing and managing device drivers and allocating resources. The hardware tree is organized by device class, and the operating system uses class installers to install drivers for all hardware classes.
Class A certification
An FCC certification for computer equipment, including mainframe and mini computers destined for use in an industrial, commercial, or office setting, rather than for personal use at home. The Class A commercial certification is less restrictive than the Class B certification.
A driver that provides system-required, hardware-independent support for a given class of physical devices. Such a driver communicates with a corresponding hardware-dependent port driver, using a set of system-defined device control requests, possibly with additional driver-defined device control requests. Under WDM, the class driver creates a device object to represent each adapter registered by minidrivers. The class driver is responsible for multiprocessor and interrupt synchronization.
A computer that has access to the network but doesn't share any of its own resources with the network.
Form of networking in which the work load is split between a client and the server computer.
An internal time-of-day and month-year calendar that is kept up-to-date by a small battery-backup system. This allows the computer to update the time even when turned off.
A mechanism used in certain chips that allows the chip to process data and instructions internally at a different speed from that used for external operations.
Also known as clock rate. The internal speed fo a computer processor, normally expressed in MHz. The faster the clock speed, the faster the computer will perform a specifc operation, assuming the other components in the system, such as disk drives, can keep up with the increased speed.
Hardware that is identical in function to an original.
The smallest unit of hard disk space that DOS can allocate to a file, consisting of one or more contiguous sectors. The number of sectors contained in a cluster depends on the hard disk type.
A type of integrated circuit used in processors and for memory. CMOS devices operate at very high speeds and use very little power, so they generate very little heat. In the PC, battery-backed CMOS is used to store operating parameters such as hard disk type when the computer is switched off.
A high-capacity cable used in networking. It contains an inner copper conductor surrounded by plastic insulation, and an outer braided copper or foil shield. Coax is used for broadband and baseband communications networks, and is usually free from external interference, and it permits very high transmission rates over long distances.
The compression/decompression system used to reduce media or transmission data volume for digitized audio or video data.
The computer startup process that begins when you turn on power to the computer. A cold boot might be needed if a program or the operating system crashes in such a way that you cannot continue. If operations are interrupted in a minor way, a warm boot may suffice.
The command processor for MS-DOS based systems. It provides the C> prompt, and it interprest the usesr’s English commands and performs the operation requested.
Also called command interpreter. The command processor is that part of the operating system that displays the command prompt on the screen, interprets and executes all the commands and file names that you enter, and displays error messages when appropriate.
It also contains the environment a memory area that holds values for important system definitions or defaults that are used by the system, and which can be changed by the user.
A key component of the WBEM architecture. A central message of WBEM is uniform data representation encapsulated in object-oriented fashion in the CIM. CIMOM provides a collection point and manipulation point for these objects. Formerly HMOM.
CD. A non-magnetic, polished, optical disk used to store large amounts of digital information. Digital information is tored ont he CD as a series of microscopic pits and smooth areas that have different reflective properties. A beam of laser light shines on the disk so that the reflections can be detected and converted into digital data.
An asynchronous, host-to-peripheral parallel port channel defined in the IEEE 1284-1944 standard. Compatible with existing peripherals that attach to the Centronics-style PC parallel port.
An ID used by the Plug and Play Manager to locate an INF to install a device if there was no match on the hardware IDs for the device.
A specification for DMI related to the service layer.
In DOS, the device name used to denote a serial communications port. In versions of DOS after 3.3 four COM ports are supported, COM1, COM2, COM3, and COM4.
Also refers to,Component Object Model; the core of OLE. Defines how OLE objects and their clients interact within processes or across process boundaries.
A signal that combines the luminance, chrominance, and synchronized video information onto a single line. This has been the most prevalent NTSC video format.
The translation of data (video, audio, digital, or a combination) to a more compact form for storage or transmission.
A comparison of the amount of space saved by data compression. A compression ratio of 2:1 ("two to one") results in a doubling of the storage capacity.
A digital video image or segment that has been processed using a variety of computer algorithms and other techniques to reduce the amount of data required to accurately represent the content and thus the space required to store the content.
A condition where the speed of operation of the processor actually limits the speed of program execution. The processor is limited by the number of arithmetic operations it must perform.
To join sequentially.
In DOS and OS/2 a special text file containing settings that control the way that the operating system works. It must be located in the root directory of the default boot disk, normally drive C, and is read by the operating system only onces as the system starts running.
The process of establishing your own preferred setup for an application program or computer system. Configuration information is usually stored in a configuration file so that it can be loaded automatically next time you start your computer.
A file, created by an application program or by the operationg system, containing configuration information specific to your own computing environment. Application program config. files may have a file-name extension of CPG or SET; Window's config. files use the INI file-name extension.
The Windows Plug and Play system component that drives the process of locating devices, setting up their nodes in the hardware tree, and running the resource allocation process. Each of the three phases of configuration management--boot time, real mode, and protected mode--have their own configuration managers.
A negotiated method of communication between devices, whether implemented in hardware or software.
(CAV) An unchanging speed of rotation. Hard disks use a constant angular velocity encoding scheme, where the disk rotates at a constant rate. This means that sectors on the disk are at the maximum density along the inside track of the disk; as the read/write heads move outwords, the sectors must spread out to cover the increased track circumference , and therefore the data transfer rate falls off.
A changing speed of rotation. CD-ROM disk drives use a CLV encoding scheme to make sure that the data density remains constant.
Also host-based controller. A modem that consists of a DSP without the usual microcontroller. The host CPU provides the AT command interpreter, modem-control functions, and v.42 bis implementation. Compare with software modem.
A definition of how an ACPI-compatible operating system can perform a simple hardware task. For example, the operating system invokes control methods to read the temperature of a thermal zone. Control methods are written in an encoded language called AML.
The amount of memory accessible by DOS in PCs using an Intel processor operating in real mode, normally the first 640K.
The alignment of the three electron guns (one each for red,blue and green) in a monitor that create the colors you see on the screen.
A form of multitasking in which all running applications must work together to share system resources.
A secondary processor used to speed up operations by taking over a specific part of the main processor's work. See floating-point coprocessor.
an unexpected program halt, sometimes due to hardware failure, but most often due to a software error, from which there is no recovery.
A special tool used to attach connectors to cables.
Simply put customer premise equipment is the equipment that big company's that provide broadband services use;i.e., voice ports,channel banks, PBX's,Integrated Access Mulitplexers,etc. This is as opposed to subscriber premise equipment.
A hard disk consists of two or more platters, each with two sides. Each side is further divided into concentric circles known as tracks; and all the tracks at the same concentric position on a disk are known collectively as a cynlider.