Glossary

Analog: Representing changing values by a variable physical property such as voltage in a circuit or liquid level in a thermometer. As contrasted to digital (see below), which represents changing values by binary digits, or bits.

Bandwidth: The speed or capacity of a network connection. The more bandwidth a particular medium has, the faster data can be transmitted across it.

Bit: Binary digit, the basic unit of information carried by digital systems, transmitted as a single on or off pulse. Bits are grouped together in different sequences to represent all kinds of information-numbers, words, sounds, images, etc.

Broadband: Network connection that can carry multiple signals at once, each on separate channels. Broadband networks can transmit a lot of data, including voice and video, rapidly over long distances. CD-ROM: Compact Disk-Read Only Memory; a format for storing large amounts of data (e.g., an encyclopedia, complete with photographs and drawings) on compact disks.

Digital: Representing data as discrete bits, as opposed to analog (see above). For example, CD players are digital: they convert and store sound as bits. Record players, by contrast, are analog devices. Distance learning: Using video technology to allow students in one location to participate in a class being broadcast from another location.

E-mail: Electronic mail-messages transmitted electronically between computers.

Ethernet: A protocol and set of cabling specifications for local area networks. Ethernet has a transfer rate of 10 megabits per second.

Hard disk: A computer storage medium that is a fixed part of the computer's hardware (specifically, the data storage part of the computer's hard disk drive). As contrasted to floppy disk, a portable computer storage medium that can be inserted into or removed from various computers easily and quickly.

Interactive: Referring to programs or applications that respond directly to the user, taking instructions and giving feedback.

Internet: An international computer network that links over ten thousand individual networks and supports millions of users.

ISDN: Integrated Services Digital Network, a worldwide digital transmission network and format that can carry both data and voice over a single cable at speeds of 56 kbps and higher.

Kbps: Kilobits per second, the number of bits, transmitted every second as measured in multiples of about one thousand (1024) bits per second.

LAN: Local Area Network, a group of computers and related equipment connected locally-usually within a single building-by a communications channel capable of sharing information among several users.

Mbps: Megabits per second, the number of bits transmitted every second as measured in multiples of about one million (1,048, 576) bits per second.

Multimedia: Communication that combines text with graphics, sound, animation, full-motion video, etc.-usually in a highly interactive way (see above).

Multimedia-capable computer: A computer that is capable of operating multimedia applications.

Narrowband: A voice-grade transmission channel capable of transmitting a maximum of 34,000 bits per second. See bandwidth.

On-line: Describes any application or information directly accessible on a computer or computer network, such as an "on-line database."

POTS: Plain Old Telephone Service; a POTS line is a standard analog telephone line operating at narrowband speeds.

RAM: Random Access Memory-the main system memory in a computer, used for data, applications, and operations.

RBOC: Regional Bell Operating Company, or "Baby Bell."

T-1: A long distance, point-to-point communications channel that transmits 1.5 megabits per second and can carry both voice and data.

T-3: A long distance, point-to-point communications circuit that transmits 44.7 megabits per second and can provide up to 28 T-1 channels. It usually runs over fiber-optic cable.

WAN: Wide Area Network, a long-distance computer network that enables users to share information across large geographical distances (e.g., state to state). A WAN may interconnect a number of LANs (see above) at different sites.

Wideband: A transmission channel capable of transmitting more information (as measured by bits per second) than narrowband, but less than broadband.


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