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The following is a glossary of communication terms, arranged alphabetically:

adapter Another name for a printed-circuit board or card that fits in a computer's expansion slot and allows dedicated processing of data.
AIB Application Interface Board. A PCM mezzanine card that attaches to an ARTIC PCI-bus adapter to enable customized communications.
API Application Programming Interface. Software designed to make computer functions available to application programs.
ARTIC A Realtime Interface Coprocessor. A line of dedicated real-time communications cards originally produced by IBM in 1986.
asynchronous A common method of transmitting data where each character is transmitted separately with no time synchronization between sending and receiving devices. It is cheap and dependable, but slow.
backbone A transmission facility that connects lower-speed distribution channels or clusters of users and devices.
baseband Digital data transmission in which a wire or cable carries only one signal. In contrast, broadband transmission carries multiple simultaneous signals. Most PCs use baseband for communicating with printers, monitors, and modems.
bisynchronous Binary Synchronous. Also BSC or bisync. An IBM standard for synchronous transmission of binary-coded data as a serial stream of binary digits.
broadband Digital data transmission in which a wire or cable carries multiple simultaneous signals. In contrast, baseband transmission carries only one signal.
A collection of wires through which data are transmitted from one part of a computer to another.
bus width Bus width is a measure of data transmission speed on computer buses. Typical widths are 8, 16, 32, or 64 bits at a time.
channel The communication path between two computers of devices. It can refer to the physical medium (such as coaxial cables), or to a set of properties that differentiate channels.
CCITT Comite Consultatif International Telegraphique et Telephonique. A communications standards agency of the United Nations that was reorganized in 1993 to become the International Telecommunications Union (ITU).
co-processor An intelligent adapter that has its own on-card processor to share the processing load with the host computer's CPU.
communications The transmission of data from one computer (or device) to another.
Compact PCI Compact PCI is electrically a superset of PCI with a different physical form factor. CompactPCI utilizes the Eurocard form factor popularized by the VME bus, designated as 3U or 6U card size.
CSU/DSU Channel Service Unit / Data Service Unit. The two units are usually packaged together. The CSU connects a terminal to a digital telecommunications line; the DSU performs protective and diagnostic functions for the line. The same brand of CSU/DSU is requir
DCE Data Circuit Terminating Equipment. Sets up and maintains a data connection link over a communications medium. For example, a modem.
DTE Data Terminal Equipment. The part of a data station that serves as a data source, destination, or both and that provides for the data communications control function according to protocols. This will be used to describe a router or similar device.
duplex Simultaneous transmission in both directions, sometimes referred to as full duplex to differentiate it from half duplex, which alternates transmission in one direction, then in the other.
E1 A European dedicated phone connection that supports a data rate of 2.048 Mbps. An E1 line consists of 32 channels, each of which supports a rate of 64 Kbps.
EIA Electronics Industries Association. A United States electronics trade organization that concentrates on hardware interface standards.
EIB Electrical Interface Board. A smaller card that attaches to an ARTIC adapter and determines the number of ports and physical electrical standard the signals will adhere to.
expansion bus This is a PC computer bus that allows expansion cards (such as communications cards) to access the computer's CPU and memory. The bus width determines how many bits of data can be transmitted at once; typical widths are 8, 16, 32, or 64. The bus clock spe
Fractional T1 One of the 24 channels that comprise a full T1 data line. Fractional T1 lines can usually be leased individually.
frame relay Frame relay is a high-speed packet-switching protocol used in wide area networks. It uses variable-length frames. Frame relay is faster than earlier protocols because it omits flow control and error correction. It provides service up to T1 (or DS1) rates of 1.544 Mbps.
full duplex A communications system or channel capable of simultaneous transmission in two directions. Same as "duplex."
half duplex A communications channel allowing alternating transmission in two directions, but not in both directions simultaneously.
HDLC High level Data Link Control. An ISO-standard set of protocols for transmitting data with error detection and flow control. Similar to IBM's SDLC.
IP Internet Protocol. The IP part of the TCP/IP protocol routes a message across networks.
ISA Industry Standard Architecture. This computer architecture, developed by IBM, allows 16 bits of data at a time to flow between the motherboard circuitry and adapters on the ISA bus.
ITU International Telecommunications Union. New name in 1993 for the former CCITT. They produce technical recommendations for radio, telegraph, telephone and data communication interfaces that become international standards. The ITU-T sector deals with telecommunications, and the standards they produce are prefaced with an ITU-TS identifier.
Kbps Abbreviation for a data transmission speed of kilobits per second, usually considered to be 1024 bits/second.
LAN Local Area Network. A LAN is a group of computer devices (such as PCs, workstations, printers and storage devices) connected in a network in close proximity to each other. For example, a LAN might connect all computers within one building.
LAP-B Link Access Protocol B. A link set-up routine to establish and maintain computer links.
leased line A phone line that is rented for exclusive use from one location to another.
Mbps Abbreviation for a data transmission speed of megabits per second, usually considered to be 1,048,576 bits/second.
MCA Micro Channel Architecture. Developed by IBM for its desktop computers, MCA was an improvement, but Its proprietary nature discouraged other manufacturers, and IBM has dropped it from their systems.
Micro Channel Micro Channel Architecture (MCA). Developed by IBM for its desktop computers, MCA was an improvement, but Its proprietary nature discouraged other manufacturers, and IBM has dropped it from their systems.
modem Modulator-Demodulator. An electronic device that allows computers to communicate over ordinary telephone lines. It transforms digital computer signals into analog signals that are then transmitted over phone lines to another modem that reconstructs the di
modem eliminator A device that replaces a modem when the distances are short. It take power from the transmission line.
multiplexing An electronic or optical process that combines a large number of lower-speed transmission lines into one high-speed line, thereby concentrating traffic and improving efficiency.
packet A group of binary digits that are grouped, uniquely labeled, and transmitted together.
packet switching A digital technique whereby messages are divided into packets before they are sent, and reassembled correctly once they reach their destination. Each packet contains message data and code that describes the origin, final destination, and packet order for
PCI Peripheral Component Interconnect. PCI is a bus standard developed by Intel Corporation for PCs. PCI is a 64-bit bus, but can be implemented as a 32-bit bus; it can run at speeds of 33 MHz or 66 MHz.
PMC PCI Mezzanine Card. The PMC is a small card that plugs into a PCI card, that them plugs into the computer bus as a unit.
port A communication point of access where information goes into and/or out of a computer.
PPP Point to Point Protocol. A communications protocol that allows a computer to use a regular telephone line and a modem to make connections. Best known for TCP/IP connection to the Internet.
protocol An agreed-upon set of rules or format for transmitting data between two computer devices. A protocol will always include data, and may also define methods for error-checking, data-compression, end-of-message notice, and receipt-of-message notice.
PSTN Public Switched Telephone Network. This is the familiar telephone service based on copper wire that carries analog voice data. It is also called POTS (Plain Old Telephone Service).
RCM Realtime Control Microcode. This is the ARTIC-specific, multitasking operating system that manages the ARTIC processor tasks and resources.
real time A transmission or data processing mode in which the data is entered in an interactive session where an application can respond fast enough to affect later data input.
router A special-purpose computer or software package that handles the connection between two or more networks. A router handles packets by looking at their destination addresses and accordingly sending them via a given route.
RS-232 A TIA/EIA standard, also called EIA-232. A common serial communication electrical standard used by computers with data rates up to 20 Kbps. It is suitable for both synchronous and asynchronous communications.
RS-422 A TIA/EIA standard, also called EIA-422. This is a balanced implementation of EIA-449 for high speed data transmission. RS-422 can use either a 37-pin connector defined by RS-449, or a 25-pin connector defined by RS-530.
RS-449 A TIA/EIA standard, also called EIA-449. This 37-pin standard supports data transmission up to 2 Mbps. Each signal line has its own return line instead of a common ground return.
RS-485 A TIA/EIA standard, also called EIA-485.
SDLC Synchronous Data Link Control. An IBM standard protocol used in their SNA systems. Can be used with full or half duplex lines.
SS7 Signaling System 7. SS7 is an international telecommunications protocol standard for transmitting digital data on a broadband network.
switch A device that opens or closes circuits or selects the path or circuits to be used for transmission of information.
synchronous Data transmission at a fixed rate. It eliminates the need for start and stop bits that asynchronous transmission requires. The receiver and transmitter must be synchronized to work at the same rate.
T1 A North American dedicated phone connection that supports an aggregate data rate of 1.544 Mbps. A T1 line consists of 24 channels, each of which supports a rate of 64 Kbps and can often be individually leased as "fractional T1" lines. Also called DS1 lines.
TCP The TCP part of the TCP/IP protocol suite provides transport protocol rules which ensure that the data sent is received correctly at the other end.
TCP/IP Transmission Control Protocol/Internet Program. A suite of protocols that enables linking of dissimilar computers to access the Internet or another network.
throughput The amount of data transferred from one place to another. Throughput is typically expressed in Kbps or Mbps.
V.35 A CCITT electrical standard. It specifies 34-pin connections and data transmissions at 48 Kbps, although it is frequently used for data rates up to 64 Kbps.
WAN Wide Area Network. A WAN is a group of distant computer systems connected in a network. For example, a WAN might connect bank computers in the 10 largest cities in Australia.
X.21 A synchronous signaling interface specified by CCITT (now the ITU). It has error checking and supports data transfer to 64 Kbps.
X.25 A CCITT (now the ITU) standard for interfacing over a packet-switched data network.


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