Multi Tech Equipment ISIHI-2S manual UTP unshielded twisted pair Telephone-type wiring

Glossary

Toggle: Alternate back and forth between two states.

Tone dialing: One of two methods of dialing a telephone, usually associated with push button phones. Compare with pulse dialing.

Transistor: A semiconductor device used to amplify a signal, or open and close a circuit. In digital computers, it functions as an electronic switch.

TSR (Terminate and Stay Resident): A software program that remains active and in memory after its user interface is closed. Similar to a daemon in UNIX environments.

Twisted pair wiring: A type of cabling with one or more pairs of insulated wires wrapped around each other. An inexpensive wiring method used for LAN and telephone applications, also called UTP wiring.

U

UART (Universal Asynchronous Receiver/Transmitter): A chip that transmits and receives data on the serial port. It converts bytes into serial bits for transmission, and vice versa, and generates and strips the start and stop bits appended to each character.

UNIX: A multi-user, multitasking operating system, first developed by AT&T in the 1970’s. It now runs on a wide variety of computer systems from micro to mainframe, and is controlled by UNIX System Laboratories (USL).

UTP (unshielded twisted pair): Telephone-type wiring.

V

V.21: The CCITT modulation standard for 300 bps, full- duplex transmission over dial-up lines.

V.22: The CCITT modulation standard for 1200 bps, full- duplex transmission over a dial-up or 2-wire leased line. This is not common in North America.

V.22bis: The CCITT modulation standard for 2400 bps, full- duplex transmission over a dial-up or a 2-wire leased line.

V.23: The CCITT modulation standard for 75/1200 bps, half- duplex transmission over dial-up lines. This is not common in North America.

V.24: The CCITT hardware interface specification for interchange circuits between the DTE and DCE.

V.25bis: A dialing command set developed by the CCITT for both synchronous and asynchronous devices. Since

V.25bis does not provide any modem configuration com- mands, it is primarily used for its synchronous dialing commands, while the “AT” commands are used for asyn- chronous dialing and for modem configuration.

V.26: The CCITT modulation standard for 2400 bps, full- duplex transmission over 4-wire leased lines. Primarily for synchronous use. Not common in North America.

V.27: The CCITT modulation standard for 4800 bps, full or half-duplex transmission. Primarily for synchronous use. Not common in North America. V.27ter is used by Group 2 fax-modems for 4800 bps fax transmission.

V.29: The CCITT modulation standard for 9600 bps, 2-wire (half-duplex) or 4-wire (full-duplex) transmissions, primarily over leased lines (synchronous or asynchronous). V.29 is used for Group 3 fax transmissions.

V.32: The CCITT modulation standard for synchronous or asynchronous input to be transmitted at 9600 bps over the PSTN. V.32 operates in half- or full-duplex mode.

V.32bis: The CCITT modulation standard for synchronous or asynchronous input to be transmitted at 14,400 bps over the PSTN. V.32bis operates in half- or full-duplex mode.

V.32terbo: An AT&T recommendation for synchronous or asynchronous input to be transmitted at 14,400 bps over the PSTN. V32terbo operates in half- or full-duplex mode.

V.32: The CCITT modulation standard for synchronous or asynchronous input to be transmitted at 9600 bps over the PSTN. V.32 operates in half- or full-duplex mode.

V.33: A CCITT modulation standard for 14,400 bps synchro- nous transmission over a 40wire leased line.

V.35: The CCITT hardware interface specification com- monly used by DSU/CSUs and other high-speed devices.

V.42: A CCITT recommendation for error-control hardware on a modem that accepts asynchronous input. V.42 recom- mends for manufactures to implement LAP-M and makes a provision for MNP-5 as a alternative because of its popular- ity. Most modem makers provide both.

V.42bis: A CCITT recommendation for data compressing hardware on a modem that accepts asynchronous input. V.42bis is based on a dynamically updated dictionary that looks up common strings and replaces the strings with code words. This reduces the amount of characters actually transmitted. V.42bis has been found to be most effective for file transfers that contain long strings of repetitive informa- tion and least effective for short strings of unique data.

V.54: The CCITT recommendation to standardize Bit Error Rate Testing (BERT) and Loopback testing (Local Analog and Digital Loopback, as well as Remote Analog and Digital Loopback).

VRC (Vertical Redundancy Check): An error checking method that generates and tests a parity bit for each byte of data that is moved or transmitted.

W

WATS (Wide Area Telephone Service): A discounted long- distance calling plan that allows calls in or out. The popular 800 numbers are WATS lines in. The calls are charges to the holder of the 800 number at a discounted rate.

MultiModemISI Hybrid Series, ISIHI-2S 179