3Com 56K manual Glossary

GLOSSARY 7

HDLC See High Level Data Link Control.

High Speed 3Com' proprietary signaling scheme, design and error control protocol Technology (HST) for high-speed modems. HST incorporates trellis-coded modulation, for greater immunity from variable phone line conditions, and asymmetrical

modulation for more efficient use of the phone channel at speeds of 4800 bps and above. HST also incorporates MNP-compatible error control procedures adapted to asymmetrical modulation.

Hz (Hertz) A frequency measurement unit used internationally to indicate one cycle per second.

Industry Standard The most common type of computer expansion bus. Other types Architecture (ISA) include Extended Industry Standard Architecture (EISA) and

Microchannel Architecture (MCA).

interrupt request A number that must be assigned to devices that plug in to your (IRQ) computer's expansion bus.

IP Internet Protocol.

IPX Novell's Internet Packet Exchange protocol.

IRQ See interrupt request.

ISA See Industry Standard Architecture.

ITU-TInternational Telecommunication Union-Telecommunication sector. Formerly referred to as CCITT. An international organization that defines standards for telegraphic and telephone equipment. For example, the Bell 212A standard for 1200 bps communication in North America is observed internationally as ITU-T V.22. For 2400 bps communication, most U.S. manufacturers observe V.22 bis.

jumper A switch composed of pins and a shunt. The shunt's position on the pins determines the jumper setting.

Kbps Kilobits per second, or thousand bits per second.

LAPM See Link Access Procedure for Modems.

Link Access Link Access Procedure for Modems, an error control protocol Procedure for incorporated in ITU-T Recommendation V.42. Like the MNP and HST

Modems (LAPM) protocols, LAPM uses cyclic redundancy checking (CRC) and retransmission of corrupted data (ARQ) to ensure data reliability.