3Com 56K manual Glossary

GLOSSARY 13

speed when line quality is impaired, and fall back further as necessary. They fall forward to the next higher speed when line quality improves.

V.32 terbo Modulation scheme that extends the V.32 connection range: 4800, 7200, 9600, 12K, 14.4K, 16.8K, 19.2K, and 21.6 Kbps. V.32 terbo modems fall back to the next lower speed when line quality is impaired, and fall back further as necessary. They fall forward to the next higher speed when line quality improves.

V.34 An ITU-T standard that allows data rates as high as 28.8 Kbps.

V.35 An ITU-T standard trunk interface between a device and a packet network, using signaling of at least 19200 bps.

V.42 An ITU-T standard for modem communications that defines a two-stage process of detection for LAPM error control.

V.42 bis An extension of ITU-T V.42 that defines a specific data compression scheme for use with V.42 error control.

V.Fast Class (V.FC) Proprietary modulation scheme developed by Rockwell International for data communication speeds up to 28.8 Kbps.

word length The number of bits in a data character without parity, start or stop bits.

XMODEM The first of a family of error control software protocols used to transfer files between modems. These protocols are in the public domain and are available from many bulletin board services.

XON/XOFF Standard ASCII control characters used to tell a device to stop/resume transmitting data. In most systems typing <Ctrl>-S sends the XOFF character. Some devices, including the Business Modem, understand <Ctrl>-Q as XON; others interpret the pressing of any key after <Ctrl>-S as XON.

YMODEM An error-correcting file transfer protocol that is related to, but faster than, XMODEM.

ZMODEM An error-correcting file transfer protocol that is related to, but faster than, XMODEM or YMODEM.