3Com 1.024.1644-00 manual 42 bis, Xmodem, Ymodem G, Zmodem

Glossary

V.42

An ITU-Tstandard for modem communications that defines a two-stage process of detection and negotiation for LAPM error control.

V.42 bis

An extension of ITU-TV.42 that defines a specific data compression scheme for use during V.42 connections.

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 an intelligent device to stop/resume transmitting data.

Ymodem

An error-checking protocol that can send several files of data at a time in 1024-byte (1K) blocks. This protocol can use either checksums or CRC for error checking.

Ymodem G

This is similar to Ymodem, except it relies on the modem for error checking, which makes it faster.

Zmodem

This is similar to Xmodem and Ymodem, except it includes batch transfer, the ability to recover from a partially complete transfer, an autostart feature, and improved efficiency.

56K Voice Faxmodem Internal - User’s Guide 51