Date   : Wed, 19 Jun 1985 10:19:00 MDT
From   : Keith Petersen <W8SDZ@SIMTEL20.ARPA>
Subject: Diff. between Xmodem and Modem7?

Mark, XMODEM was derived from MODEM2.  MODEM7 is an enhancement of
MODEM2.  The CRC option of MODEM7 was added to XMODEM some time ago,
allowing it to use either CHECKSUM or CRC mode.

In the CHECKSUM mode MODEM2, MODEM7 and XMODEM (all versions of each)
are totally compatible.  Any version of all which has the CRC mode is
compatible with any other version with same.

What machine are you using XMODEM on?  Be certain you have initialized
your data port for 8 bits, no parity and ONE stop bit.  This is
required by the Christensen protocol.

--Keith Petersen
Arpa:  W8SDZ@SIMTEL20.ARPA
uucp:  ...!{decvax,unc,hao,cbosgd,seismo,aplvax,uci}!brl-bmd!w8sdz
uucp:  ...!{ihnp4!cbosgd,cmcl2!esquire}!brl-bmd!w8sdz