Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site utcs.uucp Path: utzoo!utcs!flaps From: flaps@utcs.uucp (Alan J Rosenthal) Newsgroups: net.micro.apple,net.dcom Subject: Re: Data Protocol Question Message-ID: <947@utcs.uucp> Date: Wed, 30-Oct-85 20:10:24 EST Article-I.D.: utcs.947 Posted: Wed Oct 30 20:10:24 1985 Date-Received: Wed, 30-Oct-85 21:26:56 EST References: <557@ihlpm.UUCP> Reply-To: flaps@utcs.UUCP (Alan J Rosenthal) Distribution: net Organization: University of Toronto Lines: 19 Xref: utcs net.micro.apple:2253 net.dcom:1425 Summary: In article <557@ihlpm.UUCP> terry2@ihlpm.UUCP (t. nelson) writes: >I am now exploring the world of Bulletin Boards. Most seem to >use various forms of data exchange protocol like XMODEM or >XMODEM/CRC. Access II uses Christensen (sp?) protocol. I have >been told that XMODEM and Christensen protocols are the same. >Is this true? What's the difference between XMODEM, XMODEM/CRC >and some other popular protocols? XMODEM describes how each individual block is sent. Ward Christensen is XMODEM protocol with a particular description of block 0, and the fact that the other blocks are data blocks. I will post a (technical) description of the protocol if requested. CRC stands for Cyclic Redundancy Check. It is a complex form of checksum. I would assume that XMODEM/CRC is just an XMODEM that outputs the CRC after transmission. Alan J Rosenthal {ihnp4|allegra|linus|decvax}!utzoo!utcs!flaps, cbosgd!utcs!flaps