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Path: utzoo!hcrvax!hugh
From: hugh@hcrvax.UUCP (Hugh Redelmeier)
Newsgroups: net.micro
Subject: Re: CRC algorithm ?
Message-ID: <1531@hcrvax.UUCP>
Date: Wed, 21-Nov-84 15:29:46 EST
Article-I.D.: hcrvax.1531
Posted: Wed Nov 21 15:29:46 1984
Date-Received: Thu, 22-Nov-84 02:03:01 EST
References: <34500017@uiucuxc.UUCP>
Organization: Human Computing Resources, Toronto
Lines: 11

There are several standard CRC formulae;  CRC is a kind of hash
("Cyclic Redundancy Check").  It is easily computed using a
shift register with feedback; how it is connected determines the
formula.  The two popular standards are called CRC16 and CCITT.
Further complication: sometimes the initial value for the shift
register is all-zeros, sometimes all-ones!

The "CRC" used in some later xmodems is not a CRC at all, but some
other hash!

See my submission to net.sources last Thursday.