HP3000-L Archives

October 2001, Week 2

HP3000-L@RAVEN.UTC.EDU
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Subject:
Re: Checksum Logic
From:
"Steve Dirickson (Volt)" <[log in to unmask]>
Reply To:
Steve Dirickson (Volt)
Date:
Wed, 10 Oct 2001 15:04:19 -0700
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> bursts and never changes just one bit, whereas many 
> operations on a database
> record might only change a single bit, which would increase 
> the possibility
> that the CRC code would miss the "error".

If this wants to say that CRCs will miss single-bit errors, it is incorrect: single-bit errors are the one error that a CRC is guaranteed to detect; I believe that that guarantee is independent of the length of the data used to generate the CRC. They won't help you find the error (you need ECC for that), but you'll know that it happened. CRCs will also detect most two-bit errors; someone with better math skills than mine could probably figure out exactly which forms of two-bit errors will slip through.

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