H. Peter Anvin wrote:
Bill Davidsen wrote:
When last I looked at Hamming code, and that would be 1989 or 1990, I
believe that I learned that the number of Hamming bits needed to
cover N data bits was 1+log2(N), which for 512 bytes would be 1+12,
and fit into a 16 bit field nicely. I don't know that I would go that
way, fix any one bit error, detect any two bit error, rather than a
CRC which gives me only one chance in 64k of an undetected data
error, but I find it interesting.
A Hamming code across the bytes of a sector is pretty darn pointless,
since that's not a typical failure pattern.
I just thought it was perhaps one of those little known facts that
meaningful ECC could fit in 16 bits. I mentioned that I wouldn't go that
way, mainly because it would be less effective catching multibit errors.
This was a "fun fact" for all those folks who missed Hamming codes in
their education, because they are old tech.
--
bill davidsen <[EMAIL PROTECTED]>
CTO TMR Associates, Inc
Doing interesting things with small computers since 1979
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