Re: mismatch_cnt questions

[Bill Davidsen <davidsen@tmr.com>]

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 <davidsen@tmr.com>
  CTO TMR Associates, Inc
  Doing interesting things with small computers since 1979