ECC on MFM drive

Alexander Sholohov ra9yer at yahoo.com
Mon Sep 8 05:34:41 CDT 2008


Hello,

Could someone help me understand the algorithm used
for data integrity check on ST251 MFM drive.

I have ST251 drive and an Adaptec controller. Also I
have ability to view recorded data in raw format.

On the track I see ID field block protected by CCITT
CRC16. And the data block protected by some 32-bit
ECC. This is definitely not a CRC32. The algorithm in
general looks like shift register for polynomial
multiplication with polynomial equal to
x32+x28+x26+x19+x17+x10+x6+x2+1 . But, this is not
just a multiplication. The circuit has some other
logic that I did not understand yet.
I’ve found very useful document 
(http://www.national.com/an/AN/ AN-413.pdf) It has a
mention about algorithm called “Glover 140A0443 “ May
be this is that I have?

Please advice.
Thank you.

Alexander.



      



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