ECC on MFM drive - test-drb@ccmp.vtda.org

12 Sep 2008

...
 > Yes. Indeed. I checked it again and it is the
regular
...
 > CRC circuit with unusual initial value and
polynomial.

...
  What are these values? They are not documented in
the data sheet.

The polynomial is 0x140a0445
(x32+x28+x26+x19+x17+x10+x6+x2+1), the initial value
is 0x9dcd57c0.

It is need to do following steps to check crc:
1 Init sift register by initial value
2 Process 0xf8  (MSB first)
3 Process 512 bytes of data
4 Process 4 bytes CRC.

If everything is ok then value in the shift register
will be zero.

Alexander.