National Semiconductor 48-bit and 56-bit ECC polynomials

Eric Smith spacewar at
Thu Nov 17 17:07:40 CST 2016

On Thu, Nov 17, 2016 at 3:59 PM, dwight <dkelvey at> wrote:

> Do you have working hardware?

No, only a drive that 48-bit ECC. I don't know whether it used a National
Semiconductor based controller, but it doesn't use the Western Digital
polynomial, so NS is my first guess.  If it used the DP8466, it might have
used the NS Sooper-Sekrit 48-bit polynomial, or some other polynomial.

> A lot can be deduced by using simple data, like all 0's and different
data lengths.

If I got my hands on a DP8496 or DP8497, or a SCSI drive containing one of
them, I might be able to hack up something like you describe in order to
reverse-engineer the polynomials.

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