National Semiconductor 48-bit and 56-bit ECC polynomials

Ed Spittles ed.spittles at
Thu Nov 17 12:42:10 CST 2016

Signal boosting (For me, Eric's post landed in the naughty corner)

On 16 November 2016 at 00:19, Eric Smith <spacewar at> wrote:

> Has anyone determined what 48-bit and 56-bit ECC polynomials are used by
> the National Semiconductor hard disk controllers?  The DP8496/97 allows
> choice of hard-wired 16-bit CRC, or 32-bit, 48-bit, or 56-bit ECC.  The
> 32-bit ECC is a common polynomial known as the Glover polynomial, and it's
> the same one used by WD and others.  However, National was apparently
> extremely proud of the 48-bit and 56-bit polynomials they chose, and the
> data sheets say that they require a license agreement with National.
> The more common DP8466 supports 32-bit 48-bit, but allows the user to
> configure the polynomial. The data sheet states that National's 48-bit
> polynomial is available under license.
> WD wasn't as proud of their 56-bit polynomial; it's given in the WD42C22
> data sheet. It doesn't seem to match National Semicondutor's 56-bit
> polynomial.

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