> The idea is that 1 extra
> bit per byte (as in parity RAM) for error detection is overkill.
> You only *need* 6 extra bits for every 64 bits to detect an error
> (being that 2**6=64). Since there are 72 bits of memory for each 64 in
> parity or ECC RAM, there are actually 8 "extra" bits per 64 for error
> checking. The 2 memory bits beyond the required 6 can be used to correct
> a single error, or tell you when there are two errors per byte.
>
> Regards,
> Bill
>

        To single error correct 64 bits you need 7 bits, since the error
may be also in the parity bits. I agree this is covered with 72 bits, but
to be precise...

************************************
Javier Vizcaino. Ability Electronics. [log in to unmask]
  Starting point:        (-1)^(-1) = -1
  Applying logarithms: (-1)*ln(-1) = ln(-1)
  Since ln(-1) <> 0, dividing:  -1 = 1     (ln(-1) is complex, but exists)