> From: Andrew Warren <fastfwd@IX.NETCOM.COM>
>
> Tjaart van der Walt <tjaart@wasp.co.za> wrote:
>
> > Here's the easiest way. You can do it in hardware or software.
> > Although it is not *truly* random, it is quite good indeed :
> >
> > Take a shift register (the longer the better), and tap two or three
> > of the stages. Add the taps (discard the carry - it is the same as
> > XORing) and feed back into the input of the shift register.
>
> Tjaart:
>
> This only works well if you pick the CORRECT two or three taps...
> Just choosing an arbitrary pair is unlikely to give a reasonably-long
> sequence.
>
> There are a couple of linear-feedback shift-register routines on my
> web page...

This is true, but getting off-track from the original request, which
was a way to determine a 'really random' seed value on power up.
With a deterministic machine such as a PIC, one must refer to some
'random' external event to initialise a shift register etc. otherwise
the machine will repeat the same sequence each time.

Regards,
SJH
Canberra, Australia