Re: 8 Bit Random Numbers

On Feb 3, 9:59 am, nos...@xxxxxxxxxx wrote:

What part of

"A linear feedback shift register (LFSR) is a shift
register whose input bit is a linear function of its
previous state. The only linear functions of single
bits are xor and inverse-xor..."

are you having trouble understanding?


I'm having trouble with the linear part. From what I understand a
linear output would suggest an equal number of ones and zeros over a
long period of time, or about 1024 of each for an 8 bit register
during each complete cycle. This is the case for Fields circuit using
the extra 7 input nor, and extra xor.

The standard LFSR with the missing "0" state yields 1024 "ones" but
only 1016 "zeros" for each complete cycle, since 8 zeros are left out.

So, which approach would you say is more linear?

BTW, for most applications a standard Galois LFSR is superior
to what Fields posted. When implemented using logic gates,
The XOR gates are run in parallel rather than in serial,
reducing propagation delay and allowing for faster cycling.
When implemented in software, it is is more efficient
because the XOR can computed a word at a time. Code it or
breadboard it and see.

Yes, I know about that, but haven't figured out the exact 8 bit word
to xor against the 8 bit random word in a parallel fashion to get the
desired result. Maybe you know what it is?

-Bill
.

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