Re: 8 Bit Random Numbers

On Mon, 02 Feb 2009 04:03:27 +0000, Nobody <nobody@xxxxxxxxxxx> wrote:

On Sun, 01 Feb 2009 17:24:40 -0600, John Fields wrote:

What you cannot do is make an XOR-based PRNG that pseudorandomly cycles
through all values from 0 to 255.

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Not true.

If you run the LTspice circuit list or the BASIC program I posted
earlier (or build it, even) you can see all 256 states exercised.

Your LTspice circuit isn't an "XOR-based PRNG" (i.e. LFSR), as it
includes 2 (inclusive-) OR gates.

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Sorry, but that's not right.

It's EXOR _based_ because the basic polynomial is generated by A4, A10,
and A11 (EXOR gates) with taps along the register located at Q3,Q5,Q6, and
Q8.

Well, we could argue forever about what constitutes "[E]XOR-based", but
it's not an LFSR, and I thought it was clear that's what "nospam" was
referring to by "XOR-based PRNG".
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He was, and you're both wrong.

What you're saying, in effect, is that if an 8 cylinder ICE fitted with
a 7 cylinder ignition system was fitted with a system winch allowed all
8 cylinders to work it would no longer be an ICE, which is total
nonsense.
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I don't think that anone would contest that there exist *other* circuits
which will cycle through all 256 8-bit values, or at least don't have the
lock-up state.

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Your point being???

JF
.

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