Re: UDA revisited

From: Colin Geoffrey Hales <c.hales.domain.name.hidden>
Date: Sun, 26 Nov 2006 17:58:28 +1100 (EST)

> Colin Geoffrey Hales wrote:
>
>> BTW there's no such thing as a truly digital computer. They are all
>> actually analogue. We just ignore the analogue parts of the state
>> transitions and time it all so it makes sense.
>
> And if the analogue part intrudes, the computer has malfunctioned
> in some way. So correctly functioning computers are digital.
>

Not so in the case of all the computers we have. 0 and 1 are an
interpretation put on a voltage by you and I. Depending on the voltage
levels of the computer chip.

Eg TTL <0.2 volts = 0, >4.2ish volts = 1

If you get a logic gate and control the voltage fed to it you can see the
transition from 0.2....4.whatever and up to 5 volts usually. It's a nice
smooth transition. Let it go under it's own steam and the transition is
very fast, but still all analogue real world potential measureed in
conducting crytalline environment. You're talking to an electronic
engineer here.

> (And "analogue" physics might turn out to be digital)
>

Digital is a conceptual representation metaphor only. Anything with 2
stable states can be called digital. Even quantum computers playing with
spin states are analogue in that the transition (although scarily fast) is
not instantaneous (I think the concept of instant takes a beating in that
case!...but no matter)

Nuff said.


Colin



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Received on Sun Nov 26 2006 - 01:59:52 PST

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