TTL computing

From: <(>
Date: Fri Apr 12 20:05:55 2002

On Fri, 12 Apr 2002, Richard Erlacher wrote:

> > Then there's the Turing machine. Again, an fsm with infinite memory (the
> > 'tape), but memory that can be sequentially accessed one cell at a time.
> > I believe nobody has ever proposed a machine that's more powerful than
> > the turing machine. I also seem to remember that a PDA with _2_ separate
> > infinite stacks is proveably equivalent to a Turing machine.
> >
> > OK, those of you who actually learnt some computer science, please correct
> the above...
> >
> I see a major implementation problem, in that you throw around the word
> infinite quite freely. It's possible to build counters of 2^64 bits, and it's
> possible to hook up 64TB memory arrays, but it's still nowhere as large as
> infinite. Until you have an infinitely fast computer, it wouldn't make sense
> to have an infinite memory, since you wouldn't be able to test/verify
> whether/that your infinite stacks, or whatever, work properly. If you can't
> do that, it's not useable.
> >

It looks like some people need to understand the difference between
'applied' and 'theoretical. Turing machines are theoretical devices that
we try to approximate with physical (applied) devices. While you can't
'in reality' have infinite storage, you can quite easily have 'theoretical
infinite storage'.

FSMs are theoretical tools that can be 'exactly' implemented in real life
(no approximations).

Anyways, assuming the universe is truely infinite in size, who says you
can't realy build something infinitely big? (where 'you' could mean an
infinite number of beings over an infinite amount of time)

--> Practial != Possible <--

-- Pat
Received on Fri Apr 12 2002 - 20:05:55 BST

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