On Sun, May 11, 2008 at 10:11:26AM +0100, Bob W wrote:
> ...the Babbage difference engine number 2:
>
> http://news.bbc.co.uk/1/hi/technology/7391593.stm
>
> A quote from the article:
> "... in the 1930s where pioneers of the electronic computer age
> reinvented all the essential principles of computing largely in
> ignorance of Babbage's designs."
>
> This sounds wrong to me. The essential property of a Turing machine is
> that it is universal - it can be programmed to become any machine -
> and Turing provided the mathematical basis which led to the later
> physical implementations. The Babbage machines were not universal
> machines, and certainly not Turing machines, nor did Babbage provide
> any such mathematical basis for future computing, and to that extent
> his work was a fascinating dead end.
That's not correct. Although the Babbage Difference Engine was not
a general-purpose computer, the same can not be said of his grand
design - the Analytical Engine. That did incorporate just about
all the features of modern computing equipment - programmability
(via punched cards), conditional execution, etc., etc. It has
more than enough capabilities to implement a Turing machine (not
that that says very much; load/store, increment, decrement, test
and skip are sufficient). It even had a hardware multiplier!
Even the Difference Engine incorporated parallel execution,
pipelineing, and micro-coding (though Babbage would not have
understood those words).
I've been immersed in Babbage quite a bit, recently:
http://www.computerhistory.org/babbage/
http://www.jfwaf.com/PAW/PAW.php?name=PAW0816&style=1
My favourite quote comes from Doron Swade (curator at the
London Science Museum responsible for building the machine)
Charles Babbage is equally famous for two things:
o Designing the first computer
o Failing to build it
>
> Anyway, it's an interesting article and it will be interesting for
> those of you in the area to see the machine.
>
> Bob
>
>
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