Annals of OS and network history

On 1998-03-10 classiccmp(a)u.washington.edu said to lisard(a)zetnet.co.uk :It's been a long time since I've looked at a CS book, but I :remember the Turing machine as a *theoretical* machine that reads :and writes symbols on an *infinitely long* tape. I'm sure somebody :could build an approximation of this, but the main interest in the :Turing machine is that it is used as the definition of :computational "power." One of theories is that no machine built :today, or at any time in the future, no matter what the :architecture, will be able to compute anything that a simple Turing :machine cannot compute.. that's the one. alan turing defined these machines as part of his contribution to the proof that mathematics has some unprovables. anything that can be proved, period, can be proved by a turing machine; anything that a turing machine can't prove is unprovable. kurt godel (most famously, perhaps?) and alonzo church producd alternative theorems to demonstrate the same thing, but turing's work laid the basis for computer science, and turing himself became quite active within the field of early uk computation (the original ACE design is his, and he subsequently worked on manchester's computers). there are even such things as "universal turing machines", which can be given definitions of turing machines and used to solve such problems, which we suspect led directly on to universal computers which could be programmed to simulate special purpose devices. the "infinite tape" idea is as important as you suggested, however. -- Communa (together) we remember... we'll see you falling you know soft spoken changes nothing to sing within her...