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Miloslav Ciz 2024-03-24 21:52:08 +01:00
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@ -4,6 +4,8 @@ Turing machine is a mathematical model of a [computer](computer.md) which works
The advantage of a Turing machine is that it's firstly very simple (it's basically a finite state automaton operating on a memory tape), so it can be mathematically grasped very easily, and secondly it is, unlike many other systems of computations, actually similar to real computers in principle, mainly by its sequential instruction execution and possession of an explicit memory tape it operates on (equivalent to [RAM](ram.md) in traditional computers). However note that a **pure Turing machine cannot exist in reality** because there can never exist a computer with infinite amount of memory which Turing machine possesses; computers that can physically exist are really equivalent to [finite state automata](finite_state_automaton.md), i.e. the "weakest" kind of systems of computation. However we can see our physical computers as [approximations](approximation.md) of a Turing machine that in most relevant cases behave the same, so we do tend to theoretically view computers as "Turing machines with limited memory".
{ Although purely hypothetically we could entertain an idea of a computer that's capable of manufacturing itself a new tape cell whenever one is needed, which could then have something like unbounded memory tape, but still it would be limited at least by the amount of matter in observable universe. ~drummyfish }
In Turing machine data and program are separated (data is stored on the tape, program is represented by the control unit), i.e. it is closer to [Harvard architecture](harvard_architecture.md) than [von Neumann architecture](von_neumann_architecture.md).
**Is there anything computationally more powerful than a Turing machine?** Well, yes, but it's just kind of "mathematical fantasy". See e.g. [oracle machine](oracle_machine.md) which adds a special "oracle" device to a Turing machine to make it [magically](magic.md) solve undecidable problems.