Turing Machine

• original idea of a computing machine was described by Alan Turing

• theoretical model of a computer, which a lot of computers are based on

• Turing machine consists of the following four basic elements

  • A tape, which is divided into cells, one next to the other. Each cell contains a symbol from some finite alphabet. This tape is assumed to be infinitely long on both ends. It can be read or written

    • memory and disks

  • A head that can read and write symbols on the tape.

    • I/O controllers (memory bus, disk controllers, and network port)

  • A table of instructions that tell the machine what to do next, based on the current state of the machine and the symbols it is reading on the tape

  • A state register that stores the states of the machine

    • state + table = cpu

• Turing machine has two assumptions, which is not real in live software:

  • unlimited storage space

  • completing a task regardless of the amount of time it takes