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Programmable devices

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• Programmable machines, programs and instructions
  • Programmable machine:

    Programmable machine = a device which function can be altered by a program

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  • Program:

    Program = a series of instructions that accomplishes a specific task

    Example:

    Each row of holes in the card board is an instruction for some machine The position of a hole encodes a certain meaning The program consists of a series of rows (= instructions) on the card board

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• Examples of Programmable machines

  • Examples:

    Mechanical piano/music box	Mechanical loom
    A mechanical piano can play different songs The drum in the center of the piano contains spikes and rotates slowly Spikes at different position causes the piano to play a different note Different spike patterns (on different drums) will cause the piano to play a different song	The mechanical loom can weave fabric in different patterns The loom's movement is controlled by holes punched in a card Different hole patterns (on different cards) will casue the loom to weave a different pattern See: http://en.wikipedia.org/wiki/Joseph_Marie_Jacquard

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• Instruction encoding

  • Instructions (= program instructions) tells a machine what to do

  • Instructions are represented using a encoding method

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  • Example encoding:

    1 means add 2 means subtract And so on.

  • Another example: encoding a song on paper

    The location of a hole in the paper corresponds to a particular musical note Encoding a song: a series of holes in the paper make the mechanical piano/music box play the notes of a song