Computability


Turing said that any problem that can be converted into a binary code could be worked by a simple machine. The computer chip is such a machine: all it does is check the position of a switch, flip (or not flip) that switch, and move on to a new position. The technical limitations of the computer chip are the same as those for the Turing machine: the length of the tape (or the total number or switches) and the speed of the processor.

Learn More About Chips!

Today's chips have more than 16 million switches.

Turing realized that the instructions for a machine could also be written in binary code. One "Universal Turing Machine" could perform many tasks. One tape contains the instructions for a specific task to be done with another tape. The instruction codes for the modern computer are the software.

In a modern computer, many Turing machines operate together in a nested or cascading way. The chip (or CPU) runs a set of instructions (the operating system). That set of instructions is used to read other tapes: the programs, and these sets of instructions are used to interpret files (word processor documents, spreadsheets, images, audio, etc.).

The usefulness of Turing's idea depends on special devices for imputing and displaying data. The keyboard and monitor are not Turing Machines, but they function on either end of the Turing process: the keyboard (with help from software) allows the user to encode alphanumerical information into binary code, and the monitor allows the computer to decode binary information and display it as pixels. These pieces of equipment are know as input/output devices

See the Parts of a Computer!

The processor and memory function together with input/output devices.