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The ignition switch of an automobile is discrete — it has definite states — but there are usually more than two states (off, running, start, accessories ) A button on a electronic calculator is a binary device. It is either on or off. Ordinarily it is off. When you push it, it is on. It springs back to off when you release it, which is different from a toggle switch, but it still is a binary device.

Why Computers use Binary

Claude Shannon

There are many advantages to binary. Here are four (somewhat overlapping) important reasons for using binary:

  1. Binary devices are Simple and easy to build.
  2. Binary signals are Unambiguous (which gives them noise immunity).
  3. Flawless copies can be made of binary data.
  4. Anything that can be represented with some sort of pattern can be represented with patterns of bits.

These characteristics of binary were realized by Claude Shannon, a mathematician at Bell Telephone Laboratories. His 1948 paper A Mathematical Theory of Communication is the foundation of information theory and much of computer science.


Which is easier to build: