Section 1.4
Representing Binary Quantities

In digital systems the information that is being processed is usually presented in binary form. Binary quantities can be represented by any device that has only two operating states or possible conditions. Eg. a switch has only open or closed. We arbitrarily (as we define them) let an open switch represent binary 0 and a closed switch represent binary 1. Thus we can represent any binary number by using series of switches.

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Typical Voltage Assignment

Binary 1: Any voltage between 2V to 5V
Binary 0: Any voltage between 0V to 0.8V
Not used: Voltage between 0.8V to 2V, this may cause error in a digital circuit.

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We can see another significant difference between digital and analog systems. In digital systems, the exact value of a voltage is not important; eg, a voltage of 3.6V means the same as a voltage of 4.3V. In analog systems, the exact value of a voltage is important.

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