Logic State Definition/Meaning:
The logical sense, true or false, of a given binary signal. A binary
signal is a digital signal that has only two valid values. In physical terms
the logical sense of a binary signal is determined by the voltage level or
current value of the signal, and this in turn is determined by the device
technology. In TTL circuits, for example, a true state is represented by a
logic 1, approximately equal to + 5 volts on a signal line; logic 0 is
approximately 0 volts. Voltage levels between 0 and +5 volts are considered
undefined.
Since only two logic states, logic 1 and logic 0, are possible, the
techniques of Boolean algebra may be used to analyze digital circuits involving
binary signals. The term positive logic is applied to circuits where logic 1 is
assigned to the highest voltage level; in negative logic circuits a logic 1 is
indicated by the lower voltage level.
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