Counters

The name counter is generally used for any clocked, sequential circuit whose state diagram contians a single cycle.
The modulus of a couter is the number of states in the cycle.
A counter with m states is called a modulo-m counter, or sometimes a divide-by-m counter.
Probably the most common counter is an n-bit binary counter.
- Has n flip-flops, 2^n states.
- States are visited in the sequence 0,1,2,...,2^n-1,0,1,...
- Each state is coded as an n-bit binary integer.