A sequence detector tracks how much of a target bit pattern has been matched. An overlapping detector retains a suffix that can also begin the next match. A non-overlapping detector restarts after detection. Choose the behavior before deriving the transitions.
Worked example
For target 101 and stream 10101, an overlapping detector reports matches ending at bits 3 and 5. After the first match, its final 1 is also the first 1 of a potential new match. A non-overlapping detector discards that reused bit and reports only the first match in this stream.
What to watch for
On a mismatch, do not always return to the initial state. A suffix of the observed bits may still match a useful prefix of the target.
Try it yourself
After detecting 101, what prefix should an overlapping detector remember?
Answer: The prefix 1, because the last bit of the detected pattern can begin the next 101.
How to study this topic
Begin with named states and a complete transition table. Then choose encodings and derive the logic. Trace inputs over several cycles, checking outputs as well as next states, including reset and unexpected encodings.
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Digital Electronics