🔍 Sequence Detector FSM

Mealy Machine — Detects pattern "1011" with overlapping

State Diagram

S0 "" S1 "1" S2 "10" S3 "101" S1 --> 1/0 S0 (self-loop) --> 0/0 S2 --> 0/0 S1 (self-loop) --> 1/0 S3 --> 1/0 S0 --> 0/0 S1 (DETECTION! Output=1) --> 1/1 DETECT! S2 --> 0/0
FSM Type: Mealy Machine
In a Mealy machine, the output depends on both the current state AND the input. Notice the transition labels show input/output. The output is 1 only on the S3→S1 transition (when we see "1011" complete).
💡 Overlapping Detection
This FSM detects overlapping patterns! For example, in "101011", after detecting "1011", we go to S1 (not S0) because the final "1" could start a new "1011". Try input: 1011011 — it detects twice!

Input Stream

Bit Stream
_
Waiting for pattern "1011"...
0
Detections
0
Bits Input
Current State
S0 — No partial match. Looking for '1' to start.

Transition Table

State Match In=0 In=1
S0 "" S0/0 S1/0
S1 "1" S2/0 S1/0
S2 "10" S0/0 S3/0
S3 "101" S2/0 S1/1