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Russell H., Programmer & Coder
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# A sequence recognizer is a special kind of sequential circuit

### Customer Question

a sequence recognizer is a special kind of sequential circuit that looks for a special bit pattern in some input. The recognizer circuit has only one input, X. One bit of input is supplied on every clock cycle. For example, it would take 20 cycles to scan a 20-bit input. This is an easy way to permit arbitrarily long input sequences.
There is one output, Z, which is 1 when the desired pattern is found. we will design a sequence recognizer that detects the bit pattern "0101”
a) Defined the needed states and also state diagram for this sequence recognizer
b) Make a state assignment for the states using 2-bit codes and find the encoded state table.
c) Find an optimized circuit implementation for the encoded state table from (part b) using JK flip-flops, NAND gates, and inverters. This requires you to use the excitation table for JK flip-flop to determine the J, K inputs, converting a JK flipflop into a D flipflop to complete the design doesn't satisfy the requirements for this question. Make sure all the intermediate steps, k-maps, etc. are included in your answer.
Submitted: 2 years ago.
Category: Programming
Customer: replied 2 years ago.
Answer is no longer needed, thank you.
Expert:  Russell H. replied 2 years ago.
Hi - my name is***** I feel that some sort of answer should be offered to your question, though you have said it is not needed now.Basic circuit design of this kind requires an understanding of how circuitry, esp. gates and JK flip-flops, work.JK flip-flops can be specifically designated to only change state or 'switch' when a certain bit-pattern is present on the J and K inputs. They can be used to select either a bit 0 or bit 1 state.Having encoded that bit 0 or bit 1 state for each bit of the pattern or 'sequence' required, the whole sequence of flip-flops will only change state, from the first to the last, once all bits are present in their required values. Supposing the bits to be sequential not simultaneous, and the clock speed to the flip-flops to be much faster than the state-changing speed of the flip-flops, this will work.