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Flip-flops |
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Basic building blocks |
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Combinational circuits:
gates |
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Sequential circuits:
flip-flops |
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Examples of flip-flops |
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State: flip-flop stores 1
bit |
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Inputs: |
control (D or T) |
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clock (positive edge) |
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Output: |
Q and Q' (negation) |
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Q is current state |
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Why both Q and Q'? |
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Because we can! |
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Flip-flops
can be built with NOR and NAND gates, and the negated output is |
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essentially free |
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Additional input (rarely
drawn) |
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CLR': asynchronous clear |
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When set to 0, Q is
immediately (asynchronously) set to 0 |
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This is called active low
(consumes less power) |
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