Slide 1What is Sequential Logic?Combinational LogicSlide 4Sequential LogicUsesBuilding BlocksHow?How (cont.)JK Flip FlopJK Flip Flop (cont.)Slide 12Slide 13Basic Flip FlopSR Flip FlopD Flip FlopT Flip FlopMaster – Slave Flip FlopAcknowledgementsSlide 20By Stephen VoglewedeCS 1472/23/10What is Sequential Logic?Combinational LogicCombinational Logic•The output of a combinational circuit is a function of it’s input.•Consequently, it doesn’t matter what the previous output was.•Or what the future output will be.Sequential Logic•Input depends on both present input and previous input.•To do this, a sequential circuit must have storage.Uses•Some types of computer memory•Finite state machines•Other delay and storage elementsBecause of its ability to store previous input, Sequential circuits are essential components of:Building Blocks•The basic unit of a Sequential circuit is the Flip Flop. •There are many types of Flip Flops: D, T, JK, SR, etc.How?•The driving feature of the flip flop is the feedback loop.How (cont.)This circuit takes advantage of the feedback loopJK Flip Flop•Origin of name unclear. •Typically represented as a “black box”.JK Flip Flop (cont.)JK Flip Flop (cont.)•If Preset P = 0, Q = 1•If Clear C = 0, Q = 0•If both are 1, J & K come into playJK flip flops connected in the toggle mode can be connected together to create a binary counter system. Start with one JK flip flop, apply a clock waveform and sketch the Q output response. Assume PRE and Clr has been disabled (=1) on all flip flops.JK ClockJKQaQa>Clk11InputQa will toggle on each negative edge of the input clock. QaConnect a second stage to output Qa. JKQbQb>Clk11Qb will toggle on each negative edge of Qa.QbConnect a third stage to output Qb. Qc will toggle on each negative edge of Qb.JKQcQc>Clk11Qc0 0 0QcQbQaIn012345670 1 2 3 4 5 6 70 0 10 1 00 1 11 0 01 0 11 1 01 1 1Basic Flip FlopSR Flip FlopD Flip FlopT Flip FlopMaster – Slave Flip FlopAcknowledgements •http://en.wikipedia.org/wiki/File:D-Type_Flip-flop_Diagram.svg•http://computer.howstuffworks.com/boolean5.htm•http://technology.niagarac.on.ca/courses/elnc331/PowerPoint/Lab05.pps•http://wearcam.org/ece385/lectureflipflops/flipflops/The
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