Sequential LogicWhat Is A Sequential Circuit?Simple memorySR Flip-FlopHow does a SR Flip-Flop work?Clocked D Flip-FlopHow does Clocked D Flip-Flop Circuit Work?Clocked JK Flip-FlopEdge DetectionT Flip-FlopRandom-Access MemoryBinary CounterRegisterClocks and SequencersReal World ApplicationSourcesSequential LogicSequential LogicFlip-Flop CircuitsFlip-Flop CircuitsBy Dylan SmederBy Dylan SmederWhat Is A Sequential Circuit?What Is A Sequential Circuit?Circuit that has memoryCircuit that has memorySequence of inputs creates memorySequence of inputs creates memoryAt the simplest a Flip-Flop circuitAt the simplest a Flip-Flop circuit““Sequential Circuits along with Sequential Circuits along with combinational circuits are the combinational circuits are the building blocks of computers”building blocks of computers”Simple memorySimple memoryFlip-Flop circuits have the ability to store 1 bit Flip-Flop circuits have the ability to store 1 bit integers which is represented by either 1 or 0integers which is represented by either 1 or 0The output of an operation is used as input for The output of an operation is used as input for the next operationthe next operationThe truth table is affected by memory instead of The truth table is affected by memory instead of having one set of output for a set of input there having one set of output for a set of input there are two different sets of outputare two different sets of outputSR Flip-FlopSR Flip-FlopSimple Flip-Flop circuitSimple Flip-Flop circuitTwo inputs “S” and “R”Two inputs “S” and “R”S = Set S = Set R= ResetR= ResetTwo outputs which are the complements of each other Q Two outputs which are the complements of each other Q and Q’and Q’Truth table has strange outputTruth table has strange outputIf S==1 and R==1 Q=0 and Q’=1 then If S==1 and R==1 Q=0 and Q’=1 then Case A Q is 0 NOR 0 which equals 1Case A Q is 0 NOR 0 which equals 1Cases A B C are similar to ACases A B C are similar to ACase D and E are different. Each depends Case D and E are different. Each depends on the previous output. If in the previous on the previous output. If in the previous output Q==0 and Q’==1output Q==0 and Q’==1then Q=1 and Q’=0 then Q=1 and Q’=0 If Q==1 and Q’==0 then Q=0 and Q’=1If Q==1 and Q’==0 then Q=0 and Q’=1How does a SR Flip-Flop How does a SR Flip-Flop work?work?Clocked D Flip-FlopClocked D Flip-FlopVariation of a SR CircuitVariation of a SR CircuitCan be set with a single inputCan be set with a single inputPulse input CKPulse input CKD inputD inputHow does Clocked D Flip-Flop How does Clocked D Flip-Flop Circuit Work?Circuit Work?When CP is equal to 0 the input from D is ignored When CP is equal to 0 the input from D is ignored When CP equals 1 D and its complement are When CP equals 1 D and its complement are inputted in to the SR circuitinputted in to the SR circuitClocked JK Flip-FlopClocked JK Flip-FlopVariation of a Clocked D Flip-Flop Variation of a Clocked D Flip-Flop CircuitCircuitWhen CP equals 0 input from K and J When CP equals 0 input from K and J are Ignoredare IgnoredWhen CP equals 1 if K=J=1 it sets if in When CP equals 1 if K=J=1 it sets if in reset it resets if in setreset it resets if in setEdge DetectionEdge Detection With a single input there can be various signal levels but the With a single input there can be various signal levels but the only level needed is when it switches from 1 to 0 or 0 to 1only level needed is when it switches from 1 to 0 or 0 to 1Edge detection only records theses changesEdge detection only records theses changesEffectively levels out oscillations Effectively levels out oscillations If it records a positive edge it is called a positive edge If it records a positive edge it is called a positive edge triggered triggered If it records a negative edge it is called a negative edge If it records a negative edge it is called a negative edge triggeredtriggeredT Flip-FlopT Flip-FlopPositive edge triggered JK Flip-FlopPositive edge triggered JK Flip-FlopJ and K inputs are tied togetherJ and K inputs are tied togetherUsed as countersUsed as countersRandom-Access MemoryRandom-Access MemoryCan read and write at any point in Can read and write at any point in memorymemoryImplemented using D Flip-FlopsImplemented using D Flip-FlopsEach row contains 16 Flip-Flops Each row contains 16 Flip-Flops A DecoderA DecoderBinary CounterBinary Counter Holds each pulse in memoryHolds each pulse in memoryEach pulse add another number Each pulse add another number Binary format Binary formatRegisterRegisterUsed to hold one item of informationUsed to hold one item of informationCPU’s have many registers CPU’s have many registers AX is an example in AssemblyAX is an example in AssemblyClocks and SequencersClocks and SequencersTo perform operations a CPU often To perform operations a CPU often requires a specific sequence of sub requires a specific sequence of sub operations operations A sequencer is used to make sure A sequencer is used to make sure operations happen in correct order operations happen in correct order A clock is a circuit that outputs 0’s A clock is a circuit that outputs 0’s and 1’s at specific frequencies and 1’s at specific frequenciesReal World ApplicationReal World ApplicationThe RAM discussed is a model for a The RAM discussed is a model for a chip that can actually be found in a chip that can actually be found in a computercomputerThe binary counter can be bought at The binary counter can be bought at http://www.web-tronics.com/webtronhttp://www.web-tronics.com/webtronics/74hc161n.htmlics/74hc161n.html for 45 cents each for 45 cents eachThe Flip-Flop circuits are models of The Flip-Flop circuits are models of usable chipsusable chipsSourcesSourceshttp://www.wearcam.org/ece385/lectureflipflops/flihttp://www.wearcam.org/ece385/lectureflipflops/flipflops/pflops/http://www.web-tronics.com/webtronics/74hc161nhttp://www.web-tronics.com/webtronics/74hc161n.html.htmlAssembly language and computer architecture Assembly language and computer architecture using C++ and JAVA, Anthony J Dos Reis, 2004using C++ and JAVA, Anthony J Dos Reis,
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