The D flip-flop shown in Figure is a modification of the clocked SR flip-flop. The D input goes directly into the S input and the complement of the D input goes to the R input. The D input is sampled during the occurrence of a clock pulse. If it is 1, the flip-flop is switched to the set state (unless it was already set). If it is 0, the flip-flop switches to the clear state. Logic Symbol of D Flipflop Logic diagram of D Flipflop Q D Q(t+1) 0 0 0 0 1 1 1 0 0 1 1 1 Transition Truth table of D Flipflop
Advantages of digital systems over analog systems Digital systems are used extensively in computation and data processing, control systems, communications and measurement. Following are the advantages of digital systems over analog systems: Digital systems are easier to design. Information storage is easy. Accuracy and precision are greater. Digital systems are more versatile. Less affected by noise. Can be fabricated on IC chips. Reliability is more.
Sequential switching circuits are those whose output levels at any instant of time are dependent not only on the levels present at the inputs at that time, but also on the state of the circuit, i.e on the prior input level conditions. The past history is provided by feedback from the output back to the input. It means that sequential switching circuits have memory. Sequential circuits are thus made of combinational circuits and memory elements. The past history is provided by feedback from the output back to the input. Figure shows the block diagram of a sequential circuit. Sequential circuits A memory element is a device which can store information in terms of 1 or 0 and its state can be modified by clock signal and data inputs. A flipflop is one bit memory element which can store 1 or 0. Flipflop is an electronic circuit or device which is used to store data in binary form.
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