11/21/2023 0 Comments Sequential logic circuitIn digital circuit theory, sequential logic is a type of logic circuit whose output depends not only on the present value of its input signals but on the past history of its inputs. In asynchronous circuits the state of the device can change at any time in response to changing inputs.įreebase Rate this definition: 0.0 / 0 votes In synchronous sequential circuits, the state of the device changes only at discrete times in response to a clock signal. When a "channel up" or "channel down" input is given to it, the sequential logic of the channel selection circuitry calculates the new channel from the input and the current channel.ĭigital sequential logic circuits are divided into synchronous and asynchronous types. The television stores the current channel as part of its state. In order for the channel selection to operate correctly, the television must be aware of which channel it is currently receiving, which was determined by past channel selections. However, if the television is on channel 8, pressing "up" switches it to channel "9". If the television is on channel 5, pressing "up" switches it to receive channel 6. Pressing the "up" button gives the television an input telling it to switch to the next channel above the one it is currently receiving. Virtually all circuits in practical digital devices are a mixture of combinational and sequential logic.Ī familiar example of a device with sequential logic is a television set with "channel up" and "channel down" buttons. Sequential logic is used to construct finite-state machines, a basic building block in all digital circuitry. That is, sequential logic has state (memory) while combinational logic does not. This is in contrast to combinational logic, whose output is a function of only the present input. In automata theory, sequential logic is a type of logic circuit whose output depends on the present value of its input signals and on the sequence of past inputs, the input history. In a sequential circuit, everything is combinational except the memory and feedback.Wikipedia Rate this definition: 0.0 / 0 votes So this will become past output and this past output will go to the input and it can be called as the feedback will go as the feedback and the present output will depend upon this present input and the past output. So as a result there is a present inputs and the outputs and also the memory element which has already stored the output from the previous inputs. Let’s say time comes and it’s time to use the values stored in this memory and these values will be used as the inputs. This memory will keep the output till the time the it will be going to be used again. You can see inputs and outputs on the diagram and also at the same time there is a storing process happening that particular output on outputs on the memory block. The present state and present inputs will define output and new state. The information stored in the sequential circuit represents the present state. That means past inputs are past output and the present state is nothing but past outputs. Here the present state depends upon past inputs only. In a sequential circuit, the present output depends on the present input as well as the present state(past output).
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