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Sequential and Combinational circuits

Date: 29 Dec 2009   Posted By: Bibin     Group: Computers    Category: Hardware   


What are sequential and combinational circuits?
What are their applications?

Author: M.MOHAMED MEERAN    30 Dec 2009      Member Level: Silver     Points : 2    Voting Score: 0

COMBINATIONAL CIRCUITS are logic circuits in which the output depends only on the input.These circuits have no previous state information stored or otherwise stated these circuits have no memory.

SEQUENTIAL CIRCUITS are logic circuits in which the output depends on the input and previous state.These circuits feedback the previous state which is stored and so they are said to have a memory.

Applications of combinational circuits are multiplexer,demultiplexer,encoder,decoder,seven segment decoder,half adder,full adder,binary adder,half subtracter,full subtracter.

Applications of swquential circuits are flipflops,shift register,counters.

Author: Vijay Kumar Vishwakarma    20 Jan 2010      Member Level: Gold     Points : 2    Voting Score: 0

Combinational Circuits:

A combinational circuit is a connected arrangement of logic gates with a set of inputs and outputs. At any given time, the binary values of the outputs are a function of the binary conbination of the inputs.

The n binary input variables come from an external source, the m binary output variables go to an external destination, and in between there is an interconnection of logic gates. A combinational circuit transforms binary information from the given input data to the required output data. Combinational circuits are employed in digital computers for generating binary control decisions and for providing digital components required for data processing.

Applications of Combinational Ciruits:
1. Half-Adder/Full-Adder
2. Half-Substractor/Full-Substractor
3. Multiplexer/Demultiplexer
4. Encoder/Decoder
5. Binary Adder...etc.

Sequential Circuits:

A sequential circuit is an interconnection of flip-flops and gates. The gates by themselves constitute a combinational circuit, but when included with the flip-flops, the overall circuit is classified as a sequential circuit.

It consists of a combinational circuit and a number of clocked flip-flops. In general, any number or type of flip-flops may be included.

Applications of Sequential Circuits:

1. Shift Registers
2. Counters
3. Flip-flops...etc.

Sequential Ckt.
Combinational Ckt.
1. The output of these ckt. are depends on present as well as
past input.
1. These ckt. only depends on present input.
2. These ckt. has feedback of output to input. 2. These ckt. don't have feedback.
3. These ckt. has memory to store data. 3. These ckt. don't have memory.

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