 Hello everyone, myself, Sanjay Utke, assistant professor, department of electronics engineering, Walchand Institute of Technology, Solopore. Today, we are going to discuss combinational logic circuits, learning outcomes. At the end of this session, students will be able to analyze various combinational logic circuits. Outline, introduction part 1, analog signal, introduction part 2, digital signal, digital systems, combinational logic circuits, question, answer, functions of combinational logic circuits references. Introduction part 1, analog signal. Analog signal is a time varying quantity that can carry information. A signal is a function that conveys information about the behavior or attributes of some phenomena. Analog signal is a continuous signal represented by a sine wave described by the amplitude, period or frequency and phase. It has no fixed range. Analog signal is more prone to the distortion. So, this is the graphical representation of an analog signal. It is a sinusoidal quantity. It may be a voltage or current. As I said earlier, this is a continuous signal. The meaning of the continuous signal can be explained with the help of this waveform. Suppose this is a voltage waveform whose positive maximum is 10 volt and negative maximum is minus 10 volt. It means that it is having this analog voltage or sinusoidal voltage will have values starting from 0 to 10 plus 10 volt or 0 to minus 10 volt. It means a continuous signal will have all possible values between 0 to 10. For example, starting from 0.001, then 0.1 volt, 0.12 volt, 0.13 volt, 0.14 volt, up to 0.20 volt, then 0.3 volts, 0.4 volts, 0.5 volts, up to 0.10 volts, then 0.20, 0.30, 0.40, 0.50, up to 1 volt, then 2 volts, then 3 volts, 3.5, 4, 4.5, 5, 5.5, 5.6, 6 volt, 6.5, 7 volt, 7.5, 7.6, 8 volt, 8.5, 8.6, 8.7, 9 volt, 9.5, 9.99 and 10 volts. So, the meaning of the continuous signal means this will have all possible values. It will cover all the possible values between 0 to 10 and similar is the case for 0 to minus 10. Introduction part 2. It is a digital signal. A digital signal has a discrete value that carries information in binary form. Digital signal is represented by a square wave. Digital signal is described by bit rate and bit intervals. Digital signal has a finite range that is between 0 and 1. Digital signal is less prone to distortion. It carries data in the form of binary that is 0 and 1. Digital signal is used for the transmission in a computer system. The meaning of the transmission means the data can be stored in the form of 0s and 1. It may be a image or it may be a information or data also can be retried from a computer in the form of 0s and 1s. So, what are the processing done with the computer? It is in the form of digital signal which is a stream of binary 0s and 1. Introduction part 2 again. It is the digital signal. This is an example of a square wave which is called as a digital signal. Look at this wave form. It has got only 2 levels 0 volt and the 5 volt. It means that this digital signal has got only 2 values or we can say in other terms it possesses only 2 discrete or distinct values that is only 0 volt and the 5 volt. So, digital signal will not have another value that is it will not have a value apart from 0 volt or 5 volt. Like analog signal it may have all possible values between 0 to 5. Here we will have only 2 values that is 0 volt and 5 volt. So, this can be 0 volt can be termed as logic 0 or logic low level whereas 5 volt can be treated as logic 1 or logic high. Digital system. Digital system stores data in discrete form. This has been discussed earlier. The opposite is an analog system which stores the data in a continuous way. Digital system stores the information of binary way that is every bit of information cannot have a value other than 0 or 1 or off or on. The input and output of this system is 2 binary value which is 0 and 1. Digital system. Digital systems are designed to store to process and to communicate information in digital form. They are found in a wide range of applications including process control, communication systems, digital instruments and communication and zoomer products. The digital computer more commonly called the computer is an example of typical digital system. So, in summary the digital system it takes the data in the form of binary form and it communicate or it processes this binary data and it is used for the further process control. It can be used in the communication system. It can be used in the digital instrumentation system. In the communication system that is from analog to digital communication we are using optical fiber. Digital systems. Digital circuits. There are two types of digital circuits. One is the combinational circuits. Second one is the sequential circuits. Now, let us see what is a combinational logic circuits. Outputs at any instant of time depends upon the inputs present at that instant of time. It means that combinational logic circuit it is a digital circuit and the output will be present only when the inputs are present. So, there is no memory in this circuit. It means that the output that this combinational logic circuit will respond that means it will give the output only when the input is present. So, we do not need additional circuitry as a memory element. It consists of input variables, logic gates and output variables. These input and output variables simply we can term it as input data and the output data. Combination logic circuits are memory less digital logic circuits whose output at any instant in time depends only on the combination of its inputs. Combination logic circuits. The result is that combination logic circuits have no feedback and any changes to the signals being applied to their input will immediately have an effect at the output. Combination circuits are made up from the basic logic NAND gates, NOR gates, NORD gates that are combined or connected together to produce more complicated switching circuits. These logic gates are the building blocks of the combinational logic circuits. So, in summary the combinational logic circuit does not require a memory element. It does not have a feedback. The output will present only when the input is present. So, this is the block diagram of the combinational logic circuit. So, at the center which is shown as a block, a combinational logic circuit made up of logic gates, universal gates, basic gates. It has got any inputs and M outputs. So, this is the simple example of combinational logic circuit with different gates as at the input side. There is NAND gate and NOR gate. Output of these two gates is given to a NAND gate. Output of the inputs at NAND gate has got the inputs A and B. Output is obviously AB bar. Output of the NOR gate has got the input AB again. Its output is A plus B bar. So, AB bar and A plus B bar these two outputs are given along with the C input to the NAND gate which is shown at the output. So, what is the application of combinational logic circuit? Combinational logic circuit covers arithmetic and logic functions, data transmission and code conversion. So, in arithmetic logic functions are obtained by adder circuits, subtractor circuits and program logic devices. Similarly, data transmission can be achieved by multiplexer, demultiplexer, encoders and decoders. Whereas, code conversion, BCD 7's argument and functions of combinational logic circuits. The function of combinational logic circuit can be specified in three main ways such as truth table Boolean algebra logic diagram dot B. These are the references. Thank you.