Page 97 - Computer science 868 Class 12
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18.  Draw the logic gate diagram for the reduced expression. Assume that the variables and their complements are available as
                       inputs.                                                                                   [ISC 2018]
                   Ans.  Logic gate diagram:
                       A

                       B'

                       C'
                                                            F
                       D'

                       A'

                       C'
                    19. (a)  What is an Encoder? Draw the Encoder circuit to convert A-F hexadecimal numbers to binary. State an application of a
                          Multiplexer.                                                                           [ISC 2018]
                   Ans.  An Encoder is a combinational circuit that convert decimal, octal or hexadecimal numbers to its equivalent binary form.
                        Circuit diagram to convert A-F hexadecimal numbers to binary:
                       A

                       B
                       C
                       D
                       E
                       F






                       Application of a Multiplexer:
                        1.  Used for Routing of signals
                        2.   Data Transmission
                        3.   Telephone Exchanges/TV etc
                       (b)   Using only NAND gates, draw the logic circuit diagram for A' + B.                   [ISC 2018]
                   Ans.  Logic circuit diagram for A' + B using only NAND gates.
                       A

                                                                          A' + B'


                       B

                    20.  Name and draw the logic gate represented by the following truth table, where A and B are inputs and X is the output. [ISC 2019]
                           A        B        X
                           0        0        0
                           0        1        1
                           1        0        1
                           1        1        0
                   Ans.  XOR Gate

                       A                X
                       B


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