Page 77 - Computer science 868 Class 12
P. 77

The block diagram of a Decimal to Binary encoder is given below:
                                              0
                                              1                                            B
                                                                                            3
                                              2
                                              3                                            B
                                              4                 Decimal to                  2
                                              5               Binary Encoder
                                              6                                            B 1
                                              7
                                              8                                            B 0
                                              9
                 The truth table is drawn below:
                              Decimal number        B 3             B 2             B 1             B 0

                                    0               0               0               0                0
                                    1               0               0               0                1
                                    2               0               0               1                0
                                    3               0               0               1                1
                                    4               0               1               0                0
                                    5               0               1               0                1
                                    6               0               1               1                0
                                    7               0               1               1                1
                                    8               1               0               0                0
                                    9               1               0               0                1
                 B , B , B  and B  represent the OR gates If the Octal numbers are represented by switches I  to I  then from the truth
                        2
                  0
                     1
                                                                                                      9
                                                                                                  0
                              3
                 table we can conclude that
                 B  =  I  + I  + I  + I  + I 9
                         3
                                7
                  0
                             5
                      1
                 B  =  I  + I  + I  + I 7
                  1
                             6
                         3
                      2
                 B  =  I  + I  + I  + I 7
                  2
                      4
                         5
                             6
                 B  =  I  + I 9
                  3
                      8
                 The logic circuit diagram is as follows:
                                            0
                                            1
                                            2
                                            3
                                            4
                                            5
                                            6
                                            7
                                            8
                                            9



                                                         B 3        B 2        B 1        B 0


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