1) A decoder is a circuit that converts binary input into octal or decimal output by activating one of its output lines. It has fewer output lines than input lines. 2) An encoder performs the reverse operation of a decoder - it converts octal or decimal input into binary output. It has fewer input lines than output lines. 3) A multiplexer is a circuit that selects one of several input lines and directs it to a single output line based on the value of a selection input. It allows transmission of multiple information over fewer channels.

1. NAME IBRAR KHAN SUBJECT DLD 2 nd SEMESTER MCS TEACHER ISRAR AHMAD

2. WHAT IS ENCODER? DECODER? MULTIPLEXER?

3. DECODER A decoder is a combinational circuit that converts binary information form n put lines to a maximum of 2n outlines The three input variable may represent a binary number and the output will represent the eight digits in the octal number system . Input n=output 2N

4. D 0=x`y`z` D 1=x`y`z D 2=x`y z` D 3=x`y z D 4=x y` z` D 7=x y z D 6=x y z` D 5=x y` z z y D 0 x inverter x y z xyz 1 1 1 1 AND 3-to-8 line decoder circuit

5. The three input x y z are decoded into eight output. Each output representing one of the minterms. Of the 3 input variables. Truth table 3 to 8 line decoder x y z D0 D1 D2 D3 D4 D5 D6 D7 outputs inputs 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 1 0 0 0 1

6. Encoder An Encoder is a digital function that produce a reverse operation from that of a Decoder. An encoder 2n input line and n output line. Example when we enter a word or hexadecimal number in the keyboard ,behind the keyboard a circuit works which convert the word or hexadecimal to binary.

7. D 0 D 1 D 2 D 3 D 4 D 5 D 6 D 7 X=D4+D5+D6+D7 y=D2+D3+D6+D7 z=D1+D3+D5+D7 Octal to binary encoder x y z x+y+z o o o 0 1 0 0 1 OR

8. Truth table of octal to binary encoder input output D0 D1 D2 D3 D4 D5 D6 D7 X Y Z 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1

9. Multiplexers Multiplexing mean transmitting a large number of information unite over a smaller number of channel or lines. A digital multiplexer is a combinational circuit that selects binary information from one of many inpt line and directed it to a single output .

10. S1 S0 y 0 0 0 1 0 1 1 i0 i1 i2 i3 S1 s0 i0 i3 i2 i1 y A 4 to 1 line multiplexer x y x y 0 0 0 0 1 0 0 0 1 1 1 AND

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