Decoder Chapter 12 Subject: Digital System Year: 2009

3 Overview Decoder Encoder Code Converter

4 Decoder Decoder is a digital circuit that detect the presence of specified combination of bits (code) on its inputs and indicates the presence of code by a specified output level Decoder n to 2 n IOIO I1I1 InIn YOYO Y1Y1 Y (2 n-1 )

5 Decoder

6 Decoder Application

7 BCD to Decimal Decoder

8 The BCD to 7 Segment Decoder

9 Encoders An Encoder is a combinational logic circuit that essentially performs a “reverse” decoder function. INPUTOUTPUT I 0 I 1 I 2 I 3 I 0 I 1 I 2 I 3 X Y X Y I 2 + I 3 X = I 2 + I 3 I 1 + I 3 Y = I 1 + I 3

10 The Decimal to BCD Encoder

11 The Decimal to BCD Encoder

12 Encoder Application

Code Converter Method of using combinational logic circuit to convert from one code to another code BCD to Binary Conversion –One Method of BCD to Binary code conversion uses adder circuit. This basic conversion process is as follows :,The value, or weight, of each bit in the BCD number is represented by a binary number. All of the binary representations of the weights of bits that are 1s in the BCD number are added The result of this addition is the binary equivalent of the BCD number Bina Nusantara University 13

Example Bina Nusantara University 14