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Designing Binary Adders with decoders. C(X,Y,Z) = S m(3,5,6,7) S(X,Y,Z) = S m(1,2,4,7); . Example: design a full binary adder using one decoder. S(X,Y,Z) = S m(1,2,4,7); C(X,Y,Z) = S m(3,5,6,7) . Chapter 2 Encoder. Dr. Bernard Chen Ph.D. University of Central Arkansas
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Designing Binary Adders with decoders C(X,Y,Z) = S m(3,5,6,7) S(X,Y,Z) = S m(1,2,4,7);
Example: design a full binary adder using one decoder. • S(X,Y,Z) = S m(1,2,4,7); • C(X,Y,Z) = S m(3,5,6,7)
Chapter 2 Encoder Dr. Bernard Chen Ph.D. University of Central Arkansas Spring 2009
Encoders • Perform the inverse operation of a decoder • 2n (or less) input lines and n output lines
Encoders Perform the inverse operation of a decoder 2n (or less) input lines and n output lines
Encoders • Can be implemented with 3 OR gates A0 = D1 + D3 + D5 + D7; A1 = D2 + D3 + D6 + D7; A2 = D4 + D5 + D6 + D7; If more than 2 inputs are active we need to use priority encoder (priority for inputs)
Accepts multiple values and encodes them Works when more than one input is active Consists of: Inputs (2n) Outputs when more than one output is active, sets output to correspond to highest input V (indicates whether any of the inputs are active) Selectors / Enable (active high or active low) Priority Encoder
