lecture12 - CMPT 150 Combinational Circuits Page 4 Priority...

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CMPT 150 Combinational Circuits Page 1 Implementing an Encoder b An Encoder does the opposite of what a Decoder does: 4x2 Enc D 0 D 1 D 2 D 3 A 0 A 1 E D 0 D 1 D 2 D 3 A 1 A 0 1 1 0 0 0 1 0 1 0 0 0 0 1 0 0 0 0 1 0 b It is implemented as follows: A 0 = A 1 = E 1 0 0 1 0 1 0 0 0 1 0 X X X X 1 0 1 1 X X CMPT 150 Combinational Circuits Page 2 Priority Encoders b The encoders we’ve looked at so far have the limitation that only one of the inputs can be 1 at a time E.g. b Priority Encoders solve this by behaving such that if two or more inputs are equal to 1 at the same time, the input having the highest priority takes precedence. b b We also add an output V to indicate whether at least one of the inputs is 1. CMPT 150 Combinational Circuits Page 3 Truth Table for Priority Encoder
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Unformatted text preview: CMPT 150 Combinational Circuits Page 4 Priority Encoder: K-maps CMPT 150 Combinational Circuits Page 5 Priority Encoder: Logic Diagram CMPT 150 Combinational Circuits Page 6 Multiplexers b Routes one of many inputs to the single output b A 2 n x1 MUX has: b b x1 E S S Y b b Analogy with music: Music selected from different sources (CD player, radio, etc) to be played on only one speaker. 4x1 Mux 1 I I 1 I 2 I 3 CMPT 150 Combinational Circuits Page 7 Multiplexer Implementation 4x1 Mux E S S 1 I I 1 I 2 I 3 Y E S 1 S Y 1 0 0 1 0 1 1 1 0 1 1 1 I I 1 I 2 I 0 X X 3...
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This note was uploaded on 04/27/2011 for the course CMPT 150 taught by Professor Dr.anthonydixon during the Spring '08 term at Simon Fraser.

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lecture12 - CMPT 150 Combinational Circuits Page 4 Priority...

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