# ECE/CS 352 Digital Systems Fundamentals - PowerPoint PPT Presentation

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ECE/CS 352 Digital Systems Fundamentals. Spring 2001 Chapter 3 -Part 2. Tom Kaminski & Charles R. Kime. Functional Block: Decoders. 2-to-4 Line Decoder. 2-to-4 Line Demultiplexer. Example: 74F138 Demultiplexer.

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ECE/CS 352 Digital Systems Fundamentals

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## ECE/CS 352 Digital Systems Fundamentals

Spring 2001

Chapter 3 -Part 2

Tom Kaminski& Charles R. Kime

ECE/CS 352 Digital System Fundamentals

### Functional Block: Decoders

ECE/CS 352 Digital System Fundamentals

### 2-to-4 Line Decoder

ECE/CS 352 Digital System Fundamentals

### 2-to-4 Line Demultiplexer

ECE/CS 352 Digital System Fundamentals

### Example: 74F138 Demultiplexer

Note: This "Truth Table" uses the "x" to mean "this could be either 0 or 1". Thus, it "compacts" some of 26=64 lines.

ECE/CS 352 Digital System Fundamentals

### Implementing Logic with Decoders

ECE/CS 352 Digital System Fundamentals

### Example 1:F(A,B) = m(0,3)

ECE/CS 352 Digital System Fundamentals

### Example 1:F(X,Y,Z) = m(0,3,5,6)

ECE/CS 352 Digital System Fundamentals

### Implementing Larger Minterms

ECE/CS 352 Digital System Fundamentals

### Functional Block: Encoders

ECE/CS 352 Digital System Fundamentals

### Review: Decoders and Encoders

ECE/CS 352 Digital System Fundamentals

### Multiplexers

ECE/CS 352 Digital System Fundamentals

### Example: A 4-to-1 multiplexer

ECE/CS 352 Digital System Fundamentals

### Multiplexer Versus Decoder

Note how similar the two are internally.

ECE/CS 352 Digital System Fundamentals

### Functions with Multiplexers

ECE/CS 352 Digital System Fundamentals

### Example: Gray to Binary Code

ECE/CS 352 Digital System Fundamentals

### Gray to Binary (Continued)

ECE/CS 352 Digital System Fundamentals

### Gray to Binary (Continued)

ECE/CS 352 Digital System Fundamentals

### Gray to Binary (Continued)

ECE/CS 352 Digital System Fundamentals

### Other MUX Implementations

B

Y

00

01

11

10

B

Z

00

01

11

10

0

1

0

1

0

1

0

1

D0

D1

D3

D2

D0

D1

D3

D2

A

1

0

1

0

A

0

0

1

1

C

C

A

A

A

A

ECE/CS 352 Digital System Fundamentals

### MUX Implementations (Cont.)

ECE/CS 352 Digital System Fundamentals

### MUX: (Cont.) Factoring Out C

ECE/CS 352 Digital System Fundamentals

### MUX: (Cont.) Factoring out B

ECE/CS 352 Digital System Fundamentals

### MUX: (Cont.) Factoring out A

ECE/CS 352 Digital System Fundamentals

### Summary

• Know the functions performed by the following functional blocks:

• Decoders

• Demultiplexers

• Encoders

• Multiplexers

• Know how to implement Boolean functions using:

• Multiplexers

• Decoders

ECE/CS 352 Digital System Fundamentals