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Combinational Logic Design

The document discusses digital logic, focusing on combinational logic design. It outlines the structure of logic circuits, including inputs, outputs, and specifications, and differentiates between combinational and sequential logic. Additionally, it presents rules for combinational composition and various circuit elements.

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tlan44326
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6 views9 pages

Combinational Logic Design

The document discusses digital logic, focusing on combinational logic design. It outlines the structure of logic circuits, including inputs, outputs, and specifications, and differentiates between combinational and sequential logic. Additionally, it presents rules for combinational composition and various circuit elements.

Uploaded by

tlan44326
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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Chapter 1

Digital Logic

Combinational Logic Design


朱金辉

华南理工大学软件学院

1
Chapter 2 :: Topics
1. Introduction
2. Boolean Equations
3. Boolean Algebra
4. From Logic to Gates
5. Multilevel Combinational Logic
6. X’s and Z’s, Oh My
7. Karnaugh Maps
8. Combinational Building Blocks
9. Timing

2
Introduction
A logic circuit is composed of:
• Inputs（输入）
• Outputs（输出）
• Functional specification（功能规范）：
describe the relationship between inputs and
output
• Timing specification（时序规范）：describe
the delay between inputs changing and outputs
responding
functional spec
inputs outputs
timing spec

3
Circuits
• Nodes（节点）: A node is a wire, whose
voltage conveys a discrete-valued variable
– Inputs（输入节点）: A, B, C
– Outputs（输出节点）: Y, Z
– Internal（内部节点）: n1

• Circuit elements（电路元件）: An
elements is itself a circuit with inputs,
outputs, and a specification
– E1, E2, E3
n1
– Each a circuit A E1
B E3 Y
C E2 Z

4
Televison Remote Controller

5
Types of Logic Circuits
• Combinational Logic（组合逻辑电路）
– Memoryless
– Outputs determined by current values of inputs
• Sequential Logic（时序逻辑电路）
– Has memory
– Outputs determined by previous and current values
of inputs
functional spec
inputs outputs
timing spec

6
Rules of Combinational Composition
• Every element is combinational
• Every node is either an input or connects
to exactly one output
• The circuit contains no cyclic paths
• Example:

7
Rules of Combinational Composition

8
Hw2.1

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