Digital Systems: Principles and Design

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Digital Systems

FIGURE 4.2 The logic symbols as well as truth tables of NOR, XOR NOT-XOR and Buffer gates.

4.2.2 NOR Gate

An OR circuit followed a NOT circuit gives a NOR gate and is shown in Figure 4.2(a). Its

unique property is that its output is 0 if any of the inputs is 1. A two input NOR has

F =

AA

12

+ ...(4.8)

4.3 THE XOR, NOT-XOR, NOT-NOT LOGIC OPERATIONS

4.3.1 XOR Logic Operation

An XOR gate (Figure 4.2(b)) is called Exclusive OR gate. Its unique property is that the

output is 1 only if odd numbers of the inputs at it are 1s. The output

F = A

1

×

A

2

+

A

1

× A

2

or A

1

Å A

2

...(4.9)

Exclusive OR operation symbol is Å (Equation (4.9)) XOR symbol in ...