0195136047.pdf

6.1 DIGITAL BUILDING BLOCKS 275

A

A

AB

00

01

10

11

F

0

1

1

1

F

Off

Off

On

On

B

F = A + B

F = 1 (light is on) if either A or B

(or both) is equal to 1 (switch on)

B
Input
(a) (b) (c)

Output

Inputs Output

+

−

Figure 6.1.1Two-input OR gate.(a)Symbol or physical representation.(b)Truth table.(c)Illustration of
OR operation.

A

A

AB

00

01

10

11

F

0

0

0

1

F

Off (0) Off (0)

On (1) On (1)

B

F = A ⋅ B

B (also F = AB)

Input

(a) (b) (c)

Output

Inputs Output +

−

F = 0 (light is off)

F = 1 (light is on) if and

only if A = B = 1

Figure 6.1.2Two-input AND gate.(a)Symbol or physical representation.(b)Truth table.(c)Illustration
of AND operation.

A

A

0

1

F

1

Input F = A^0

(a) (b)

Output

Input Output Figure 6.1.3NOT gate (complement).

(a)Symbol or physical representation.

(b)Truth table.

A

AB

10

10

11

11

F

1

1

1

0

00

00

01

01

C

0

1

0

1

0

1

0

1

1

1

1

1

F = A ⋅ B ⋅ C
C
(a) (b)

Inputs Output

B

Figure 6.1.4NAND gate.

(a)Logic symbol.(b)Truth table.