Digital Circuits & Design, 1st Education by Pearson

6.20 | Chapter 6

6.3.1 | Four-to-Two Line Binary Encoder

An encoder is a combinational logic function that has 2

2

input lines and 2 output lines. The

2 output lines generate the binary code for the possible 2

2

input lines. A 4-to-2 line encoder

has four input lines, and two output lines representing the two-bit binary equivalent. The

truth table of such an encoder is given in Table 6.10. In the truth table, I

0

to I

3

represent four

digits 0 to 3. b

1

and b

0

represent the binary digits.

TABLE 6.10 | Four-to-two line encoder

Decimal

Value

Input Output

I

3

I

2

I

1

I

0

b

1

b

0

0 0 0 0 1 0 0

1 0 0 1 0 0 1

2 0 1 0 0 1 0

3 1 0 0 0 1 1

The output, b

0

is 1 when I

3

or ...