Digital Systems: Principles and Design

205Problem Formulation and Design of the Combinational Circuits

(i) Y 3, Y 2, Y1, and Y 0 implement by the equations in the Example 9.5 after taking A4

= Y 4.

(ii) Y 4 implements by the implementing A3.A1 + A3.A2.

(ii) Y 0, Y 7, Y6 and Y5 are obtained from four circuits as follows:

Y7 = Y 4.

Y

4,

Y6 = Y 4.

Y

4 and

Y5 = Y 4.

Y

4

Y0 = A0.A0

Calculate the number of four literal AND-OR gates used for the circuits in Figure 9.7.

Solution

Table 9.5 gives the number of AND-OR gates used. Neglecting ANDing with

A

7.

A

6.

A

5

Example 9.7

TABLE 9.5 Number of AND-OR gates used for the BCD converter in Example 9.3

Outputs Gates used

ANDs ORs

; 71 0

; 61 0

; 51 0

; 42 1

; 31 0

; 22