# vlsi interview questions-11

1. Draw a truth table for the equation T = AB’C’ + AB (i.e. solve for T) for all possible combinations of A, B, and C.

2. Draw a truth table for the following equations:

(a) T = wx + xy

(b) V = r(s’ + t’)

3. Draw a truth table that expresses your ability to “cross a river” based upon three variables being true or false:

First variable: the river is frozen (variable F)

Second variable: the boat (available to you) leaks (variable L)

Third variable: you can swim (variable S)

Thus, the truth table has three inputs (F, L, S) and one output (i.e. X, meaning you can cross the river)

4. Demorganize the following expressions:

(a) (AB’ + C’DE)’

(b) (A + (BC)’ + D’E)’

5. Using the basic and theorems, reduce the following Boolean equations

(a) AB’ + A’B + AB + A’B’ (d) C[(ABC)’ + AB’C]

(b) AB’D + AB’D + B’D’ (e) A[B + C(AB + AC)’]

(c) WX’(W + Y) + WY(W’ + X’) (f) (A’+C)(A’+C)(A+B+C’D)

6. Obtain the complement of the following expressions

(a) F1 = AB’C + A’BC + A’B’

(b) F2 = x’yz + xy’z + (xyz)’

7. Convert the following Boolean expressions to logic diagrams:

(a) AB’C + A’BC + A’B’

(b) x’yz + xy’z + (xyz)’

8. Given the following truth table, write the Boolean expression that expresses F3 as a sum of minterms

x y z F3

0 0 0 1

0 0 1 1

0 1 0 0

0 1 1 0

1 0 0 1

1 0 1 0

1 1 0 1

1 1 1 1

9. Using the truth table from above, write the Boolean expression that expresses F3 as a product of Maxterms

10. Convert the following Boolean functions to canonical form (i.e. sum-of-minterms):

(a) AB + AC’ + BC

(b) A’B’C’ + B + BC + AC’