We will continue reviewing Chapter 3 on Combinational Logic Design.

Also, today I really will collect Lab 2 and Assignment 1 for marking.

For this week’s assignment, answer question 3-6 from the text book. Your answer to Assignment 2 is due on Thursday June 2.

#### Assignment 2

Q 3-6. A low-voltage lighting system is to use a binary logic control for a particular light. This light lies at the intersection point of a T-shaped hallway. There is a switch for this light at each of the three endpoints of the T. These switches have binary outputs 0 and 1 depending on their position and are named X1, X2, and X3. The light is controlled by a buffer driving a thyristor, an electronic part that can switch power-circuit current. When Z, the input to the buffer, is 1, the light is ON, and when Z is 0, the light is OFF. You are to find a function Z=F(X1, X2, X3) so that if any one of the switches is changed, the value of Z changes, turning the light ON or OFF.

Express the function using only NAND gates and invertors (NOT gates).

Hint: Draw a truth table with inputs X1, X2, X3 and determine if the if the light should be on or off as the switches are operated.