# 2013F002/HW3

HW 3 Due on Tuesday September 10th before class starts.

Name:_______________________________

This homework covers Logic_Gates A_Basic_Computer. Some of these web pages have solved problems in the Questions section that may help.

• You may use http://logic.ly/demo/ to check your answers. Note that you may use the copy icon and CTRL+V (for some reason there is no paste icon for this program) to copy and paste the 1-bit adder circuit.
• You may write your answers on a piece of notebook paper.

# 1. Logic Gate Combinations I

In the image below, four logic gates are connected. What are the values of Z andOutput if B = 1 and A = 0? For reference, the logic table associated with a NAND gate is shown.

1. Z = 1, Output = 0
2. Z = 0, Output = 0
3. Z = 1, Output = 1
4. Z = 0, Output = 1

Input A Input B Output
0 0 1
0 1 1
1 0 1
1 1 0

# 2. Logic Gate Combinations II

In the image below, a NAND and an AND gate are connected, with three inputs, A, B, and C. What are the values A, B, and C so that the light goes out?

What are A & B?

# 3. Basic Computer

In the image below, two bit adders are combined forming a 2-bit adder which is combined with a switch to an LED. Determine the switch combinations of A, B, C, D, E, F, so that the following LED Outputs are obtained. Note the LED reads a 4 bit pattern (4 inputs), so there are 16 combinations ranging from 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F that can be displayed by the LED. Note that the letter A in the LED mean the decimal number 10, and the letter E means 14.

1. What are A, B, C, D, E, and F to give LED = C?
2. What are A, B, C, D, E, and F to give LED = A?
3. What are A, B, C, D, E, and F to give LED = 4?