Peter Lau

Bill Chun Wai Hung

Lab 13 Report – S3 Logic Gate

8 August 2004

A. Describe the Set-up

The Circuit setup is shown in figure 1.

 

Figure 1

B1. Describe Inputs

Stimuli:

DC 5V

 

4 Inverters: 7404

4 Nand Gates: 7400

 

Table 1

a b c | S3
0 0 0 | 1
0 0 1 | 0
0 1 0 | 1
0 1 1 | 1
1 0 0 | 0
1 0 1 | 1
1 1 0 | 1
1 1 1 | 1

 

S3 = b + a'c' + ac

 

C. Describe What you Observe

The LED lit up when the S3 value indicated in Table 1 is 1, and the LED is off when the S3 value indicated in Table 1 is 0.

 

D. What you can deduce

The Boolean formula from the lecture was right, and the table 1 logic is right for the circuit shown in figure 1.

 

The logic works according to table 1.

 

Q1) If you had  only 3 nand gates, how would you have connected the LED and the resistor to S3 in order to obtain the same result?

 

This questions is completely ignored.