1.To Demonstrate How a NOR Gate Can Be Used As an AND, OR, Or NOT Gate

Activity 4.3A – Duality of Logic

Functions – NOR gate

Purpose

1.To demonstrate how a NOR gate can be used as an AND, OR, or NOT gate.

2.To recognize the advantages of using a NOR gate only logic circuit.

Equipment

Computer Simulation Software

Logic Switches

Procedure

The NOR gate can be used to simulate the AND gate, OR gate, and NOT gate. By using only a NOR gate to represent the A-I-O functions the cost of circuit manufacture can be reduced. It is also possible to reduce the number of gates required by the circuit. If gates can be cancelled or eliminated then the number of chips required by the circuit could also be reduced. This duality of functions can be used to save money in the manufacture of logic circuits.

Part 1:

In this part of the Activity, you will demonstrate the universality of the NOR gate by simulating the NOT gates, the AND gate and the OR gate.

1.Using software simulation, connect the circuit shown in below. Connect the appropriate switches and sources to drive the input A and B, and use a digital probe to monitor the output, X.

Compete the truth table shown below:

A / L1 -OUTPUT
0
1

Based on the output of the truth table, this arrangement functions the same as what basic gate?

______

2.Using software simulation, connect the circuit shown in below. Connect the required switches and sources to apply voltage to the inputs and use a digital probe to monitor the output.

Compete the truth table shown below:

A / B / L1 -OUTPUT
0 / 0
0 / 1
1 / 0
1 / 1

Based on the output of the truth table, this arrangement functions the same as what basic gate?

______

3.Using software simulation, connect the circuit shown in below. Connect the required switches and sources to apply voltage to the inputs and use a digital probe to monitor the output.

Compete the truth table shown below:

A / B / L1 -OUTPUT
0 / 0
0 / 1
1 / 0
1 / 1

Based on the output of the truth table, this arrangement functions the same as what basic gate?

______

Part 2: Circuit Implementation

A logic network composed of several types of gates can be represented by NOR gates only. To do the transformation, perform the following steps:

Convert the A-I-O circuit into two input gates only
Replace each two input A-I-O gate with its NOR only representation
If there are two NOR-only NOT gates in consecutive sequence (one after the other) then remove them both and replace them with a wire conductor.
Continue the remove consecutive “NOT” gates until all are removed.

1.Using the computer simulation software, create an A-I-O circuit using only two-input gates from the circuit shown below.

Tape a printout of the computer simulated circuit below:

Test the circuit and fill in the truth table for the 4 inputs and the one output.

A / B / C / D / Y
0 / 0 / 0 / 0
0 / 0 / 0 / 1
0 / 0 / 1 / 0
0 / 0 / 1 / 1
0 / 1 / 0 / 0
0 / 1 / 0 / 1
0 / 1 / 1 / 0
0 / 1 / 1 / 1
1 / 0 / 0 / 0
1 / 0 / 0 / 1
1 / 0 / 1 / 0
1 / 0 / 1 / 1
1 / 1 / 0 / 0
1 / 1 / 0 / 1
1 / 1 / 1 / 0
1 / 1 / 1 / 1

2.Convert the two-input A-I-O circuit above into a NOR only circuit. Draw it by hand in the space below:

3.Using the computer simulation software, draw the A-I-O circuit from above. Use logic switches on the inputs and a probe attached to the output to indicate the output status. Tape a printout of the computer simulated circuit below:

Test the circuit and fill in the truth table for the 4 inputs and the one output.

Does the NOR-only truth table from part 3 above verify with the A-I-O truth table in part 1? ______

Conclusion

What are the steps used to implement a NOR only circuit from an A-I-O circuit?

How many gates did you use in the NOR only circuit? ______

How many Chips? ______

In the two input A-I-O circuit:

How many AND gate chips? ______

How many OR gate chips? ______

How many NOT gate chips? ______

4.Consider the information from #2 and #3 above. Should a company use an A-O-I circuit, or a NOR only circuit?