CSC364  Lab #1

EXPERIMENT 1: Investigating the Digital Training Kit

For this part, concentrate only on the flatter part of the Digital Kit, not the circuit board that is upright, facing you. Please follow the steps below.

1. Power OFF. Connect a wire between the Logic Indicator L4 and the Logic Switch A. Activate Switch A, and observe the LED (Light Emitting Diode) turn ON and OFF. Switch the wire from A to A-Bar, and see how the LED reacts .
2. Power OFF. Same experiment, but this time replace the Logic Switch by one of the Data Switches.
3. Power OFF. Connect one of the Logic Indicators to the Clock signal. Connect a second wire from another Logic Indicator to the Clock-bar signal. Make sure the sliding switch is on the 1Hz mark. Power UP. What do you observe?
4. Slide the switch to 1KHz. What happens? Why? Is there any difference in the brightness of the LED? Why?

EXPERIMENT 2: The 7408 INTEGRATED CIRCUIT

Take a 7408 (or 74LS08, or 74S08) Integrated Circuit (IC) and put it on the bread-board part of the kit. Use the information shown in Figure 3 to help you wire the circuit. Always make sure that the circuit is connected to +5V through its pin 14, and to GND via its pin 7.



Figure 3: Wiring of an IC on the breadboard. Always identify pin 1 of the IC which is on the left (or below) the notch or circle embossed on the top of the chip.

Connect pin 1 of the IC to Switch 1 (input A), pin 2 to Switch 2 (input B), and pin 3 to a logic indicator. Find the nature of the logic gate you are testing by activating all combinations of A and B.

A	B	Output
0	0
0	1
1	0
1	1

Do the same for pin 4, 5 (inputs), and 6 (output). And for pins 13, 12 (inputs), and 11 (output). And for pins 10, 9 (inputs), and 8 (output).

Draw a diagram showing the contents of the integrated circuit.

EXPERIMENT #3: THE 7432

Swap the 7408 for a 7432, and repeat the same experiment. What logic function do you now have?

A	B	Output
0	0
0	1
1	0
1	1

EXPERIMENT #4: THE 7400

Swap the 7432 for a 7400, and repeat the same experiment. What logic function do you now have?

A	B	Output
0	0
0	1
1	0
1	1

When you leave an input disconnected, what does the circuit see it as, a 1 or a 0?

EXPERIMENT #5: THE 7402

The 7402 is wired slightly differently than the other circuits. Connect its pin 1 to a logic indicator, and Pins 2 and 3 to data switches. What is its logic function?

A	B	Output
0	0
0	1
1	0
1	1

EXPERIMENT #6: THE 7404

Let's now test the 7404. Connect pins 1 and 3 to data switches, and pin 2 to a logic indicator. What is the logic function implemented by this circuit?

A	B	Output
0	0
0	1
1	0
1	1

EXPERIMENT #7: A TWO-BIT ADDER

Your last experiment for this lab is to wire up a two-bit adder. It will have two inputs, A and B, and two outputs, SUM and CARRY. First fill out the truth table below, where SUM and CARRY are the two functions that you need to implement, and that represent the arithmetic sum of the two inputs.

A	B	Sum	Carry
0	0
0	1
1	0
1	1

Now that you have the truth tables, find the simplest expressions for SUM and CARRY, and draw their logic diagram. Draw the logic diagrams cleanly, and do not hesitate to make them large, as you will need to add more information to them.

Once you are at this stage, get a set of data sheets from your instructor, showing the schematics of the circuits we have at our disposition.



Identify the circuits numbers (e.g. 7408) corresponding to your logic gates, and write these numbers INSIDE the gates in your diagram. Then identify which gate in the circuit you will be using, and write the pin-numbers of the gate next to the inputs and outputs. The figure on the left shows an example of how one would label an AND gate, assuming that we use the first AND of a 7408, with inputs on pins 1 and 2, and output on pin 3.

When you are done labeling all the gates in this fashion, put the ICs you need on the breadboard, and turn the power off. Connect the chips' power and gnd pins to +5 and GND.

Then add wires between the gates, making the connections that you have shown on your diagram. As you add wires, highlight or redraw in bold the corresponding lines in your logic diagram, so that you can easily see which connections are made and which ones are left. Make sure you generate the A and B inputs from data switches, and that you connect the SUM and CARRY outputs to Logic Indicators.

Turn the power on, and test your circuit. Does it add?

LAB REPORT

You need to write a lab report for each lab you do. The key part of a lab report is that it should be self-contained. The answer to a question may not be very useful if the question is not also part of the report. Ideally, a good lab report should be all that is needed for someone else to repeat the experiment.

A simple way to accomplish this is to use the text of this Web page as appendix to your report, to include all the truth tables, the diagrams, and a paragraph (3 to 5 lines are sufficient) explaining your results.

If an experiment does not work, report the experiment as you experienced it, and do not guess what you think should have happened.

Your lab report is due a week after the lab is performed. It will count as 1/2 of a homework assignment, and the possible grades are A, C, or E. A C- or E-grade represent lab reports that are missing a serious amount of information.