© D. Thiébaut 2003

We will be using the horizontal part of the kit in the first few labs. The goal for now is to get a sense of how the different parts operate.
With your partner, going at your own pace, follow the steps outlined below.
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You will now run some simple experiments with the clock circuitry, and in particular the clock signal. The clock signal will be useful when we move from combinational circuits (first quarter of the course) to sequential circuits (second quarter).
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In this part you will wire up a simple circuit just so that you get the feel for wiring up digital circuits, and understanding how boolean logic maps to electrical signals. Do not worry too much if you don't understand much of the theory. Today we are interested in the mechanical aspect of wiring circuits.
The integrated circuit and its connections to the 5V supply are shown above. Below is a list of step by step instructions for realizing the complete wiring and testing it.
Make sure you follow the rules for good wiring as you go along (highlighted in red in the text below). More information and details will be given out during the lab.
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Put the circuit (which we will sometimes refer to as chip, or IC--short for integrated circuit) with the designation 74LS32 on the breadboard area of the kit, with the notch to your left (in other words, you should be able to read the markings on the chip without problems). Make sure it sits over the middle groove. |
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Add wires as shown in the picture to the left.
When wiring circuits up, always use short
wires if possible, so as to avoid huge loops and spaghetti-type
results.
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Then add wires between two switches and the chip. |
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Then a wire between the chip and a logic indicator. |
Figure 2 shows an AND gate implemented with two diodes and a resistor. The figure shows only the gate, and not the input and output circuits necessary to test it.

Connect the inputs to Data Switches and the output to an Indicator, and test the AND gate. Use the voltmeter to Measure the voltages at the inputs and at the output when you activate the switches and set them to all four possible combinations (00, 01, 10, 11). Record your observation in a truth table.
Look especially at the way the current flows through the output wire when the output voltage is low and when it is high. What is interesting (puzzling maybe) about the flow of information and the flow of current.
What happens when the two inputs are disconnected from the Data Switches? What signals does the circuit "see" on its inputs in that case? In other words, is a disconnected input treated as a high signal, or as a low signal?

That's it for this lab! Translate your notes into a lab report that you will hand in next Wednesday. It will not be graded, but you will get feedback to help you better organize the next reports. When preparing your lab reports, keep these important points in mind: