WEBVTT
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The diagram shows an XOR gate.
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If input A is zero and input B is zero, what will the output be?
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Okay, so, in this diagram, we’ve been given an XOR gate.
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And we’ve been told that for this XOR gate, both input A and B have values of zero.
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Based on this information, we need to work out what the output is.
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So, to do this we need to recall the truth table for an XOR gate.
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So, here’s the truth table for an XOR gate.
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Now an easy way to remember this is that an XOR gate is an exclusive OR Gate.
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In other words, if exclusively one of the inputs has a value of one, then the output will be one as well.
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Otherwise, the output will be zero.
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So, basically, what we mean by this is that if both input A and input B are zero, then the output is zero as well.
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However, if input A is zero and input B is one, then the output is one because in this case exclusively one input is one.
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In this case, it’s input B.
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And the same is true for the next row.
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We can see that input A is one, but input B is zero.
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That gives us an output of one.
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However, in the situation where both inputs are one, the output is zero.
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And so, what we see is that exclusively one input or the other must be one in order to give us an output of one.
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And that’s how to memorize the truth table for an XOR gate.
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But anyway, so, coming back to the question, we’ve been told that both input A and input B are set to zero.
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So, to find out the value of the output, we look at the first row of the table.
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Input A is zero and input B is zero as well.
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This row tells us that the output must be zero also.
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And so, we’ve got the answer to our question.
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For an XOR gate, if both inputs are set to zero, then the output will be zero as well.