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Unformatted text preview: ECE 2 5 Homework 3 Solutions Problem 2.31 Solution The last two terms are the definition of the XOR function so we have A B C _ D + H A D L . We now need to convert the OR operation into a combination of XOR and AND operations. We start by noting that the OR operation can be written as X + Y = H X Y L + X Y which can be verfied by a truth table. Therefore if two terms are OR'ed together such that the product of those two terms is zero (e.g. X Y = 0), then the OR operation can be replaced by the XOR operation. Let X = A B C _ D and let Y = H A D L . If we form the truth table of X Y (not shown), we can easily show that X Y = 0. Therefore, for this special case, we can replace the OR operation with an XOR operation to yield A B C _ D H A D L . Note that you CANNOT in general replace an OR by XOR unless the product of the two terms is zero. Problem 3.3 Solution Since each buffer can only drive 16 loads, then the total number required to drive 38 loads is three with two of...
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 Fall '08
 bill lin

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