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Efficient K-map (Don't Care)

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kumar91

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in case of don't care we generally treat don't care as 1 while solving through K-map. But if we choose 0 in place of 1 will it be an efficient way..????
Also what is the efficient method to solve don't care containing problems..???
 

preethi_k4

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if u choose 0 in place of 1 it gives a complex solution. If you want to consider it as '0' then u nees to calculate based on POS. check this extract from http://www.allaboutcircuits.com/vol_4/chpt_8/10.html

14155.png

Above is an example of a logic function where the desired output is 1 for input ABC = 101 over the range from 000 to 101. We do not care what the output is for the other possible inputs (110, 111). Map those two as don't cares. We show two solutions. The solution on the right Out = AB'C is the more complex solution since we did not use the don't care cells. The solution in the middle, Out=AC, is less complex because we grouped a don't care cell with the single 1 to form a group of two. The third solution, a Product-Of-Sums on the right, results from grouping a don't care with three zeros forming a group of four 0s. This is the same, less complex, Out=AC. We have illustrated that the don't care cells may be used as either 1s or 0s, whichever is useful.
 

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