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Published byKristian Walsh Modified over 9 years ago
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Karnaugh Maps Not in textbook
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Karnaugh Maps K-maps provide a simple approach to reducing Boolean expressions from a input-output table. The output from the table is used to fill-in the K-map. – 1’s are used to create a Sum of Product (SOP) solution. (min terms) – 0’s are used to create a Product of Sum (POS) solution. (max terms)
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Min Terms Canonical representation of a Boolean expression is in the form of ^ v ~ (AND, OR, NOT). – Example: A^B v ~A^~B v A^~B (AB + AB + AB) Candidates for canonical representation are taken from the truth table (input-output). Candidates are identified where the output is “1”. (Max Term canonical representation candidates are identified by “0”)
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Min Terms Min terms are taken directly from the truth tables. Where ever there is a “1” for an output, F(), we note the min term value and place a “1” in the K-map corresponding to the min term value of the table. Min term short hand is often used to replace a full input-output table. The short hand indicate the variables and the min terms that are “1”. Example: f(A,B,C) =
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Examples f(A,B,C) = InputOutput min termABCF(A,B,C) 0000 1 1001 1 2010 3011 4100 5101 1 6110 7111 1 InputOutput min termABF(A,B) 000 101 1 210 1 311 f(A,B) =
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K-Map Tables K-map tables are organized based on the number of variables. – Example: showing min terms in italic bold.
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K-Map Examples ~BB A\B 01 ~A0 1 A1 1 f(A,B) = Reducing a Boolean expression using K-map 1.Identify min terms (from table or function form) 2.Fill-in appropriate K-map. 3.Group min terms in largest grouping using 4-neighbor rule. 1.a min term is a number if it is either to the right, left, top, or bottom. 2.K-map edges are connected as neighbors. 4.Write out the groupings as the reduced expression (circuit). f(A,B) = ~A^~B v A^B
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K-Map Examples ~BB A\B 01 ~A0 1 A1 1 f(A,B) = f(A,B) = ~B ~BB A\B 01 ~A0 A1 11 f(A,B) = f(A,B) = A ~BB A\B 01 ~A0 1 A1 11 f(A,B) = f(A,B) = B v A
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K-Map Examples InputOutput min termABCF(A,B,C) 0000 1 1001 1 2010 3011 4100 5101 1 6110 7111 1 ~B~B / CB / CB A\BC 00011110 ~A0 11 A1 11 f(A,B,C) = ~A^~B v A^C ~B~B / CB / CB A\BC 00011110 ~A0 11 A1 1 f(A,B,C) = f(A,B,C) = ~A^~C v ~B^~C
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K-Map Examples f(A,B,C,D) = ~C~C / DC / DC AB\CD 00011110 ~A 00 ~A / B 01 11 A / B 11 11 A 10 f(A,B,C) = B^D f(A,B,C,D) = ~C~C / DC / DC AB\CD 00011110 ~A 00 1111 ~A / B 01 A / B 11 A 10 1111 f(A,B,C) = ~B
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K-Map Examples f(A,B,C,D) = ~C~C / DC / DC AB\CD 00011110 ~A 00 111 ~A / B 01 A / B 11 1 A 10 111 f(A,B,C) = ~B^~C v ~B^~D v A^B^C^D
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HMWK Due 2/4 1.Build the input-output table from the following min term list of 4-variables: 2.Using a K-map reduce the expression from 1 such that you minimize the number of connectives (AND, OR, NOT). Remember the answer should be in the sum of product form.
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