K-Map Redundant and Don’t Care Digital Logic and Computer Design by Ravinder Nath Rajotiya - September 14, 2023September 14, 20230 Introduction In Simplification using K-Map we used minterms or Maxterms to group 1's or 0's respectively to form pair, quad or octets. There may be situations where all the 1's which are part of one group are overlapped by other groups or certain input conditions may not be contributing in getting the minterms or maxterms of the output functions. In the following discussions, we will see how to account for such conditions. Redundant Groups A redundant group is one whose all the 1’s have been used or ovelapped by other groups. We can always eliminate such group. Let us take an example and understand how redundant group can be dropped thus not part of solution. Example: Simplify the SOP equation given by F(ABC) = ∑(2,3,5,7). Figure-1 There
Simplification using K-Map Digital Logic and Computer Design by Ravinder Nath Rajotiya - September 12, 2023September 12, 20230 K-Map A K-Map is a pictorial representation of the Boolean expression. By entering the values of the minterm or Maxterm an SOP or POS equation can be very easily simplified. It is very easy tool for simplifying up to 5-variable Boolean equation, but as the variable increases, solution become tedious. To begin, we will learn how to draw a 2, 3 and 4 variable K-Map. Draw 2-Variable K-Map Draw 3-Variable K-Map Draw 4-Variable K-Map Simplification Using K-Map Simplifying 2-Variable SOP equation Ex-1: Simplifying F= A'B + AB Ex-2: Simplify A'B + AB + AB' Simplifying 3-Variable SOP equation Ex-3: Ex-4 Simplifying 4-Variable SOP Equation Ex-5 Simplify F(ABCD)=∑(m1, m3, m5, m7, m9, m10,m13, m15) Ans: D Practice Problem: Simplify F= A'B'+A'B+AB' Simplify F(WXY)=∑m(1,2,3,5,7) Simplify F(ABC)=∑m(2,3,4,5 ) Simplify F(ABC)=∑m(2,3,7) + d(1,5) Simplify F(ABCD)=∑m(2,3,5,7,10,15)+d(0, 4,9,13)