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)
Boolean Function Digital Logic and Computer Design by Ravinder Nath Rajotiya - September 6, 2023September 10, 20230 Boolean function A Boolean function is a Boolean algebraic equation derived generally from the word statement of the given problem or from the truth table. Such a function has two or more input variables. The function will produce a LOW or HIGH output when certain combinations of the input signal (binary value) is applied to the input variables. Two forms of Boolean functions Sum of Product Product of Sum Sum of Product: A sum of product (or SOP) equation is obtained by ORing the product or the minterms Minterm : A Minterm is also called as product term is one that produces a HIGH output when the values of the input variables are ANDed together. It is written for a ‘1’ or HIGH values in
Floating Point Number representation Digital Logic and Computer Design by Ravinder Nath Rajotiya - August 29, 2023September 10, 20230 Representation of Real Numbers: Real numbers can be represented using the following two representations. · Fixed point Notation · Floating point notation Fixed point representation A fixed point number is one which is stored with fixed number of bits for integer part and also a fixed number of bits for the fraction part. It has the following parts · Integer Part · binary Point · Fraction Part IIIIIIIIIIIII . FFFFFF Suppose we have 8 bits storage to store a real number, of these 5 bits to store the integer part and 3 bits to store the fractional part as shown below: ( 1 0 1 0 1 . 1 0 1)2 = 1*24 +0*23 + 1*22 + 0*21 + 1*20 + 1*2-1 + 0*2-2 + 1*2-3 Smallest and largest Fixed point number With 8 bit
Design of ALU Digital Logic and Computer Design by Ravinder Nath Rajotiya - December 15, 2022December 15, 20220 Design of ALU ALU forms one of the important block of a digital computer. It is a multi-operation, combinational circuit. Number of operations supported depend on the complexity of its design. It takes two numbers of n-bit wide as input, performs an operation depending on the function select inputs and produces the output Fn, It also has carry-in input to provide additional functionality and carry-out line which can be part of the result or can act as input to the next stage when the functionality is extended to accommodate numbers with more number of bits. If an ALU has k function select lines, then it will have 2k operations. Figure-1 shows the block diagram of an ALU. Modular design technique can be