Understanding Boolean Logic, Karnaugh Maps, and Multiplexers
This lecture provides a comprehensive overview of Boolean logic, focusing on Karnaugh Maps, truth tables, and the conversion processes involving multiplexers and demultiplexers. We explore canonical forms, minterms, and maxterms, emphasizing their unique representations in Boolean expressions. Practical exercises include implementing majority functions and reducing Boolean expressions using Karnaugh Maps. Key mathematical terms such as implicants, prime-implicants, and essential prime-implicants are also covered, making it an essential session for understanding digital logic design.
Understanding Boolean Logic, Karnaugh Maps, and Multiplexers
E N D
Presentation Transcript
ITEC 352 Lecture 4 Boolean logic / Karnaugh Maps
Review • Truth tables • Conversion between • Multiplexers
Outline • Multiplexers • Math • Karnaugh Maps • Minterm / Maxterm • Relationship to gates
Multiplexers • Purpose? • Construction using gates
Demultiplexer • Only passes a 1 through if the input is 1
Combination • Why would you combine a multiplexer and a de-multiplexer?
Canonical forms • A Boolean expression can be expressed in a number of ways. • E.g., • S = X’+Y*Z can also be represented as • S = X’ + X’ + Y*Z • Hence,we use canonical forms (or normalized forms) that are unique in representing in expressions. • Note, they need not be minimal – they are just unique. • Two popular canonical forms: • Sum of products and Product of sums.
Minterms • Minterm: Boolean function that is 1 in only one row of the truth table. • Example: what are the minterms of function s. • S=X’ +Y*Z • Represent the sum (s) function using minterms.
Maxterms • Maxterm: Boolean function that is 0 in only one row of the truth table. For example, the function: • Example maxterms for the sum function. • S=X’ +Y*Z • Exercise: express F = X + Y' * Z as product of sums (in terms of maxterms)
Class exercise • Implement a majority function: • Given three inputs, the functions equals 1, if the majority of inputs are 1’s else it is a 0. • Steps: • (a) Draw the truth table. • (b) Write down the function in a canonicalized way. • (c) Draw the circuit.
K-Maps • 2 Level Maximum
Construction • Variant of a truth table • Grid format • Allows you to see patterns quickly
Terms • Implicant: a single minterm or group of minterms that can be combined together on the K-map • Prime-implicants: Implicant that can not be combined with another one to remove a literal • Essential prime implicants: prime implicant that includes a minterm not covered by any other prime implicant
Exercise • Reduce the following Boolean expression using a Karnaugh Map: • F = A’BC + AB’C + ABC + ABC’
Review • A few mathematical terms • Minterm • Maxterm • Visualization technique for Boolean expressions