In a 4-variable K-Map, a group of 4 adjacent 1s (a quad) eliminates how many variables from the product term?
In a K-Map, grouping 2^k cells eliminates k variables. Grouping 4 cells (2^2) eliminates 2 variables. Grouping 8 cells (2^3) eliminates 3 variables.
What is a 'Prime Implicant' in K-Map minimization?
A Prime Implicant (PI) is a product term obtained by combining the maximum possible number of adjacent 1s (power of 2) in a K-Map, such that it cannot be merged into any larger group.
What makes a Prime Implicant an 'Essential Prime Implicant' (EPI)?
An Essential Prime Implicant (EPI) is a prime implicant that includes at least one minterm (1) which is not covered by any other prime implicant. All EPIs must be included in the final minimal SOP expression.
How are 'Don't Care' conditions (denoted as 'd' or 'X') treated during K-Map minimization?
Don't care terms represent invalid or unused input combinations. In K-Maps, we set X = 1 if it helps form a larger group of 1s (thus eliminating variables), or X = 0 if it doesn't help.
What is the output of a 2-input XNOR gate when its inputs are A = 1 and B = 1?
An XNOR gate is an equivalence detector; its output is HIGH (1) when both inputs are equal (A=B=0 or A=B=1). Thus, for A=1, B=1, XNOR output = 1.