Combinational logic functions and Boolean algebra, logical tables, Karnaugh maps, minimization, solid execution logic and combinational logic functions
Combinational logic function

All logic circuits can be divided according to the way the proceedings into two large groups. First group of logic circuits are called combinational logic circuits with them will be described in this chapter. Logic circuits of the second group are sequential logic circuits that are covered in chapter No. 5. The fundamental difference between the two groups is the ability of memory circuit status, and time control.

## Solution of combinational logic circuits

Combinational logic circuits have no memory and their output depends only on the combination of inputs. These circuits can be created using a combination of:

- logic gates AND, OR, and inverter or:
- function NAND (Sheffer function),
- NOR function (Pierce functions).

To solve combinational logic circuits is possible to use two forms of solution: disjunctive normal form or conjunctive normal form. Both forms list all logical functions, which can be a solution to the task. Disjunctive normal form looks for solutions in which the output variable takes values 1 In contrast, normal form conjunctive searching solution when the output variable with values 0, which is a partial solution to the problem. The final negation partial solution is obtained by solving the task. The result of the solution does not depend on the form of a solution. Therefore, the form of solution collected by the difficulty of the procedure. In layman's terms, if it contains more zeros Karnaugh map is selected disjunctive form, otherwise conjunctive form.

### Example: 4.9

Write Karnaugh map for the four variables, where Y = 1, where only two inputs a value of 0, find the mathematical expression.

solution

SOLUTION

Disjunctive normal form:

Conjunctive normal form solution: