SIMULATION OF BOOLEAN FUNCTIONS IN A DECIMAL COMPUTER.

This article presents information about a method for simulating logical functions in a digital computer by means of simple arithmetic and control instructions. This method is of practical value when the computer used does not have built-in logical instructions. In this method, it is assumed that x, y and z are integer variables whose value is maintained at 1 or 0 at all times. It is also assumed that A, B and C are Boolean variables whose value is either 1 or 0 by definition. The logical operations of AND, OR and NOT may be executed with the integer variables x, y and z using arithmetic and control instructions. The result of an AND operation with any number of Boolean variables is exactly the same as the (arithmetic) multiplication operation with the integer variables. The result of an OR operation is with any number of Boolean variables is the same as the arithmetic addition of the integer variables. The result of a NOT operation with a Boolean variable is the same as subtracting an integer variable x from 1. The OR operation needs a control statement after the arithmetic addition is performed in order to restore the value of the variable to unity. This may be simplified by using a function subprogram to calculate the result of the OR operation, thus eliminating the need for repetition of the control statements.