All calculations, including comparisons, are made by the ALU. The data and instructions, stored in the primary memory, are transferred to the ALU for processing.
Results generated in the ALU are transferred to the primary memory. After completion of processing, the final results are sent to an output device, such as printer.
ALU’s are designed to perform four basic arithmetic operations – add, subtract, multiply, divide – and logic operations or comparisons such as less then, equal to, or greater than.
ALU accepts operands from accumulator and temporary register. It stores the result in accumulator or temporary register. It provides states of result to the flag register. It looks after the branching decisions.
The computer’s memory is often accessed by the arithmetic logic unit. This memory, which is often referred to as random access memory, or RAM, is always in a state of flux. This happens because the unit accesses the memory and makes changes to it frequently in order to follow instructions given by various programs.
In some cases, the arithmetic and logical functions are divided up and processed in two discrete central processing unit components, an arithmetic unit and a logic unit.