What Is The Fundamental Concept About The Working Of Arithmetic And Logic Unit?

In this section we shall explain how arithmetic and logic unit executes the program instructions and how flow of control, data and command is organized.

Firstly a program is a set of instructions. All instructions are stored in different locations when the program is executed.

Secondly the relevant data for the program is also stored and is available in main memory addresses which are known to the system. However the programmer is completely relieved of this responsibility of locating the memory address, where a certain data element or an instruction is stored. This is done automatically by some system programs such as memory manager and the central processing unit schedules, which are in fact parts of a bigger program called the operating system that operates the computer.

Thirdly he program instructions are not stored in original form. In fact they are stored in a coded form. The control unit fetches them one by one interprets them and direct the arithmetic and logical unit to perform the required operations. Instructions are executed in sequence unless some command in the program specifically directs to change the sequence. It carries out the arithmetic operations such as addition, subtraction, multiplication and division. It performs certain logical operations.