Computer organization (cpu)

What is Computer Organization:

The internal arrangement of different parts of a computer is called the computer organization. It differs from one computer system to another. However, the basic organization remains the same for all types of computer systems.

              All computer systems perform the following five basic operations.

1. Inputting
2. Storing Processing
3. Outputting
4. Controlling

Computers receive most data from either the keyboard, scanner, mouse or disk. Information is saved on a floppy disk or hard disk. Data is manipulated or processed by the processors and the resulting output is either displayed on a monitor or printed on paper.

A block diagram of the basic computer organization is shown in figure 2.1. It depicts the five major building blocks, of functional units of a digital computer system. These five units correspond to the five basic operations performed by all computer system. The function of each of these units is described in subsequent sections.

CENTRAL PROCESSING UNIT (CPU):

The Central Processing Unit (CPU) is the brain of any computer system. In a human body, all major decisions are taken by the brain and all other parts of the body function as directed by the brain. Similarly, in a computer system, all major calculation, manipulations and comparisons are made by the CPU. The CPU is also responsible for activating and controlling the operations performed by all other unites of the computer system.

              The major pares of a CPU are:

(a)    Arithmetic and Logic unit (ALU)

(b)    Control unit (CU)

(c)     Main Memory of Primary Memory

Arithmetic and Logic unit (ALU):

All calculations are performed and all comparisons (dicisions) are made in the ALU. The data and instructions, stored on the primary memory prior to processing and manipulation of data is done in the Arithmetic and Logical Unit.

Intermediate results generated in the ALU are temporarily transferred back to the primary memory until needed again. After completions of processing, the final results available in the primary memory are sent to an output device. Such as monitor.

ALUs are designed to perform the four basic arithmetic operations- add, subtract, multiply, didide- and logic operations or comparisons such as less than, equal to, or greater than. Figure2.2 shows different operations of the computer system from the layman’s point of view.

In this figure, the calculator as a part of ALU represent the central processing Unit and the clock carries out the control function for different operations of the keyboard input and the monitor output. This figure gives more of a conceptual working of the digital computer. The actual block diagram representation, containing the jobs done by each part is shown in Figure 2.1.

Control unit:

How does the input device know that it is it is time for it to feet data into the storage unit? How dos the input device know that it is time for it to feed data into the storage unit? How does the ALU know what should be done with the data once the received? And how it is possible because of the control unit of the computer system. By selecting, instruction, the control unit is able to maintain order and direct the working of the entire computer system. Although it does not perform any processing on the data, the control unit acts as the central nervous system for all other components of the computer. It coordinates the entire computer system.