Topic 1: Introduction to Computer System

Hello Friends! Welcome to the world of computers. Computer system is the most powerful machine man has ever made. Today we cannot even imagine our ordinary life without computers. It is in our homes, offices, colleges, hospitals, industries, banks, everywhere. It is in our backpack, our lap, pocket, and of course, right now it’s in front of us. We can’t escape to the computers. Knowingly or unknowingly we all use it every day. It’s like magic that has made our life a lot easier. So let’s go on an exciting journey to the world of the computer and explore how this magic happens and how it becomes an important part of our life.

In this journey, we will explore the fundamental concepts of computers and their programming languages. We will find how the software works together with the hardware. We will also go into the past to explore how computers and their programming languages was evolved in history. Let’s start…

What is a Computer System?

Computer System is an electronic machine. It is made of two major components: hardware and software. Machines were evolved to exceed the limits of the human body. A machine could do specific work with more precision and speed. Like any other machine, computer hardware can also perform a task in a blink of an eye. But this is not why the computer is the most powerful machine ever made. Unlike any other machine, the computer hardware can perform a task according to its program or software. This means software to control the hardware. That’s how the computer became a more versatile machine. It can perform a variety of tasks with the help of various different software.


Computer System is an electronic machine synthesis of hardware and software. It is used to manipulate the data according to a list of instructions known as a program.

How Computer System Works?

A Computer is basically an electronic data processing machine. It has five fundamental operations:

Input: The computer takes data (row facts and figures) as input.
Store: Inputted data and programs are stored in memory and used as required.
Process: The computer processes the data and converts it into useful information according to the stored program.
Output: After processing it output the information in the desired format.
Control: It controls all the above-mentioned operations.

Block Diagram of Computer

A computer has various functional units to perform various operations. Following is the block diagram of a digital computer:

DigitalG1 Block Diagram of CPU
Block Diagram of CPU

Let’s discuss its components…

Data: Data is unorganized raw facts and figures. It may about some objects, persons, or anything else. It is bits of information but not the information itself. So the data is useless until it is processed and organized in a meaningful way.
e.g. Attendance record of students, Employee salary, Hostal visitors record, etc.

Information: Information is derived by processing the data. It is a more useful and intelligible form of data that can be used directly for decision-making.
e.g. Attendance percentage of students, Income tax, List of daily visitors, etc.

Input Unit: The data and instructions can be inputted into the computer using input devices. These devices take the input from the outside world and convert it into a form that the computer can understand. After that converted data is supplied to the computer for further processing. Keyboard and mouse are the most commonly used input devices. Other input devices are the touchpad, camera, joystick, scanner, etc.

Output Unit: After processing, the processed data or information is to be supplied to the outside world. Output devices collect this information from the computer and convert it into a format that humans can understand. Monitors are the most commonly used output devices. Other output devices are speaker, printer, plotter, etc.

Primary Storage (Main Memory): Primary Memory is also called main memory or internal memory. It is memory storage where the program, data, and intermediate results are stored during processing. These types of memory can be directly accessed by the processor using the data bus. RAM, ROM, Cache Memory and CPU registers are examples of primary memory. These memories are manufactured by using semiconductor devices. These are limited in capacity, very fast, and expensive. Except for ROM, all these memories are volatile in nature. So that the data is lost when power is switched off.

Secondary Storage: Primary memory has very limited capacity and is also volatile in nature. So it could not store a huge amount of data for a long time. Secondary memories are used to overcome this problem. However, these memories are slower than the primary memory and could not be accessed directly by the CPU. But it can store a huge amount of data, programs, and information for a long period without a continuous power source. Moreover, most of the operating systems used secondary memory as virtual memory to artificially increase the primary memory.

Central Processing Unit (CPU): Central Processing Unit or CPU or simply called processor is an electronic circuit within a computer. It is one of the most important elements of a computer system. All the operations performed by a computer are directly or indirectly done by the CPU.
CPU acts like the brain of a computer. It carries out the instructions of a computer program by performing the basic arithmetic, logical, control, and input/output operations. CPU consist of three major parts.

    • Arithmetic and Logic Unit (ALU): ALU fetches the data from CPU registers and performs basic arithmetic and logical operations such as addition, subtraction, logical AND, OR and EX-OR, etc.
      Control Unit
    • (CU): Control Unit controls all the operations of a computer. It controls the input-output devices, memory, etc, and directs them to perform the specified task.
    • CPU Registers: CPU Registers are special purpose, high speed, volatile memory units. They store the data, instructions, and intermediate results of calculation while executing a program.

Components of a Computer System

A computer consists of two major components: hardware and software. Both could not work without each other.

Hardware: Computer hardware are physical devices that make up a computer. These devices have small electronic and mechanical parts. Monitor, Keyboard, Mouse, Motherboard, Processor, RAM, etc. are examples of hardware.

Software: Unlike hardware, software are not physical objects, rather it is a sequence of instructions that tells computer hardware what to do. Such as Microsoft windows, Photoshop, Skype, Google Chrome, Adobe reader, etc.

Author – Aditya Saini

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