Basic computer

 What is a Computer?

An electronic device that accepts data and processes it into useful information is called a Computer. There are two main aspects of the computer:

• Input: The data we enter into the computer is called the input. Input, basically are raw facts for which we want the system to process and give us an outcome

Input Device Definition: A piece of equipment/hardware which helps us enter data into a computer is called an input device. For example keyboard, mouse, etc. 

List of Input Devices

1. Keyboard -
2. The keyboard is an essential input device and computer and laptops both use keyboards to give commands to the computer

2. Mouse

• It is also known as a pointing device
• Using mouse we can directly click on the various icons present on the system and open up various files and programs

3. Joy Stick

• It is a device which comprises a stick which is attached at an angle to the base so that it can be moved and controlled
• Mostly used to control the movement in video games

4. Light Pen

• It is a wand-like looking device which can directly be moved over the device’s screen
• It is light-sensitive

5. Microphone

• Using a microphone, sound can be stored in a device in its digital form
• It converts sound into an electrical signal
• To record or reproduce a sound created using a microphone, it needs to be connected with an amplifier

6. Scanner

• This device can scan images or text and convert it into a digital signal

7. Barcode Reader

• It is a kind of an optical scanner
• It can read bar codes

• Output: The answer that the computer provides in return of the raw data entered, is called output

1. Monitor

• The device which displays all the icons, text, images, etc. over a screen is called the Monitor

2. Printer

• A device which makes a copy of the pictorial or textual content, usually over a paper is called a printer

3. Speakers

• A device through which we can listen to a sound as an outcome of what we command a computer to do is called a speaker

4. Projector

• An optical device which presents an image or moving images onto a projection screen is called a projector
• Most commonly these projectors are used in auditoriums and movie theatres for the display of the videos or lighting

5. Headphones

• They perform the same function as a speaker, the only difference is the frequency of sound

Computer devices can also be classified into categories:

• Hardware
• Software

Hardware 

Hardware is physical in nature and hence one can touch and see hardware

Hardware cannot be infected by Viruses

Computer hardware examples:

Few examples of computer hardware are –

• Motherboard – it is the circuit board that contains IC sockets and slots.
• Central Processing Unit (CPU) – it is the heart of the computer
• Peripheral of CPU such as Keyboard, Mouse, Monitor, Printer, Speaker, UPS etc.

Software 

The software cannot be physically touched but still can be used and seen

The software can be infected by Viruses

he computer software is divided into two major parts:

1. System Softwares – System software operates directly on hardware devices of the computer. It provides a platform to run an application and helps to run the hardware of the computer and the system itself. Operating systems, diagnostic tools, device drivers are some included in system software. These are mostly pre-installed on computers. Examples are Windows, Linux, Unix, etc. 
2. Application Softwares – Designed for user-benefit to complete different tasks. These are either pre-installed in the computers or can be installed as per the need. It includes word processing, Language processors, web browsing, translators, editors and almost any other task for which we install the software. Examples are Word, Excel, PowerPoint, Oracle, etc.

RAM

 Ram Stand for Random Access Memory

Data of RAM is very volatile, it will exist as long as there is no interruption in power.

ROM

 ROM stand for Read-only Memory 

Data in ROM can only be read, it cannot be modified or erased.

Data present in Read-Only Memory (ROM) is not volatile, it is permanent. Data will remain unchanged even when there is a disruption in the power supply.

Generations of Computer

There are a total of five Generations of Computers

each Generation something new was discovered to improvise the functioning and the use of the computer systems.

First Generation (Vacuum Tubes) – 1940-1956:

• The price of managing these computers was very high
• They were huge
• They were not capable of multitasking, and only one task could be performed at a time
• There was no use of monitors; the output was directly given in the form of print outs
• The electricity consumption was very high

Second Generation (Transistors) – 1956-1963:

• The speed of the transistor decided the speed of the computer
• It was less expensive in comparison to the 1st Generation computers
• The electricity consumption had also reduced with the use of transistors
• There was no change in the output as it was still received through a printout
• From machine language, there was a change to usage assembly language in computers. Thus, now computers could understand words
• High-level programming languages were used

Third Generation (Integrated Circuits) – 1964-1971:

• The Integrated circuits were used where small circuits could work as efficiently as the larger ones
• Multitasking could be done in the computers developed during the 3rd phase
• Functions of the computer were based on the memory of the monitor

Fourth Generation (Microprocessors) – 1972-2010:

• The first microprocessor, Intel 4004 chip was discovered by Ted Hoff and was made commercially available in 1971. This led to the introduction of personal computers
• This Generation saw revised versions of computers being introduced in the form of laptops and tablets
• GUI – Graphical User Interface was developed during this phase
• Speed, memory and storage had also improved in the computers of this Generation

Fifth Generation (Artificial Intelligence) – 2010-till date: 

• Artificial intelligence is being used in devices currently which has enabled millions on tasks to be completed within seconds on a device
• Advancement in the functioning of laptops, palmtops, etc.
• Other robotic devices have started being used to reduce human labour
• The devices from this generation are cost-effective, faster, consume lesser electricity and are easily portable and convenient to use

Types of Computer

There are majorly 4 types of computers which have been described briefly below.

1. Super Computer – The computers which are used to process a huge amount of data at once are called Supercomputers. They are mostly used in scientific and engineering operations where the processing is complex. They are expensive and complicated to work. For example – The computers used by NASA to launch space shuttles.
2. Mainframe Computer – Computers designed to be used in large firms and organizations where a lot of people have to work on the same database are called mainframe computers. They are almost equally as expensive as Supercomputers and are the fastest working computers at present. They are mostly used in Banks.
3. Workstation – Usually a single user system is called a work station. The RAM for such systems is more, and the processors are quite fast. They are mostly used by an individual and can be used for multiple purposes.
4. Microcomputer – Designed for personal use only. This type of computers can easily be moved from one place to the other. They have a personal storage area, input & output unit and a Central Processing Unit. Examples for microcomputer are desktop, laptop, mobile phone, tables, etc. 

Computer Devices

The image given below shows the different devices which can be connected to a computer:

What is a Computer Virus?

A computer virus is a program which can harm our device and files and infect them for no further use. When a virus program is executed, it replicates itself by modifying other computer programs and instead enters its own coding. This code infects a file or program and if it spreads massively, it may ultimately result in crashing of the device. 

Types of Computer Virus

Discussed below are the different types of computer viruses:

• Boot Sector Virus – It is a type of virus that infects the boot sector of floppy disks or the Master Boot Record (MBR) of hard disks. The Boot sector comprises all the files which are required to start the Operating system of the computer. The virus either overwrites the existing program or copies itself to another part of the disk.
• Direct Action Virus – When a virus attaches itself directly to a .exe or .com file and enters the device while its execution is called a Direct Action Virus. If it gets installed in the memory, it keeps itself hidden. It is also known as Non-Resident Virus.
• Resident Virus – A virus which saves itself in the memory of the computer and then infects other files and programs when its originating program is no longer working. This virus can easily infect other files because it is hidden in the memory and is hard to be removed from the system.
• Multipartite Virus – A virus which can attack both, the boot sector and the executable files of an already infected computer is called a multipartite virus. If a multipartite virus attacks your system, you are at risk of cyber threat.
• Overwrite Virus – One of the most harmful viruses, the overwrite virus can completely remove the existing program and replace it with the malicious code by overwriting it. Gradually it can completely replace the host’s programming code with the harmful code.
• Polymorphic Virus – Spread through spam and infected websites, the polymorphic virus are file infectors which are complex and are tough to detect. They create a modified or morphed version of the existing program and infect the system and retain the original code.
• File Infector Virus – As the name suggests, it first infects a single file and then later spreads itself to other executable files and programs. The main source of this virus are games and word processors.
• Spacefiller Virus – It is a rare type of virus which fills in the empty spaces of a file with viruses. It is known as cavity virus. It will neither affect the size of the file nor can be detected easily.
• Macro Virus – A virus written in the same macro language as used in the software program and infects the computer if a word processor file is opened. Mainly the source of such viruses is via emails.

How To Protect Your Computer from Virus?

The most suitable way of making your computer virus-free is by installing an Anti-virus software. Such software help in removing the viruses from the device and can be installed in a computer via two means:

• Online download
• Buying an Anti-virus software and installing it

What is an Anti-Virus?

An anti-virus is a software which comprises programs or set of programs which can detect and remove all the harmful and malicious software from your device. This anti-virus software is designed in a manner that they can search through the files in a computer and determine the files which are heavy or mildly infected by a virus. 

Given below is a list of few of the major antivirus software which is most commonly used:

• Norton Antivirus
• F-Secure Antivirus
• Kaspersky Antivirus
• AVAST Antivirus
• Comodo Antivirus
• McAfee Antivirus

 . What is the definition of a computer virus?

Ans. A computer virus is a kind of malicious computer program, which when executed, replicates itself and inserts its own code, which spreads a harmful virus in the system. This computer virus ultimately affects the functioning and programming of the device.

. What are the main computer viruses?

Ans. The main types of computer virus are as follows:

• Boot Sector Virus
• Direct Action Virus
• Multipartite Virus
• Polymorphic Virus
• Resident Virus
• File Infector Virus