computers

What is a computer?

A computer is an electronic device that manipulates information or data. It has the ability to store, retrieve, and process data.

Hardware versus Software

Hardware is any part of your computer that has a physical structure, such as the keyboard or mouse.

Software is any set of instructions that tells the hardware what to do and how to do it. There are three categories of software:

a. System software - Software required to run the hardware parts of the computer and other application software are called system software. System software acts as an interface between hardware and user applications. Based on its function, the system software is of four types –

• Operating system: System software that is responsible for the functioning of all hardware parts and their interoperability to carry out tasks successfully is called an operating system (OS). OS is the first software to be loaded into computer memory when the computer is switched on and this is called booting.
• Language processor: Program written in a high-level programming language like Java, C++, etc is called source code. Set of instructions in machine-readable form is called object code or machine code. System software that converts source code to object code is called language processor.
• Device Drivers: System software that controls and monitors the functioning of a specific device on the computer is called a device driver. 

b. Application software – It is a software that performs a single task and nothing else. Here is some commonly used application software −

• Word processing
• Spreadsheet
• Presentation
• Database management
• Multimedia tools

c. Utility software - Application software that assists system software in doing their work is called utility software. Examples of utility software include −

• Antivirus software
• Disk management tools
• File management tools
• Compression tools
• Backup tools

Different types of computers

• Desktop computers – These are designed to be placed on a desk, and they are typically made up of a few different parts, including the computer case, monitor, keyboard, and mouse.
• Laptops – These are battery-powered computers that are more portable than desktops, allowing you to use them almost anywhere.
• Tablets – These are handheld computers that are even more portable than laptops. Instead of a keyboard and mouse, tablets use a touch-sensitive screen for typing and navigation. For example, iPad.
• Server – It is a computer that serves up information to other computers on a network.
• Mainframe - Mainframes are computers used by organizations like banks, airlines and railways to handle millions and trillions of online transactions per second.
• Supercomputers are the fastest computers on Earth. They are used for carrying out complex, fast and time-intensive calculations for scientific and engineering applications.

Other types of specialized computers

• Smartphones – Many cell phones can do a lot of things computers can do, including browsing the internet and playing games. They are often called smartphones.
• Wearables – Wearable technology devices (or wearables) like fitness trackers and smartwatches. 
• Game consoles: A game console is a specialized type of computer that is used for playing video games on your TV.
• TVs: Many TVs now include applications—or apps—that let you access various types of online content. For example, you can stream video from the Internet directly onto your TV

PCs and MACs

PCs are the most common type of personal computers, and they typically include the Microsoft Windows operating system.

The Macintosh computer was introduced in 1984, and it was the first widely sold personal computer with a graphical user interface, or GUI (pronounced gooey). All Macs are made by one company (Apple), and they almost always use the Mac OS X operating system.

Basic parts of a computer

1. Input unit – Devices like keyboard and mouse that are used to input data and instructions to the computer are called input unit.
2. Output unit – Devices like printers and visual display units that are used to provide information to the user in the desired format are called output unit.
3. Control unit – This unit controls all the functions of the computer. All devices or parts of a computer interact through the control unit.
4. Arithmetic Logic Unit - This is the brain of the computer where all arithmetic operations and logical operations take place.
5. Memory − All input data, instructions and data interim to the processes are stored in the memory. Memory is of two types – primary memory and secondary memory. Primary memory resides within the CPU whereas secondary memory is external to it.

Control unit, arithmetic logic unit, and memory are together called the central processing unit or CPU.

Booting

Starting a computer or a computer-embedded device is called booting. Booting takes place in two steps −

• Switching on the power supply
• Loading the operating system into the computer’s main memory
• Keeping all applications in a state of readiness in case needed by the user

The first program or set of instructions that run when the computer is switched on is called BIOS or Basic Input Output System. BIO is a firmware, i.e. a piece of software permanently programmed into the hardware.

If a system is already running but needs to be restarted, it is called rebooting. Rebooting may be required if a software or hardware has been installed or system is unusually slow.

There are two types of booting −

• Cold Booting − When the system is started by switching on the power supply it is called cold booting. The next step in cold booting is the loading of BIOS.
• Warm Booting − When the system is already running and needs to be restarted or rebooted, it is called warm booting. Warm booting is faster than cold booting because BIOS is not reloaded.