Classification of Computer
The Computers are distributed depending on their processing power, size, speed and price. However, the systematization/distribution of computers is not very straight-forward. The distinction between these categories is sometimes not very clear. Some characteristics overlap different categories. Computers can be classified into the following categories:
· Personal Computer
· Mobile Devices
· Mainframe Computer
· Embedded Computer
Personal Computers / Micro Computers
Personal computer is also called micro-computer. It is designed to be used by one person at a time. It consists of a processor, memory and one or more input, output and storage devices. It also often contains a communication device. Personal computers are available in different sizes and shapes. They are widely used by individuals and businesses. The price of personal computer is from several hundred to several thousand dollars.
Most commonly used personal computers are PC and Apple. PC and its compatible computers use Windows operating systems. Apple computers use Mac OS operating system. PC and its compatible computers follow the specifications of the original IBM personal computer. Different companies such as Dell, Acer, HP and Asus sell PC and its compatible computers. Major types of personal computers are desktop computer and portable computer.
Desktop computers are the most common type of personal computer. It is designed in a way that all its components fit on a desk or table. In one model, the system unit is placed horizontally on the desktop or table and monitor is placed on the system unit. In another model, called tower model, both monitor and system unit are placed on the table. The system unit in tower model is placed vertically. Some desktop computers also have touch screens.
Different desktop computers are as follows:
All-in-one computer combines monitor and system unit into a single device. Many all-in-one models also have touch screen technology. These computers save desktop space but can be difficult to upgrade. HP TouchSmart and Apple iMac are examples, of all-in-one-computer.
Workstation is more powerful and expensive desktop computer. It is used for calculations and graphics work. A workstation can tackle the tasks that require a lot of processing speed. It is mostly used by engineers, graphics artists and architects. Architecture uses a workstation to view and create maps. A graphic artist uses a workstation to create computer-animated special effects for full-length motion pictures and video games.
A desktop computer can be configured to work as server. A server computer provides services and controls access to the hardware, programs and data in the network. It also provides a centralized storage area for programs, data and information.
Portable computer is a mobile personal computer that can be carried from one place to other easily. It has input, output, storage and processing components integrated into a single unit. It can receive power from an electrical outlet or a battery.
Portable computers are affecting our daily routine in this modern era both positively and negatively. People can use mobile computer anywhere at home, in office or classroom and during travel etc. The businessmen can use it during travel to manage and monitor business activities. The students can use it in class to perform different educational activities. A salesperson can use it to give presentation to the clients and store information about them anywhere. However, portable computers are creating some negative effects as well. People use them so often to stay online, play games and chatting etc. It is disturbing social interaction among the people.
Different types of portable computers include laptop and tablet.
A laptop is a mobile computer that has keyboard, screen and other devices integrated into a single compact case. It is designed to fit in the lap. It uses less power than desktop computer and can be used outdoors without the need of electrical outlet. It has batteries and can be used for many hours without continuous power supply. A laptop computer can perform same basic functions as a desktop computer. It typically has built-in wireless communication facility. Some laptops come with touch screens. Laptop is also known as notebook computer.
Ultrabook is a thin, lightweight and full-featured laptop. It has high-end processing and video capabilities. It typically uses SSD drives so it boots up very fast. It uses very less power and provides longer battery life than traditional laptop. It does not have any optical drive. Some examples of ultrabooks are Apple Macbook Air and Asus Zenbook.
Netbook is a small, lightweight and impressive laptop computer. It has longer battery life than laptop. It has built-in wireless capacities and is suited for general computing and web-based applications. It has limited memory and storage. It provides reduced computing power ascompared to a full-size laptop computer. It has no optical drives.
Tablet is a thin and lightweight mobile computer with touch screen. It is usually smaller than a laptop. Some tablets include a stylus that looks like a small pen. It can be used to enter data and select different objects on touch screen. A physical keyboard can also be attached to a tablet. It provides longer battery life than laptop.
Tablet comes with a variety of pre-installed programs called mobile applications or mobile apps. It can be used to browse the web, send and receive email and watch videos etc. There are extensive collections of applications for tablets that can be downloaded on tablet for free or for a small price. The Apple iPad is an example of a tablet computer.
Two basic designs of tablets are Slate and Convertible.
1. Slate Tablet: This type of tablet does not contain a physical keyboard. It uses an on-screen virtual keyboard for input. The user can also attach physical keyboard with Bluetooth or wireless.
2. Convertible:This type of tablet has a display screen attached to a keyboard. It can be rotated 180 degrees and folded down over the keyboard. It can be repositioned to look like a notebook computer.
A mobile device is a computing device designed to hold in the hand. Mobile devices typically have small screens and some of them have keyboards. Mobile devices usually have no disk drives. The programs and data are permanently stored on special memory or on a small storage media such as smart card. Mobile devices can be connected to large network to exchange data. Mobile devices are almost always powered by a rechargeable battery system. It has built-in wireless connectivity for Internet access. Popular types of mobile devices are smart phones, handheld computer, portable media players and e-book.
A smartphone is a cell phone that includes many features of computer and can run general purpose computing applications. Many smartphones have touch screens to input data using fingertip or a stylus. Some have a built-in mini keyboard. iPhone is an example of smartphone.
Some features of smartphones are as follows:
· Internet access
· Make and answer phone calls
· Send text messages, picture messages and video messages
· Personal information management such as calendar, address book and calculator etc.
· Send and receive email messages
· Communicate wirelessly with other devices or computers
· Built-in camera to share images or video with others
· Conduct live video calls
· Play and organize music
· Voice recording
· GPS services
· Computing power to run programs like word processors etc.
2. Handheld Computers
A handheld computer is a small, lightweight computer that easily fits in the hand. Many handheld computers communicate wirelessly with other devices or computers. Some have small keyboards and others have a touch screen and also include a stylus for input. Many handheld computers are used by mobile employees such as parcel delivery people or warehouse employees to take inventory and check supplies etc.
Handheld computer is not very powerful and cannot perform many tasks that can be accomplished by desktop and notebook computer.
3. Portable Media Player
A portable media player is a mobile device designed to store, organize and play digital media. Digital media includes music, photos and videos. These devices offer camera, access to the Internet and variety of applications.
Some portable media player models have a touch screen or a touch-sensitive pad. A touch-sensitive pad contains buttons and wheels to be used with a thumb or finger. It can be used to scroll, play music, view photos, watch videos and adjust volume etc. Portable media players usually include a set of earbuds that are small speakers that rest inside each ear canal. iPod Touch is an example of portable media player.
4. E-Book Reader
E-book reader is designed for reading books, magazines and other digital publications. It is also called e-reader. An e-book is an electronic version of a printed book readable on computers and other mobile devices. E-reader device can hold thousands of e-books.
Most e-readers have a touch screen and have built-in wireless technology to connect to the Internet. An on-screen keyboard can be used to navigate, search, and highlight the contents. The user can browse an electronic bookstore and download new eBooks in seconds via wireless connection.
Some e-readers use e-ink technology. It makes screens easy to read and extends battery life for up to two months. The reader can feel the experience of reading a printed book. The screen can easily be read even in bright sunlight. Some e-readers have LCD screens similar to laptops and tablets. LCD screens can display colors and are used to view magazines and books with colorful photos. However, it is more difficult to read contents in bright sunlight.
Minicomputer is typically larger, more powerful and more expensive than desktop computer. It is more reliable than desktop computer. It is also called mid-range server. It generally consists of two or more processors.
Minicomputer can serve up to several hundred connected computers simultaneously. It is normally accessed by users through a personal computer or a terminal. A device with a monitor and keyboard is called terminal. It is also called dumb terminal. It has no processing power and cannot work as a stand-alone computer. It has to be connected to a server.
Examples of minicomputers are as follows:
· Prime 9955
· HP 3000
· AS 400
· VAX 8600
Use of Mini Computers
Mini computers are often used by small and medium-sized companies or departments. They provide centralized store of information and computer programs.
A mainframe computer is a large computer in terms of price, power and speed. It is more powerful than minicomputer. It consists of multiple processor. It is specially designed to perform multiple tasks for multiple users simultaneously. It is designed for high reliability. It often runs twenty four hours a day. It can be serviced and upgraded while it is running. It is also known as enterprise server or high-ended server.
Mainframe computer can serve several thousand users simultaneously. These computers can store large amounts of data, information and programs. The users access a mainframe computer through a terminal or personal computer. The mainframe computer is very expensive starting from many thousand dollars and can be up to many million dollars. IBM, Sun and Unisys are leading manufacturers of mainframe computers.
Examples of mainframe computers are as follows:
· IBM S-390
· NEC 610
· DEC 10
· IBM System ZIO
Uses of Mainframe Computers
Mainframe computers are used in large organizations such as banks, educational institutions and government departments etc. For example, airlines use these computers to maintain flight schedules, ticket reservation system etc. Govt. departments such as NADRA use mainframe computers to maintain the information of population. Many shopping chains interconnect their stores with mainframe computer to track transactions immediately and maintain stock.
Supercomputer is the fastest and the most powerful computer. It is the biggest in size and more expensive in price than any other computer. It is used to perform complex tasks. It consist of a very high storage capacity and can store many thousand times more data than a normal PC or precisely, desktop computer. It also consumes a large amount of energy. It can process trillions of instructions in one second.
The modern supercomputer consists of thousands of microprocessors. The cost of one supercomputer can be up to several billion dollars.
Examples of supercomputers are as follows:
· Blue Gene
· Deep Blue
· ASCI White
Uses of Supercomputers
Supercomputer is mostly used for weather predictions, weapon design and atomic research etc. Super computer is also used in business and industry field. Aircraft manufacturers use it to simulate aircraft and check its performance.
Governments use super computers for different calculations and heavy jobs. Many Hollywood movies use it for animation purposes.
An embedded computer is designed for special purposes. It works as anelement in a larger product. These computers are micro in size and have a bounded hardware. They perform various functions according to the requirements of the product in which they are embedded.
Embedded computers are used in commonly used product such as:
· Electronics: P DAs, mobile, video recorders and DVD players etc.
· Home Devices: Security monitoring systems & programmable microwave ovens etc.
· Automobiles: Car engine controller, airbag controller etc.