Computer are available in different shapes, size and weights, due to these different shapes and sizes they perform different sort of jobs, all the computers are designed by the qualified architectures as per requirement.
Basically there are two types or classes of computers
An analog computer is a type of computer or machine that work on the continuously-changeable aspects of physical phenomena of electrical, mechanical, or hydraulic quantities as input behavior and solve the problem.
In other words analog computers do their jobs on variable input quantities.
In contrast, digital computers work on numerical values called digits .
Analog computers uses continuous variables for mathematical operations and utilizes mechanical or electrical signals, they were commonly used in science and industry for measuring values and other required operations like temperature & volume.
Tablet PC or slate-shaped mobile computer, equipped with a touch screen type of notebook computer having LCD screen on which the user can write using a special-purpose pen called Stylus .
The handwriting is digitized and can be converted to standard text through handwriting recognition or can be remained as handwritten text. Like PCs Tablet PCs uses keyboard and mouse for input.
The tablet PC relies on digital ink (technology that digitally represents handwriting in its natural form ) technology, where a digitizer is laid under or over an LCD screen to create an electromagnetic field that can capture the movement of the special-purpose pen and record the movement on the LCD screen.
Its effect is like writing on paper with liquid ink.
PDA is a handheld lightweight consumer electronic device that looks like a hand-held computer but instead performs specific tasks and can serve as a digital diary, computing, electronic organizer,, entering, storing, and displaying schedules, appointments, addresses, phone numbers, other personal data, telephone/fax, and networking features together,
A typical PDA can function as a cellular phone, fax sender, and personal organizer. Unlike portable computers, most PDAs are pen-based, using a stylus rather than a keyboard for input.
Some PDAs can also react to voice input by using voice recognition technologies.
PDA such as a Palm Pilot is a next-generation Cell Phone which could capable data and voice . Many of these devices now provide the ability to access web content remotely, over wireless networks.
Palmtop Palmtop is a small computer that literally fits in your palm also pocket computers, comparing to full-size computers they work for certain functions such as phone books and calendars. Because of their small size, most palmtop computers do not include disk drives but PCMCIA slots enable you to add disk drives, modems, memory, and other devices. Palmtops are smaller, lightweight with sufficient battery life, palmtops larger and heavier version is called handheld computer. The Palmtop is designed with a small keyboard and a flip-up screen and is more usable to surf the web while you are on the move.
Smart cellphones Smart cell phone is simply a phone with advanced features like e-mail, Internet and e-book reader capabilities and built-in keyboard. In other words, it is a miniature computer that has phone capability smart cell phone is a mobile phone offering advanced capabilities, often with PC-like functionality and can work PC-Mobile handset conversion.
Chat servers enable a large number of users to exchange text, voice, pics and other online content using real-time capabilities.
One of the most important server of Internet cloud, mail servers send/recieve and store mails using the network of LAN and WAN.
Yahoo, Gmail, Hotmail are the best examples of mail servers.
Proxy server basically designed to provide internet services to its network clients, govt institutions, business points, small networks and cyber cafes are ideal for internet browsing using proxy server.
This is one of the core server is designed to save and provide access to huge databases of an organization, research centre, banks and database institutions.
In size and power, minicomputers are between workstations and mainframes.
In the past decade, there was little difference between large minicomputers and small mainframes.
Minicomputer is a multiprocessing system capable of supporting from 4 to about 200 users when are in networking environment.
Minicomputers and PCs are ideal home network, mid- range server to serve multiple users.
Mainframes Mainframe is based on the cabinet containing central processor unit or "main frame" in a entire room, it is an other giant computer after the super computer is Mainframe, which can also process millions of instructions per second and capable of accessing billions of data. This type of computer commonly used in big hospitals, air lines reservations companies because its capability to get, manage and retrieve bulk of data. Likewise super computer it is also most expensive and recommended for specials applications.
Nowadays a Mainframe is a very large and expensive computer capable of supporting hundreds, or even thousands, of users simultaneously.
The chief difference between a supercomputer and a mainframe is that a supercomputer channels all its power into executing a few programs as fast as possible, whereas a mainframe uses its power to execute many programs concurrently.
Mainframe you are able to build a large network for several hundred clients. You can process millions of transactions daily with the mainframe because of its high capacity. Most of enterprises such as large organizations, insurance businesses, industry, banking usually use the mainframe for processing and storing enormous amounts of data every day
Super Computer The biggest in size, the most expensive in price than any other is classified and known as super computer. It can process trillions of instructions n seconds, this computer is neither used as a PC in a home nor student in college. This is special purpose computer, most govt. institutions use this type of computer for their different calculations and heavy job, different industries use this huge computer for designing the products.
Supercomputer is a broad term for one of the fastest computers currently available.
It is used in weather forecasting requires a supercomputer. Other uses of supercomputers scientific simulations, (animated) graphics, fluid dynamic calculations, nuclear energy research, electronic design, and analysis of geological data, petrochemical applications.
Hollywood movies use this computer for animation to movies also used in advance weather forecast.
Wearable computers The latest trend in computing is wearable computers possessing email, database, multimedia, calander/schedular are integrted into watches, cell phones, visors and even clothing. When the users hands and other sensory organs are engaged in other activities, wearable computers are of great help in tracking human actions, these computers are consistently in operation as they do not have to be turned on and off and are constantly interacting with the user. Wearable computers are worn on the body parts and they have been applied to areas such as behavioral modeling, health monitoring systems.