CLASSIFICATION OF COMPUTER

The differences between both are as follow:

Analog	Digital
Analog signal is a continuous signal which represents physical measurements.	Digital signals are discrete time signals generated by digital modulation.
Denoted by sine waves	Denoted by square waves
Uses a continuous range of values to represent information	Uses discrete or discontinuous values to represent information
Subjected to deterioration by noise during transmission and write/read cycle.	Can be noise-immune without deterioration during transmission and write/read cycle.
Analog instrument draws large power	Digital instrument draws only negligible power
Low cost and portable	Cost is high and not easily portable

Fig: Analog and Digital Signals

Analog instrument draws large power. A supercomputer is a computer with great speed and memory. This kind of computer can do jobs faster than any other computer of its generation. They are usually thousands of times faster than ordinary personal computers made at that time. Supercomputers can do calculation jobs very fast, so they are used for weather forecasting, code-breaking, genetic analysis and other jobs that need many calculations. When new computers of all classes become more powerful, new ordinary computers are made with powers that only supercomputers had in the past, while new supercomputers continue to outclass them.

Mainframes use proprietary operating systems, most of which are based on Unix, and a growing number on Linux. Over the years they have evolved from being room-sized to networked configurations of workstations and servers that are extremely competitive and cost-effective platforms for e-commerce development and hosting. Mainframes are so called because the earliest ones were housed in large metal frames.

A microcomputer is a computer with a microprocessor as its central processing unit. They are physically small compared to mainframe and minicomputers. Many microcomputers (when equipped with a keyboard and screen for input and output) are also personal computers. However, as microprocessors and semiconductor memory became less expensive, microcomputers, in turn, grew cheaper and easier to use.

A minicomputer is a type of computer that possesses most of the features and capabilities of a large computer but is smaller in physical size.

A minicomputer fills the space between the mainframe and microcomputer and is smaller than the former but larger than the latter. Minicomputers are mainly used as small or midrange servers operating business and scientific applications. However, the use of the term minicomputer has diminished and has merged with servers.

Hybrid computers are computers that exhibit features of analog computers and digital computers. The digital component normally serves as the controller and provides logical operations, while the analog component normally serves as a solver of differential equations. The HRS-100 was a prominent example in the 1970s. Late in the 20th century, hybrids dwindled with the increasing capabilities of digital computers including digital signal processors.

IBM is an abbreviated form of International Business Machine. They are manufactured by IBM Company. It is one of the popular companies in the manufacture of Computers.

IBM compatible referred to as an IBM clone, IBM compatible is a term used to describe a computer, hardware, or software that is IBM/PC Compatible. This does not necessarily mean that the computer was manufactured by IBM. Today, the majority of computers manufactured and used are either PC (IBM compatible) or Apple Macintosh compatible.

On the basis of brand, the computer can be classified as IBM PC, IBM compatibles and Apple/Macintosh computer.

a)  IBM PC: IBM PC is the largest computer manufacturing company establishing the USA. The computer manufactures by IBM PC or branded computer. Personal Computer (PC) is the most important type of micro computer system. The micro computer manufactures by IBM Company are called IBM PC. These computers are reliable, durable and have better quality but they are costly.

b)  IBM Compatibles: The computers that have some functional characteristics and principles of IBM computer are called IBM compatibles. In another word, all the computer are manufactured by another company rather than the IBM company are Known as IBM compatibles. All the software and hardware of IBM compatibles. These are cheaper and Their Parts are easily available in Market. They are also duplicate or assemble the computer.

c)  Apple/Macintosh Computer: All the computers manufacture by apple cooperation, a leading computers manufacturing computer in the USA are known as Apple/Macintosh computers. These computers use their own software and hardware. They are totally different than that of IBM computers, In terms of both hardware and software. For e.g software developed for Apple computer can't run or IBM computers and vice-versa. Similarly, floppy disk formatting in IBM computer can't be recognized by Apple Macintosh computer and vice-versa. It is popularly used in desktop publishing (DTP) houses as they provide a better quality of graphic output.

On the basis of the model, a computer is classified as:

a)  XT (Extended / Extra Technology) Computer: The computers that use 8086, 8088 microprocessors are called XT computers. The time periods for this computer are from 1975 - 1982. XT computers have a processing speed of 4.77 MHz and are comparatively slow in speed. These processors are of 4, 8 or 16 bits of word length.

b)  AT (Advanced Technology) Computer: With the development of 80286 microprocessors AT computer were introduced in the field of computers. The processors are of 8, 16, 32 or 64 bits of word length. The computers using Pentium I, Pentium pro & Pentium II are the examples of AT computers. The time periods for these computers are from 1982 - 1995. These computers can run any type of soft wares including text-based as well as graphical base and processor speed of these computers is up to 233 MHz.

c)  PS/2 (Personal System / 2) Computer: IBM started manufacturing the next model of computer in 1990. This model is called PS? 2 computers. Most of the computers manufactured after 1990 including laptop, belongs to this model. These computers are a refinement of AT computers. These computers can run almost all software & programs.

Mobile computing is a human-computer interaction by which a computer is expected to be transported during normal usage. Mobile computing involves mobile communication, mobile hardware, and mobile software. Communication issues include ad hoc and infrastructure networks as well as communication properties, protocols, data formats and concrete technologies. Hardware includes mobile devices or device components. Mobile software deals with the characteristics and requirements of mobile applications.

a)  Flexibility: We no longer need to stay plugged into a specific location for working on your computer. Mobile computing allows us the unprecedented flexibility to move about and perform our activities at the same time

b)  Saves Time: This technology is just the thing to use such transit time more effectively. It also allows to instantly connecting with our family anywhere and anytime. We can connect with them over the Internet using portable computing devices such as Internet phones and share the fun.

c)  Enhanced Productivity: Increased work flexibility is directly proportionate to enhanced work productivity - the fact that you can do your work from any place you want, without waiting for, and making efforts to, get access to computing facility translates into people being able to do more work with greater flexibility.

d)  Ease of Research: Motile computing and the flexibility offered by it enable students as well as professionals to conduct in-depth research on just about any topic or subject even when on the go!

e)  Entertainment: Getting bored is so last-decade now what with zillions of entertainment options available on mobile communication and computing devices these days. For example:- games, movies, music, videos, etc.

The differences between them are as follows:

	Minicomputer	Mainframe computer
Speed	They can support up to 50 terminals.	They can support more than 100 terminals.
Memory	32-bit microprocessor	Greater than 64-bit microprocessor
storage	The storage disk capacity is nearly 1TB	The storage disk capacity is several terabytes.

A super computer is the fastest type of computer which performs at a rate of speed which is far above that of other computers which harness immense processing power so that they are incredibly fast, sophisticated and powerful.

Supercomputers are very expensive and are employed for specialized applications that require immense amounts of mathematical calculations. For example, weather forecasting requires a supercomputer. Other uses of supercomputers include animated graphics, fluid dynamic calculation, and nuclear energy research and petroleum explorations.

The primary use for supercomputers is in scientific computing, which requires high power computers to perform complex calculations. Scientific organizations like NASA use the supercomputer for the purpose of performing calculations, rendering complex formulas and performing other tasks which require a formidable amount of computer power. Some supercomputers also have been designed for very specific functions like cracking codes and playing chess.