Branded and Un-branded Computer (availability of Computers)

Availability of Computers:-

Computers available in market can be categorized in two groups. Branded Computers and Un-branded Computers.

Branded Computers:-

These Computers are marked under a brand name. It means some company assemble these computers under its trade name and sale it to end-users. For example IBM, APPLE, ACER, COMPAQ, HP, DELL etc. These computers are high in quality and cost as well.

Un-branded Computers:-

These computers have no brand name or trade name of seller. These computers are usually made in Taiwan and Korea. Or some time local sellers assemble different parts together to sale them as computers. These are are cheap computing machine and less reliable then Branded computers.

Classification of Computer Depending upon Technology

Generations of Computers:-

A generation of computer starts with use of newer technology available to build computers. The technologies used in computers change many time in past. computers have travel very long journey to reach the recent state. It is the name of advancement from vacuum tube to microprocessor.

First Generation of Computer(1945-1959)

The first generation of computer start with use of vacuum tubes and capacitors as electronic components. These machines were very large in size. The machines produce eminence amount of heat. These were very slow and need special operators. ENIAC, ADVAC, EDSAC fall under this class of computers.

Second Generation of Computers(1959-1965)

The second generation of computers start with invention of transistor in 1947. But first computer were produce in 1956-1959 using transistor. The use of transistor make computer smaller and reliable. UNIVAC-III and IBM-7070 fall under this category.

Third Generation of Computers(1966-1971)

The third generation of computer starts with the use of Integrated Circuit (IC) in 1966. An IC is composed of hundreds of thousand of electronics components packed together. These computer were very small in size. These computers use disks to store data. These computers were less expensive then previous versions of computer. The concept of operating system was introduced in third generation computers.

Fourth Generation of Computers(1971-Present)

This generation of computers starts with use of very large scale integrated Circuits in 1971. These computers were very cheap and a single user can purchase this machine. Now computers were produced in bulk quantity. Application software were introduced in fourth generation. Now a days computers are so advance and developed that user can do an thing on computer.

Fifth Generation of Computers(Future):-

The Fourth generation of computer is still in use, but the architecture of today's Micro processor has reached its limits. Now it is very hard to increase the speed of computer using these processors. Scientist today are working on the processing technology of the future. The modern computers will use quantum computing or light beam technology. The future processors will work at speed of electrons or other technology will make them as faster as light beam.

The second thing to be used in computers is artificial intelligence. The modern computers will not only too fast but they will be able to think like human.

Classification of Computer Depending upon Working Principle

Analogue Computers:-

Analogue computers use continuously changeable values of data as input and produce their graphical image after processing. These computers mostly use Electrical, Mechanical or hydraulic quantities to model a problem. These computer take input in form of signal and produce output in form of graph. This output is 90% to 95% accurate. For example Thermometer, ECG, Multi-meter, Wall clock etc.

Digital Computers:-

The computers in which input is given in form of Digits and their output is also produced in digits are called digital computers. Digital meters, Digital Watch and Calculators are examples of Digital Computers.

Hybrid Computers:-

The computers that convert analogue data into digital data or produce analogue results from digital data are called hybrid computers. PCs are examples of Hybrid Computers.

Classification of Computer Depending upon Size

Super Computers:-

1. Super computers are most powerful computers of the world.
2. Super computers are most fastest computers of the world.
3. Super computers are most expensive computers of the world.
4. Super computers are very large in size.
5. Super computers have very large amount of Main Memory and Storage.
6. Super Computers use many processors to process data.
7. Some super computers are task specific as they do only one task with extreme concentration.
8. Super Computers are Multi-user computers as more then one user can use them at a time.
9. Super Computers are mostly used in research laboratories, Institutes and space stations.
10. JAGUAR (Oak Ridge National Laboratory), NEBULAE (China), ROADRUNNER (Los Alamos National Laboratory), KRAKEN (National Institute for Computational Sciences), JUGENE (Juelich Supercomputing Center, Germany), PLEIADES (NASA Ames Research Center) and TIANHE-1 (China) are examples of Modern super computers.

Mainframe Computers

The IBM Dictionary Of Computing defines "mainframe" as "a large computer, in particular one to which other computers can be connected so that they can share facilities the mainframe provides (for example, a System/370 computing system to which personal computers are attached so that they can upload and download programs and data). The term usually refers to hardware only, namely, main storage, execution circuitry and peripheral units."

1. Mainframe computers are also very powerful computers
2. Speed of main frames is also good enough
3. These are also expensive computers
4. These computers have large main memory and storage.
5. These are multi-user computers.
6. These computers are mostly used in medium scale research organizations, Banks, industries and governments.
7. IBM Z-series and IBM 360 Series are examples of Mainframe computers.

Minicomputers:-

1. Minicomputers were designed to cut-off the huge price of Mainframe and supercomputers.
2. These computer are enough powerful to work as servers in networks.
3. These computers are also enough speed to support multi tasking
4. These computers are usually found in small organizations and educational institutes
5. These computers are used as servers as well as for minor scale research.
6. Web Servers and E-mail clients are also mostly installed on minicomputers.
7. Small scale industries also use minicomputers to integrate their offices
8. These computers have large memory and storage.
9. Data General, Prime, Adage, Computer Automation, Four Phase, General Automation and Interdata are some examples of minicomputers

Microcomputers:-

1. Microcomputers are very small in size.
2. Microcomputers are very cheap computers.
3. These computers are so small and cheap that everyone can buy them. Hence these computers are called Personal Computers or PCs.
4. These computers have enough speed to support a user to perform work.
5. These computers come with enough main memory and storage capacity
6. These computers are single user.
7. These computers are multi tasking.
8. These computer are simple to use even children under 5 year age can use them.
9. These computers are general purpose computers it means that you can do what ever you want.
10. HP DC series, Intel Desktop series, IBM Think-pad series are examples of Microcomputers

Classification of Computers

Classification of Computers:-

Computers are classified according to their size, Technology and Working Principle into following different categories. 

Depending upon their Size

Super Computer

Mainframe Computer

Mini Computers

Microcomputers

Depending upon their Working Principle

Analogue Computers

Digital Computers

Hybrid Computer

Depending Upon their Technology (Generations of Computer)

First Generation of Computer (1945-1959)

Second Generation of Computer (1959-1965)

Third Generation of Computer (1965-1971)

Forth Generation of Computer (1971-Present)

Fifth Generation of Computer (Future)