Types of Computers

The computer is divided into three broad categories, and a category has its own categories given as below:





On the basis of Work:
Digital, Analog and Hybrid Computer:

Sn	Digital computer	Analog Computer	Hybrid Computer
1.	Computers that use binary digits to display discrete information is called digital computer.	A computer that uses analog signal to display information is called analog computer.	A computer that is able to understand binary as well as analog signal to display information is called Hybrid computer.
2.	Information is in discrete form. It displays information in the form of text, graphics, and pictures.	Information in continuous form and displayed in the form of curves. It is used to measure continuous physical quantity like as current flow, temperature, blood pressure, heart beats.	Information depends on operating mode of computer. It can display information in discrete and continuous form because for digital processing and next part is for analog processing.
3.	Slow	Fast	Intermediate in Speed

On the basis of Size:
Super, Mainframe, Mini and Microcomputer:
(a) Super Computer: Multi-user, multiprocessor large computer of very high efficiency and storing capacity is called supercomputer able to solve very difficult and complex problem within a nano seconds. A number of RISC (Reduced Instruction Set Computer) processors are used. Its word length is 64 bits.

Super computer

Applications of Super computer:
(i) Used to forecast the Weather and global climates
(ii) Used in military research and defense systems
(iii) In automobile, aircraft, and space craft designing
(iv) In encrypting and decoding sensitive intelligence information
(v) Used in seismography, plasma and nuclear research.
(vi) Protein folding analysis
(vii) Study of DNA structure and gene engineering
(viii) Digital film rendering

Example: C-DAC (Center for Development of Advanced Computer) of India has developed PARAM series of Super Computer.
ANURAG is also Indian Super Computer. Other Super computers are CRAY XMP/14, CDC-205 etc. Mr. Seymour Cray was a pioneer person in the field of supercomputer production. He had developed the first super computer Cray-1 in 1976.

(b) Mainframe Computer: It is also very powerful multi-user computer used in large business organizations, examination department of examinations, industries and defense to process data of complex nature. It can response several hundred request very quickly. It uses several CPU for data processing.
More than 100 users can use mainframe computer at a time because it works on time sharing mode. Its word length is 48 bits to 64 bits. IBM built the first Mainframe Computer, System/ 360, in 1964.
Example: IBM S/390, IBM S/709, ICL 39, CDC 6600

IBM S/390

Applications of Mainframe Computer:
(i) Government and civilian
(ii) Credit card processing
(iii) Bank
(iv) Marketing
(V) Business data processing in large organization
(vi) Air traffic control system
(vii) Industrial design

(c) Minicomputer: Minicomputers are larger and more powerful than most microcomputers but are smaller and less powerful than most large mainframe computer systems. However, this is not a precise destination. High-end models of microcomputer systems (super micros) are more powerful than some midrange computers, while high—end models of midrange systems (supermini) are more powerful than some smaller models of mainframe computers.
It is also multi-user computer and supports more than dozens of people at a time. It is costlier than microcomputer. It is also used in university, large business organizations to process complex data. It is also used in scientific research, instrumentation system, engineering analysis, and industrial process monitoring and control.
Example: PDP-11, VAX etc.

VAX

(d) Microcomputer: In 1976 the first personal Computer – Apple-1, Apple computer is designed. In 1981 August, IBM had announced the IBM 5150 PC, in New York. Now a day mostly used computers are microcomputers. It is called Home PC or Personal computer (PC) because it is a single user computer. It supports many higher level languages, multimedia, graphics, 3D graphics and games.
It is popular among students, professionals and home wives due to small size, low price, and low maintenance cost and easy in operation. The Internet is popular due to PC and it is available for all income groups. The American weekly magazine regarded it “Machine of year” in 1982 when IBM lunched PC in market first time. The first IBM PC was equipped with following components:

• Intel 8088 Processor of 4.77 MHZ

• 64 KB RAM (expandable to 256 KB)

• 40MB ROM

• 5.25″ floppy drive (160KB)

• PC-DOS 1.0 (MS DOS)

Example: IBM PCs, Apple Mac, IBM PS/2 etc.

Laptop and Palmtop Computers
These handheld computers are not replacements for desktop computers. Desktop computers continue to perform major processing functions, while palmtops are satellite for quick and mobile information access and communication. Computers are small, portable, less power consuming and equipped with all the facilities of modern PC. These computers can be operated by battery. These computers have no enough storing capacities like as desktop computers, but not less in other facilities. It has CD drive, floppy drive, modem and other input/output ports.
The typical handheld computers come with personal information manager (PIM) functions: calendar, address list, task list, and memos. These would appear to be the core features of the machine, but they really only scratch the surface of its potential.
The idea of laptop computer was originated by Alan Kay of Xerox Palo Alto Research Center in 1970 and named to notebook like computer as Dynabook, but first Laptop was designed in 1979 by William Moggridge of Grid System Crops. In 1983, Gavilan produced a laptop computer with 64 Kilobyte memory, MS-DOS operating system, touchpad mouse, portable printer of weight 9Ib.

PALMTOP

Learning and self-improvement are critical to educational leaders. Enormous amounts of information are created constantly, and the lifelong learner needs to have timely access to it. Web pages and other digital documents can be put on palmtop computers for enrichment. Palmtop computers are boon for remote area where there is no electricity facilities available.
The higher authorities, social workers, researcher working in remote rural area get more benefits by palmtop or laptop computers. The desktop is your personal computer seated at the top of your desk, laptop has no problem on your lap, and palmtop is happy in your palm.

Multimedia Computer
The term multimedia is not unknown among computer users. Multimedia is a combined form of two or more media like as text, graphics, sound, animation etc. Now a day, the multimedia PC is a choice of all. Analog Digital Converter (ADC) converts the sound wave into digital signal in multimedia computer. Without the talk of MPEG (Motion Picture Expert Group), the multimedia is uncompleted. It is a standard used to compress sound (audio) and videos for computer. It is named as MPEG-1, MPEG-2 etc.
The creative sound blaster 16 bits is proved as revolutionary steps in the world of multimedia and computer become more popular than Television sets.

On the basis of Brand:
On the basis of brand computer has two worldwide brands:

1. IBM PC and
2. Apple / Macintosh Computer

The Apple series of microcomputers was developed by Steve Wozniak and Steve Jobs in 1976. This used 8-bit microprocessor chips. The chip enabled them to put together a complete computer, a keyboard for input, and processors in memory and screen all in small box. Apple II is known as personal computer.

IBM PC and its compatible versions have largest share in PC market. Most of the users of the world have IBM PC, but Macs have its own users, mostly people interested in graphics works and publishing sectors.

On the basis of Model:
On the basis of Model computer is classified as:
(a) xT Computer (eXtra Technology): It cannot support GUI based operating system. Its processing speed is 4.77 MHz and Intel 8080, 8086, 8088 series of microprocessors is used.
(b) AT Computer (Advance Technology): It supports GUI based operating systems. Its speed is 2 G Hz and word length64 bits. Its processors are Intel series of 80286, 80386, 80486, Pentium I, Pentium II etc.
(c) PS/2 Computer: It is a laptop computer with rechargeable and battery based system. It is operated with OS/2 operating system.