What are the different types of computers?

When most people hear the word computer, they think of a personal computer such as a desktop or laptop. However, computers come in many shapes and sizes, and they perform many different functions in our daily lives. When you withdraw cash from an ATM, scan groceries at the store, or use a calculator, you're using a type of computer.

Full Form 

C ( Calculate ) गणना करना

O ( Operate ) प्रचालित करना

M ( Machine/Memorize) किसी चीज को भली भाती

P ( Print ) छापना 

U ( Update) नवीनतम सूचना देना 

T ( Tabulate ) अंकरो को सारणी में क्रमबद्ध करना

E ( Edit ) काट-छाट करना

R ( Response ) उत्तर या प्रक्रिया

The word computer comes from the Latin word “computer” meaning to compute.

What is computer?

Computer is an electronic machine that helps us to store and process our data or instruction at high speed with accuracy. It can receive information, perform basic operation like calculations and comparisons and produce results according to given instructions in a desirable form.

OR

Computer is an electronic machine which is capable to perform Arithmetical, Logical and Graphical functions as well as comparisons. It receive any type of information process it, in systematic way and give the actual result according to given instructions by the computer user.                                 

  Arithmetical Functions

+ Addition

     ---      Subtraction

          X           Multiplication

   /     Divide etc.

Logical Functions

< Less than

> Greater than

= Equal

Or, not, Like ect.

Logical functions provide answer in two modes Yes or No.

Example: - 8>7 Yes 8<7 No

Comparison 

8=7 False 8=8 True

SOME IMPORTANT TERM

DATA: -

         It is derived form of Latin word “datum” (means Facts and figure).

It is a collection of facts and figures which are not in directly usable form.

It is raw fact material which is given by the computer user into the computer  system.

INFORMATION: -

It is the processed data or final result of any type of user activities.

TYPES OF DATA

There are four types of data. 1) Textual/Alphabet data

                 2) Numeric/ Numerical data

               3) Logical data

               4) Graphical data

Textual Data: -

Textual data refers to all kinds of alphabets, digits, symbols, word, sentences and paragraphs. It is made from A to Z letters.

Numeric Data: -

Numeric data refers to all kind of numbers. For Example 45, 90, 201, 512 etc. It is made from 0 to 9 digit.

Logical Data: -

Logical data refers to whose data that may have only two value Yes and No or True and False. Such type of data consist logical symbols such as <, >, <>, or, not, like, (, ) etc. 8>7 Yes 7>8 No 8=7 False 8=8 True

Graphical Data: -

Graphical data Refers to all kind of shapes and pictures. 

For Example….

Shape    Picture 

How to work computer

Computer work on the basic principle of Input, Process and Output.

Input: -

The data feeding process through input devices is called Input.

The data feeding process is called Input. It is done by Input devices.

Such as Keyboard:- Mouse, Track Ball, Joystick, Microphone, Light pen, Card Reader, Digital Camera, Scanner, Touch Plat Panel Monitor, Audio Input unit/ Voce data, OMR,  MICR, BCR, OCR.

                    Keyboa                  Mouse             Joy Stick           Light pen

                            Track Ball              Scanner        Graphic Tablet        Microphone

                         MICR                                         BCR                   OCR                   OMR

               Digital Camera                               Video Camera                                   Web Camera

                  Joystick                                                                                       Micro Phone

OMR ( Optical Mark Reader)

MICR( Magnetic Ink Character Reader)

BCR( Bar Code Reader)

OCR( Optical Character Reader)

Process: - Computer work on the given data is called process. It is done by processing device called CPU.

    जब कंप्यूटर दिए हुए डाटा पर काम करता है तो उसे प्रोसस्सिंग कहा जाता हैl 

Output: -

The taken actual result or information after processing through the output devices is called output.

Some output device are Monitor, Printer, Plotter, Speaker, Head Phone, ear phone etc. 

   प्रोसस्सिंग के बाद कंप्यूटर के द्वारा दिए गए परिणाम को आउटपुट कहा जाता हैl  यह हमेसा ओउटपुट डीभास पर दीखता है या निकलता हैl

Combination Example

            Input                               Processing                       Output

Main Parts of Computer System (कंप्यूटर सिस्टम के मुख्य भाग ) 

There are four main parts of computer system.

1.Monitor      2.Keyboard          3.Mouse             4.   CPU

1. Monitor: -

It is an output device that displays any information. It is also known as VDU (Visual Display Unit).

Types of Monitor

   1.Black & White Monitor  / Monochrome Monitor               

       2.  Color Monitor

              1) CRT Monitor

               2) LCD Monitor

              3) TFT/LET Monitor

CRT MONITOR: -

Such type of monitor is made up Cathode Ray Tube. Which are flow electrons in this tube and generated output on the screen. It is consumed more electricity. Its graphic quality is better than LCD Monitor.

LCD MONITOR:-

In this recent time most popular monitor are LCD (Liquid Crystal Display).

 The screen of LCD monitor is made up of a special substance (Liquid Crystal) sheet of glass.

It is consumed less electricity. Its graphic quality is lower than CRT Monitor.

TFT/LED MONITOR: -

It is also a type of monitor. It stands for Thin Film Transistor. 

This is made from LED (Light Emitting Diode) Substance. Its graphic quality is 

Better than LCD monitor and consumed less amount of electricity.

2. Keyboard: -

The computer keyboard is one of the basic ways of entering information  into the computer. 

Or

             It is a basic way to entering any type of data into the computer system.

             यह एक सामान्य रास्ता है जिससे किसी भी तरह के डाटा को कंप्यूटर के अंदर डाला  जाता हैl

Types of keyboard

(कीबोर्ड के प्रकार) 

                             1. Normal Keyboard      2.  Standard Keyboard/ Multimedia Keyboard

Normal Keyboard: -

A normal keyboard contain 101/102 keys.

Standard Keyboard/Multimedia Keyboard:-

 A standard keyboard contains more than 102 keys. These extra keys located upper area of the keyboard for some special functions or multimedia purpose. Such as Play Song, Push, Next, Previous button etc.

User study keyboard keys in categories form. Those keys available in six categories……….

1.Function Keys

2.Special Character keys/Symbolic Keys

3.Special keys

4.Alphabet keys

5.Numeric keys/ Number keys

6.Arrow Keys/Direction Keys/Cursor Control Keys/Navigation Keys

I) Function Keys: -

These keys are present on top most row of the keyboard and are make F1 to F12. These keys are responsible for performing some particular or special functions.

II) Special Character Keys/ Symbolic Keys: -

These keys contain the signs/symbols. Which are printed on the upper portion of the keyboard. They are used in combination with Shift key.

III) Special Keys: - These types of key perform some special work. Such as Page Up, Page Down, Enter, Back Space, Tab, Shift, Ctrl, Alt, Space Bar, Ins, Del, Num Lock, Caps, Window key etc.

IV) Alphabet Key: -

These key are make from A to Z that can help write any types of letter, word, Sentence and Paragraph.

V) Numeric Keys: -

These key are make from 0 – 9. That can help to enter the numerical data. It is located just below the function key and right side sector of keyboard.

VI) Arrow key: -

These key are allow to move the cursor in a specified direction.

3). Mouse: -

Mouse is a palm sized pointing and drawing device. That can help select or open any object. It contains two or three button and a wheel.     

      माउस एक हथेली के आकार का पोइंटिंग और ड्राविंग डिभाइस होता हैl जिसके मदद से  किसी भी ऑब्जेक्ट को सेलेक्ट और खोला जाता हैl 

Types of Mouse

(माउस के प्रकार)                            1.   Normal Mouse         2.  Optical Mouse

Normal Mouse: -

Normal mouse contain a ball. It is fitted at the bottom of the mouse. The mouse is moved on a mouse pad. The ball rotates and these movements are translated into digital signals.

        PS 1 Normal Mouse

Optical Mouse: -

It contains a lense and fitted at the bottom of the mouse. When leaser light emit to lense than its signal translate into digital signal.  

PS 2 Optical Mouse

Trackball: -

This is like a mouse turned upside down. You roll a ball around with your fingers to control the location of the pointer.

4) CPU: -

CPU stands for Central Processing Unit. It is one of the important parts of the computer also called the brain of the computer. Processing on the input data is done by the CPU. It is the combination of ALU, CU and the Memory.

सी पी यू का विस्तृत रूप सेंट्रल प्रोसेसिंग यूनिट होता हैl  इसे कम्प्युटर का मस्तिस्क कहा जाता हैl यह कंप्यूटर सिस्टम का एक महत्वपूर्ण भाग होता हैंl डlटl का परोसेसिग सी पी यू के अनदर होतl हैंl यह ए एल यू , मेमोरी और सीयू का संयोगिक रूप होता हैl 

ALU: - (Arithmetical and Logical Unit) 

It is capable to perform addition, Subtraction, Multiplication, Divisions as well as comparisons. It is also known as CPU and Processor.

CU (Control Unit ) : -

It control all the functions like Input, Storage, Process and Output. It gives command to transfer data from the input devices to memory and from memory to ALU. It transfer the results from memory to output Unit.

MEMORY

Primary Memory: -

The memory unit that directly communicates with the CPU is called the main memory or primary memory. The primary memory also has two parts namely...

1.RAM

2.ROM

RAM : -

It is volatile memory and it losses data when we switch OFF the computer. It is also known as Main Memory, Temporary Memory and Primary Memory.  It is installed in motherboard.

TYPES OF  RAM

SRAM: -

Static random access memory uses multiple transistors, typically four to six, for each memory cell but doesn't have a capacitor in each cell. It is used primarily for cache.

DRAM: -

Dynamic random access memory has memory cells with a paired transistor and capacitor requiring constant refreshing.

EDO DRAM: -

Extended data-out dynamic random access memory does not wait for all of the processing of the first bit before continuing to the next one. As soon as the address of the first bit is located, EDO DRAM begins looking for the next bit. It is about five percent faster than FPM. Maximum transfer rate to L2 cache is approximately 264 MBps.

SDRAM: -

Synchronous dynamic random access memory takes advantage of the burst mode concept to greatly improve performance. It does this by staying on the row containing the requested bit and moving rapidly through the columns, reading each bit as it goes. The idea is that most of the time the data needed by the CPU will be in sequence. SDRAM is about five percent faster than EDO RAM and is the most common form in desktops today. Maximum transfer rate to L2 cache is approximately 528 MBps

ROM : -

It is a memory where necessary commands and information are stored for boot the computer. It is inbuilt in motherboard.

TYPES OF ROM

1.Programmable read-only memory (PROM), or one-time programmable ROM (OTP), can be written to or programmed via a special device called a PROM programmer. Typically, this device uses high voltages to permanently destroy or create internal links within the chip. Consequently, a PROM can only be programmed once.

2.Erasable programmable read-only memory (EPROM) can be erased by exposure to strong ultraviolet light (typically for 10 minutes or longer), then rewritten with a process that again needs higher than usual voltage applied. Repeated exposure to UV light will eventually wear out an EPROM, but the endurance of most EPROM chips exceeds 1000 cycles of erasing and reprogramming. EPROM chip packages can often be identified by the prominent quartz "window" which allows UV light to enter. After programming, the window is typically covered with a label to prevent accidental erasure. Some EPROM chips are factory-erased before they are packaged, and include no window; these are effectively PROM.

3.Electrically erasable programmable read-only memory (EEPROM) is based on a similar semiconductor structure to EPROM, but allows its entire contents (or selected banks) to be electrically erased, then rewritten electrically, so that they need not be removed from the computer (or camera, MP3 player, etc.). Writing or flashing an EEPROM is much slower (milliseconds per bit) than reading from a ROM or writing to a RAM (nanoseconds in both cases).

Type of Electrically Erasable Programmable Read Only Memory

Electrically alterable read-only memory (EAROM) is a type of EEPROM that can be modified one bit at a time. Writing is a very slow process and again needs higher voltage (usually around 12 V) than is used for read access. EAROMs are intended for applications that require infrequent and only partial rewriting. EAROM may be used as non-volatile storage for critical system setup information; in many applications, EAROM has been supplanted by CMOS RAM supplied by mains power and backed-up with a lithium battery.

Flash memory (or simply flash) is a modern type of EEPROM invented in 1984. Flash memory can be erased and rewritten faster than ordinary EEPROM, and newer designs feature very high endurance (exceeding 1,000,000 cycles). Modern NAND flash makes efficient use of silicon chip area, resulting in individual ICs with a capacity as high as 32 GB as of 2007; this feature, along with its endurance and physical durability, has allowed NAND flash to replace magnetic in some applications (such as USB flash drives). Flash memory is sometimes called flash ROM or flash EEPROM when used as a replacement for older ROM types, but not in applications that take advantage of its ability to be modified quickly and frequently.

SECONDARY MEMORY

HARD DISK : - It is a permanent Storage area of computer where we can store a lot of data. Such as file, folder, programs etc.

A Hard-Disk coated with magnetic plates. A set of such magnetic plates are fixed to a spindle one below the other to make up a disk pack. 

 Cache memory is a very high speed semiconductor memory which can speed up CPU. It acts as a buffer between the CPU and main memory. It is used to hold those parts of data and program which are most frequently used by CPU. The parts of data and programs are transferred from disk to cache memory by operating system, from where CPU can access them. 

Foppy Disk Drive : -

A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles. They are read and written by a floppy disk drive (FDD) 

CD-ROMs : -

CD-ROMs are popularly used to distribute computer software, including video games and multimedia applications, though any data can be stored (up to the capacity limit of a disc). Some CDs hold both computer data and audio with the latter capable of being played on a CD player, while data (such as software or digital video) is only usable on a computer (such as ISO 9660 format PC CD-ROMs). These are called enhanced CDs.

DVD Drive: -

DVD is an optical disc storage format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than Compact Discs while having the same dimensions.

Magnetic tape data storage uses digital recording on to magnetic tape to store digital information. Modern magnetic tape is most commonly packaged in cartridges and cassettes. The device that performs actual writing or reading of data is a tape drive. Autoloaders and tape libraries are frequently used to automate cartridge handling.

BIOS(Basic input/output system):  A type of ROM that is used by the computer to establish basic communications when the computer is first turned on caching-The storing of frequently used data in extremely fast RAM that connects directly to the CPU. 

Virtual Memory:

space on hard disk used to temporarily store data and swap it in and out of RAM as needed. 

MEMORY UNIT

4 BITS = 1 NIBBLE

8 BITS = 1 BYTE OR 1 CHARACTER

1024 BYTE (210 ) = 1 Kilo Byte

1024 KB (220) = 1 MEGA BYTE

1024 MB (230) = 1 GIGA BYTE

1024 GB (240) = 1 TERA BYTE

1024 TB (250) = 1 PETA BYTE

1024 PB (260) = 1 EXA BYTE

1024 EB (270) = 1 ZETTA BYTE

1024 ZB (280) = 1 YOTTA BYTE

Advantage of computer

Computers have been invented to help people. It provides lot of advantages over manual operations. Let us look at a few of them.

Speed: -

A computer is a very fast device. It can perform in a few seconds the amount of work that a human being can do in an entire year. 

Computers are capable of performing calculations much faster than manual method. The time required to execute basic operations like addition, varies from a few microseconds to hundreds of nanoseconds depending on the capability of the computer. The following are standard units of measurement of speed.

Unit of time part of a second: -

Accuracy: -

The accuracy of a computer is consistently high and the degree of accuracy of a particular computer depends upon its design. But for a particular computer, each and every calculation is performed with the same accuracy.

Computers do the calculation without errors. If the data entered is correct and if the sequence of instructions (program) is reliable, then we can expect accurate output.

When a spacecraft moving at great speed is to be controlled, very accurate and quick control is needed, only computers can provide such control.

Storage capacity: -

computes can store large volume of data in its primary memory but it is volatile that it is lost once the machine is switched off. To store the data permanently the computer uses the secondary storage. Every piece of information can be retained as long as desired by the user and can be accessed as and when required.

Reliability: -

computes do not fail and rarely need maintenance.

Versatility: -

Computers are capable of performing almost any task, provided that the task can be reduced to a series of logical steps.

Processing Capability: -

Computer processing is the fastest and most accurate way of performing data processing. Data processing comprises of capturing the data, manipulating it and managing the output. Manipulation of data ma includes classifying, sorting or summarizing.

Diligence: -

computers do not get tired or bored. They perform their task very religiously. Human being on the other hand is affected by repetitive task. Even if computer has to perform 10 million calculations it will do even the last one with the same accuracy and speed as the first.

Automation: -

once a program is in the computer’s memory, the individual instructions are than transferred. One after another, the control unit for execution. The CPU follows these instructions unit it meets a last instruction to stop program execution, hence leading to automation.

Limitations of computer: -

a computer will produce wrong result if incorrect data is fed in to it. This is popularly known as garbage-in-garbage-out (GIGO). 

HESTORY OF COMPUTER GENERATION

The history of modern computers is divided into many steps according to the techniques used in them. Each step is called a generation. Till now five generations of computer have come into existence. Features of computers of these generations are described below.

First Generation Computers

The time of this computer generation is considered from 1946 to 1955. In these computers vacuum tubes were used. These computers were very big in size and generated show much heat that air conditioning was necessary requirement. These were also very slow in speed and capacity of storing data was very limited. These consumed a lot of electricity. Names of some of the main computers of this generation are: ENIAC, EDSAC, EDVAC, UNIVAC-1, UNIVAC-2, Mark-2, Mark-3, INM-701, etc.

MARK-1: - The first electronic computer, called MSRK-1, was developed by “Howard Aiken”. It was abort 15 meters long and the wires connecting the various parts of the machine were about 800 kilometers long. The main advantage of MARK-1 was that it was fully automatic. It was also more reliable than the early electronic computers. 

ENIAC: - ENIAC (Electronic Numerical Integrator And Computer) was the first fully electronic digital computer developed by J. Presper Eckert and John Mauchly. It contained approximately 17,500 Vacuum tubes, occupied 680 sq. ft. area, and weighed more than 27,000 Kg. Since ENIAC was initially not a stored program machine, it had to be reprogrammed by manual rewiring for each task.

EDVAC: - EDVAC (Electronic Discrete Variable Automatic Computer), like its predecessor the ENIAC, was developed by J. Presper Eckert and John Mauchly. EDVAC was a stored program Machine, unlike the ENIAC.

UNIVAC I: - UNIVAC I (UNIVersal Automatic Computer I), was the first commercially available electronic computer developed by J. Persper Eckert and John Mauchly. UNIVAC I was also the first computer to handle both numeric and text data.

Second Generation Computers

The time of computers of this generation is considered from 1955 to 1965. in these computers transistors were used in place of vacuum tubes. Computers of this generation were comparatively smaller in size and faster in speed and were also more reliable. These consumed less electricity and generated less heat, still air conditioning was required.

 Input-output devices in computers of this generation were very convenient and it was easy to store data and get results. The most famous computer of this generation was INM-1401 which was very popular.

Third Generation Computers

      The time of this generation of computers is considered from 1965 to 1975.In these computers integrated circuits or chip were used in place of transistors. Due to this, their storage capacity increased considerably. Computer made with these were smaller in size, very fast in speed and much more reliable. These consumed a little electricity and could do laces of additions in a second’s time. 

      With third generation of computers devices for storing data outside computer were also developed. This increased the utilization of computers. As the prices dropped, it was possible for small companies and government offices to install computers. On these computers many persons could word together at the same time. Main computers of this generation are: IBM-360 and IBM-370 series, ICL-1900 and ICL-2900 series. And Burroughs  5700, 6700 and 7700 series.   

Fourth Generation Computers

     The time of this generation of computers is considered from 1975 to 1995, although even today these computers are in wide use. These computers are based on micro a processor, which is a silicon chip, on which all integrated circuits of a Computer are placed. Computers using these chips are called Micro Computers.

      Micro computers are so much small in size that they can be placed on the corner of a table. These consume a little electricity and can work on normal temperature also. Price of these computers is so little that even small shopkeepers and students can purchase them. A special class of these computes is known as personal computers or PC. There is a big number of companies manufacturing micro computer. They have manufactured personal computers of various types, such as PC. These days a new series of personal computers has been developed which is compared with the largest computers in terms of their speed and capacity. These are called Pentium. In this series, Pentium-1, Pentium-2, Pentium-3, and Pentium-4 have been manufactured. At present, computers of Pentium-4 series are being manufactured and used in large numbers.

Fifth Generation Computer

After 1990, efforts are on to develop computers which will have power of logic, making decisions and thinking. These are called fifth generation computers. Although so far these efforts have not been successful to develop such computers but some computers have been made which are much more powerful than fourth generation computers. These are super computers. These can do the work equal to thousands of computers alone. Although number of super computers is very limited in the world. 

NAME OF MACHINE      YEAR OF INVENTION    NAME OF THE COUNTRY      NAME OF THE INVANTOR

Abacus                             5000 yrs ago                  China                                    Lee Kai Chen

Napier s bones                   1617                              Scotland                              John Napier

Pascaline                         1642                               France                              Blaise Pascal

Difference Engine          1822                                   England                        Charles Babbage

Analytical Engine              1834                              England                           Charles Babbage

What is a printer?

A printer is an output device that produces text and graphics on paper. 

Type of Printer

1. Dot Matrix:-

The term DOT matrix refers to the process of placing dots to form an image; the quality of the image being determined by the dots per inch. 

Dot matrix printers were first introduced by Centronics in 1970 and is a printer that uses print heads to shoot ink or strike an ink ribbon to place hundreds to thousands of little dots to form text or images. Today dot matrix printers are rarely used or found because of the low quality print outs when compared to ink jet printers or other later printer technologies 

2. Inkjet Printer:-

The most popular printer for home computer users that prints by spraying streams of quick-drying ink on paper. The ink is stored in disposable ink cartridges, often a separate cartridge is used for each of the major colors. These colors are usually Black, Red/Magenta, Green/Cyan, and Yellow (CYMK). In the picture to the right, is an example of a computer inkjet printer.

3. Ledger Printer:-

First developed at Xerox PARC by Gary Stark weather and released in 1971, a laser printer is a printer that utilizes laser technology to print images on the paper. Laser printers are often used in corporate, school, and other environments that require print jobs to be completed quickly and in large quantities. In the picture to the right, is an example of what a laser printer may look like. This picture is of the Lexmark C782n laser printer and as can be seen much larger than an ink jet printer found in most homes. Finally, below is a chart of the steps a laser printer takes to print. 

4. Thermal Printer:-

Traditional thermal printers use direct thermal method by pushing electrically heated pins against heat-sensitive paper (thermal paper).  The coating on the thermal paper turns black in the areas where it is heated, producing characters or images.  Direct thermal printers have no ink, toner or ribbon.  These printers are durable, easy to use and cost less to print than other printers.  However, the thermal paper is sensitive to heat, light, water, and abrasion and the text and images may fade over time.

Line Printers:-

Line Printer can Print One Line at a Time. The line printer is a form of high speed impact printer. They can Print 300 to 3000 Lines per Minute. So that they are very fast. Large Computer system typically use Line Printer. The Line Printers are of two Types.

Chain Printers:-

These are also Line Printers, which Prints one Line at a Time. All the Characters are printed on the Chain and the Set of Characters are placed on the Chain. There are 48 and 64 and 96 Characters set Printers are Available. There are also Some Hammers, those are Placed in Front of the Chain, and Paper is Placed between the Hammer and the Inked Ribbon. The Total Number of Hammers will be Equals to the Total Number of Print Positions.

Plotter Printer:-

The plotter is a computer printer for printing vector graphics. In the past, plotters were used in applications such as computer-aided design, though they have generally been replaced with wide-format conventional printers. It is now commonplace to refer to such wide-format printers as "plotters," even though they technically are not.