1. COMPUTER                                                       

    Satish Kumar


History of Computer

          Today’s century is totally, dependent on science. Computer is one of the important will of science. Computer are the inalienable partners, their impact is being felt daily in our homes through TV, VCR, Satellite imaging, electronic mail etc. Computer, now a days, has become an important part of our day to day life. Knowledge about computer to an individual (user) irrespective of the field in which he/she works, has become essential.

          The history of computers starts out about 2000 years ago, at the birth of the abacus, a wooden rack holding two horizontal wires with beads strung on them. In 1615, John Napier a Scottish mathematician developed a primitive form of slide rule known as "Napier bones" and used it to calculate first table of logarithms. It was Blaise Pascal who invented the first digital machine in 1642. It added numbers entered with dials and was made to help his father, a tax collector. In 1671, Gottfried Wilhelm Von Leibniz invented a computer that was built in 1694. It could add and multiply. Thomas of Colmar created the first successful mechanical calculator that could add, subtract, multiply, and divide. In 1833, Charles Babbage constructed 'Analytical' Engine which could store information, make decisions, and carry out instructions based on its decisions.    

First Generation: First fully electronic computer ENIAC was constructed by John P. Eckert and John W. Mauchly in 1946 which could multiply at a rate of 300 per second. It was around 1000 times faster used 19000 vacuum tubes in about 15000 square feet of floor space, consuming about 180000 watts of electrical power.

Second Generation: Invention of transistors made a revolution in computers. First computer was build using transistors in place of vacuum tube in 1958 by IBM which could perform up to 10000 calculations per second.

Third Generation: Transistors replaced by integrated circuits (ICs). Single IC could replace hundreds of transistors and perform millions of calculations per second. First computer of this generation was IBM370 in 1964.

Fourth Generation/Microprocessor: Fourth generation computers saw the advent of the microprocessor. A microprocessor is an entire CPU on a single chip, and replaced many of the larger components of a computer. The microprocessor allowed the computer to find its way onto people's desktop. INTEL 1971 built first microprocessor.

Fifth generation: (Yet to come) A promise but not yet a reality. Genuine IQ  and parallel(Multiple task simultaneously).One step at a time. Knowledge Processing. Merely deductivebut also inductive. KIPS but not DIPS/LIPS.  OS- PROLOG (Programming in logic). Final machine which will Talk with human beings,  See and Delivered pictures.Hear the normal natural language.  

Operating Systems (DOS/WINDOWS):

A set of programs that controls and coordinates the use of computer hardware among various application programs is called as Operating System. It provides an environment within which user can execute programs. Operating system manages the resources of computer and provides the interface between human and computer. All computers must have an OS. The OS controls input and output; makes reasonable effort to control peripherals; and in short acts as the interface between you the user, the software, and the hardware.

UNIX and VAX/VMS developed for powerful machines like workstations, mini and main frame computers are powerful but not suitable for small machine like PC. For PC, 8-bit OS were developed like DOS, CP/M and Apple DOS. Windows, an extension of DOS is a powerful operating systems on PC's is user-friendly and provide graphics user interface. A computer comprises of hardware, operating system, applications programs & users. It is the operating system that manages all the above components. 


1.  Controlling Input/Output devices (Keyboard, Mouse, Monitor, Printer, Plotter)

2.   Memory and File storage management

3.   CPU Scheduling and controlling processes

4.   Loading, initiating, executing and supervising user applications programs

5.   Handling errors and restarting

6.   Providing command interface between user and computer system 

Introduction to DOS / WINDOWS: 

Though UNIX was a powerful operating system available, but it was not suitable for 8-bit 8086 microprocessor based Personal Computers. So there was a need for a small operating system that could work in 640K memory (RAM). 


DOS was a variant of CP/M (Control Program/Monitor) which ran for the first time on IBM-PC in 1981. The different versions of MS-DOS have evolved over a period of time with Microsoft introducing new features in each new releases. There are various versions of DOS like MS-DOS (Microsoft), PC-DOS (IBM), Apple DOS, and Dr-DOS etc. 

Basic DOS Commands: 

Directory Commands:

DIR : To list all or specific files of any directory on a specified disk.

MD : To make directory or subdirectory on a specified disk/drive.

CD or CHDIR : Change DOS current working directory to specified directory on specified disk or to check for the current directory on the specified or default drive.

RMDIR or RD : Removes a specified sub-directory only when it is empty. This command cannot remove root directory (C:\) or current working directory.

TREE : Displays all of the directory paths found on the specified drive.

PATH : Sets a sequential search path for the executables files, if the same are not available in the current directory.

SUBST : Substitutes a string alias for the pathname and creates a virtual drive. 

File Management Commands :

COPY : Copies one or more files from source disk/drive to the specified disk/drive.

XCOPY : Copies files and directories, including lower-level directories if they exists.

DEL : Removes specified files from specified disk/drive.

REN : Changes the name of a file(Renaming).

ATTRIB : Sets or shows file attributes (read, write, hidden, Archive).

BACKUP : Stores or back up one or more files/directories from source disk/drive to other destination disk/drive.

RESTORE : Restores files that were backed up using BACKUP command.

EDIT : Provides a full screen editor to create or edit a text file.

FORMAT : Formats a disk/drive for data storage and use. 

General Commands :

TIME : sets or displays the system time.

DATE: Sets or displays system date.

TYPE: Displays the contents of at the specified file.

PROMPT: Customizes the DOS command prompt.

If a users requires help on any DOS commands he/she may type help and command name at the command prompt. 


Windows was similar to APPLE Mach operating system interface on IBM-PC. The main features of windows are easy to use graphical user interface (GUI), device independent graphics and multitasking support. The first version of windows 1.0 was introduced in 1985. Windows was an application of MS-DOS using the basic commands of DOS. WINDOWS-95 released in 1995 is a 32-bit operating system which includes MS-DOS7.0 and takes control of computer system after starting. WINDOWS-98, 2000 released in 1998, 2000 respt. 


1.   Windows is easier to learn and use than any of its predecessors.

2.     Windows and its applications run under the PCs protected mode, which mean that one ill behaved program cannot compromise the memory and resources of another. This approach adds a large measure of reliability to the total operating environment. The crash of a single errant program does not automatically crash the operating system or any of other programs that you are running.

3.     Windows is a pre-emptive multitasking means you can comfortably type into word processors while your database system backs up all its files. Under Windows 3.1 the typed key displays lagged behind while the backup procedure logged the processor.

4.     Windows integrates virtually all of your computing tasks and resources like networks, E-mail, multimedia, system administration, printing, faxing, applications into one common user interface. 

Desktop: The most visible change in Windows 98 over earlier versions of Windows is the new user interface. The full screen display you see when you boot your PC and from which you work with documents and applications.

Icon : An icon is a picture . Windows 98 uses small video icons that represents objects – documents, applications, folders, devices, and computers. An icon has a text label that further describes the object.

Selection : Selecting an object is pointing to it without taking any further action. To select the object, move the mouse cursor onto the icon and press the left mouse button once. If the currently selected object is in a group, you can change the selected object with arrow Keys. You can change groups with Tab and Shift- Tab keys and then use arrow keys to select an object in the selected group.

Drag and Drop : To drag and drop an object onto another object, move the mouse cursor onto the icon of the object to be dragged. Press down the left mouse button and hold it down while you move mouse cursor to be destination object’s icon.

Release the button from that position to complete the drop.

The Right Mouse Button : If you move the mouse to almost anywhere or anything on the desktop or in a Window and click the right mouse button, Windows 98 displays a menu with common commands for the object. To close the menu, click the left mouse button anywhere else on the desktop or press the keyboard’s Esc key.

Icons on the Desktop : The upper left corner contain four icons. Those icons provides access to your files and documents. Four icons are: My computer, Network Neighborhood, Recycle bin and Briefcase.

My Computer : The "My Computer" icon on the desktops opens a view into the resources of the local computer . The contents of the My computer Window depend on the disk drives on your PC and the network support that is installed.

Network Neighborhood: This icon displays the computers and shared printers connected on the windows network.

Recycle Bin: This icon receives all deleted objects like files, folders, documents, applications etc. These deleted objects can be restored back they can be permanently deleted from the disk by choosing EMPTY RECYCLE BIN selection on the file menu.

Briefcase: The commonly used personal documents can be put or stored in the briefcase. This briefcase can be moved to a disk or copied across a network.


Folders on the desktop can contain other folders, documents, applications and shortcuts to devices such as printer. To add a folder to the desktop, move the mouse cursor to an empty spot on the desktop and press the right mouse button. Click the Folder command. A folder icon labelled "New Folder" appears on the desktop.


The references to the current documents are stored in the documents object. The documents list includes Word processing documents, spreadsheets, database files, graphics file etc. 

Computer Organization:

Digital computers are electronic machines capable of performing high speed arithmetic/logical operations and data processing. It has two major parts i) computer hardware and ii) computer software. Computer hardware consists physical entities like electronics circuit, transistors, capacitors etc. Computer software is basically set of instruction code which instructs the computer to perform a task requested by user. Computer software consists of programs which monitor and coordinates all internal operations and provides easy interface between computer and user. 


Computer hardware, a physical entities like electronic circuit, transistors, capacitors has four major parts i) Central processing unit (CPU); ii) Input unit; iii) Output unit and iv) Memory. The CPU in computer is similar to brain in human. It performs all the calculations, it execute all the instruction received from user. It also control activity of computer. Input devices provides the means to input to computer. Following computer devices are commonly used by users i) Keyboard: consists array of key switches; ii) Mouse: it is a pointing device usually contain two or three button; iii) Joysticks: used to play games etc. Output devices are the means by which computer present its result in human readable form. Following computer output devices are commonly used by users i) Monitor/screen : displays data as text or in graphics ii) Printers: allow to print the data; iii) Plotters: used to plot the graphs. Storage devices are used to store and retrieve data in computers. Broadly, it can be classified in two categories i) primary storage and ii) secondary storage. Primary storage are semiconductor memories used access data quickly and randomly (e.g. RAM, ROM). Secondary storage also called Magnetic storage devices. These storage devices are cheaper and reliable (e.g. Floppy disk, Hard disk, Optical disk) 

Characteristics of Computers:

1.      Calculates at very high speed

2.      Takes in Information & Stores for further retrieval

3.      Takes in & Stores the program (set of instructions written in the

       language of computers)

4.      Obeys a sequence of instructions/programs

5.      Uses simple logical rules to make decisions for their own internal control

       or for the role of some external activity

6.      Communicates with other systems

7.      Exploits a complex internal structure of micro electronic circuits in a variety

       of ways

8.      Privacy

9.      Security

10.   Individuality 

Applications of Computers:

1.    Main mode of procuring offline and online information available from databases

2.   Disease-Diagnosis, Drugs, Vaccines, Pathogenesis, Treatment, Rehabilitation updates

3.   Patient care information

4.   Medical Directories

5.   Machines are computer based

6.   Thesis, Research articles

7.   Scientific Research

8.   Communications

9.   Desktop Applications

10. Business Applications

11. Word Processing

12. Banking

13. Industrial Applications

14. Space Technology

15. Transportation

16. Browsing relevant websites for updates 


1.     Not seen (in computer word) by naked eyes i.e. not present physically but co-ordinates hardware. 

2.     Logic/intelligence which run  your computer

3.      Set of the instruction (program) which carries out the job/work provided by the user.  

System Software (Mostly operating systems)

1.      Machinery with no intelligence but tremendous capacity  for hard work.

2.      Shell-OS—interpreter-interprets human (English) & computer (Binary) language

3.      Os commands are necessary to learn

4.      OS understand the command and converts the computer language, perform work intended and come out with the result

5.      OS converts these results (computer language) back into ‘Human Readable Format’ and display on monitor

6.      Pry Jobs- Machine Maintenance/Machine/Administration/Allocation of Resources

7.      Single user Single Task  ----DOS

8.      Single user Multiple task- Window

9.      Multiple user Multiple task-UNIX

10. Networking-NetWare/Windows/UNIX/LINUX

Application software:

1.      Does jobs like text processing, calculation, drawing a picture, accounting etc.

2.      Graphics: Allows to draw/view/edit pictures

3.      Multimedia: Allows to hear/see/watch presentation

4.      Text processing: Standard text processing jobs like spell check, tabulation  etc.

5.      Database: Allows to store/Retrieve/Analyze/Present Information of particular task

6.      Accounting: Maintains accounting information.

7.      Games: Allows to play interactive Videogame may contains text, visual and audio Browser

8.      Development Tools: Allows developing software.