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NOTES FOR COMPUTER PACKAGES AND INTRODUCTION TO COMPUTER SCIENCE
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Course No. STCA-301 Credits: 2 (1+1) Course Title: Introduction to Computer Applications THEORY S. No. Topic/Lesson 1 Introduction to Computers, Definition, Advantages & Limitations 2 Anatomy of Computers – Components of Computers and its functions - Overview of Input devices of Computer 3 Overview of Output devices of Computer, Memory, Processors, Hardware, Software & Speed 4 Types of Software – Operating System, Translators & Programming languages 5 Types of Software – Application Programmes, Utility Programmes & General Purpose Programmes, Classification of Computers 6 Operating System – Functions of OS – Types of OS-DOS and WINDOWS, Booting process 7 Some fundamental DOS commands – FORMAT, DIR, COPY, PATH, LABEL, VOL, MD, CD, DEL and TREE 8 WINDOWS:GUI, Desktop and its elements, Anatomy of a window – Title Bar, Minimize, Maximize, Restore and Close Buttons, Scroll Bars, Menus and Tool - Starting and shutting down of windows 9 WINDOWS Explorer , working with organization of files and folders, Copy, Move and Print files – setting time and date 10 MSWORD: Word processing and units of document, features of word- processing packages 11 MSWORD: Creating, Editing, Formatting and Saving a document in MSWORD – Features of File, Edit and Format menus 12 MSEXCEL: Electronic Spreadsheets – concept, packages, creating, editing and saving a spreadsheet with MSEXCEL 13 MSEXCEL: Use of in-built Statistical and other functions and writing expressions, Creating Data Analysis option in Tools Menu, Use of Data Analysis Tools – Correlation and Regression, t-test for two samples, Creating Graphs 14 MSACCESS: Concept of Database, Units of database 15 MSACCESS: creating database 16 Internet - World Wide Web (WWW), Concepts
INTRODUCTION
Definition : A Computer is an electronic device that can perform activities that involve Mathematical, Logical and graphical manipulations. Generally, the term is used to describe a collection of devices that function together as a system. It performs the following three operations in sequence.
Vacuum tubes
Second Generation (1955-1965)
Transistors
Third Generation (1968-1975 )
Integrated Circuits ( IC )
Fourth Generation ( 1976-1980)
Very Large Scale Integrated Circuits ( VLSI) Fifth Generation (1980 – till today )
Ultra Scale Integrated Circuits ( ULSI) Micro Processor ( SILICON CHIP)
ANATOMY OF COMPUTERS The computer system consists of three units:
Block diagram of a Computer :
The various functions of these units can be summarized as:
Unit Function 1.Input device : Reads information from input media and enters to the computer in a coded form
2.CPU
(a) Memory unit : Stores program and data (b) Arithmetic Logic unit : Performs arithmetic and logical functions (c) Control Unit : Interprets program instructions and controls the input and output devices
Central Processing Unit : It is the part of the computer that carries out the instructions of a computer program. It is the unit that reads and executes program instructions. Hence it is known as the ―brain‖ of the computer. The CPU consists of storage or memory unit, Arithmetic Logic Unit (ALU) and control unit.
(a). Memory Unit: It is also known as the primary storage or main memory. It stores data, program instructions, internal results and final output temporarily before it is sent to an appropriate output device. It consists of thousands of cells called ―storage locations‖. These cells activate with ―off-on‖ or binary digits(0,1) mechanism. Thus a character either a letter or numerical digit is stored as a string of (0,1) Binary digits ( BITS). These bits are used to store instructions and data by their combinations.
(b) Arithmetic and Logical Unit(ALU): It is the unit where all Arithmetic operations (addition, subtraction etc.) and logical functions such as true or false, male or female are performed. Once data are fed into the main memory from input devices, they are held and transferred as needed to ALU where processing takes place. No process occurs in primary storage. Intermediate generated results in ALU
Memory unit
Control Unit
Input Devices Devices used to provide data and instructions to the computer are called Input devices. Some important input devices are Key board, Mouse, Scanner, MICR, Web camera, Microphone etc.
2.. Mouse: It is a device that controls the movement of the cursor on a monitor. A mouse will have 2 buttons on its top. The left button is the most frequently used button. There will be a wheel between the left and right buttons. This wheel enables us to smoothly scroll through screens of information. As we move the mouse, the pointer on the monitor moves in the same direction. Optical mouse is another advanced pointing device that uses a light emitting component instead of the mouse ball. Mouse cannot be used for entering the data. It is only useful to select the options on the screen.
Scanners are of two types: i) optical scanners ii) MICR i) Optical scanners: a. Optical character Recognition(OCR): In this, characters are read with the help of a light. This is used in office atomization, documentation in library etc. b. Optical mark recognition(OMR): It is a technology where an OMR device senses the presence or absence of a mark such as a pencil mark. OMR is used in tests such as aptitude tests. c. Optical barcode recognition(OBCR): Barcode readers are photoelectric scanners that read the bar codes or vertical zebra striped marks printed on product containers. This is used in super markets, book shops etc. ii. MICR: This is widely used in banks to process the cheques. This allows the computer to recognize characters printed using magnetic ink.
Output devices
Any device that is capable of representing information on a computer is called an Output device. Output devices receive information from the CPU and present it to the user in the desired form.
Some important Output devices are : Monitor, Printer
2. Printer : A printer is used to transfer data from a computer onto paper. The paper copy obtained from a printer is often referred as ―printout‖. The different printers and their speeds are as follows: S. No. Type Mode of Printing Speed 1 Dot – Matrix printer
Prints the character in dotted pattern through printer ribbon using either 24 pin or 9 pin
200/300 to 700 CPS
2 Ink Jet printer Work by spraying ionized ink Slow, 90 CPS 3 Laser printer Also called page printer. Uses laser beam to produce an image.
6 to 12 PPM
4 Line printer Prints lines at a time instead of single characters.
300 to 600 LPM
5 Plotter Produces drawings or graphs through pens which are filled with different colours. ( CPS: Characters Per Second; PPM: Pages Per Minutes; LPM : Lines Per Minute)
Laser printer
It is called Read-only memory as information can only be read from and not written or changed onto ROM. ROM is the ‗built-in‘ memory of a computer. It stores some basic input – output instructions put by the manufacturer to operate the computer. The storage of data and instructions in ROM is permanent. It does not depend on the power supply. i.e it is non-volatile memory.
Secondary memory: The primary memory which is faster (and hence expensive) is generally not sufficient for large storage of data. As a result, additional memory, called the ―auxiliary‖ or ―secondary memory‖ is used. It is also referred as ―backup storage‖ as it is used to store large volume of data on a permanent basis which can be transferred to the primary memory whenever required for processing. Data are stored in secondary storage in the same binary codes as in the main (primary memory) storage. Some of the devices of secondary storages are Floppy Disk, Hard Disk, CD-ROM, DVD and Flash drive.
1_._ Floppy Disk : It is also referred as ―Diskette: and is made of flexible Vinyl material. It has a small hole on one side called ―Right protect notch‖, Which protects accidental writing/deleting the information from the disk. There is a hole in the centre through which the spindle of drive unit rotates the disk. The disks are available in two sizes of 5.25 and 3.5 inches and these could be either low- density or high-density floppies. Storage capacity of floppies are measured in kilobytes (KB) and megabytes (MB). The details about the storage capacities of the floppies are presented below: Floppy Disk Storage Capacity Size (Diameter) Low Density 360 KB 5.25 inches High Density 1.2 MB 5.25 inches High Density 1.44 MB 3.5 inches Extended 2.8 MB 3.5 inches
translates or executes the first instruction before it goes to the second, while a compiler translates the whole program before execution.
The major difference between compiler and interpreter is
The high level languages are convenient for writing programs as they can be written without any codes. These languages follow rules like ―English‖ language. Because of their English like nature, less time is required to write a program.
They are machine independent. A program written in any HLL can be run on computers of different types without any modifications.
Several High Level Languages which are in common use:
FORTRAN : FORmula TRANslation
COBOL : Common Business Oriented Language
BASIC : Beginner‘s All purpose Symbolic Instruction Code
PROLOG: PROgramming in LOGic
ALGOL : ALGOrithmic Language
Example: COPY, SORT, MAILING, virus scanning software etc.,
Example: Payroll, Billing, Railway Reservation etc.
5. General Purpose Packages: These packages are developed to suit the needs of research workers / scientists in different fields. These packages are categorized as :
i) Data Analysis ii) Word Processing iii) Spread Sheet iv) Graphics and v) Databases
Data Analysis Ex: SPSS (Statistical Package for Social Science), MSTAT, MICROSTAT, GENSTAT, SAS etc. Word Processing Ex: WORD PERFECT, WORDSTAR, MS-Word, CHIRATOR, NORTON EDITOR etc.
Spread Sheet Ex: LOTUS, Qpro, VP-PLANNER, SYMPHONY, MS-Excel etc. Graphics Ex: LOTUS, STORY-BOARD, POWER-POINT etc. Databases Ex: dBASE, FOX-BASE, FOX-PRO, ORACLE, MS-Access etc.
Functions of Operating System : Today most operating systems perform the following important functions :
d) Micro Computers : A micro computer is the smallest general purpose processing system. Micro computers are also referred as ―personal computers‖(PC). These are self contained units and usually developed for use by one person at a time but can be linked to very large systems. They are cheap, easy to use even at homes and can be read for variety of applications from small to medium range. These are available in three models:
PERSONAL COMPUTERS Personal Computer: A personal computer has a Monitor (VDU), a keyboard , Disk Drive (s), printer and CPU. The CPU of PC has a mother board with several chips mounted on a circuit board. The major components of the circuit board are : Microprocessor, RAM and ROM chips and other supporting circuits.
Microprocessor: The Microprocessor chip is like a brain of human being which contains circuits and registers to perform arithmetic, logic and control functions. i.e it contains ALU & CU. These chips will be able to retrieve data from the input output devices, store, manipulate and process a byte of data at a time. There is an address bus which is built into these chips to determine the storage locations (of RAM) of the data and the instructions of the program.
Over the years, different microprocessors were developed and the first in the series is INTEL
Clock Speed : The speed with which the instruction is executed or number of pulses per second is called the clock speed. It is measured in terms of million pulses per second (MHZs).
The following table gives the differences among the different processors that intel has introduced over the years :
S.No. Microprocessor Date Transistors Clock speed Data width 1 8080 1974 6000 2MHZ 8 bits 2 8088 1979 29,000 5 MHZ 16 bits 8 - bit bus 3 80286 1982 134,000 6 MHZ 16 bits 4 80386 1985 275,000 16 MHZ 32 bits 5 80486 1989 1,200,000 25 MHZ 32 bits 6 Pentium I 1993 3,100,000 60 MHZ 32 bits 64 - bit bus 7 Pentium II 1997 7,500,000 233 MHZ 32 bits 64 - bit bus 8 Pentium III 1999 9,500,000 450 MHZ 32 bits 64 - bit bus 9 Pentium 4 2000 42,000,000 1.5 GHZ 32 bits 64 - bit bus 10 Pentium 4 ―Prescott‖
2004 125,000,000 3.6 GHZ 32 bits 64 - bit bus
Peripherals : The input, output and secondary storage units like floppy drives, keyboard, mouse, etc., are called peripherals. Classification of PCs : PCs are mainly classified on the basis of primary memory (RAM), Microprocessor, clock speed and peripherals. The classification is presented in the following table: S.No. PC-Type RAM Microprocessor Clock speed Peripherals 1 PC 640 KB 8088/8086 8 MHZ Floppy Drives, key board and printer 2 PC-XT 1 MB 8088/8086 18 MHZ Floppy Drives, Hard- Disk Drive, Key board and printer 3 PC-AT 1 MB to 32 MB
80286 to 80486 25 MHZ and above
Floppy drives, Hard disk, Keyboard, Mouse and Printer
MS-DOS
MS-DOS is a collection of programs and other files. It is a single user and single programming environment. MS-DOS is designed to provide a method of organizing and using the information stored on disks, application programs, system programs and the computer itself.
Files and File names : A file is a collection of related information. The files should have suitable names for their identification in later use. Rules for naming the files:
Executable Files: The files with extension of either .COM or .EXE are called executable files. These files are directly executed by typing their names (without the extension) by the computer. A file with .COM extension refers to COMMAND file name and the other with .EXE extension refers EXECUTABLE program file. Batch Files: the file containing a series of DOS commands, which are executed automatically one at a time in the order entered, is known as the batch file. A batch file has the extension .BAT. If the batch file is given a special name AUTOEXEC.BAT, it is automatically executed when the computer is switched on or during booting.
Backup Files: These are backup files of a file and have extension .BAK. These files are such that their contents can not be altered (edited). These files are created while working with WORDSTAR package for typing a document. System Files: These are program files developed for system control. They have .SYS extension. Directory: It is a collection of files, size, date and time of creation of files. The relation between files, directories and disk is similar to the relation between papers, filing folders and filling cabinets. Just as a cabinet contain papers and other folders, a directory may contain directories also. The main directory of a drive is called Root Directory into which several directories and sub-directories may exist.
Types of DOS commands : There are two types of commands: i) internal and ii) external i) Internal DOS commands: Internal commands are those commands which manage files. They are loaded into the memory of the PC when PC is booted. These are stored in a large file with file name COMMAND.COM, when a PC is booted.
Del stats deletes the file ―stats‖. Del stats.* deletes all extensions of the file ―stats‖. Suppose you want to delete a file COMPUTER.DOC on A drive, the command will be: C:> DEL A: COMPUTER.DOC
Ex: 1. COPY STATS MATHS copies a file ―STATS‖ with the name ―MATHS‖ on the same drive