STUDY
MATERIAL
FUNDAMENTALS
AND
OPERATING
SYSTEM
PUBLISHED
BY ADVANCED COMPUTER TECHNOLOGIES, THIRUVANANTHAPURAM
COMPUTER
Computer
is an electronic device which is capable to accept, store, manipulate data and
result through step by step instruction. The word Computer comes from the Greek
word ‘Computare’ which means to ‘Calculate’.
COMPUTER PIONEERS
The History of computing begins from
3000 years ago. The different machines used before the present day’s computers
were developed.
Abacus (Chinese People)
It has a rectangular wooden frame it consists of a row of
wires fixed on a wooden frame. The wires have multicolored beads strung on
them. Addition or subtraction on the Abacus was done by changing of the beads
along the wire.
Thousands of years ago, the Abacus a
single device for calculations was used in China ,
Japan and Russia .
Napier’s Bones
In the 17 the century a
Mathematician called John Napier invented a device for doing multiplication. It
was called Napier’s bones. Napier’s bones was a set of rods. Each rod had four
faces. The numbers (0-9) were marked on them that you could find out the
product of any numbers by placing the rods side by side.
Blaise Pascal (Pascaline)
In 1642 a French genius called
Blaise Pascal invented the first mechanical calculating machine for addition
and subtraction. It was called Pascaline.
Pascaline consists of set of
interlocking cogs and wheels on various axels. It was just like the modern
milometer used for measuring the distance covered by a vehicle.
GENERAL CHARACTERISTICS OF COMPUTERS
1.
Speed:-
As
the computer is electronic, its internal speed is virtually instantaneous. Thus
computer access data and process them at a very fast rate in terms of several
million operations per second.
2. Reliability:-
Today’s computers are extremely reliable
and results are always same as Per
design. There are two sources of errors.
a.
Human error in programmer design and logic.
b.
Machine error.
3. Automatic Operation:-
Computers are automatic in
operation. Once data and programme are fed to a computer, operation of computer
is automatic in the sequence of steps defined by the programmer.
4.Storage:-
Computers have got in built and auxiliary
memory. It can store a great amount of information at a time. Any item of data
or instructions stored in the memory can be retrieved by the computer at very
high speed.
5. Integrity:-
It is the ability of computer to obey a
sequence of instructions called
programme written in the language of computer.
6. Endurance:-
Computer can perform the same task number
of times repeatedly. It never Finds any
sort of weakness even after serving any period of time.
7. Versatility:-
It is the ability of computer to be linked
suitably with other systems and adopt several modes like audio visual graphic,
users friendly, etc.
APPLICATIONS OF COMPUTERS
1.
Scientific and engineering
Eg: Navigation, surveying, earthquake
calculations.
2.
Business, administration and others
Eg: Financial accounting, billing,
hospital management, account payable
3.
Humanities area
Eg:
Music analysis and composition, computer art
Limitations of Computer
1.
Reflects human error.
2.
Not having intelligence.
3. High initial costs.
COMPUTER
GENERATION
First Generation (1945-1960)
In the first generation
vacuum tubes were used as active devices. The ENIAC (Electronic Numeric
Integrator and Calculator), EDSAC (Electronic Delay Storage Automatic
Calculator) and UNIVAC-I (Universal Automatic Computer) are examples for first
generation computers. The first generation computers were very large in size
and required high power. It was very slow and the programming capability was
limited. The tubes used in the computer had short life. In this generation the
computer programming was done in machine language.
Second Generation
(1960-1965)
In
this generation tubes were replaced by transistors. Here the computers Become
faster and smaller and were more reliable than first generation. During this
period magnetic cores were invented for storing. High-level programming
languages like FORTRAN, COBOL, etc were developed during this generation.
Third Generation
(1965-1970)
The
third generation was made by the use of integrated circuits. Integrated
circuits consisting of transistors, resistors and capacitors molded on a single
chip of silicon wired interconnection between components. The usage of IC is
made the system faster and smaller.
Fourth Generation (1970 onwards)
The fourth generation computers use microprocessor chip.
Here large Scale integration is used to integrate the complete circuit of the
computer in a single silicon chip. Magnetic core memories were replaced by
semiconductor memory. During this period networks of computer systems were
developed. Its speed refers in large-scale integration.Fifth Generation
It
is based on ultra scale integration (ULSI) it involves the principles of
artificial intelligence (AI) and Robotics. The Japanese call their fifth
generation computers as knowledge information processing system (KIPS).
COMPONENTS OF A COMPUTER /BASIC STRUCTURE OF A DIGITAL COMPUTER
A
computer consists three major units namely
1.
Central processing unit.
2.
Input unit
3.
Output unit
In the figure each
functional unit is represented by a rectangular box.
CENTRAL PROCESSING UNIT
The combination of the memory
unit, the Arithmetic and logic unit and control unit is known as central
processing unit.
CPU
is the heart of the computer. The solid line with arrow mark represents
the two way connections between the respective units with regards to the flow
of data. The broken line with arrow mark shows the communication between
control unit and respective unit. Actual computation work is carried out in
CPU. Internally it consists of three sub-units Memory unit, Control unit and Arithmetic
and logic unit.
Memory Unit: -
This is the part of CPU. Memory
unit is the section were all Data, programme and results are stored. The memory
unit consists of many cells – each capable of storing a unit of instruction.
These cells are electro magnetic in nature and also called storage locations.
To distinguish cells they are numbered sequentially. These numbers are often
referred to as address.
Control Unit: -
Control unit co-ordinates all
activities of various Components of the computer. It sends out command and
control signals and determines the sequence of the various instructions. A
special programme called supervisor is responsible for controlling the
operation of the system. It activates Arithmetic unit to perform the required
calculations and then to send back the processed t result to the memory. It
also direct the input and output devices in receiving data and instructions
into memory and in sending the result to the output devices.
ALU: -
ALU consists of electronic
circuits. This unit of Computer has the ability to carryout arithmetic
operations such as addition, subtraction, multiplication, division and some of
the logical operations. Whenever the computer performs arithmetic operations
the CPU activates ALU special accumulators for performing the arithmetic
operations. After arithmetic processing over the results are transmitted to the
memory unit for storage
INPUT UNIT
It is the unit meant to receive the
data and instructions contained in the programme. In other words it is the unit
through which the programmer communicates with the computer. Input devices take
up the data is in human readable form from the user, convert it to the binary
equivalent and place it in memory.
Eg: - Keyboard, Mouse, etc.
OUT PUT UNIT
It is the unit to receive the
results of computations from the memory unit of CPU in the form of binary
signals into human readable form some of the output devices produce only a
temporary copy of results (like the monitor), while some others produce a
permanent copy (like the printers).
Eg. Printer, Plotter,
Speaker
MEMORY
Basically there
are two types of memories.
(1)
Primary storage (Main memory)
(2)
Secondary storage (Auxiliary memory)
PRIMARY
STORAGE: -
It
is also called computer’s main memory. Like human memory it is able to store information, which can be recalled
or accessed, when required. Primary storage is with in the boundary of CPU
circuitry. All information and data which are to be processed by the computer
are kept ready in this memory. The results obtained after processing in the
arithmetic unit are also stored in the main memory. The primary storage is
volatile because all storage relating to a programme is lost once the power is
off. Commonly used memories are semiconductor memory and magnetic memory.
SECONDARY STORAGE: -
The
storage unit which is permanent in nature and usually placed outside The CPU is known as Secondary storage or
auxiliary memory. The programme and data Which require any further use is
stored in a secondary storage. Recording, erasing and re-recording for a number
of time are possible in an auxiliary storage unit. As compared to primary
memory it has much larger capacity but is not as fast as that of the primary
memory.
PRIMARY STORAGE DEVICES
The
primary memory is classified as Random Access Memory (RAM) and Read Only Memory
(ROM).
ROM: -
This
is type of memory on to which we cannot write anything. They can only be read.
This is achieved by storing the information in to the ROM at the manufacturing
stage. The data stored inside ROM is permanent. This remains here even when
power is switched off. It is non-volatile memory.
Following are
the types of ROMs
PROM (Programmable Read Only Memory)
EPROM (Erasable Programmable Read Only Memory)
EEPROM (Electrically Erasable Programmable Read Only Memory)
EAROM (Electrically Alterable Read Only Memory)
RAM: -
RAM
is commonly known as read / write memory. The important feature of this memory
is that is volatile. This memory is rightly called Random Access Memory because
the data from this memory is taken in Random. RAM is classified in to two DRAM
(Dynamic RAM), SRAM (Static RAM).
SECONDARY STORAGE DEVICES
The following are few secondary
storage devices – floppy disk, hard disk, magnetic tap, CDROM.
FLOPPY DISK: -
A
floppy disk is a flexible plastic disk, coated with magnetic material and
Enclosed with in a plastic envelop. A floppy is divided in to concentric
circles called tracks, which in term are further subdivided in to sectors. Data
is stored on a floppy disk by encoding bits of data along tracks of disk. An
index hole is used to identify sector.
Advantages of floppy disk: -
1.
It is relatively cheap
and can be reused many times.
It is relatively cheap
and can be reused many times.
2.
It is easy to carry.
Disadvantage: -
1.
Floppy disks are to be handled carefully.
2. They are easily damaged by heat,
dust, etc.
HARD DISK: -
Hard disks are made of
smooth metal plates coated with thin film of Magnetic material on both sides. A
set of such magnetic plates are fixed to a spindle one below the other to make
up a disk pack. The disk pack is mounted on a disk drive at equal intervals.
Data are stored on all surface of disk except the upper surface of the top disk
and lower surface of the bottom disk. The disk pack is permanently sealed
inside a metal casing to protect from dust and others.
Advantages:
-
1.
It can hold much larger volume of information than
floppies.
2.
Fast in reading and writing.
Disadvantages:
-
1.
Costly and bulky.
CDROM: -
Compact
Disk Read Only Memory is another widely used storage device. It has Storing
large volume of data retrieval capabilities. These operate on the basic
principles of storing data by altering some optical properties of the media
corresponding to digitized information. It has no physical contact required
with writing surface. It is made through laser beam. A typical 12 cm diameter
CDROM has a capacity of about 650 millions characters. It can be used to store
graphics, digitized video and sound files. The data capacity of CDROM is either
540 MB or 680 MB.
DVD
ROMS
DVD (also known as "Digital Versatile Disc" and "Digital Video Disc") is a popular optical
disc storage media format used for data
storage. Its main uses are for movies, software, and data archiving. Most DVDs are of the same
dimensions as compact discs (CDs) but store more than 6 times the data.The term DVD is used in
describing three ways that data is stored on the disks — DVD-ROM has data
which can only be read and not written, DVD-R can be written
once and then functions as a DVD-ROM, and DVD-RAM holds
data that can be re-written multiple times
FLASH
DRIVES
Flash memory is non-volatile computer
memory that can be electrically erased and reprogrammed. It is a technology
that is primarily used in memory cards, USB
flash drives (thumb drives, handy drive, memory stick, flash stick, jump
drive), which are used for general storage and transfer of data between
computers and other digital products. It is a specific type of EEPROM that is
erased and programmed in large blocks.It is very easy to use.
INPUT DEVICES
KEYBOARD
Keyboard is an input device. It is used to enter data or
give instruction to the computer. The keyboard is a flat rectangular board with
many keys on it. There are keys for all the letters of the alphabets, numbers,
mathematical symbols, punctuations marks and set of function keys. The keyboard
is connected to the CPU box with a cable.MOUSE
Mouse is an input device. It is a palm sized device with
two or three buttons. The mouse is kept and moved over a mouse pad. The mouse
points to a location on the screen. It is used to quickly move the mouse
pointer anywhere on the screen to select an icon, or a command or a tool on a
menu. The mouse is connected to the CPU box with a cable. SCANNER
Scanner is possible to store both and images like
pictures. It is used to store images like photographs. It converts text and
line art in to digital format. The image of the object is captured with color
depth using the scanner.CARD READER
This is the input device used to
read data from the punched card. The punched holes are sensed by the card
reader and then converted in to binary digits 0 and 1.
BARCODE READER
Certain data like the product codes
of things and books, etc can be recorded on small strips. Optical reading is
done by using printed ‘bar-codes’. That is alternating lines and spaces which
represent data in binary form.
LIGHT PEN
It is a pointing device to draw
sketches and diagrams directly on the screen.
MICR
In MICR (Magnetic Ink Character Recognition) specially
designed characters are used which are printed in ink containing magnetic
particles. These characters can then only be ready by MICR reader. This is
mainly used in banks to avoid forgery. OCR
By using this device we can optically scan documents and
be able to recognize character shapes. It has the ability to identify the
recorded symbol as a familiar form. OCR (Optical Character Reader) devices are
expensive. MICROPHONE
This is an input device to input
sound which is then stored in digital form. This is used for various
applications like adding sound to a multimedia presentation or for mixing
music.
CAMERA
Cameras are
input devices which capture and store images for use in multimedia
presentations. There are two types of cameras used for input. One is still
camera used for inputting still pictures and other is video camera which can be
used to input moving pictures.
OUTPUT DEVICES
PRINTER
Printer is an output
device. Any information, data or result can be printed on paper with the help
of a printer. The printer can print both text and picture. The printout of the
text or picture is called its hard copy.
The copy stored in the computer is called soft copy. The printer connected to
the CPU box with a cable.
There
are two types of printers. They are Impact printer and Non-impact printer.
IMPACT PRINTER: -
These printers
have type head striking on ribbon. They are known as impact printers.
Eg:
- Dot matrix, Line printer
Dot matrix Printer: -
A Dot matrix printer has a small set
of needles (pins) to print words or pictures. The printing pins are arranged
one below the other in a single column. Each pin can be independently activated
electronically. When a pin is activated it prints a small dot on the paper. So
the words or pictures are printed in the form of dot.
Advantages:
-
1.
Simple mechanism.
2.
Can be produced different fonts.
3.
Cost is not high.
4.
Graphic capacity.
Disadvantages:
-
1.
Noisy.
2.
Print only one character at a time.
3.
Poor print quality
Line Printer: -
Line Printer is an impact printer.
It prints a complete line of information at a time. The most common type of
line printer is chain printer. These type of printers are used When a large volume of information are not to
be printed. Line printers can print multiple copies at very high speed. They
are used only for text and not for graphics.
Advantages:
-
1.
Prints a complete line of information at a time.
2.
The speed is high.
3.
The printer matter looks like a typed matter.
Disadvantages: -
1.
Costly.
2.
Noisy.
The
quality of printing is poor in terms of style.
NON-IMPACT PRINTER: -
Printers do not
have a type head striking on the ribbon. They are known as Non-impact printer.
Eg:
- Laser printer, Inkjets printer.
Inkjet Printer: -
The head of an inkjet printer has
many tiny holes on it. Ink is forced out of these holes to form words or
pictures on the paper. Inkjet printers can print in both black and white
colors. They work at speeds around one or two pages per minute.
Laser Printer: -
The laser printer is a non-impact
printer. It is a high speed page printer with high quality. This printer prints
words or picture with the help of a laser beam. It is the best printer
available today for good quality printing. Xerox machine principle is used in
this printer. Laser printer can print over thousand lines per minute.
Advantages:
-
1.
Very excellent letter quality.
2.
Very high speed.
3.
Different fonts of character.
4.
No mechanical movement and hence noiseless.
Disadvantages:
-
1.
High initial costs.
MONITOR
The monitor is an output device. It looks like a TV
screen. It is also known as Visual Display Unit (VDU). Any data type using the
keyboard can be seen on the monitor. The results are also displayed on the
monitor. VDU consists of Cathode Ray Tube (CRT).
LCD
(Liquid crystal Display) Monitor is also available. Low power consumption is
the advantage of LCD Monitor.
SPEAKER
This is an output device that gives
output in the form of sound. This is used in multimedia presentation – that is
presentation using sound, pictures and text.
HARDWARE
The physical equipment and
components which one can see, touch and feel in the computer system is called
hardware. It includes the whole mechanical, electrical or electronic, magnetic
and optical device.
Eg: - CPU, Input
Output devices, Memory devices, etc.
SOFTWARE
Software is the general form that
describes all the written procedure and rules that controls computer
operations.
Eg: - Operating
system, User developed programmes, etc.
Computer software may be
classified as (1) Application software, (2) Utilities,
And (3) System
software
1.
Application software: -
Application
software is the collection of programmes such as Inventory control, payroll,
and railway reservation. It also includes general purpose application
programmes such as word processing, electronic spreadsheet, graphics, etc.
2.
Utilities: -
Utilities
are general purpose programmes or tools, available for standard applications such as sorting, merging,
formatting disks for use, etc.
3.
System software: -
It
helps the computer manage itself and carryout our work. It controls the Machine
resources such as input and output devices, schedules the work with in the
machine and enables the hardware to understand our commands that are given in
English like language.
Eg: - Compilers,
Interpreters
BITS AND BYTES
A single binary digit is
called a bit. A set of eight such bit is called a byte.
4
bits = 1 nibble
1 byte = 8 bits
1 kilobyte = 1024 bytes
1 Megabyte = 1024 Kilobyte
1 Gigabyte = 1024 Megabyte
TYPES
OF COMPUTER/ CLASSIFICATION OF COMPUTER BASED ON OPERATIONS
Based on
operating and constructing principles computers can be classifies in to
following types.
1.
Analog computer
2.
Digital computer
3.
Hybrid computer
1.
ANALOG
COMPUTER: -
Analog
is a Greek word which means establishing similarities between two quantities. This type of computer
operates by measuring rather than by counting. In Analog computers similarities
are establish in the form of current or voltage signals. Analog computers can
not make decision and are not very accurate.
2.
DIGITAL
COMPUTER: -
Digital
computers are also known as data processor. These computers Work on the principles of counting. They
operate on discrete numbers represented by a digit. Its accuracy is high.
Digital computer can be used for both data processing and scientific
applications.
3.
HYBRID
COMPUTER: -
Hybrid
computers are a combination of digital and analog computers. A Hybrid computer contains some special devices
by the use of the analog values of data could be converted in to digital and
vice versa. So that the desired output
can be accomplished.
CLASSIFICATION OF DIGITAL COMPUTER BASED ON THE SIZE AND CAPACITY
Based
on the size and capacity computers can be grouped in to four major groups.
1.
Micro computer,
2.
Mini Computer,
3.
Mainframe Computer
4.
Super computer.
MICRO COMPUTER: -
These
are the smallest general purpose computer systems. This system Have all the
functional elements that are found in most of the larger system. They are
basically designed for the single user system facility. Cost wise these systems
are cheapest among all the systems.
Eg:
- Apple, BBC Micro, APX 432, ……
MINI COMPUTERS: -
A
Mini computer is a medium sized computer. The computing power of Mini computer is larger than Micro computer.
They are constructed on the single rack to accommodate its CPU and auxiliary
(secondary) storage unit. It is designed for multiple user system facility.
Eg: - VAX, Hall Mark II,
SN 32, ……..
MAINFRAME COMPUTER:-
Mainframe
computers offers faster processing speeds and greater storage capacity than any
computers other than Super computers. The CPU of Mainframe computer is capable
of doing many jobs at a time. This type of computer provides larger storage
capacity and faster CPU access..
Eg:
- IBM 4381, CYBER 170
SUPER COMPUTER: -
Super computers have a
very large memory capacity and high Speed of processing. The processing speed
is almost comparable to the speed of light. These are most costly and powerful
computers. Super computers are mainly used for applications like weather
forecasting and research, etc.
Eg:
- PARAM 8600
COMPUTER LANGUAGES
A
language is system of communication. A computer language is set of codes used
to write programmes. Computer languages can be classified as low level
languages and high level languages.
Low level Language: -
Low
level languages can be classified as machine language and assembly language.
Machine Language: -
When the computers were
invented, the programmes had to be written as strings of zeros and ones. All
instructions and data should be written using these codes are called binary
codes. These binary codes are also called machine languages. This is machine
depended. It is difficult to correct or modify machine language programme.
Assembly Language: -
Assembly
language is a symbolic language used to develop programmes.
Operation codes
used in machine languages are replaced by mnemonics which are easier to
remember. It is machine depended.
Eg: - ADD a, b (add for addition)
SUB a, b (sub for subtraction)
High level languages: -
High level languages are the
languages in which we write English like instructions to guide the computer.
The instructions are not directly executed by the computer. The programmes
written in High level language are transmitted in to machine language of the
computer by compilers of interpreters. Followings are some commonly used High
level languages.
BASIC
(Beginners All Purpose Symbolic
Instruction Code)
COBOL
(Common Business Oriented
Language)
FORTRAN (Formula Translator)
C
Language, ORACLE
SOURCE AND OBJECT PROGRAMME
A
programme written in High level language is known as source programme. The
equivalent programme in the machine language is called object programme.
MODEM (Modulation Demodulation)
Modem
is converts digital signals from the computer to analog signals and analog
signals to digital. It is used to connect the computer to a telephone line. It
transmits and receives data between computers.
NETWORK
A
network is a group of inter connected computers that share information and
resources. The networks are connected through telephone lines, underground
coaxial cables, etc. The commonly used networks are LAN, WAN, MAN.
LAN (Local Area Network): -
The
most common form of network is the Local Area Network. LAN is a group of
computer interconnected with in a building or campus setting. Usually 10 to 100
interconnected systems come under LAN.
WAN (Wide Area Network): -
When
a computer must share information over long distances, the Wide Area Network is
used. WANs are typically much slower than LANs. This type of communication
network may be developed to around the world.
MAN (Metropolitan Area Network): -
The MAN is a network that
covers an entire city using LAN technology. Cable Television Networks are examples
for analog MAN s for Television distribution.
HUB
HUB is a device used to
connect two or more network devices.
BRIDGE
ABRIDGE
is a device that can join two LAN s. A BRIDGE can also divide an over loaded
network in to separate networks.
OPERATING
SYSTEM
An operating system
is a
computer program that manages the hardware and software resources of a
computer. It act as an interface between system and user.
Operating
system performs basic tasks such as
v Controlling and
Allocating memory
v Prioritizing system
requests
v Controlling input and
output devices
v facilitate networking
v Managing files
Provide a graphical user interface for higher level functions.
Eg.
:DOS, Windows, MAC, Unix, GNU, Linux
BOOTING
The process of
loading the Operating System programs from the secondary memory into the main
memory is called booting.
DISK
OPERATING SYSTEM
The DOS was the first operating system developed for the
IBM-PC by Microsoft Corporation. This was called DOS because, in the beginning
when DOS was introduced, all the program files requires to start this operating
system were stored on a floppy diskette. It is a single user operating system.
It is also a character-based operating system.
DOS is collection of three system files
1.
IO.SYS- Handles
input/output management
2.
MS-DOS.SYS-Performs disk organization
3.
COMMAND.COM-Interprets the commands given by the user
IO.SYS and MS-DOS.
SYS are known as hidden files
DOS
PROPMPT
After DOS is
successfully loaded into memory, either C:> or D:> is displayed on the
screen which is known as DOS Prompt. DOS Commands are typed against these
prompts to execute them.
DOS COMMANDS
The
DOS Commands can be classified into Internal Commands and External Commands
Internal commands are those
commands, which are loaded into the computer memory at the time of booting. So
they are also known as ‘Memory resident Commands’.
Eg:- DATE, TIME, DIR, TYPE,…
External
commands, which require certain special files for being executed, and are not
loaded at the time of booting. They are known as ‘Disk Resident Commands’
Eg:- FORMAT,
TREE, DISKCOPY, DISKCOMP.,……………
FILES AND DIRECTORIES
A
file is a collection of related information that is treated by the system as a
unit. Directories are the place for
placing these files.
FILE NAMES
A
file name is used for identification. A file name has two parts Primary name
and Extension name. The general format of a filename is ‘Primary name.Extension
name’
The
maximunm number of characters allowed for primary name is 8 characters and for
extension name is 3 characters. The extension name is optional. The primary
name and extension name must be seperated by a dot.. there is no space before
or after the dot. File name may contain any alphanumeric characters and some
special characters.
INTERNAL COMMANDS
CLS
This
command is used to clear the screen
DATE
This
command diplay the current date and allows the user to change if it is to be
changed.
TIME
This
command diplay the current time and allows the user to change if it is to be
changed.
VER
It diplays the DOS Version
Number.
VOL
This
command gives the volume label of the disk in the current drive.
COPY CON
This
command is used to create a file. Using ctrl +Z or F6 can save the file.
Syntax-: COPY
CON <file name>
TYPE
It displays the contents of the
specified file.
Syntax-: TYPE
<file name>
COPY
This command is used to copy
file.
Syntax : COPY
<Source file name> < Destination file name>
REN
This
command is used to change the name of a file. The file content remains same.
Only the filename is changed.
Syntax : REN
<Source file name> < Destination file name>
MD
This
command is used to create a sub directory.
Syntax : MD
Directory name
CD
It is used to changes the
directory
Syntax : CD
Directory name
a.
CD...
To change to the previous directory or parent directory
b.
CD\
To change to the root directory
RD
To
remove a sub directory
Syntax : RD Directory name
DIR
The DIR command produces a list
of files and subdirectories in the current drive
Syntax : DIR
DIR/P: -To display the
filename in page wise
DIR/ W: - To display the
filename in width wise
DIR/O: -To display the
filename in sorted order
DIR/S: -To display the
subdirectories also.
This command is used to delete a
file
Syntax-: DEL <file name>
PROMPT
PROMPT command helps to change to
the DOS Prompt
Syntax-: PROMPT
$P$G (Gives the default prompt)
WILD CARDS
Wild card character are used to
select a group files. There are a special characters that can be used as wild
card characters * and ?
The wild cards can be used with DIR
command for the selective list of directory.
Eg.:-
DIR *.Bat- to display filename with
extension bat
DIR
*.* - To displayfilename with starting charACTER a
DIR
*- To display filenames having no extension
DIR?
A*. *- To display filenames having second character of primary name is A
DIR???
- To display files having up to 3 characters in primary part and having no
extension
EXTERNAL COMMANDS
MEM
This
command is used to display a report about the memory like used memory, free
memory etc.
Syntax-: MEM
TREE
It is used to display the
subdirectory structure graphically.
Syntax-: TREE
DELTREE
It is used to remove a complete
TREE structure
Syntax-: DELTREE
<sub directory>
MORE
It
is used to display the content of a filename, page by page.
Syntax-: MORE <File name>
SORT
It
is used to arrange the data of a specified file in ascending or descending
order.
Syntax-: SORT <File name>
SORT /R is used to
sort the data in descending order.
Syntax-: SORT/R <File name>
FORMAT
The
format command removes all the contents of the disk and create a new root
directory..
Syntax-: FORMAT drive:
LABEL
To
create, change or delete the label of a disk.
Syntax-: LABEL <drive name> :
<Label name>
DISK COPY
It
is used to copy the content of a floppy disk, to another track by track. Here
both the source and target drives should be of same capacity.
Syntax-: DISKCOPY <source
drive>: <target drive>
FIND
It
is used to search a specified string with in a file.
Syntax-: FIND “string” file name.
(The string should be entered in double quotation.)
FIND/V
“string” file name:- To display lines that does not contain the string
FIND/C
“string” file name:- To count the number of lines
FIND/N“string”
file name:- To display the matching lines with corresponding line numbers
FIND/I
“string” file name :- Specifies that the search is not to be case sensitive
(Upper and Lower case are taken)
ATTRIB
It
is used to display or change the hidden ,read only attributes of files or sub
directory.
ATTRIB
+R :- To set read only attribute
ATTRIB
–R :- To remove read only attribute
EDIT
It
is a text editor, used to create or edit a text file. It is as menu driven
program.
Syntax- : EDIT <File name>
MICROSOFT
WINDOWS
Windows
is a user-friendly operating system with graphical interface. It is a GUI based
operating system. GUI, Graphical User Interface that means user can interact
system with graphical method. It provides networking and communication
capabilities. Windows is a multi user and multi tasking operating system. It
allows more users and more work on multiple applications simultaneously. It has
more user friendly and facility to transfer data between applications.
FEATURES
1. Graphical User interface (GUI)
GUI means interacting with the computer
through graphical methods by the user.
2. Dynamic Data Exchange (DDE)
DDE is a technique by which data is
transferred between different window programs. It helps to view more than one
program at a time through its windows.
3. Object Linking Embedding (OLE)
OLE helps to current program calls another
programs either as linked object or embedded object.
4. Windows provide an easy way to organize and
start program through the task bar
5. It provides many useful accessories like
paint, WordPad, Calculator, Media player
VERSIONS
OF WINDOWS
Windows was first introduced in the year 1983
and known as interface manager. Various versions of windows are given below
1. Win 3.x
2. 
Win 9x
Win 9x
3. Windows 95
4. Windows 98
5. Windows 98 SE and ME
6. Windows NT
7. Windows 2000
8. Windows XP
9. Windows vista
ELEMENTS
OF WINDOWS
The
main elements of Windows operating system are as follows.
1.
Desktop
2.
Start Menu
3.
Controls
4.
Folders and Files
5.
My Computer
6.
Recycle bin
7.
Windows Explorer
8.
Accessories
9.
Control Panel
DESK TOP
The main screen of
the windows is called desktop. The active desktop is user interface. The small
pictures that can see on the desktop are called icons. An icon represent a
program
Taskbar is the bar
at the bottom of the desktop. The taskbar shows the start button, clock and
buttons for each applications that are currently running.
START MENU
The start button
which appears on the left of the task bar, displays a menu that contains every
thing in the windows. The common sub options in the start button is given below
Programs: Contains
shortcuts to applications and application sub folders, such as the accessories
folder.
Documents:
Contains shortcuts to recently used documents.
Settings:
Contains shortcuts to the control panel folder, printers folder, and the
taskbar and Start menu properties dialog box, Folder options, Active desktop
options, and windows update.
Search:
Contains commands to find files, folders, computers, internet sites, and people
on the internet.
Help:
Starts the online and offline help system for windows
Run:
Opens a dialog box from which you can type a command to open programs, folders,
or web sites.
Log
off username: Lets you close all programs and log on as a different user.
Shut
down: Provides Stand by, shut down and restart options.
Program
menu: It contains the shortcuts to programs and additional folders.
Controls
Window
controls are graphical elements such as windows borders, title bars and close
buttons that you can use to control the size and position of folder and
application windows.
Close
Button is used to close the window
Maximize
button enlarges the window. After a window has been maximized the maximized
button becomes a restore button.
Restore
button restore a maximized window to its previous size.
Sizing
Pointer: The mouse pointer becomes a sizing pointer when you rest it on a
window border or corner. This indicates that you can size the window by dragging
its border.
System
menu buttons Click these to open a menu that controls the window
Title
bar displays the name of the program
Dialog
box Contains the controls that provide different ways for specify a setting
or choose an option.
Text
box is used to type information
Check
box is used to select or deselect an option. A check mark in the box
indicates the option is selected.
Common
Dialog box. Windows provides common dialog boxes to help you browse folders
when selecting saving and opening files on local and network drives. So many file management
tasks are perform in these dialog boxes.
Look
in box shows the current folder. Click to select a different folder from
the hierarchy of folders in your computer.
Up
one level button is used to select the parent folder of the current folder
Create
new folder button is used to create a new folder in the current folder
View button show files and folders in
different views
FILES AND FOLDERS
Folders
store related items such as files and other folders. In older version of
windows folders were called directories. Files are items that store
information, such as the data you create when using an application.
File
names may contain spaces and can be as long as 256 characters. They cannot
contains the characters like \*?’<>|. You can copy files and folders from
one location to another using menu commands or drag and drop. You can also
rename a file or folder.
MY COMPUTER
My
computer is a system folder that appears on the desktop. It contains disk drive
and system folder icons. My computer icon is used as a starting point to browse
all the drives connected to the computer including network drives that have
been mapped.
RECYCLE BIN
The
Recycle Bin is a system folder in which windows stores the items delete.
Commands to return selected items to their original locations or permanently
delete them are also available.
WINDOWS EXPLORER
Using
windows explorer you can browse folders and the files they contain. In the
Windows explorer window, the left pane shows the hierarchy of folders in your
computer, while the right pane shows the content of the folder selected in the
left pane.
For
exploring a particular folder right click that folder and click the explore sub
option.
ACCESSORIES
The
important accessories elements are given below
Calculator
Performs standard and
advanced calculations. Store values in memory. Copy and paste data to and from
the clipboard.
Clipboard
Viewer
Clipboard is a temporary
data storage place. With the help of Clipboard viewer you can store , save,
open and change the format of data stored.
Imaging
Due to this option you can
Preview images such as fax and scanned documents, Annotate, edit scan and print images.
Notepad
Notepad is basically a text
editor. It is used to create and edit ASCII text files.
Paint
Paint is used to create and edit bitmap graphics with text.
Entertainment
In this option
Entertainment such as Playing audio and video cd’s, Sound recording is included.
System
tools
In
this option included system care utilities like Disk cleanup, defragmentation,
Backup…. Etc.
WordPad
WordPad is also an
text editor. Word pad is used to create or edit text files that contain
formatting or graphics.
CONTROL PANEL
From
the control panel you can change a wide
range of computer settings. Some of the features are given below
1.
Accessibility options
2.
Add new hardware
3.
Add/ Remove programs
4.
Date/ Time
5.
Display
6.
Fonts
7.
Internet
8.
Keyboard
9.
Modems
10. Mouse
11. Multimedia
12. Printers
and Faxes
DISADVANTAGES OF WINDOWS
1. Microsoft Windows is a closed-source operating system
2. Microsoft Windows is not flexible
3. windows is less secure than Linux in case of virus, worms.
4. Windows is expensive. For server use, Windows is very expensive compared to Linux.
LINUX
Linux is a user-friendly operating system with graphical
interface. It is a GUI based operating system. GUI, Graphical User Interface
that means user can interact system with graphical method. It provides
networking
FREE SOFTWARE
Linux
is Free software the concept is that The
freedom to run the program, for any purpose ,The freedom to study how the
program works, and adapt it to your needs ,
Access to the
source code is a precondition for this. The freedom to redistribute copies so
you can help your neighbor.The freedom to improve the program, and release your
improvements to the public, so that the whole community benefits . Access to the source code is a precondition
for this.
ADVANTAGES OF LINUX-
Low
cost
Stability:
Linux doesn’t need to be rebooted periodically to maintain performance levels.
It doesn’t freeze up or slow down over time due to memory leaks and such.
Performance:
Linux provides persistent high performance on workstations and on networks. It
can handle unusually large numbers of users simultaneously.
Network friendliness:
Linux has strong support for network functionality; client and server systems
can be easily set up on any computer running Linux.
Choice:
The large number of Linux distributions gives you a choice.. You can pick the
one you like best; most software runs on most distributions.
Fast and easy
installation: Most Linux distributions come with user-friendly installation
and setup programs.
Full use of
hard disk: Linux continues work well even when the hard disk is almost
full.
Multitasking: Linux is
designed to do many things at the same time; e.g., a large printing job in the
background won’t slow down your other work.
Security:
Linux is one of the most secure OS. “Walls” and flexible file access permission
systems prevent access by unwanted visitors or viruses.
Open source
Flexibility: Linux can be used for high performance server applications,
desktop applications, and embedded systems. You can save disk space by only
installing the components needed for a particular use.
Compatibility:
It runs all common Unix software packages and can process all common file formats.
DISADVANTAGES OF LINUX
1.
LINUX is on the road to become a good OS.
