Embed Size (px)
Citation preview
1 COMPUTER SCIENCE
Computer fundamentals
And office tools
1
1 COMPUTER SCIENCE
(Q)What is computer? What are the characteristics and limitations of computer ?
Definition: Computer is an electronic device. It will accept data, store data, Process the data and output to the user in required format. It can also perform all arithmetic and logical functions according to instructions.
CHARECTERSTICS OF COMPUTERS:
1. High Speed
Computer is a very fast device.
It can perform millions of calculations in a few seconds.
The computer speed is also measured in microseconds, nanoseconds and even the
picoseconds.
2. Accuracy
Computers are very accurate.
The computer has performed calculations 100% error free.
Computers perform all jobs with 100% accuracy.
3. Storage
Memory is a very important characteristic of computers.
The computer has more storage capacity than human beings.
It can store large amount of data.
It can store any type of data such as images, videos, text, audio and any other type.
4. Diligence
It can work continuously without creating any error.
It can do repeated work with same speed and same accuracy.
5. Versatility
A computer is a very versatile machine.
A computer is very flexible in performing the jobs to be done.
It performs more than one task at a time i.e., multitasking.
6. Reliability
A computer is a reliable machine.
Modern electronic components have failure free long lives.
Computers are designed to make maintenance easy.
2
1 COMPUTER SCIENCE
7. Automation
Computer is an automatic machine.
Automation means ability to perform the task automatically.
Once a program is given to computer i.e., to perform the task without human interaction.
LIMITATION OF COMPUTER
No I.Q (Intelligence Quotient)
A computer is a machine. It has no intelligence of its own to perform any task.
Each and every instruction has to be given to computer.
A computer cannot take any decision on its own.
No Feelings
Computer has no feeling or emotions.
It cannot make Judgments based on feeling, taste, and experience.
Dependency
It can perform function as instructed by user. So, it is fully dependent on human being.
Q. What are the advantages of computers (or) Explain Applications of computers
Definition: Computer is an electronic device. It will accept data, store data, Process the data and output to the user in required format. It can also perform all arithmetic and logical functions according to instructions.
1. Business: Computer used in business organization for Payroll calculations, budgeting, Sales
analysis, managing employee’s database, maintenance of stocks etc.
2. Banking: Today Banking is almost totally dependent on computer. Banks provide following
facilities:
Internet Banking
Mobile Banking ATM is used for customers to deal with banks.
3. Insurance: Insurance companies are keeping all records up to date with the help of computer.
Insurance Companies are maintaining a database of all clients with information
4. Education: The computer has provided a lot of facilities in the Education System. The uses of
computer provide a tool in the Education system is known as CBE (Computer Based Education)
5. Marketing: In Marketing ,computer can be used for Advertising and selling more products.
6. Health Care: Computers have become important part in all Medical Systems. The computers
are being used in hospitals to keep the record of patients and medicines. It is also used in
3
1 COMPUTER SCIENCE
scanning and diagnosing different diseases. Nowadays, computers are also used in performing
surgery.
7. Engineering: Computers are widely used in engineering purposes. CAD stand for Computer
aided design. CAD provides creation, edition, and modification of image.
8. Defense: Computers are largely used in defence; Missiles, weapons etc. employ computerized
control systems.
9. Communication: Communication means to convey a message, an idea, a picture or speech
that is received and understood clearly and correctly by the person. E-mail, chatting, Facebook,
twitter, video-conferencing are some examples of communications.
10. Government Applications: Computers play an important role in government applications.
Some major fields in this category are
Budgets Sales tax department
Income tax department Male/Female ratio
Computerization of voters lists Computerization of PAN card
Weather Forecasting.
11. OTHER USES: They are also used in stores, shops, hotels, schools, colleges, hospitals,
sports, ticket reservation counters and even agricultural field etc.
Q. Explain about the History of computers.
Definition: Computer is an electronic device. It will accept data, store data, Process the data and output to the user in required format. It can also perform all arithmetic and logical functions according to instructions.
In olden days man used to count things with fingers for counting .They started inventing
machine to calculate and to count.
1. ABACUS: It was the first manual calculating machine. It was invented by Chinese in 3000
B.C.It is used for counting and calculating additions and subtractions. The shape of abacus is
rectangle and it is made up of wood.
2. NAPIER BONES: It was invented by JOHN NAPIER in 1617. It is used for multiplication
& division. It was made up of carved bones.
3. PASCALINE: It was invented by BLAISE PASCALINE in 1642. It is the first mechanical
calculator used for additions & subtraction.
4. ARITHMETICAL REPLICA: It was invented by GOTTFRIED LIBNIZ in 1673. It is used
to solve all kinds of arithmetical programs.
5. DIFFERENTIAL AND ANALYTICAL ENGINES: Computer was invented by Charles
Babbage. Differential and analytical engines are developed by Charles Babbage in 1822 & 1842
respectively. He is known as the father of computers.
4
1 COMPUTER SCIENCE
6.JOHN VON NEUMANN: He is an originator of stored-program concept.
7. MARK- 1: It was the first electro-mechanical computer. It was developed by HAWARD
AIKINES in 1937.He used punched cards concept for input and output.
8.ENIAC: It standards for Electronic Numerical Integrator and Calculator. It was the first
electronic computer. It was developed by JOHN MAUCHLY and ECKERT in 1947.
9.EDSAC: It standards for Electronic Delayed Storage Automatic Computer. It was the first
stored program computer. It was developed by MAURICE V.WILKES in 1949.
10.EDVAC: It standards for Electronic Discrete Variable Automatic Computer. It is the
second stored program computer. It was developed by ECKERT and VON NEUMANN in
1949.
11. UNIVAC-1.It standards for(Universal Automatic Computer: It was the first computer
designed and sold commercially. It was developed by MAUCHLY and ECKERT in 1951.
12.IBM SYSTEM/360: It is the series of mainframe computer. It is the first general purpose
digital computer to use integrated circuits. It was developed by GENE AMDAHL in 1960s.
13.MICRO COMPUTER: First micro computer was developed by H. EDWARD
ROBERTS in 1975.
Q. Explain about Block diagram of digital computer. (or) Explain about the logical
Organization of DIGITAL Computer
Definition: Computer is an electronic device. It will accept data, store data, Process the data and
output to the user in required format. It can also perform all arithmetic and logical functions
according to instructions.
5
1 COMPUTER SCIENCE
A computer system consists of the following components:
1. Input unit
2. Central Processing Unit (CPU).
3. Output unit
1. Input unit: This unit contains devices. Using this, we enter data into computer. This unit
makes link between user and computer. The input devices translate the human being information
into the form understandable by computer.
Examples: keyboard, mouse , scanner etc.
2.CPU: It stands for Central Processing Unit. It is considered as the brain of the computer. CPU
performs all types of data processing operations. It stores data, results and instructions
(program).It controls the operation of all parts of computer.
A CPU consists of t three parts:
i. Memory unit
ii. Control Unit (CU)
iii. Arithmetic Logic Unit (ALU)
i..Memory Unit: Memory unit is the component of a computer system. It is used to store data,
instructions and information before and after the processing by ALU. It is actually a work area
within a computer where CPU stores data and instructions. It is also known as a main memory
or primary or internal memory.
ii. Control Unit: This unit controls the operations of all parts of computer. It does not carry out
any actual data processing operations. It communicates with Input/output devices for transfer of
data or results from storage.
Functions of control unit
It manages and coordinates all the units of the computer.
6
1 COMPUTER SCIENCE
It communicates with Input/output devices for transfer of data or results from storage.
iii. Arithmetic Logic Unit (ALU):It standards for Arithmetic and Logical unit.This unit
consists of two subsection namely Arithmetic section and Logic Section.
Arithmetic section: It is used to perform arithmetic operations like addition, subtraction, multiplication and division. All complex operations are done by use of above operations.Logic Section: It is used to perform logic operations such as comparing, selecting, matching and merging of data.Function of Memory Unit
It stores all the data to be processed and the instructions required for processing.
It stores final results of processing before these results are released to an output device.
All inputs and outputs are transmitted through main memory.
3.Output Unit: With the help of this device, we get the information from computer. This unit is
a link between computer and users. Output devices translate the computer's output into the form
understandable by users. It is also called as VDU(Visual Display Unit)
Examples: Monitor, Printer, Speakers etc.,
(Q) Explain about Generations of computers.
Definition: Computer is an electronic device. It will accept data, store data, Process the data and
output to the user in required format. It can also perform all arithmetic and logical functions
according to instructions.
Generation in computer terminology is a change in technology a computer is being used.
Nowadays, generation includes both hardware and software, which together make up an entire
computer system.
There are totally five computer generations.
1. First Generation: (1946-1959)
2. Second Generation: (1959-1965)
3. Third Generation: (1965-1971)
4. Fourth Generation: (1971-1980)
5. Fifth Generation: (1980-till date)
First Generation: The period of first generation was 1946-1959.First generation of computer
started with using vacuum tubes as the basic components for memory and circuitry for CPU
(Central Processing Unit). These tubes like electric bulbs produced a lot of heat.
Characteristics:
Vacuum tube technology
Unreliable
Supported Machine language only
7
1 COMPUTER SCIENCE
Very costly
Generate lot of heat
Large size
Need of A.C
Non portable
Consumed lot of electricity
Second Generation: The period of second generation was 1959-1965.This generation using the
transistor were more reliable and faster than the first generation.
Characteristics
Use of transistors
Reliable as compared to First generation computers
Smaller size as compared to First generation computers
Generate less heat as compared to First generation computers
Consumed less electricity as compared to First generation computers
Faster than first generation computers
Still very costly
A.C. needed
Support machine and assembly languages
Third Generation: The period of third generation was 1965-1971.The third generation of
computer is marked by the use of Integrated Circuits (IC's) in place of transistors. A single I.C
has many transistors, resistors and capacitors.
Characteristics
IC used More reliable Smaller size Generate less heat Lesser maintenance Support high level language Support Operating systems
Fourth Generation: The period of Fourth Generation was 1971-1980.The fourth generation of
computers is marked by the use of Very Large Scale Integrated (VLSI) circuits. In this
generation ,All the Higher level languages like C and C++, Java etc. were used in this
generation.
Characteristics
VLSI technology used
Very cheap
Portable and reliable
8
1 COMPUTER SCIENCE
Use of PC's
Very small size
No A.C. needed
LAN and WANS were developed used d.
Fifth Generation: The period of Fifth Generation is 1980-till date. In the fifth generation, the
VLSI technology became ULSI (Ultra Large Scale Integration) technology, resulting in the
production of microprocessor chips having ten million electronic components.
This generation is based on parallel processing hardware and AI (Artificial Intelligence)
software.
AI includes Robotics, networks and Game Playing.
Characteristics:
ULSI technology
Development of true artificial intelligence
Development of expert systems to make decisions in real life situations.
Development of Natural language processing
More user friendly interfaces with multimedia feature
Q. Explain classification of computers.
Definition: Computer is an electronic device. It will accept data, store data, Process the data and output
to the user in required format. It can also perform all arithmetic and logical functions according to
instructions.
Classification of computers according to their size:
1. Mini computers
2. Mainframe computers
3. Super computers
4. Micro Computers
1. Mini computers: It was first released in the 1960s.It is a midsize computer. A minicomputer
is a multi-processing system capable of supporting from up to 250 users simultaneously
2. Mainframe Computers: It is a very large in size and is an expensive computer capable of
supporting hundreds, or even thousands, of users simultaneously. Mainframe executes many
programs concurrently. Mainframe computers are used in large organizations such as insurance
companies and banks, where many people frequently need to use the same data.
3. Super computers: They are one of the fastest computers currently available. Supercomputers
are very expensive and are employed for specialized applications like mathematical calculations
For example, weather forecasting , scientific simulations, (animated) graphics, fluid dynamic
9
1 COMPUTER SCIENCE
calculations, nuclear energy research, electronic design, and analysis of geological data (e.g. in
petrochemical prospecting).
4. Micro Computers: They are based on micro processor technology. They are designed to be
used by only one person at a time. A microcomputer uses a microprocessor as its central
Processing Unit (CPU). This can be divided based on sizes as fallows:
a. Desktop computers.
b. Workstations.
c. Laptop (or) Notebook computers.
d. Tablet computers.
e. Handheld computers.
f. Smart phones.
a .Desktop Computers
Many people use desktop computers at work, home, school, or the library. They can be small,
medium, or large in style, and usually sit on a desk.
b. Workstations: It is a computer used for engineering applications (CAD/CAM), desktop
publishing and software development.
c. Laptop Computers: The another type of computer is called as laptop computer, or simply
laptops . Laptops are more portable than desktop computers. A laptop computer is sometimes
called a notebook computer because of its size.
d. Tablet Computers: These use a touch-sensitive screen for typing and navigation. Since they
don't require a keyboard or mouse. They are more portable than laptops. The iPad is an example
of a tablet computer.
e. Handheld PCs: Handheld personal computers are computing devices small enough to fit in
our hand. A popular type of handheld computer is the personal digital assistant (PDA). It is
normally used for special applications, such as taking notes, displaying telephone numbers and
addresses
f. Smart Phones: Many mobile phones can do a lot of things a computer can do, such as
browsing the internet or playing games. These phones are called smart phones.
Q) WHAT ARE THE VARIOUS OF INPUT DEVICES?
INPUT DEVICES: Input devices are used to provide data or information to the computer. The
computer follows the instructions given to it by and input device. Following are few of the
important input devices which are used in Computer Systems.
1.Keyboard 2.Mouse 3.Scanner 4.Track ball 5.Track pad or touchpad
10
1 COMPUTER SCIENCE
6.Touch Screen 7.Light pen 8.Joystick 9.OMR 10.Bar Code Reader
11.OCR 12.MICR
1.Keyboard. It is known as the standard input device. It is similar to type writer but also contains
additional keys. It is used to enter textual data into the computer. It contains 108 keys. It exists
in QWERTY arrangement. Keyboard keys are categorized into Numerical keys, Alphabetic
Keys, Function Keys, Special Character Keys and White Space Character Keys.
2.Mouse:It is most popular Pointing device. It is used to select objects. The parts of mouse are Left button, Right button, Scroll Wheel and cable. The two types of mouse are Mechanical mouse and Optical mouse.3. Joystick: It is also a pointing device. It is used to move cursor position on a monitor screen. The Joystick can be moved in all four directions. It is mainly used in Computer Aided Designing(CAD) and playing computer games.4.Light Pen:Light pen is a pointing device which is similar to a pen. It is used to select a displayed menu item or draw pictures on the monitor screen. 5.Track Ball: It is an input device that is mostly used in notebook or laptop computer, instead of a mouse. It requires less space than a mouse. 6.Scanner:It is an input device which works more like a photocopy machine. It scans or reads text and picture printed on a paper and enters them directly into the computer memory for further manipulation. 7.Microphone:It is an input device to input sound that is then stored in digital form. The microphone is used for various applications like adding sound to a multimedia presentation or for mixing music.8.Magnetic Ink Card Reader(MICR):MICR input device is generally used in banks because of a large number of cheques to be processed every day. The bank's code number and cheque number are printed on the cheques with a special type of ink.This reading process is called Magnetic Ink Character Recognition (MICR). The main advantage of MICR is that it is fast.9.Optical Character Reader(OCR): OCR is an input device used to read a printed text. OCR scans text optically character by character, converts them into a machine readable code and stores the text on the system memory.10.Bar Code Readers: It is a device. It is used for reading bar coded data (data in form of light and dark lines). Bar Code Reader scans a bar code image, converts it into an alphanumeric value.Bar coded data is generally used in labeling goods, numbering the books etc. 12.Optical Mark Reader(OMR): OMR is a special type of optical scanner used to recognize the type of mark made by pen or pencil. It is specially used for checking the answer sheets of examinations having multiple choice questions.13. Web Cameras : They are used to capture images and input them to the computer. Digital
camera will create an image of the object in digital form.
Q. WRITE ABOUT OUTPUT DEVICES.
11
1 COMPUTER SCIENCE
An output device is used to display the data or information that we receive from the
computer. An output device can be used to display or print the final results performed by
computer.
Following are few of the important output devices which are used in Computer Systems
1. Monitor
2. Printer
3.Speakers
4.Plotters
2. Monitor:
It commonly called as Visual Display Unit (VDU) .It is the main output device of a computer.
When we are typing a letter, copying files, or surfing the Internet that are looking at our monitor. It
forms images from called pixels, which are arranged in a rectangular form. The sharpness of the
image depends upon the no. of the pixels.
i.Cathode-Ray Tube (CRT) Monitor:
The cathode ray tube (CRT) monitor comes with most desktop computers.
disadvantages
Large in Size
High Power consumption
ii. Flat- Panel Display: The Flat-panel monitors are used for primarily on portable computers.
Examples: plasma LCD (Liquid-Crystal Device), LED (Light-Emitting Diodes).
2. Printers:
Printer is the most important output device, which is used to print information on paper.
There are two types of printers. There are two types of printers
i. Impact Printers
ii. Non-Impact Printers
Impact Printers:
The printers that print the characters by striking against the ribbon and onto the paper, are called impact printers. These printers are of two types
(i) Character printers (ii) Line printers.
Advantages
Very low cost
Impact printers are very noisy
Useful for bulk printing due to low cost
12
1 COMPUTER SCIENCE
Non-impact Printers: The printers that print the characters without striking against the ribbon
and onto the paper, are called Non-impact Printers. These printers print a complete page at a
time, also called as Page Printers.
Advantages
1. Very high speed.
2. Very high quality output.
3. Give good graphics quality.
4. Support many fonts and different character size.
These printers are of two types: (i) Laser Printers
(ii) Inkjet Printers
PLOTTERS: Plotter is a special output device. It is used to produce high quality hard copy
output. Plotters are designed to produce large drawings or images such as construction plans for
buildings.
MEMORY: It is the device where the information is stored. Memory is primarily of three types1.Primary Memory/Main Memory2.Secondary Memory3.Cache Memory
1.Primary memory: It holds data and instructions on which computer is currently working. It has limited capacity and data get lost when power is switched off. It is generally made up of semiconductor devices. Characteristic These are semiconductor memories.
It known as main memory. Usually volatile memory. Data is lost in case power is switch off. It is working memory of the computer. Faster than secondary memories. Computer cannot run without primary memory. It is divided into two types RAM and ROM.
RAM: It the internal memory of the CPU for storing data, program and program result. It is read/write memory. It is called Random Access Memory (RAM).RAM is volatile, i.e. data stored in it is lost when we switch off the computer or if there is a power failure. RAM is of two types
Static RAM (SRAM) Dynamic RAM (DRAM)
Static RAM (SRAM)Data is lost when the power gets down due to volatile nature. SRAM chips use a matrix of 6-transistors and no capacitors. Characteristic
It has long data lifetime There is no need to refresh Used as cache memory
13
1 COMPUTER SCIENCE
Expansive High power consumption
Dynamic RAM (DRAM) DRAM is used for most system memory because it is cheap and small. All DRAMs are made up of memory cells. These cells are composed of one capacitor and one transistor.Characteristic
It has short data lifetime Need to refresh continuously Slower as compared to SRAM Used as RAM lesser in size Less expensive
ROM: It stands for Read Only Memory. The memory from which we can only read but cannot write on it. This type of memory is non-volatile. The information is stored permanently in such memories during manufacture.Characteristic
Non-volatile in nature These cannot be accidentally changed Cheaper than RAMs Easy to test Reliable than RAMs
Types of ROMsPROM : It stands for Programmable Read only Memory. It is read-only memory that can be modified only once by a user. It can be programmed only once and is not erasable.EPROM:It stands for Erasable and Programmable Read Only Memory. It can be erased by ultra-violet light for a duration of unto 40 minutes. EEPROM: It stands for Electrically Erasable and Programmable Read Only Memory. The EEPROM is programmed and erased electrically. It can be erased and reprogrammed about ten thousand times. EEPROMs can be erased one byte at a time, rather than erasing the entire chip. Hence, the process of re-programming is flexible but slow.SECONDARY STORAGE DEVICESSecond storage: These are used for storing large amounts of data/Information permanently. It is also called auxiliary storage or mass storage. The information stored in this memory is used by the CPU by first bringing it to main memory. It is slower than primary memory.Characteristic
It is known as backup memory. It is non-volatile memory. Data is permanently stored even if power is switched off. It is used for storage of the data in the computer. Computer may run without secondary memory. The Secondary Memory is also known as Auxiliary Memory or Backup Memory. These are three types
1. magnetic memories.2. Optical memories3. Memory devices1.Magnetic memories: They are classified into the following types. They are
1. Magnetic tape2. Floppy Disk 3. Hard Disk
1.Magnetic tape: It is also secondary storage device. It is used to access data serially like an audio cassette. When we want to access some particular data from the tape, the device has to
14
1 COMPUTER SCIENCE
scan through all the data. Magnetic storage is widely used because it is relatively cheap in comparison with other storage technologies. The access speed can be slow when the tape is long
2. Floppy disk: It is an example of magnetic device. It is a small removable and portable storage device. It is made of polyester film coated with a metal oxide compound. It is readable by a computer with a floppy disk drive. They are introduced by IBM in 1972. They were available in 3 ½ and 5 ½ inches. They have a storage capacity of 1.44 MB and 2.88 MB respectively.
3. Hard disk: It is another storage device. Hard disk is a thin circular metal plate coated both side with a magnetic material. A hard disk pack consists of a number of disks mounted on central shaft which rotate at a speed of 2400 rpm or more. In a hard disk information is stored on both the surfaces of each disk plate except the upper and the lower surfaces of the bottom plate which are not used. Information is recorded on the track of the disk surfaces in the form of invisible tiny magnetic spot. The presence of a magnetic spot represent 1 bit and its absence represents 0 bit. Data are recorded on the tracks of a spinning disk surface and read from the surface by one or more read/write heads. 2.OPTICAL MEMORIES i. CD-R (Compact disc Recordable): Data can be written onto it just once. The stored data can be read. Data once written onto it cannot be erased. It is portable and can hold a large amount of data.ii. CD-RW (Compact disc Rewritable):It is also called erasable CD. Data once written onto it can be erased to write or record new information many times. The storage capacity of most CD-ROMs is approximately 650 MB or 700 MB.iii. CD-ROM: CD-ROM stands for Compact Disk–Read Only Memoryiv. DVD (Digital Versatile Disc): DVD stands for Digital Versatile Disc. It is similar to a CD-ROM. The storage capacity of a DVD is at least 4.7MB. DVDs that can store up to 17GBs are also available.3.Memory devices1. pen Drive(Flash Drive): It is a small and portable device. It can be used to store, access and transfer data. Due to its small size, it is commonly called Pen drive. It is also called USB drive. We can read, write, copy, delete, and move data from computer to pen drive or pen drive to computer. It comes in various storage capacities of 2GB, 4GB, 8GB etc.. 2. Memory cards: A memory card or flash card is an electronic flash memory data storage device .It is used for storing digital information. They are commonly used in many electronic devices, including digital cameras, mobile phones, laptop computers, MP3 players and video games. They are small, re-recordable.1. Flash Memory: It is commonly used in digital cameras and multimedia players i.e.MP3
players. These devices usually connect to a computer’s USB.
CACHE MEMORY: A Cache (Pronounced as cash) is a small and very fast temporary storage memory. It is designed to speed up the transfer of data and instructions. It is placed between CPU and main memory. It is faster than RAM. Data/instructions that are most recently or most frequently used by CPU are stored in cache.
The data and instructions are retrieved from RAM when CPU uses them for the first time. A copy of that data or instructions is stored in cache. It is retrieved from cache memory instead of main memory. It speeds up the working of CPU.
Hardware: It is any physical electronic device. Hardware includes every computer-related object that we can physically touch and handle like disks, screens, keyboards, printers, chips, wires, central processing unit, USB ports, pen drives etc.
15
1 COMPUTER SCIENCE
Software Software: It is a set of programs, which is designed to perform a well defined function. A program is a sequence of instructions written to solve a particular problem. It provides overall control for computer hardware, and applications.
Types of softwares
Applications software: That is of individual liking and need. It can range from games to professional work-related programs like database management systems, word processors, spreadsheets etc.
Systems software: This makes the computer run and thereafter, makes the applications software on your computer function properly. Without systems software, the applications software cannot be run because the computer needs to be started up with systems software. Systems software is also known as the operating system of a computer.
Firmware: Firmware is basically a type of software, Firmware still falls into this category as it is programmed information that is responsible for the operation of certain hardware.Peopleware: It is a term used to refer to one of the three core aspects of computer technology: hardware, software, and peopleware. Peopleware can refer to anything that has to do with the role of people the development or use of computer software and hardware systems, including such issues as developer productivity, teamwork, group dynamics, the psychology of programming, project management, organizational factors, human interface design, and human-machine-interaction.
Q.EXPLAIN ABOUT TYPES OF BOOTINGS.
Booting : The process of switching on the computer is referred to as the booting. It is a process
of loading O.S. from secondary memory to primary memory. The disk from which startup or
booting is done is called as bootable disk.
Types of Booting
Cold Booting: When the P.C. is switched on it loads the bootable program from the disk to the
memory. This type of booting is a slow process. It can be done only from on / off switch
button on the cabinet of the CPU.
Hot Booting: It is faster than cold booting. If the computer hangs due to some reason then we
can restart the computer by pressing the CTRL + ALT + DEL key on the keyboard or press
the reset button on the cabinet of the CPU.
Dual Booting: It is a process of loading two different operating systems at the same time from
secondary memory to primary memory.
Q. Explain types of Operating Systems.
Operating system: An operating system is a system software that provides an interface between the user. It consists of programs and data that runs on computers and manages computer hardware.
Examples: MS-DOS, WINDOWS, LINUX, UNIXIt provides mainly two tasks1.It is an interface between user and the computer[hardware]
16
1 COMPUTER SCIENCE
2. It controls all the parts of computer that were connectedTypes of operating systems Based on their process
1.Batch Operating System: The users of batch operating system do not interact with the
computer directly. Each user prepares his job on an off-line device like punch cards and submits
it to the computer operator. In batch processing systems, programs are collected, grouped and
processed on a later date. Input data are collected and processed in batches.so,it is called batch
processing. It is good for executing large jobs that need little interaction,
2. Time Sharing Systems: It provides an environment where the various system resources (for
example, CPU, memory, peripheral devices) are utilized effectively. Time sharing is a logical
extension of multiprogramming a time-shared operating system allows the many users to share
the computer simultaneously.
3. Multiprogramming: When two or more programs are in memory at the same time, sharing
the processor is referred to the multiprogramming operating system. Multiprogramming uses a
single processor that is being shared. It increases CPU utilization.
4. Multi-user Operating System:- A multi-user operating system allows for multiple users to use
the same computer at the same time and/or different times. Linux, UNIX, Windows OS are
some example of multitasking operating system.
5. Multiprocessing Operating System:- An operating system capable of supporting and utilizing
more than one computer processor. Linux, UNIX, Windows OS are some example of
multitasking operating system.
6. Real Time Operating System:- It is a multitasking operating system that aims at executing
real-time applications. Immediate processing and up-to-date information are major
characteristics of a real-time system.
Examples: a flight reservation system, a banking situation.
7.Network Operating System:- A network operating system (NOS) is software that controls a
network and its message (e.g. packet) traffic and controls access by multiple users to network
resources such as files. It provides for administrative functions, including security.
8. Distributed Operating System: An operating system that manages a group of independent
computers. It is known as a distributed operating system.
Q. Explain types of Operating Systems.
Operating system: An operating system is a system software that provides an interface between the user.It consists of programs and data that runs on computers and manages computer hardware.
Examples: MS-DOS, WINDOWS, LINUX, UNIX It provides mainly two tasks1. It is an interface between user and the computer [hardware]2. It controls all the parts of computer that were connectedFunctions of operating system: Modern operating systems support the following functions.
17
1 COMPUTER SCIENCE
1. user interface 2. memory management 3. File management 4. Accessing data
5. program execution 6. I/O operation 7. Communications 8. Error detection
9. Resource allocation 10.Managing resources 11. Security 12.Utility programs
1. User Interface: Users interact with operating systems by means of command line interfaces
or graphical user interfaces.Almost all operating systems today provide a windows-like
Graphical User Interface (GUI), Beginning from Windows 95.
2. Memory Management: The operating system handles the allocation and management of
memory.The operating system controls the amount of memory allocated to application
programs. An operating system can use the same memory locations for multiple tasks.
3. File management: This method is used for storing and managing computer files and data. A
file system can be considered as a specialized storage system for the organization, access and
retrieval of data. To get some file systems like FAT 32[File Allocation Table].
4. Accessing Data: The operating system stores data in a particular storage area. Hence the data
can retrieved when it is required.
5. Program execution: The operating system gives the permission to the program for execution.
Operating system loads a program into memory and executes the program. The program must be
able to end its execution.
6. I/O Operation : Program may require any I/O device while running. So operating system
must provide the required I/O.
7. Communication : It allows two or more computers to connect and form a network or connect
to the Internet. Data transfer between two computers is required for some time. Communication
may be implemented by two methods:
8. Error detection : An o.s detects errors and should take the appropriate action .It includes
memory error, power failure and printer out of paper.
9.Resource Allocation : Operating system manages different types of resources require special
allocation code, i.e. main memory, CPU and file storage.
10.Managing Resource: These programs coordinate all the computer’s resources including
keyboard, mouse, printer, monitor, storage devices and memory.
11. Security: Security starts with each user having to authenticate to the system, by means of a
password. Most of the operating systems require its users to login to their accounts by means of
a username and password. Recent developments in technology have introduced biometry to
operating systems likeWindows Vista.
12.Utility Programs :They are specialized programs.All kinds of things can happen to a
computer system – hard disks can crash( viruses),operations can slow down, and so on.
Examples: e Format, Scan Disk, Disk Cleanup, and Anti-Virus.
18
1 COMPUTER SCIENCE
DOS commands are generally classifieds in two types.
There are two types of DOS commands- internal and external. The internal commands are those commands that are automatically loaded in the memory of your PC when DOS is loaded. These commands can be used without the need of any DOS file or diskette. The internal commands are simple and are used for common tasks, such as copying, renaming or erasing files, displaying a list of files in a diskette, creating and changing directories;
Internal Command
DOS commands for which the specifications are available in Shell (Command.com) are calledinternal commands. These are frequently used commands, and are called resident commands.
DOS Commands for which specifications are not internally available in command.com are called External Commands. They reside in the disk in the form of executable program files. They will be loaded into primary memory only at the time of execution.
Directory Structure of DOS: One thing is to be kept in mind is that a directory can have as many child (sub) directories, but the child directory can have only one parent directory.
1. CLS: this command is used to clean the screen.
2. DIR: this command allows the user to see all files and sub-directory in the current directory. DIR Command lists file information in five columns; (first) column gives primary name of the file (second) column gives extension of the file (third) column gives the file size - number of bytes used; (fourth) column gives the last updated date; (fifth) column gives the last updated time.
Dir/p - page by page display of file name and directory names;
Dir/w - width-wise display;
Dir/s - displays all sub directory and files in the sub-directory of current directory.
3. Copy con this command copies whatever typed on keyboard to the file; the file can be closed by giving the command A2 or F6 key: eg: Copy con test .....A2.
4. Date it displays two system date and allows the user to change it if desired ; it is displayed in the form of mm - dd - yy; eg:c:\> date - enter.
5. Time it displays the system type and enables the user to change it; eg: C:\> Time - enter.
6. md(mkdir) it creates a new directory in sub directory in the current directory; eg: C:\> md <New directory name>
7. rd(rmdir) this command is used to remove a directory from the disk; it can't remove a directory which contains sub directory or files, ie, the child should be removed from the parent; similarly this command can't remove the current directory and root directory. Syntax: c:\> RD<Dir name>.
19
1 COMPUTER SCIENCE
8. Type it displays the content of saved file; eg: C:\> Type> file name.
9. Ren this command changes the name of existing file or directory: Syntax: C:\> ren <old name> new name>
10. Delete delete a file from current directory; Syntax: C;\> del<file name>
11. Ver it displays the version of DOS currently being used in the system; Syntax: C:> ver
12. Copy it copies the given file or files from the source directory to the largest directory; Syntax:C:\> copy<source file name> <target file name>.
13. Prompt allows the user to set a new DOS prompt instead of usual C:\> or A:\>; eg C:\> prompt pcc; Prompt$p$g - this allows you to reset default prompt; Prompt $d (current date); Prompt $t (current time);
External Command
1. Attrib this command is used for protecting the files from accidental changes or modification. It can also be used for making a hidden file, archive files, read only files; Syntax: Attrib +R/-R/+H/-H/+A/-A <file name> +FR protects the file by making it read only, -R removes the read only protection; eg: Attrib + r <file name >
2. Scandisk/ Chkdisk this command checks the status of the disk; it shows a graphical display, information about the user file.
3. Tree this command graphically displays the path of each directory and sub directory in given drive; Syntax: C:\> tree<
4. More it displays one screen of data at a time and is used with another command when one screen is full; if you press any key on the next screen is displayed: Syntax C:\> type abc.doc| more.
5. Edit the command loads the MSDOS editor, where we can edit files, create new files, open existing files; Syntax: C:\> edit < file name>
6. Label a label is a name given to a disk which refers to collection of filers and directories on disk; Syntax: C:\>label A.
7. Sort this command is used for sorting data and displaying the result on the screen: Syntax:C:\>dir/sort/r (reverse order)
8. Format; this command prepares a disk by arranging random magnetic impulses in to a series of track and sectors so that it is addressable by a DOS version; Syntax : C:\> format A:/s
9. Sys this command transfers MSDOS System files to specified areas to make the disk boo table; Syntax: C:\>Sys A:<
10 Pipes (|) it connects two files ie the standard output of one filter command becomes standard input of another filter; eg Dir/Sort/ more ||
20
1 COMPUTER SCIENCE
11. Batchfiles all batch files on DOS must have the file extn on bat to execute the batch file, the user has just type the file name and press enter key, in addition to usual DOS command.
12. Echo this command can be used to display a message on the screen
13. Pause when this command is obeyed, the system waits for the user to press a key by displaying a line "strike a key when ready"
14. Rem a command or remark can be used on batch file by the rem command; to symbol @ can be put in a REM command to prevent DOS from displaying the commend during the execution of batch files.
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.
b) 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.
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.
2 1 - The Desktop
21
1 COMPUTER SCIENCE
The Desktop is the main Windows 7 screen(see image below). It is the work areawhere dialog boxes, windows, icons, and menus appear. Like an office desk, the Windows7 desktop contains items you can use to do your job. For instance, from your desktop, you can perform file-management tasks and run software applications. You can customize the appearance of the desktop to suit your preferences. Desktop Icons The Desktop is where you’ll find icons (small pictures) for many of your most frequently used programs. You’ll most likely see icons for Computer, Documents,Recycle Bin, and Internet Explorer.
Computer– Allows you to see what drives are attached to your computer (forexample, your local hard disk drive, your CD/DVD drives, any networked shared drives, and external drives, such as a USB flash drive). You can also view the files that are located on these drives. Documents– Supplies a ‘catch-all’ place for your personal files. Within here you can see your files, any shared files from other computer users and any music or pictures you may have stored. The Documents folder will sometimes be identified by your name instead of the word “Documents.” Recycle Bin– Stores any files you delete until you empty it. Internet Explorer Contains Windows’ built in web browser that integrates with other Windows components (such as your folders and Documents). page| Creating Icons– To create an icon, right-click anywhere on the Desktop and choose New Shortcut. Browse for the file or program you want to create the icon for, click Next,name your icon, then click Finish. Deleting Icons– To delete an icon, either right-click on the icon and select Delete, or click once on the icon and press the Delete key on your keyboard. Renaming Icons– To rename an icon, right-click on the icon and choose Rename. You can then type in the new name. Also, try clicking once on the icon, wait half a second, then click it a second time. The text area will be visible and you can type a new name. Arranging Icons– To arrange the icons on your desktop, right-click in an open area of the Desktop, click Sort Byand choose the appropriate option from the list below. oName– Sort the icons alphabetically from top to bottom, left to right. oSize– Sort the icons by file size (the amount of space the file takes up on your local computer). oType– Sorts the icons by the type of file that itis, such as Word Documents, programs, etc. oDate Modified– Arranges the icons with the most recent items in the top left hand corner. oMoving & Dragging– To move (drag) an icon, click on it once, holding down the click, and drag it to another location. You can also arrange the items wherever you would like. Simply right-click in the open area of the Desktop, click View, and choose Align to Grid. Interior Decorating Windows 7: Changing Desktop Properties So you’re bored with that plain background or that rolling green hill? Don’t like the flashing stars screen saver that
22
1 COMPUTER SCIENCE
plagues your screen? The Personalization (Display Properties) window is your answer. From here you can change your wallpaper, screen saver, and even your desktop theme. To access the window, right-click anywhere on an open space of your desktop and click Personalize. Here’s a rundown of what each area is. Change desktop icons– Allows you to select which items will appear on your desktop. Change mouse pointers– Allows you to pick a different mouse pointer. You can also change how the mouse pointer looks during such activities as clicking and selecting. Desktop– Allows you to set the Desktop background picture. Display– Allows you to set your screen resolution and other advancedmonitor and video settings. Screen Saver– Allows you to set a screen saver and its time interval. A screen saver is a picture or animation that covers your screen and appears when your computer is idle for a set period of time. Sounds– Changes which sounds are heard when you do everything from receiving e-mail to emptying your Recycle Bin. Page| 4 Window Themes– Allows you to set a theme for Windows which includes changing visual or auditory elements associated with menus, icons, backgrounds, screen savers, mouse pointers and some computer sounds. Users can set some aspects of Windows 7 to visually look like Windows XP. Taskbar & Toolbars The bottom of your screen contains various toolbars and icons that allow you to see what programs are running and what programs you can access easily by clicking its icon. From the left to right, the areas are: the Start button (which was discussed previously), the Taskbar and the NotificationArea (sometimes called the system tray). Sometimes other toolbars can show up, such as an address bar.
23
1 COMPUTER SCIENCE
Display Desktop– This feature will hide all open windows allowing the user to view their full Desktop. This feature is activated by clicking the tall rectangular object to the right of the system date and time. Click the object again to restore all of the hidden windows. Notification Area– Displays any programs you have running inthe background (such as a virus scanning program) and displays the time and date. Taskbar– Shows any programs or files you currently have open. You can click the toolbar buttons to go back and forth between open items. The new Windows 7 Taskbar is considerably different from previous incarnations of Windows. It now combines the functions of the traditional Taskbar, which was a place to show which programs were open and allow a user to switch between programs, and the Quick Launch toolbar, which was a small area that contained shortcuts to frequently used programs. Users can now “pin” programs to the Taskbar, which will place a shortcut to thatprogram directly on the Taskbar. You can do this by right-clicking on any icon in your Start Menu and choosing Pin to Taskbar. Clicking that icon will open the program and put a highlight around that icon, showing that a window is now open. You can pin as many icons to your Taskbar as you like, up to the length of the Taskbar. See the Quick View section to see how you can further utilize the icons on the Taskbar. Page| 5 Quick View (Peek) Quick view, also called Peek, allows you to quickly view glance at all open windows of any application currently open. In this example, Peek has allowed the user to quick view four websites currentlyopened in Internet Explorer. The user can simply click the window they want to access and Windows will bring the website to the foreground. To access Peek, simply place your mouse pointer over any open application. Start Menu Basics The Start Menu is, appropriately enough, your starting point
24
1 COMPUTER SCIENCE
in Windows 7. All of your programs, settings, etc. can be accessed here. To begin using it, click the Windows Icon button in the bottom left corner or press the Windows key on your keyboard. Here are some common items you’ll use on the Start Menu. Account Name – The account name for our test computer is Guest. The user will find access to all of their personal files and information stored in a single location. Computer – Formerly known as “My Computer” this start menu item provides access to all storage drives (hard drives, flash drives, network drives, CDs, etc) currently accessible through your computer.Documents – Many users will remember this item as “My Documents”. From this menu item, users can access all of their files stored in the location.Pictures – From here, users can find all of their pictures stored in this location. Music – Users will find their music files stored in this location.All Programs Menu– Stores most of your options, such as the programs you have installed on your computer including Microsoft Office. Search programs and files– Allows you to quickly search for files, folder and programs on your entire system. Page| 6 Recently Used Programs– Provides quick access to programs thatyou use frequently by placing them just above the Start button. Help and Support– Takes you to the Windows 7 Help Center. Devices and Printers– Allows you to view printers and devices currently installed on your system. Control Panel–Allows you quick access to programs that do everything from removing your programs to adjusting your mouse settings
25
1 COMPUTER SCIENCE
and setting up a firewall. Shut Down– Powers down the system. You can access more power options by clicking the arrow to the right. Run Command– The Run command gives you quick access to programs, websites, etc. Just type in the name of the file or website and click OK. You can access the Run command by typing “Run” (without quotations) into the Search programs and files box. The search field can also be used as the old Run dialog box. Simply type in the program name and hit the Enter key on your keyboard. Computer Screen The computer screen (formerly known as My Computer) has changed slightly in Windows 7.Along with showing all of the various drives attached to your computer, you also have an “Explorer” type view on the left side that will allow you easy access to the contents of those drives. Read more about the options available on this screen on the next page. Page| 7 Hard Disk Drives – This area lists all of the physical hard drivesyou have installed in your computer. This does not include any external harddrives or flash drives. Devices with Removable Storage – This area lists any external hard drives, flash drives, or CD/DVD drives. Network Locations – This area lists any network drives you may be connected to. On-campus computers will have access to the Home (H:\) drive,which is your personal network space, the Shared (K:\) drive, which is shared among users in your department, and the Apps (I:\) drive, which stores applications that CaTS provides Quick Search Have you ever opened a window, such as the Control Panel, and have trouble finding what you are looking for? Windows 7 allows users to search individual windows through Quick Search. In our example, the user was able to find
26
1 COMPUTER SCIENCE
Windows Update by typing the word “update” (without quotations) in the searchfiled located in the top right corner of the window. The Quick Search field is available most windows.
.
27
