introduction to computer

1. Computer
• Advanced electronic device that takes raw
data as input from the user and processes
these data under the control of set of
instructions(called program) and gives the
result(output) and saves output for the future
use.
• It can process both numerical and non-
numerical (arithmetic and logical) calculations.

2. Computer
• Combination of hardware and software resources
which integrate together and provides various
functionalities to the user.
• Hardware: Physical components of a computer
like processor, memory devices, monitor,
keyboard etc.
• Software: Set of programs or instructions that are
required by the hardware resources to perform
various operations as per the requirement of
users.

3. Data vs Information
Data are raw numbers or other findings which,
by themselves, are of limited value.
Information is data that has been converted into
a meaningful and useful context.
*Computers are being used extensively
nowadays in everyday life/every field in the
form of laptop, desktop, smartphone,gadgets
etc.

4. Advantages of computer
• Speed
• Accuracy
• Huge storage
• Versatility
• Tirelessness

5. Disadvantages of computer
• Data security issue
• Computer crimes
• Health risk
• Bad impact on environment if not properly
disposed off.

6. Any digital computer performs five functions in
gross term.
1. Take data as input
2. Stores data/instructions
3. Process those stored data
4. Generate the output
5. Control all above steps

7. Computing
The use of a computer to process data or
perform calculations or the act of calculating
through computer is known as computing.

8. Generations of computer
First Generation:
• 1940-56
• uses vaccum tubes
• Slow, expensive and unreliable.
• machine language was used for giving instructions.
• computers are large in size.
• Programming was difficult.
• Electricity consumption was very high.
• Generates lot of heat.
• Not very reliable as electric failure occur regularly.
• Magnetic drum is used for storage.
• Example: ENIAC, EDVAC

9. Second generation
• 1956-63
• Vaccum tubes were replaced by transistors.
• Smaller in size.
• Power required is 1/10 of vaccum tubes.(Low electricity
consumption)
• Generate less heat.
• More reliable and faster.
• Mostly suitable to scientific and bulk data processing tasks only.
• Not for business purposes
• storage devices used are magnetic tape and hard disk.
• Machines were costly.
• Frequent maintainence was required.
• Ex: IBM1400

10. Third Generation
• 1964-71
• Replace transistors with Integrated circuit known as chip.
• IC is a small electronic circuit on a small chip of silicone which is also
known as semi conductor.
• Smaller, faster,inexpensive and more reliable.
• Less power consumption.
• High level language invented.
• Size of main memory reached about 4Mb and storage about 100MB.
• From small scale integrated circuits which had 10 transistors per chip,
technology developed to MSI circuits with 100 transistors per chip.
• I/O devices used are keyboard and printer
• Storage used is hard disk and floppy disk.
• Ex: IBM360, Honeywell model

11. Fourth Generation
• 1972-Present
• LSI and VLSI were used
• Microprocessor was invented.
• Hardware technology such as silicone chips, storage devices are invented.
• A microprocessor is a specialized chip which is developed for computer memory
and logic.
• Computers are known to be microcomputer.(IBM and APPLE developed)
• High capacity harddisk was introduced.
• Portable computers developed.
• Great development in data communication.
• Different types of secondary memory for high storage capacity upto TBs are
developed.
• Programming in High Level Language.
• Smaller, faster, cheaper, more reliable
• Different I/O , memory and storage devices are used.
• Ex: Pentium, dell,IBM,Macintosh etc.

12. Fifth Generation
• Present and Beyond
• Based on AI
• Still in development
• E.g. Voice recognition application,Robotics
• Features: Parallel processing: Processors are
grouped together to function as one large
processor
• Quantum computation and molecular and
nanotechnology will change the face of
computers in years to come.

13. Block Diagram of Computer System

14. The processor unit(CPU)
• It is the Brain of computer system. All major calculations and
comparisons are made inside the CPU.
• Also responsible for controlling the operation of other unit.
• It consists of two major components: ALU and CU
• ALU(arithmetic logic unit): It performs all arithmetic operations
such as addition, subtraction,multiplication and division. It also uses
logic operation for comparison.
• CU(Control Unit): It controls all devices such as memory, I/O devices
connected to the CPU.
• CU fetches instructions from memory, decodes the instruction,
interpret the instruction to know what the task are to be performed
and sends suitable control signals to other components to perform
the necessary steps to execute the instruction.

15. I/O Unit
• It consists of devices used to transmit
information between the external world and
computer memory.
• The information fed through the input unit is
stored in computer’s memory for processing
and the final result stored in memory can be
recorded or display on the output medium.

16. Input Devices
• Helps to enter data into the computer system.
• It can send data or information to a computer
or another device.
• Input Unit: A device through which data and
programs from the outside world enter the
computer system.

17. Input Devices
• Keyboard: It is an input device which sends data
in to the computer. The data send depends on
the key pressed by the user.
• Mouse: A mouse is a small handheld input device
which controls a cursor in a graphical user
interface. It can move and select text, files,
folders etc. on our computer according to the
user input.
• Scanner: Scanner optically reads and document,
file or image and then changes it into digital
signal and sends to the computer.

18. Input Devices
• OMR: optical mark recognition/ reader, is used to
read marks on a document and send them to
computer.
• OCR: OCR stands for optical character Recognition, is
an input device which reads printed text and sends
that to computer.

19. Input Devices
• MICR: Magnetic Ink Character Reader is an
input device which generally finds application
is banks to process cheques.
• Barcode reader: It is used to read the barcode
of various items and feed the same to
computer

20. Input Devices
• Microphone: it receives audio generated by
some input source and sends the same to a
computer
• Webcam: it sends the captured images to a
computer.
• Graphics Tablets: This input device is used to
draw using hand.

21. Input Devices
• Trackballs: an upside down mouse ,encased
within a socket. Is a cursor control device.
• Gamepad: Also known as joy pad is the input
controller for video games.
• Joystick: these input devices are used to control
video games.

22. Output Device
• A device that can receive data from computer or
another device and create output with that data is
called output device. Some examples are:
• Monitor: A monitor is an output device that is
responsible for receiving data from a computer and
displaying that information as text or images for users
to see.
• Speakers: Receives sound signal from a computer and
then plays that sound signal and thus we hear songs or
music or any other audio.
• Projector: Gets data from a computer and displays or
projects the same information onto a screen or a wall.
Projector can directly accept data from a user and send
that data to another device.

23. Both Input/Output Devices
• An input/output device is capable of receiving data from users or another
devices and also sending data to another devices or computers. That means
a devices which can be used as both input device and output device are
called Input /Output (I/O) devices. Some examples of input/output devices
are as:
• USB drive: Also known as pen drive or flash stick works as both input device
to computer and as an output device. USB drives receive or save data from
a computer as an input and it can also send data to a computer or another
device.
• Facsimile: Facsimile or FAX machine has a scanner which is an input device
and a small printer to provide output.
• Modems:It is used to transmit and receive data from one computer to
another computer or other devices using telephone lines
• CD-RW drives and DVD-RW drives: Receives data from a computer as input
to copy onto and save into writable CD or DVD. We also use CDs or DVDs to
transfer data to a computer.
• Touch Screen: Touch screen is both input and output device. By touching
the screen input is provided and being a screen, it is used as an output
device.
• Headsets: Headset consists of speaker as an output device and microphone
functions as an input device.

24. Computer Memory
• It is just like human brain.
• In this, all intermediate data, instructions and
final results are stored.
• It is the storage space in the computer where
data is to be processed and instructions
required for processing are stored.

25. Memory Unit
• How much memory is required for a file/data/prpgram etc is
measured by memory units.