2. UNIT – I
Characteristics of computer
Areas of application
Components of computer
Input and Output devices
Hardware and Software
3. A computer is a machine that can
store and process information.
Most computers rely on a binary
system, which uses two variables, 0
and 1, to complete tasks such as
storing data, calculating algorithms,
and displaying information.
WHAT IS COMPUTER?
Input, Process, Output, Storage
is the correct order of the four
major functions of a computer.
• A computer device’s speed is extremely fast, as it can
perform any calculation in seconds.
• This is one of the key characteristics of computers.
• This computer characteristic also enhances the versatility of
• Computer memory is the storage space on the computer
where data to be processed and processing instructions are
• It has both primary and secondary memories.
• Because computers are so versatile, they can perform almost
any task that can be reduced to a series of logical steps.
• It refers to the ability or adaptation to quickly switch from one
task to another.
• A computer is free of fatigue, lack of concentration, and so on.
• It can work for hours without making any mistakes.
• It’s like a superman who can fly and fight for hours and hours
8. • In the banking sector, computers are used to store details of
customers and conduct transactions, such as withdrawal and
deposit of money through ATMs.
• Banks have reduced manual errors and expenses to a great
extent through extensive use of computers.
•Nowadays, computers are totally integrated into business.
• The main objective of business is transaction processing, which
involves transactions with suppliers, employees or customers.
• Computers are used in hospitals to maintain a
database of patients’ history, diagnosis, X-rays,
• Surgeons nowadays use robotic surgical
devices to perform delicate operations, conduct
• Computers are used at homes for several purposes
like online bill payment, watching movies or shows at
home, internet access, etc.
• They provide communication through electronic
• MIDI instruments greatly help people in the
entertainment industry in recording music with
• Videos can be fed from computers to full screen
• Photo editors are available with fabulous features.
10. • IPO is a short form for – Input - Process
– Output model
• IPO is the output and input after the
processing of information.
• Input is given first to get the desired
output. This input is processed before the
output is released.
• It is a critical process for users in
computation. An IPO cycle is a procedure
for processing the information.
11. Input Unit
Computer Input unit means the device of the input and a part
of the computer hardware which is used for the transport of
the data processing system.
A central processing unit, also called a central processor, main
processor or just processor, is the electronic circuitry that
executes instructions comprising a computer program.
13. Components of computer
• Arithmetic and logic Unit (ALU)
• Control Unit (CU)
• Main Memory Unit (MMU)
Arithmetic and logic unit
• In computing, an arithmetic logic unit (ALU).
• combinational digital circuit that performs arithmetic
and bitwise operations on integer binary numbers.
14. • Registers
It is used for temporary storage. Some of the
registers are instruction registers, address registers, etc.
• Program Counter
It is used to store the address of the instruction, that
is to be executed.
It is used to perform arithmetic and logical operations
• A control unit, or CU, is circuitry within
a computer's processor that directs
15. • It instructs the memory, logic unit, and both output and
input devices of the computer on how to respond to the
Main Memory Unit
• Primary storage (RAM)is called 'primary' because it is the
main memory that is accessible to the CPU.
• It is used to store data that is currently being used.
17. • This isn't to be confused with long-term data that's stored on your
hard drive, which stays there even when your computer is turned
Read Only Memory
• Read-only memory, or ROM, is a type of
computer storage containing non-volatile,
• Normally, can only be read, not written to.
• ROM contains the programming that
allows a computer to start up or
regenerate each time it is turned on.
18. The other types of ROM are
• PROM is a blank version of ROM.
• It is manufactured as blank memory
and programmed after manufacturing.
• We can say that it is kept blank at the
time of manufacturing.
• You can purchase and then program it
once using a special tool called a
• EPROM is a type of ROM that can be reprogrammed and
erased many times.
19. • It comes with a quartz window through which
a specific frequency of ultraviolet light is
passed for around 40 minutes to erase the
• So, it retains its content until it is exposed to
the ultraviolet light.
• ROM is a type of read only memory that can be
erased and reprogrammed repeatedly, up to
• It is also known as Flash EEPROM as it is similar
to flash memory.
• It is erased and reprogrammed electrically
without using ultraviolet light.
• Access time is between 45 and 200.
20. Secondary Memory
• Secondary storage is a memory that is stored external to the
• There are two types of secondary memory.
Random access memory
• An input device allows data such as
text, images, video or sound to be
entered into a computer system.
21. • The most common input device used for
• Includes keys for word processing and data
inputting, and for performing specific
• Joy Stick.
• Light pen.
• Track Ball.
• A mouse is a small device that a computer
user pushes across a desk surface.
• In order to point to a place on a display
screen and to select one or more actions to
take from that position.
22. Output Devices
• An output device allows data to be
transmitted by the computer in a human
• For example, sound being played
through a speaker.
• In computing, a printer is a peripheral
• Which makes a persistent representation
of graphics or text, usually on paper.
• While most output is human-readable,
bar code printers
• A plotter is a machine that produces vector
• Plotters draw lines on paper using a pen, or in
some applications, use a knife to cut a material
like vinyl or leather.
• In the latter case, they are sometimes
known as a cutting plotter.
24. Hardware and Software
• Software, on the other hand,
refers to a set of instructions
which enable the hardware to
perform a specific set of tasks.
• Hardware refers to the physical
and visible components of the
system such as a monitor, CPU,
keyboard and mouse.
25. OPERATING SYSTEM
• An operating system (OS) is the program
that, after being initially loaded into the
computer by a boot program.
• Manages all of the other application
programs in a computer.
Types of Operating System
• Batch OS.
• Distributed OS.
• Multitasking OS.
• Network OS.
• Mobile OS.
26. Batch operating system
• This type of operating system does not
interact with the computer directly.
• There is an operator which takes similar
jobs having the same requirement and
group them into batches.
Distributed operating system
• These types of the operating system is a
recent advancement in the world of computer
• Being widely accepted all over the world
and, that too, with a great pace.
• Various autonomous interconnected
computers communicate with each other.
27. Real time operating system
• These types of OSs serve real-time systems.
• The time interval required to process and
respond to inputs is very small.
• This time interval is called response time.
Network operation system
• These systems run on a server and provide the
capability to manage data, users, groups, security,
applications, and other networking functions.
• These types of operating systems allow shared
access of files, printers, security, applications, and
other networking functions over a small private