A computer is defined as an electronic device that can perform calculations at enormous speeds and generate output from input data according to programmed instructions. It consists of hardware, software, data, and users. The hardware is the physical machinery including input devices like keyboards, output devices like monitors, storage devices, communication devices, and the central processing unit. Software includes system software that controls the hardware and application software that allows users to perform tasks. Data are the individual facts and pieces of information processed by the computer. Users are people who operate the computer and provide it with instructions and data.

2. 
Word Computer
The Word Computer comes from word “Compute”
Computer

3. 
The Word Compute mean to calculate
Computer

4. 
Def1
 Computer is a calculating device that can perform
Arithmetic Operation at enormous speed.
Computer

5. 
Def2
 More accurately, a computer may be defined as
device that operates upon information of data
Computer

6. 
Def 3
Computer can be defined as an electronic device that
performs rapid computations and generates desired output
for users based on input data and programs. Computer can
capture, store, retrieve and process data. The data may be
numbers, characters, audio, video, images etc. Basically,
computer can recognize only two states – whether a signal is
present or not. These two states are represented using binary
digits 1 and O. All forms of data are finally converted into
binary digits for the computer to recognize and process.
Instructions are also converted into binary digits. Digital
computer has the capability to manipulate series of binary
digits according to the instructions (software) given to it.
Computer

7. 
Def 4
 Computer is an electronic device that input data,
process it, store it , and produce out with high speed
and accuracy that is useful to the human being
Computer

8. 
Def
 The Study of computer and what they can do
 The study of Computers, Computer Construction
and what they can do.
Computer Science

10. 
 Speed
Modern computers have incredible speed of
processing. Computer speed is measured in units of
millisecond (one thousandth of a second),
microsecond (one millionth of a second),
nanosecond (one billionth of a second),
and picosecond (one trillionth of a second). Advanced
computers, including recent microcomputers called
super microcomputers, operate in nanoseconds and can
carry out millions of instructions per second (MIPS).
Characteristics of Computer

11. 
 Accuracy
Computer can ensure consistently very high degree of
accuracy in computations. It processes data according
to the sequence of instructions . Hence, if input data
and procedures are correct, the output will be
consistently accurate.
Characteristics of Computer

12. 
 Huge storage and fast retrieval
Computer has huge storage capability. For a personal
computer, 128 MB RAM is almost a standard toady.
The main memory can be upgraded further by inserting
RAM chips that are available in modules of 64 MB, 128
MB and so on. Cache memory is also available in Pc.
Cache memory is faster access memory device and
hence it improves processor performance. Secondary or
auxiliary storage devices are used for permanent
storage. Modern computers have enormous secondary
storage capacity, e.g., a PC hard disk can store more
than 80 GB of data. Pen drives, DVDs, CD-ROMs, CD-
Rs, magnetic tapes etc.
Characteristics of Computer

13. 
 Versatility
Though computers are basically designed to carry out
only arithmetic operations, yet they are capable of
performing almost any task that has a series of finite
logical steps. Computers can be used for
communications, process control, research, weather
forecasting, healthcare, online trading, education,
training, defense applications and so on.
Characteristics of Computer

14. 
 Free from fatigue
Computer is free from fatigue. It does not get tired of
work and never loses concentration. It can perform
basic arithmetic operations with the same degree of
speed and accuracy for any extent of time continuously,
with the same amount of efficiency as the first
transaction.
Characteristics of Computer

15. 
 Programmable
Computer can be programmed to function
automatically and this differentiates it from any other
calculation device. It functions as programmed for any
stretch of time until the condition to terminate is
satisfied.
Characteristics of computer

16. 
 Networking capability
Computers can be interconnected into a network.
Network in turn can be connected to other networks.
Networks extend the capability of computers. The
networks provide the basic infrastructure for electronic
communications, electronic commerce, online trading
and information services.
Characteristics of Computer

18. 
1. Computer cannot think on its own. It has to be
given instructions to perform any operation.
Research is currently underway to impart artificial
intelligence to computer. Once this becomes
possible computer will be thinking on its own, then
it will be a reasonable replication of human mind.
2. It does not have intuition. It cannot draw a
conclusion without going through all intermediate
steps.
Limitations of Computer

19. 
3. It can do a task only if it can be expressed in a series
of finite steps leading to the completion of the task.
4. Similarly, it cannot handle a situation where a finite
number of steps generate an impossibly large
number of computational operations.
5. It cannot learn from experience. It will commit the
same error repeatedly and cannot learn from
experience. But changes are taking place in this area as
research progresses on artificial intelligence.
Limitations of Computer

20. A complete Computer consists of four parts
1. Hardware
2. Software
3. Data
4. User

21. 
1. Hardware
The mechanical devices that make up the computer are
called hardware. Hardware is any part of the computer
you can touch. A computer hardware consists of
interconnected electronic devices that you can use to
control the Computer’s operation, input, and out put
Parts of computer

22. 1. Input hardware
2. Output hardware
3. Storage hardware
4. Communication hardware
5. Processing hardware

23. 
1. Input hardware:- A type of hardware that is used to
enter data or commands into Computer. E.g Mouse
Keyboard etc.
2. Output Hardware:- A type of Hardware that is used to
get information from computer and display to the user.
2.1- Softcopy output Hardware:- It is type of
Hardware whose output can only be seen but
can not be touched(Monitor).
2.2- Hardcopy output Hardware:-It is type of
Hardware whose output can only be seen as well
touched(Monitor).
Types of computer Hardware

24. 
3. Memory/Storage Hardware:- A device that can accept data, hold
them, and deliver on demand at a later time.
3.1- Primary Memory:- This types of hardware is
used to store data/instruction temporarily . Such
storage devices are volatile i.e. if the power is
interrupted, then the data are lost(RAM).
3.2- Secondary Memory:- Secondary memory is used
store data/instruction permanently. Secondary
storage device are non volatile i.e. if the power is
interrupted, then the data are not lost. Secondary
memory can not be processed directly by the processor.
It must be first copied into main memory(Hard disk).
Types of Computer Hardware

25. 
4. Communication hardware:- These types of hardware are
used to transfer data between two computers or between
two units of a computer.
4.1- Internal communication hardware:- it is type of
hardware that is used to transfer data from one unit to
another unit of computer. This communication hardware is
composed of various parallel lines know as bus.
4.2- External Communication hardware:- it used to transfer
data from one computer to another computer
5. Processing hardware:- It is type of hardware used to
process data according to the given instruction to
generate output (microprocessor).
Types of computer hardware

26. 
2. Software:
A software is (1)instruction(computer programs) that
when executed provide desired features, function and
performance;(2) data structure that enable the
programs to adequately manipulate information; and(3)
documents that describe the operation and use of
programs.
Parts of Computer

27. 1. System software.
2. Application software.

28. 
1. System Software:- System software is any program
that controls the computer’s hardware or that can be
used to maintain the computer in some way so that
it runs more efficiently.
Types of software

29.  Basic Types of System Software
• Operating System:- Operating is used to control the over all operation of
the computer, and act as an interface between the computer hardware and
software. Operating system provides an environment in which the other
executer and terminate properly.
• Translator/Language Processor:- Translator is system program the
converts the program from one language to another language.
• Utility :- Utility is Program that makes the computer system easier to use
or performs high specialized function. Utilities are used to manage disks,
troubleshoot hardware problem.
• Device Driver:-A device driver, often called a driver for short, is a
computer program that is intended to allow another program (typically, an
operating system) to interact with a hardware device. Think of a driver as a
manual that gives the operating system (e.g., Windows) instructions on
how to use a particular piece of hardware. A device driver essentially
converts the more general input/output instructions of the operating
system to messages that the device type can understand.
Types of software

30. 
2. Application Software:-Application software tells the
compute how to accomplish specific tasks, such as word
processing or drawing, for the user. Some Major
categories of application software.
• Word Processing software:- It is used for creating text-
based documents such as newsletters.
• Spreadsheets Software:- Spreadsheets is used for creating
numeric-based documents such as budgets.
• Data Base Management Software for building and
manipulating large set of data.
• Presentation:- Presentation programs are used for
creating and presenting electronic slide shows
Types of Software

31. 
3. Data
Data consist of individual facts or pieces of information
that by themselves may not make much sense to a
person. A computer primary job is to process these tiny
pieces of data in various way, converting them into
useful information.
Parts of computer

32. 
4. Users
People are the computer operators, also known as
users.
Parts of Computer

33. • Using all parts of computer together , a
computer converts data into information by
performing various action on data.
• A set of steps a computer follows to receive
data , process the data according instruction
from program, display the resulting
information to user, and store the result

34. Figure
Information processing Cycle
Input Processing Output
Storage

35. 
 Input:- during this part of the cycle, the computer
accepts data from some source, such as the user or
program, for processing.
 Processing:- During this part of the cycle, the
computer’s processing components perform action
on the data, based on the instruction from the user or
program.
Information Processing Cycle

36. 
 Output:- Here the computer may be required to
display the results of its processing. For example ,
the result may as text, number, or graphics on the
computer screen.
 Storage:- In this step, the computer permanently
store the result of its processing on a disk , tape, or
some other kind of storage medium.
Information Processing Cycle

38. 
Central Processing Unit(CPU)
The Computer’s primary processing device, which
interprets and execute program instructions and
manages the function of input, output, and storage
devices. The CPU is composed of CU,ALU , built in
main memory, and supporting circuitry such as a
dedicated math processor.
Organization of Computer

39. 
Computer Organization
Central Processing Unit(CPU)
Arithmetic Logic Unit (ALU) Control Unit(CU) Main Memory

40. 
Primary Memory
A memory or store is required in a computer to store
programs and the data processed by programs. The main
memory is made up of a large number of cells with each cell
capable of storing one bit. The cells may be organized as a set
of addressable words, each word storing a string of bits. The
main memory provides random access. The main memory is
divided into Random Access Memory (RAM) and Read Only
Memory (ROM). RAM is dynamic and volatile. ROM is read
only memory and this memory cannot be erased and
rewritten. That is, ROM is non-volatile.
Organization of Computer

41. 
Arithmetic Logic Unit (ALU)
ALU does all the arithmetic and logical operations.
Arithmetical operations involve manipulation of
numerical data such as addition, subtraction, division
and multiplication. Logical operations compare relative
magnitudes of two numeric, alphabetic or alphanumeric
data items such as greater than, less than, and equal to.
Organization of Computer

42. 
Control Unit (CU)
The control unit controls and co-ordinates all the
operations of the CPU and peripheral devices. Its
functions are to ensure that the program instructions are
carried out in the desired sequence and to control and
co-ordinate the flow of data between the CPU and the
input-output devices.
Organization of Computer

43. 
External Devices:
I/O operations are accomplished through a wide
arrangement of external devices that provides a means
of exchanging data between the external environment
and the computer. An external device attaches to the
computer by a link to an I/O module. The link is used
to exchange control, status, and data between the I/O
Module and the external devices. An external device
connected to an I/O module is often referred to as
Peripheral.
Organization of Computer

44. 
I/O Module:- One of the major component of
computer. It is responsible for the control of one or
more external devices and for exchange data between
those devices and main memory and/or CPU registers.
Organization of Computer

45. 
External Devices Classification
External device are broadly classified into Three
Categories
1. Human readable:- Suitable for the communication
with computer user e.g. VDT(Video Display
terminals) and Printer(Plug and play , None Plug
and play I/O Devices).
2. Machine Readable:- Suitable for communicating
with equipment e.g. Magnetic Disk.
Organization of Computer

46. 
External Devices Classification
3. Communication:- Suitable for communication with
remote devices, which may be a human-readable
device, such as terminal, machine-readable device,
or even another computer
Organization of Computer

47. 
Secondary Memory:
Limitation of Primary Memory
 Volatile
 Expensive
 Capacity
Organization of Computer

48. 
Secondary memory:-
Memory located outside the computer system itself; that is, it
can not be process directly by the processor. It must be first
copied into main memory. Example includes disk and tape.
Secondary storage is thus supplementary to primary storage.
It is, therefore, also called auxiliary storage. Secondary
storage has larger storage capacity and is cheaper than
primary storage. But access to secondary storage is slower
than that to primary storage. Hence, secondary storage holds
data and programs not currently in use.
Organization of Computer