3. 3 Computer
A computer is an electronic device,
operating under the control of instructions
stored in its own memory that can accept
data (input), process the data according
to specified rules, produce information
(output), and store the information for
future use
4. 4 Functionalities of a computer
Any digital computer carries out five functions in gross
terms:
Takes data as input.
Stores the data/instructions in its memory and use them
when required.
Processes the data and converts it into useful
information.
Generates the output
Controls all the above four steps
7. 7 Hardware
Computer hardware is the collection of
physical elements”Tangible objects”
that constitutes a computer system.
The actual machinery, wires, transistors,
and circuits … etc.
10. 10 Computer Units
1.Input Unit
2.Central processing Unit
3.Primary Memory Unit
4.Secondary storage Unit
5.Output Unit
11. 11 Input Devices
Input device is any peripheral (piece of
computer hardware equipment to provide
data and control signals to an information
processing system such as a computer or
other information appliance.
Input device Translate data from form that
humans understand to one that the
computer can work with. Most common are
keyboard and mouse
14. 14 Example of Input Devices
Keyboard Mouse (pointing device) Microphone
Touch screen Scanner Webcam
Touchpads MIDI keyboard
Graphics Tablets Cameras Pen Input
Video Capture Hardware Microphone Trackballs
Barcode reader Digital camera Joystick
Gamepad Electronic Whiteboard
Note: The most common use keyboard is the QWERTY keyboard.
Generally standard Keyboard has 104 keys
15. 15 Central Processing Unit
CPU
known as microprocessor or processor
It is responsible for all functions and processes
16. 16 CPU Components
The CPU is comprised of three main parts
1. ALU (Arithmetic Logic Unit)
2. Control Unit (CU)
3. Registers: Stores the data that is to be
executed next.
17. 17 ALU
Executes all arithmetic and logical operations.
Arithmetic calculations like as addition,
subtraction, multiplication and division.
Logical operation like compare numbers,
letters, or special characters
18. 18 Control Unit (CU)
Control Unit (CU): controls and co-ordinates computer
components.
Read the code for the next instruction to be executed.
Increment the program counter so it points to the next instruction.
Read whatever data the instruction requires from cells in memory.
Provide the necessary data to an ALU or register.
If the instruction requires an ALU or specialized hardware to
complete, instruct the hardware to perform the requested
operation.
21. 21 Primary Memory
1. RAM: Random Access Memory: is a memory scheme
within the computer system responsible for storing data on
a temporary basis, so that it can be promptly accessed
by the processor as and when needed.
It is volatile in nature, which means that data will be
erased once supply to the storage device is turned off.
RAM stores data randomly and the processor accesses
these data randomly from the RAM storage.
RAM is considered "random access" because you can
access any memory cell directly if you know the row
and column that intersect at that cell.
22. 22 Primary Memory
2. ROM (Read Only Memory): ROM is a
permanent form of storage. ROM stays
active regardless of whether power supply
to it is turned on or off. ROM devices do not
allow data stored on them to be modified.
23. 23 Secondary Memory
Stores data and programs permanently
its retained after the power is turned off
Main Examples
1. Hard Disk
2. Optical Disk
3. Flash memory
24. 24 Hard Disk
Called Disk drive or HDD
stores and provides relatively quick access
to large amounts of data.
Stores data on an electromagnetically
charged surface or set of surfaces.
25. 25 Optical Disk & Flash
an optical disc drive (ODD) is a disk drive that uses laser
light to store data.
There are three main types of optical media: CD, DVD,
and Blu-ray disc
CD “Compact Disk” can store up to 700MB
DVD “ Digital Video Disk “ can store up to 8.4 GB
Blu-ray disc. can store up to 50 GB
26. 26 3. Flash Disk
A storage module made of flash memory chips. A Flash
disks have no mechanical platters or access arms, but
the term "disk" is used because the data are accessed
as if they were on a hard drive. The disk storage structure
is emulated.
27. 27 Output Unit
An output device is any piece of
computer hardware equipment used to
communicate the results of data
processing carried out by an information
processing system (such as a computer)
converts the electronically generated
information into human-readable form.
29. 29 Output devices Examples
1. A monitor
CRT: Cathode Ray Tube
LCD: Liquid crystal display most
familiar these days
30. 30 Output devices Examples
2. Printer:
transfers data from a computer onto paper
Printer types:
1-Laser Printer.
2-Ink Jet Printer.
3-Dot Matrix Printer
31. 31
Software
Software is a generic term for organized
collections of computer data and
instructions, often broken into two major
categories two major categories:
1. system software
2. application software
32. 32 System software
Known as Operating System
is responsible for controlling, integrating, and
managing the individual hardware
components of a computer system
Windows is an example of OS.
example of System Software:
1) Microsoft Windows
2) Linux
3) Unix
4) Mac OSX
5) DOS
33. 33 Application software
is used to accomplish specific tasks other than just running the computer system.
It may consist of:
a single program, such as an image viewer;
a small collection of programs (often called a software package) that work closely
together to accomplish a task, such as a spreadsheet or text processing system;
a larger collection (often called a software suite) of related but independent
programs and packages that have a common user interface or shared data format,
such as Microsoft Office,
34. 34 Unit of Measurements - Storage
Storage Units
Bit BIT 0 or 1
Byte B 8 bits
Kilobyte KB 1024 bytes
Megabyte MB 1024 kilobytes
Gigabyte GB 1024 megabytes
Terabyte TB 1024 gigabytes
35. 35 Size example
• 1 bit - answer to an yes/no question
• 1 byte - a number from 0 to 255.
• 90 bytes: enough to store a typical line of text from a
book.
• 4 KB: about one page of text.
• 120 KB: the text of a typical pocket book
• 3 MB - a three minute song (128k bitrate)
• 650-900 MB - an CD-ROM
• 1 GB -114 minutes of uncompressed CD-quality audio at
1.4 Mbit/s
• 8 -16 GB - size of a normal flash drive
36. 36
A. 10B is equivalent 10 * 8 = 80 bits
B. 3MB is equivalent to how many
Bits?
Answer:
• 3 *1024 = 3072 KB
• 3072*1024 = 3145728 B
• 3145728 * 8 = 25165824 bits
37. 37 Unit of Measurement -Speed
The speed of CPU measured by unit
called Hertz (Hz)
1 Hz represent 1 cycle per second.
The speed of CPU is known as Computer
Speed.
38. 38 Unit of Measurement -Speed
CPU SPEED MEASURES
1 hertz or Hz 1 cycle per second
1 MHz 1 million cycles per second or 1000 Hz
1 GHz 1 billion cycles per second or 1000 MHz
39. 39 Computer Classification
Computers can be classified by size and power
to:
1. Personal computer (PCs)
2. Workstation:
3. Minicomputer
4. Mainframe:
5. SuperComputer
40. 40 Computer Classification
Personal computer (PCs): a small, single-user
computer based on a microprocessor. In
addition to the microprocessor, a personal
computer has a keyboard for entering data, a
monitor for displaying information, and a
storage device for saving data.
41. 41
Workstation: a powerful, single-user computer. A
workstation is like a personal computer, but it has a
more powerful microprocessor and a higher-quality
monitor.
43. 43
Mainframe: powerful
multi-user computer
capable of supporting
many hundreds or
thousands of users
simultaneously.
Mainframe computers that are
used in banking institutions
store data pertaining to client
records, domestic operations
and other vital processing
information.
45. 45 Laptop computer
is a portable computer.
personal computer that can be easily
carried and used in a variety of locations.
run the same software and applications in PCs
46. 46 Netbook Computer
A netbook is a type of laptop that is
designed to be even more portable.
Cheaper and less powerful than laptops or
desktops.
They are generally less powerful than other
types of computers, but they provide
enough power for email and internet
access, which is where the name "netbook"
comes from.
47. 47 Mobile Devices
A mobile device is basically any handheld
computer.
It is designed to be extremely portable.
Some mobile devices are more powerful
Types:
1.Tablet Computers
2.Smartphones
48. 48 Tablet Computers
designed to be portable.
The most obvious difference is that tablet
computers don't have keyboards or
touchpads.
Best used for tasks like web
browsing, watching videos, reading e-
books, and playing games.
49. 49 Tablet Computers
The most obvious difference is that tablet computers don't
have keyboards or touchpads. Instead, the entire screen is
touch-sensitive, allowing you to type on a virtual keyboard
and use your finger as a mouse pointer.
Tablet computers are mostly designed for consuming media,
and they are optimized for tasks like web browsing, watching
videos, reading e-books, and playing games
50. 50 Smartphones
a powerful mobile phone
designed to run a variety of applications
in addition to phone service.
Compare it with the tablet?
Internet access is an important feature of
smartphones. (3G or 4G)(Wi-Fi Service)
52. 52 Characteristics of Computer
Speed :The computer can process data very
fast, at the rate of millions of instructions per
second
Accuracy: Computer provides a high degree of accuracy.
For example, the computer can accurately give the result of
division of any two numbers up to 10 decimal places.
Diligence: When used for a longer period of time, the
computer does not get tired or fatigued. It can perform long
and complex calculations with the same speed and accuracy
from the start till the end.
53. 53 Characteristics of Computer
Storage Capability: Large volumes of data and
information can be stored in the computer and also
retrieved whenever required. A limited amount of
data can be stored, temporarily, in the primary
memory. Secondary storage devices like floppy disk
and compact disk can store a large amount of data
permanently.
Versatility: Computer is versatile in nature. It can
perform different types of tasks with the same ease.
At one moment you can use the computer to
prepare a letter document and in the next moment
you may play music or print a document.
55. 55 Viruses
A computer virus is an application program
designed and written to destroy other programs.
A virus is a small piece of software that piggybacks
on real programs
virus might attach itself to a program such as a
spreadsheet program
and it has the chance to reproduce (by attaching
to other programs)
56. 56 E-mail viruses:
e-mail virus travels as an attachment to e-mail
messages
Replicates itself by automatically mailing itself to
dozens of people in the victim's e-mail address
book.
57. 57 Trojan horses
simply a computer program
The program claims to do one thing (it
may claim to be a game) but instead
does damage when you run it
58. 58 Worms
A worm is a small piece of software that
uses computer networks and security
holes to replicate itself.بڑھانا تعداد اپنی
worm scans the network for another
machine that has a specific security hole.
59. 59 Malicious Software
How do you know if you have a virus?
Lack of storage capability
Decrease in the speed of executing
programs
Unexpected error messages
Halting the system
60. Tips to avoid viruses and lessen their impact?
1. Delete e-mails from unknown or suspicious,
untrustworthy (unreliable) sources, especially
those with files attached to an e-mail.
2. Never open a file attached to an e-mail unless
you know what it is, even if it appears to come
from a friend.
3. Download files from the Internet only from
legitimate and reputable sources.
4. Update your antivirus software at least every two
weeks as over 200 viruses are discovered each
month.
5. Backup your files periodically
60
