1. LECTURE 2
Rubina Adnan

2. Computers In Society

More impact than any other invention
 Changed
work and leisure activities
 Used by all demographic groups

Computers are important because:
 Provide
information to users
 Information is critical to our society
 Managing information is difficult

3. Computers In Society

Computers at home
Many homes have multiple computers
 Examples

Staying in touch with family and friends
 Information like weather


Computers are used for
Business
 Entertainment
 Communication
 Education


4. Computers In Society

Computers in education


Computer literacy required at all levels
Computers in small business
Makes businesses more profitable
 Allows owners to manage
 Small business can handle their own accounts and
payrolls


Computers in industry
Computers are used to design products
 Assembly lines are automated


5. Computers In Society

Computers in government
 Necessary
to track data for population
 Police
officers
 Tax calculation and collection
 Millitary
 Governments
were the first computer users and
responsible for development of new technology
 US government played a key role in development
of internet

6. Computers In Society

Computers in health care
 Revolutionized
health care
 New treatments possible
 Scheduling of patients has improved
 Delivery of medicine is safer
 More easy for doctors to share information

7. Parts of the Computer System
1B-7

Computer systems have four parts
 Hardware
 Software
 Data
 User

8. Parts of the Computer System

Hardware
 Mechanical
devices in the computer
 Anything that can be touched

Software
 Tell
the computer what to do
 Also called a program
 Thousands of programs exist

9. Parts of the Computer System

Data
 Pieces
of information
 Computer organize and present data

Users
 People
operating the computer
 Most important part
 Tell the computer what to do

10. Information Processing Cycle





Steps followed to process data
Input
Processing
Output
Storage

11. Essential Computer Hardware


Computers use the same basic hardware
Hardware categorized into four types

12. A simplified view of a computer
system
Monitor
Keyboard
Central
Processing
Unit
Main
Memory
Hard Disk

13. Hardware Devices

Input Devices (Get information)
 Keyboard
 Mouse
 Scanner

Output Devices (Give information)
 Screen/monitor
 Printer

14. Motherboard

Every device in a computer is either attached
to the motherboard directly or it is connected
to the motherboard.

The processor is usually directly on the
motherboard

Has circuits to connect the processor with
other components such as memory

15. Motherboard

In most personal computers the internal
devices such as sound cards, video cards are
directly plugged into the motherboard.

16. Processor

Processing devices
 Brains
of the computer
 Carries out instructions from the program
 Manipulate the data
 Most computers have several processors
 Central Processing Unit (CPU)
 Secondary processors
 Processors made of silicon and copper

17. Processor
 Has
three basic parts
 Arithmetic

executes all the arithmetic and logic instructions
 Control

Logic Unit (ALU)
Unit
decodes instructions and determines which is next to be
executed
 Buses/Registers


Buses are paths for information entering/exiting the CPU
Registers are memory for processing information

18. Processor

19. 

Processor is also called the CPU
It is the brain of the computer and does all the
calculations and processing.

20. Multi-core processor

A multi-core processor is a
single computing component with two or more
independent actual central processing
units (called "cores“.

21. The Central Processing Unit
 The CPU continuously follows the fetch-
decode-execute cycle:
Retrieve an instruction from main memory
fetch
execute
Carry out the
instruction
decode
Determine what the
instruction is

22. Storage

Storage
 Two
types
 Primary

and secondary
Primary Storage (main memory)
 On
board memory (located on the motherboard)
 Very fast, but expensive

23. Primary Storage



On board memory (located on the
motherboard)
Very fast, but expensive
Types
– Random Access Memory
 ROM – Read Only Memory
 Registers
 Cache
 RAM

24. Random Access Memory


RAM comes in integrated circuit chips, often
called modules or sticks, which are plugged
directly into a computer's motherboard.
Main memory is directly or indirectly
connected to the central processing unit via
a memory bus

25. Random Access Memory

26. Random Access Memory

RAM - Random Access Memory
Read/write capability
 Contents lost when computer is turned off (volatile)
 A program must be in RAM for it to execute
 128 to 256MB for a typical desktop computer
 You can read or write at any address, as opposed to
sequential memory
 RAM impact on the speed and power of a computer
 The unit of measurement for RAM is byte
 These days RAM’s are so large that we talk about GB
 1GB is 1 billion bytes (1000,000,000)


27. RAM
Address
9278
9279
9280
9281
9282
9283
9284
9285
9286
Content
10011010
Each memory cell has
a numeric
address, which
uniquely identifies it
Main memory
is divided into
many memory
locations (or
cells)
Each memory cell stores a
set number of bits (usually
8 bits, or one byte)
Large values are
stored in consecutive
memory locations

28. Registers




located inside the processor
Registers are the fastest of all forms of
computer data storage.
Holds only 32 bit or 64 bit
Example we have to add 23 and 14, then one
register will store 23 and the other 14

29. Cache





The cache is a smaller, faster memory which
stores copies of the data from the most
frequently used RAM locations.
When the processor needs to read from or
write to a location in main memory, it first
checks whether a copy of that data is in the
cache.
There are two levels of cache L1 and L2
L1 is located on the processor chip itself
L2 is not on the processor chip but is very fast
as well

30. ROM

ROM - Read Only Memory
 It
is written on to only once
 Read but not write capability
 Permanent (non volatile)
 Stores the preliminary instructions to be executed
when the computer is turned on, for example
 To
check RAM
 To check communications with peripheral devices
 Bootstrap loader program

31. Secondary Storgae

Secondary Storage (secondary memory)
 External
devices (not on the motherboard);
either inside or outside the computer
 Store programs and data permanently
 Slower, but cheaper

32. Secondary Storage

Hard disk

33. Hard disk

the hard drive is its long-term memory-preserving data programs and your operating
system even while the machine is asleep or off

34. Memory Hierarchy

35. Optical Storage


The CD surface is a mirror covered with
billions of tiny bumps that are arranged in a
long, tightly wound spiral.
The CD player reads the bumps with a precise
laser and interprets the information as bits of
data.

36. DVD




DVD’s are made from the same material as a
CD and are physically the same size but they
can store a lot more data
The reason is that in a CD there is only one
layer that has data arranged in spiral form
In a DVD there are several thin layers that can
store data that are joined together.
The materials on the top layers allows the
laser to pass through to the inner layer to read
data.

37. Blu Ray



The format offers more than five times the storage
capacity of traditional DVDs and can hold up to 25GB
on a single-layer disc
While current optical disc technologies such as
DVD, DVD±R, DVD±RW, and DVD-RAM rely on a red
laser to read and write data, the new format uses a
blue-violet laser instead, hence the name Blu-ray
The benefit of using a blue-violet laser (405nm) is that
it has a shorter wavelength than a red laser
(650nm), which makes it possible to focus the laser
spot with even greater precision. This allows data to
be packed more tightly and stored in less space, so
it's possible to fit more data on the disc even though
it's the same size as a CD/DVD

38. CD vs. DVD vs. Blu Ray




Most DVDs will hold about 4 hours of quality
video
A CD can have 700 MB, or approximately 80
minutes of audio.
DVD stores 4.7 GB of data
Blu Ray can store upto 50 GB data
*to get an idea 2 GB storage can give you approximately 300 mp3 songs

40. Hardware

Units of measure
 All
done relative to a Byte (8 bits - 1 character)
 KB = Kilobyte - 1 thousand bytes (1024)
 MB = Megabyte - 1 million bytes (1,048,576)
 GB = Gigabyte - 1 billion bytes
 TB = Terabyte - 1 trillion bytes

41. Software Runs The Machine



Tells the computer what to do
Reason people purchase computers
Two types
 System
software
 Application software

42. Software Runs The Machine

System software
 Most
important software
 Operating system
 Windows
 Network
XP
operating system (OS)
 Windows
Server 2003
 Utility
 Symantec AntiVirus

43. References







http://en.wikipedia.org/wiki/Multi-core_processor
Chapter 1b of Text book
http://computer.howstuffworks.com/ram.htm
http://www.howstuffworks.com/hard-disk.htm
http://www.ehow.com/how-does_4899593_ramwork-computer.html
http://tuxthink.blogspot.com/2010/06/memoryhierarchy.html
http://en.wikipedia.org/wiki/Computer_data_storag
e