2. Topic1:Evaluation of computers
What is Computer ?
A programmable machine.
Which responds to a specific set of instructions in a well-
defined manner
3. WHAT IS A COMPUTER?
A computer is an electronic device, operating under
the control of instructions stored in its own memory
unit,
that can accept data (input),
process data arithmetically and logically,
produce results (output), and store the results
for future use.
4. COMPONENTS OF A
COMPUTER
Basic Components
Input Devices
System Unit
Output Devices
Storage Devices
Other Components
Peripheral Devices
Communication Devices
6. GENERATIONS OF
COMPUTERS
This term is also used in the different advancements of
computer technology. With each new generation, the
circuitry has gotten smaller and more advanced than
the previous generation before it.
5 generations of computer
I. First generation(1946-1959)
II. Second generation(1959-1965)
III. Third generation(1965-1971)
IV. Fourth generation(1971-1980)
V. Fifth generation(1980 onwards)
7. FIRST GENERATION(1946-
1959) VACUUM
TUBES
The first computers used vacuum tubes for
circuitry and magnetic drums for memory
Main Features
They were very expensive
Non portable
Huge size
Supported machine language
Very slow speed
Consumed lot of electricity
Generate lot of heat
Slow I/O
8. SECOND GENERATION(1959-
1965) TRANSISTORS
Transistors replaced vacuum tubes and ushered in the
second generation of computers.
Main Features
Use of transistors
Small size as compare to first generation
Generate less heat as compare to first generation
Faster than first generation
Still very costly
Support machine and assmebly languages
9. THIRD GENERATION(1965-
1971)
INTEGRATED CIRCUITS
The development of the integrated circuit was the hallmark of
the third generation of computers. Transistors were miniaturized
and placed on silicon chips, called semiconductors, which
drastically increased the speed and efficiency of computers.
Main Features
IC used
More reliabel
Still costly
Faster
Lesser maintenance
Smaller size
Support high level languages
Consumed lesser electricity
10. FOURTH GENERATION(1971-
1980) MICROPROCESSOR
The microprocessor brought the fourth generation of
computers, as thousands of integrated circuits were
built onto a single silicon chip.
Main Features
VLSI technology
Very cheap
Portable and reliable
Increased capabilities of I/O
Concept of internet was introduced
Pipeline processing
11. FIFTH GENERATION(1980
ONWARDS)
ARTIFICIAL INTELLIGENCE
Fifth generation computing devices, based on
artificial intelligence, are still in development.
though there are some applications, such as voice
recognition, that are being used today. The use of
parallel processing and superconductors is helping
to make artificial intelligence a reality.
The goal of fifth-generation computing is to
develop devices that respond to natural language
input and are capable of learning and self-
organization.
12. TOPIC 2: HARDWARE ORGANIZATION
OF A COMPUTER
Basic Computer Components
13. THE CENTRAL PROCESSING
UNIT
It is the brain of a computer system
The CPU:
receives input.
interprets instructions provided by programs.
directs other components of the system to
act.
processes data.
controls output.
14. THE CENTRAL PROCESSING
UNIT
Control Unit ALU
Register
s
Bus
CPU
Memory
Control Unit: The control unit controls the computer
by repeating 4 operations, called the machine cycle. The
4 operations are:
1. fetching program instructions from memory
2. decoding the instructions into commands that
the computer can process
3. executing the commands
4. storing the results in memory
16. THE CENTRAL PROCESSING
UNIT
Control Unit ALU
Register
s
Memory
Bus
CPU
Registers
They hold program instructions, data values, and
memory locations as the computer executes a
program.
18. THE CENTRAL PROCESSING
UNIT
Control
Unit
ALU
Register
s
Bus
CPU
Memory
Memory
accepts and holds program instruction and data
acts as the CPU’s source for data and instructions
and as a destination for operation results
holds the final processed information until it can
be sent to the desired output or storage devices, such
as printer or disk drive
20. 1. COMPUTERS CLASSIFICATION
ACCORDING TO DATA
REPRESENTATION TECHNIQUES
According to DRT ,computers can be classified into
three types
computers
Digital Analog
Hybrid
21. DIGITAL
COMPUTERS
A computer that stores data in terms of digits (numbers)
and proceeds in discrete steps from one state to the
next.
1
0
Digital computers have the capabilities of adding,
subtracting, multiplying ,dividing and comparing. These
computers provide highly accurate results.
For example:
I. Desk Calculators
II. Electronic computers
22. ANALOG
COMPUTERS
A computer that represents data in terms of physical
measures or quantities and proceeds along a continuum
constituted by its components
These computers are suitable for use as controlling
devices in factories ,military weaponry.
For example:
Speedometer
Voltmeters
Wall clock
Flight
simulators
23. HYBRID
COMPUTERS
Hybrid computers are computers that comprise features
of analog computers and digital computers. The digital
component normally serves as the controller and
provides logical operations, while the analog component
normally serves as a solver of differential equations.
For example:
Intensive care unit (I.C.U)
24. 2. COMPUTER CLASSIFICATION BY
CAPACITY
PERFORMANCE CRITERIA
(BY SIZE, COST, SPEED & MEMORY)
Computer
s
Micr
o
Min
i
Mainframe
s
Super
Deskto
p
Lapto
p
Palmto
p
25. SUPER
COMPUTERS
The biggest in size
the most expensive in price
It can process trillions of instructions in seconds.
This computer is not used as a PC in a home neither
by a student in a college.
Governments specially use this type of computer
for their different calculations and heavy jobs.
In most of the Hollywood's movies it is used
for animation purposes.
This kind of computer is also helpful for
forecasting weather reports worldwide
26. MAINFRAME
COMPUTER
This can also process millions of instructions per
second and is capable of accessing billions of data.
This computer is commonly used in big hospitals, air
line reservation companies, and many other huge
companies prefer mainframe because of its capability
of retrieving data on a huge basis.
This is normally to expensive
This kind of computer can cost thousands of dollars
27. MINI
COMPUTERS
Mini computers generally have greater size, main
and secondary memories and powerful processor.
It is capable of supporting from 4 to about 200
simultaneous users.
It is commonly used as a server in the network
environment.
Mini computers are usually multi-user systems so
they are used in interactive
applications in industries
,research organizations, colleges, and universities.
28. MICRO
COMPUTERS
A micro computer is a small and low cost
digital computer
Which usually consists of a microprocessor, a
storage unit, a power supply, appropriate peripherals.
They are mainly used for managingpersonal data of
a small company or an individual. that’s why they are
called (PC).
29. INTRODUCTION TO
MICROPROCESSOR
Microprocessor, the key component, the brain, of a
computer
its various sub-systems
Bus interface unit
Data & instruction cache memory
Instruction decoder
Arithmetic-Logic unit
Floating-point unit
Control unit
30. MICROPROCES
SOR
The key element of all computers, providing
the mathematical and decision making ability
Current state-of-the-art uPs (Pentium, Athlon,
SPARC, PowerPC) contain complex circuits consisting
of tens of millions of transistors
They operate at ultra-fast speeds – doing over a
billion operations very second
Made up from a semiconductor, Silicon
31. INTEGRATED
CIRCUITS
•Commonly known as an IC or a chip
•A tiny piece of Silicon that has several electronic
parts on it
•Most of the size of an IC comes form the pins and
packaging; the actual Silicon occupies a very small
piece of the volume
•The smallest components on an IC are much
smaller than the thickness of a human hair
33. BUS INTERFACE
UNIT
Receives instructions & data from main memory
Instructions are then sent to the instruction cache, data
to the data cache
Also receives the processed data and sends it to the
main memory
Instruction Decoder
This unit receives the programming instructions
and decodes them into a form that is understandable
by the processing units, i.e. the ALU or FPU
Then, it passes on the decoded instruction to the
ALU or FPU
34. Arithmetic & Logic Unit (ALU)
It performs whole-number math calculations (subtract,
multiply, divide, etc) comparisons (is greater than, is
smaller than, etc.) and logical operations (NOT, OR,
AND, etc)
Floating-Point Unit (FPU)
Also known as the “Numeric Unit”
It performs calculations that involve numbers
represented in the scientific notation (also known
as floating-point numbers).
Floating-point calculations are required for doing
graphics, engineering and scientific work
35. Registers
Both ALU & FPU have a very small amount of super-fast
private memory placed right next to them for their exclusive
use. These are called registers
The ALU & FPU store intermediate and final results from
their calculations in these registers
Processed data goes back to the data cache and then to main
memory from these registers
Control Unit
The brain of the uP
Manages the whole uP
Tasks include fetching instructions & data, storing data,
managing input/output devices
36. INSTRUCTION
SET
The set of machine instructions that a uP
recognizes and can execute – the only language uP
knows
An instruction set includes low-level, a single step-
at- a-time instructions, such as add, subtract, multiply,
and divide
Each uP family has its unique instruction set
Bigger instruction-sets mean more complex chips
(higher costs, reduced efficiency), but shorter
programs
37. MICROPROCESSOR
GENERATIONS
First generation: 1971-78
Behind the power
curve (16-bit, <50k
transistors)
Second Generation: 1979-85
Becoming “real”
computers (32-bit , >50k
transistors)
Third Generation: 1985-89
Challenging the “establishment”
(Reduced Instruction Set
Computer/RISC,
>100k transistors)
Fourth Generation: 1990-
Architectural and performance
leadership (64-bit, > 1M transistors,
Intel/AMD translate into RISC
internally)
38. MOORE’S
LAW
In 1965, one of the founders of Intel – Gordon Moore
– predicted that the number of transistor on an IC
(and therefore the capability of microprocessors) will
double every year. Later he modified it to 18-months
His prediction still holds true in ‘02. In fact, the time
required for doubling is contracting to the original
prediction, and is closer to a year now
43. TYPES OF
INPUT
Data
⚫ raw facts that a computer receives and processes
to produce information
Programs
⚫ instructions that direct the computer operations
Commands
⚫ key words that direct the computer to perform
certain activities
User Responses
⚫ data a user enters to respond to a
question or message.
44. A.
KEYBOARDS
The most commonly used input devices.
Contains alphanumeric, cursors
and function keys.
Function key
Numeric keyp
45. Function Keys, labeled from F1 to F12, allow user to quickly
access commands and functions, such as saving a document or
calling up a program’s Help feature.
Cursor-control Keys govern the movement of the cursor on the
screen. They include Up Arrow, Down Arrow, Left Arrow and
Right Arrow key on the keyboard.
Special Purpose Keys are used in conjunction with other keys to
enter commands into a computer. Control (Ctrl), Alternate (Alt) and
Shift keys are example of special purpose keys.
Toggle Keys are keys that, when pressed, activates a certain mode
or condition, and when pressed again, deactivates the condition.
The Num Lock key, Cap Lock key and the Scroll Lock key are
examples of toggle keys
Numeric Keypad, located in the far right portion of the keyboard,
is used for entering numbers quickly and for performing the same
operations as a calculator.
46. TYPES OF
KEYBOARDS
Serial Keyboard
A serial Keyboard is one, which communicate the data to the Central
Processing Unit one bit at a time.This mean that bit patttern that forms
a perticular character is sent on a single wire.So,bit-by-bit transmission
is made.
Parallel Keyboard
A Parallel Keboard carries one Byte(8 bits ) at a time to the
Central Processing Unit. This means that the bit pattern that
forms a character is sent on 8 different wires. Each wire
carries one bit.
47. B. POINTING DEVICES
Many people use pointing devices instead
of keyboards whenever possible.
Pointing devices minimize the amount of
typing (and the number of errors).
48. MOUS
E
Palm-sized pointing devices
a ball on the bottom senses its movement
various actions can be preformed by moving the
pointer and then pressing one of the buttons on top
of the mouse.
49. TYPES OF
MOUSE
Mechanical Mouse
A mouse that uses a rubber ball that makes contact with
wheels inside the unit when it is rolled on a pad or
desktop. Mechanical sensors within the mouse detect
the direction the ball is rolling and move the screen
pointer accordingly
Optomechanical Mouse
Same as a mechanical mouse, but uses optical sensors
to detect motion of the ball.
50. TYPES OF
MOUSE
Optical Mouse
Uses a laser to detect the mouse's movement. You must move
the mouse along a special mat with a grid so that the optical
mechanism has a frame of reference. Optical mice have no
mechanical moving parts. They respond more quickly and
precisely than mechanical and optomechanical mice, but
they are also more expensive.
Cordless Mouse
aren't physically connected at all. Instead they rely on
infrared or radio waves to communicate with the computer.
Cordless mice are more expensive than both serial and bus
mice, but they do eliminate the cord, which can sometimes
get in the way.
52. TRACKPOI
NT
Touchpad
The mouse is not practical for people using a notebook
computer in a small space. Track Point or Touch pad
is therefore used instead to control the pointer.
53. TOUCH-SENSITIVE SCREENS
Touch screens are commonly used in grocery stores, fast-
food restaurants, and information kiosks.
Touch screens enable the user to select an option by
pressing a specific part of the screen.
A touch screen kit solution
54. JOYSTICKS
Use the movement of a vertical stem to direct the pointer.
Joysticks are used mostly for computer games, but they are
also used occasionally for CAD/CAM systems and other
applications.
55. C. PEN INPUT
DEVICES
Input data with hand written characters, select items by
pressing the pen against the screen, and use gestures,
which are special symbols, to issue commands.
Light Pen
Used to select processing options or to draw on the
screen
57. OPTICAL MARK RECOGNITION
Optical marks are the filled-in shape, usually ovals
or rectangles, on scan sheets.
The data collected on the scan sheets are translated
into binary form by an optical mark reader (OMR)
Use lead pencil to mark on scan sheet Feed the scan sheets into the OMR
58. OUTPUT
DEVICES
Output is data that has been processed into a useful
form called information.
Report
Computer Graphics
Audio Output
Video Output
59. TYPES OF OUTPUT
Most output can be divided into 2 categories: Soft
copy & hard copy
Soft copy is what you see on the monitor. Soft copy
is temporary.
Hard copy can be touched and carried. Hard copy is
usually some form of paper output.
60. MONITO
RS
A visual output device of a computer.
Monitor output is a most common form of soft
copy.
CRT
Monitor
Flat-panel
Monitor
61. RESOLUTION OF DISPLAY
Images on the screen are created by configurations of
dots called pixels (picture elements)
The more the pixels, the better the resolution of the
image
⚫ SVGA = pixel configuration of 800 by 600
⚫ XVGA = pixel configuration of 1024 by 768
62. 2.PRINTER
A printer is a device that accepts text and graphic
output from a computer and transfers the
information to paper, usually to standard size
sheets of paper.
Personal computer printers can be distinguished as
impact Printers
non-impact Printers
63. PRINTERS
Produce permanent output (hard copy)
consists of 2 main types: impact & non-
impact
Types Impact Printers Non-impact Printers
Mechanisms Transfer an image by
striking the paper and
the ribbon.
Print without striking
against a sheet of paper.
Advantages Cheap consumables;
Can print on multiple
carbon copies
Fast;
High printing quality;
Quiet
Disadvantages Noisy Expensive consumable
64. TYPES OF IMPACT PRINTERS
Line Printers
Character Printers
65. CHARACTER PRINTERS
Printer that stores individual characters when needed
to print. The printer will print one character at a time
instead of one line at a time. Today, these printers are
rarely used because of speed issues and because only
text is capable of being printed.
66. A. LINE
PRINTERS
The line printer is a form of high speed impact
printer in which one line of type is printed at a time.
They are mostly associated with the early days of
computing, but the technology is still in use.
Print speeds of 600 to 1200 lines-per-
minute (approximately 10 to 20 pages per
minute) were common
The disadvantages of line printers are that
they cannot print graphics, the print quality is low, and
they are very noisy.
67. TYPES OF LINE PRINTERS
Drum printers
Chain (train) printers
Bar printers
Comb printers
68. DRUM PRINTER
MECHANISM
The hammer pushes the paper into the type slug when it rotated around to the proper
position. Such printer technologies seem ridiculous compared to the quiet, high-speed
workings of today's laser printers.
69. CHAIN PRINTER
MECHANISM
When the required character in the chain has revolved to the selected
print column, the hammer pushes the paper into the ribbon and
against the type slug of the letter or digit.
70. BAR PRINTERS
Bar printers were similar to chain printers but
were slower and less expensive.
Rather than a chain moving continuously in one
direction, the characters were on fingers mounted on
a bar that moved left-to-right and then right-to-left in
front of the paper.
An example was the IBM 1443
71. COMB
PRINTER
Comb printers, also called line matrix
printers, represent the fourth major design.
These printers were a hybrid of dot matrix
printing and line printing. In these printers, a
comb of hammers printed a portion of a row of
pixels at one time (for example, every eighth pixel).
By shifting the comb back and forth slightly,
the entire pixel row could be printed (continuing
the example, in just eight cycles). The paper
then advanced and the next pixel row was printed.
72. B. CHARACTER PRINTERS
Definition of: character printer
A printer that prints one character at a time. The
typical character printer is the dot matrix printer.
Their printing speed lies in the range of 30 to
600 character per second .
78. INK JET
PRINTERS
Characters are formed as a result of electrically
charged or heated ink being sprayed in fine jets onto
the paper.
Individual nozzles in the printing head produce high
resolution (up to 400 dots per inch or 400 dpi) dot
matrix characters
Colour cartridge showing inkjet
nozzles
Inkj t printers use colour cartridges which combine magenta, yellow and cyan inks to
create colour tones. A black cartridge is also used for crisp monochrome output.
This m thod of printing can generate up to 200 cps and allows for good quality, cheap
colour printing.
79. THERMAL
PRINTERS
Characters are formed by heated elements being
placed in contact with special heat sensitive
paper forming darkened dots when the elements
reach a critical temperature.
hermal printer paper tends to darken over time due to exposure
to sunlight and heat. The standard of print produced is poor.
• her al printers are widely used in battery powered equipment
such as portable calculators
80. LASER PRINTER
Laser Printers use a laser beam and dry powdered ink
to produce a fine dot matrix pattern. This method of
printing can generate about 4 pages of A4 paper per
minute.
The standard of print is very good and laser printers can
also produce very good quality printed graphic images
too
81. OTHER OUTPUT DEVICES
Plotter
produce high-quality line
drawings
A continuous-curve plotter is
used to draw maps from stored
data.
82. LCD Projectors
project a computer image onto screen
Voice Output Devices
generate spoken words from text
Computer Output microfilm (COM)
records output as microscopic images on roll
film.
Facsimile (FAX) Machine
transmit & receives document over telephone
line.
Multifunctional Devices (MFD)
can print, copy and fax
84. The storage unit of a computer system is
ranked according to the following criteria:
• Access Time – time required to
retrieve data.
• Storage Capacity – amount of data that
can be stored in storage unit.
• Cost/bit of storage – the goal is to
minimize the cost
Data Storage
85. Storage Devices
• The device which stores the data in
a computer.
• Also known as memory.
• It is of two types –
• Primary memory/storage device
• Secondary memory/storage
device
86. Primary Storage
• Also known as memory.
• It is of two types –
• Primary memory/storage
• Secondary
memory/storage
87. Storage Types
Why storage is required by computer?
Computer storage can be classified into following
types:
Primary Storage
>> RAM (Random Access Memory)
>> ROM (Read only Memory)
Secondary Storage
>> Floppy Disk
>> Hard Disk
>> CD (Compact Disk)
>> DVD (Digital Versatile Disk)
88. Primary Storage
1. Random Access Memory (RAM)
• Basic to all computers.
• In the form of integrated circuits that allow the
stored data to be accessed in any order i.e. at
random and without the physical movement of
the storage medium or a physical reading
head.
• Made up of several small parts known as cells.
• Each cell can store a fixed no. of bits.
• Each cell has a unique no. assigned to it
which is known as address of cell.
89. Primary Storage
•Also known as Read/Write memory.
•Volatile in nature.
•Usually it is known as memory of
computer.
90. Types of RAM
There are two basic types of RAM:
1. Dynamic RAM (DRAM) - The term dynamic indicates
that the memory must be constantly refreshed or it will
lose its contents.
2. Static RAM (SRAM) –
• Faster and more reliable than DRAM.
• The term static is derived from the fact that
it doesn't need to be refreshed like dynamic RAM.
• It can give access times as low as 10 nanoseconds.
• Much more expensive than DRAM.
• Due to its high cost, SRAM is often used only
as a memory cache.
• Cache memory - a special high-speed storage
mechanism. It can be either a reserved section of
main memory or an independent high-speed
storage device.
91. Other Types of RAM
Other than the above basic types of RAM, there are few more
newer versions –
1. FPM DRAM: Fast Page Mode DRAM, maximum data transfer rate is
176 mbps.
2. EDO DRAM: Extended data-out DRAM, maximum data transfer
rate is 264 mbps.
3. SDRAM: Synchronous Dynamic RAM, maximum data transfer rate is
528 mbps.
4. DDR SDRAM: Double Data Rate SDRAM, maximum data transfer
rate is 1064 mbps.
92. Primary Storage
2. Read Only Memory(ROM) :
• Computer memory on which data has been prerecorded.
• Information is permanently stored i.e. data stored in
ROM cannot be modified, hence known as ROM.
• Non volatile in nature.
• Stores critical programs such as the program that boots
the computer.
• Used extensively in calculators and peripheral devices
such as laser printers, whose fonts are often stored in
ROMs.
Types of ROM:
3. Programmable Read-Only Memory (PROM) –
• One-time programmable ROM (OTP), can be
programmed through a special device called a PROM
programmer.
• PROM can only be programmed once.
93. Primary Storage
2. Erasable programmable Read-Only Memory (EPROM):
• Can be erased by exposure to strong ultraviolet light,
then rewritten.
• Repeated exposure to UV light will eventually wear
out an EPROM.
3. Electrically erasable programmable Read-Only Memory
(EEPROM)
• Based on a similar semiconductor structure to EPROM,
but allows its entire contents to be electrically erased,
then rewritten electrically, so that they need not be
removed from the computer.
• Used in camera, MP3 player, etc.
• Writing or flashing an EEPROM is much slower.
94. Primary Storage
4. Electrically Alterable Read-Only Memory (EAROM):
• A type of EEPROM that can be modified one bit at a
time.
• Writing is a very slow process and again requires
higher voltage.
• intended for applications that require infrequent and
only partial rewriting.
5. Flash memory (or simply flash)
• A modern type of EEPROM invented in 1984.
• Flash memory can be erased and rewritten faster
than ordinary EEPROM.
• Modern NAND flash makes efficient use of silicon
chip area.
• Is sometimes called flash ROM or flash EEPROM when
used as a replacement for older ROM types.
96. Difference between RAM and ROM
RAM ROM
1. RAM stands
for Random Access
Memor
y
2. It is volatile in
nature. Its
contents are
erased when
power is turned
off.
3. We can read as well
as write through
this memory
1. ROM stands for
Read
only
Memory
2. It is non-volatile in
nature. Its contents
are non erased
when power is
turned off.
3. We can only read
this memory and
cannot write
through it
98. Secondary Storage
The storage capacity of primary storage is not sufficient to
store large volume of data, hence, additional memory is
used, known as secondary memory/storage.
Two methods of accessing data –
1. Sequential Access:
Data can be retrieved in same sequence in which
it is stored.
2. Direct Access:
Data can be accessed directly eg. Computerised Airline
ticket booking system
99. Types of Secondary Storage
1. Magnetic Tape:
• Data is sequentially access and retrieved .
• Made up of plastic ribbon, half inch wide, one
side coated with an iron oxide material.
• Ribbon is stored in reels of 50 to 2400 feet or a
small cartridge.
•
•
Unlimited
storage High
data density
•
•
•
Low cost
Rapid transfer
rate Ease of
handling
• Portable
BUT
• No direct access
• Environmental
problems
100. Types of Secondary Storage
1. Magnetic Disk:
• Contains a thin metal plate, coated on both sides
with a magnetic material.
• A disk pack consists of a no. of disks, mounted
about half inch apart from each other on a central
shaft which rotates at the speed of 2400or more
rpm.
• Information is stored on both sides.
• Each disk consists of a no. of invisible concentric
circles called Tracks.
• A set of corresponding tracks in all the surfaces is
called a cylinder.
• Each track is subdivided into sectors.
• Information is recorded on track and can be read
using read/write heads.
101. 1. Floppy Disk
Track
s
Sector
s
• Surface of floppy disk is coated with magnetic material.
• Data is stored on the surface of disk by magnetizing the
surface.
• That’s why FD is called magnetic storage device.
0
1
2
0
1
2
Storage Types
File address
contains
information about
track and sector of
file.
102. Floppy Disk
• Storage capacity is 1.44 MB.
• Each file has a size and location where it is stored in the floppy
disk.
• In order to locate a particular file, FAT (File Allocation Table)
is maintained:
FAT contains:
1. Name of file
2. Size of file
3. Location on disk (Starting Track and Sector)
4. Date created
5. Attributes such as Read Only, Hidden, etc.
•Formatting a floppy disk means creating tracks and sectors on the
disk
surface.
• Data is stored in files in floppy
disk.
105. OPTICAL
DISK
An optical disc is an electronic data storage medium that
can be written to and read using a low-powered laser
beam.
An optical disc holds much more data. reflectiv
e
Consist of rotating disk coated with a
highly material.
A laser beam is focussed on the surface of disk.
There is one spiral track on the disk surface.
When the laser beam is turned on, it creates a small hole
on the surface of the disk along its track while writing
the data, known as pit.
The surface of the disk is plane in the absence of data,
known as crater.
Storage capacity is higher.
106. Optical Disk
0
1
1
0
1
0
0
1
Read Head throws a beam of light on
the surface and senses the reflected
light. If the beam reflects it indicates
that 1 is stored otherwise 0 is
stored. Range of data storage is
650/700 MB.
Disk
surface
1. Compact Disk:
CD is an optical storage device.
In order to store the information, on the surface of CD, the
surface is burned accordingly. That’s why writing a CD is also
called burning a CD.
Once written, the content of CD can’t be changed.
Stored bits
Burned
places
107. DIGITAL VERSATILE DISK
DVD ("Digital Versatile Disc" or "Digital Video Disc"):
A popular optical disc storage media format that can be
used for data storage.
Including movies with high video and sound quality.
DVDs resemble CDs.
A DVD reader or writer can usually read CDs, but DVDs are
encoded in a different format of much greater density,
allowing a data storage capacity 8 times greater.
Range of storage capacity is from 2.8 Gigabytes to
4.7 Gigabytes.
108. OTHER TYPES OF STORAGE
DEVICES
PC Cards (PCMCIA)
Compact Flash Memory Card
Memory Stick
Smart Card
110. Data: raw facts, inserted into the computer to be processed.
eg typing the alphabets through keyboard – G, O, D
Information: processed data or output given by computer.
eg the word GOD displayed on monitor.
Types of Representation of Data
1. Internal Representation: values used by computer
to store and process data.
2. External Representation: Computer translates data
into the form of human understandable language of
numbers, characters, figures and sound etc.
Data Representation
112. Data Representation
Bit: A bit refers to one binary digit. Either 0 or 1.
Byte: Set of 8 bits is called byte. i.e. 1Byte = 8 Bits
Word: It is a collection of 2 bytes or 4 bytes depending on
the word size of computer, whether it is 16 bit
computer or 32 bit computer
1024 bytes = 1Kilo Bytes
1024 KB = 1 Mega Bytes
1024 MB = 1 Giga Bytes
114. THE COMPONENTS OF THE
SYSTEM UNIT
THE SYSTEM UNIT
What is the system unit?
Case that contains electronic components of the
computer used to process data
115. THE SYSTEM UNIT
Memory
power supply
What are common components inside the system unit?
drive bays
Processor
Adapter cards processor
Sound card
Video card ports memory
Ports
Drive bays
Power supply
sound card
video card
116. THE SYSTEM UNIT
What is the motherboard?
Main circuit board in system unit
Contains adapter cards, processor chips, and
memory modules
117. THE SYSTEM UNIT
What is a chip?
Small piece of semi-conducting material on
which integrated circuits are etched
Integrated circuits contain many microscopic
pathways capable of carrying electrical
current
Chips are packaged so they can be attached to a
circuit board
118. THE SYSTEM
UNIT
What is the central processing unit (CPU)?
Processor
Control
Unit
Arithmetic
Logic Unit
(ALU)
Arithmetic
Logic Unit (ALU)
Control
Unit
Interprets and carries out
basic instructions that
operate a computer
Control unit directs and
coordinates operations
Instructions
Data
Information
Input
Devices
Output
Devices
Memory
Data Information
in computer
Arithmetic logic unit
(ALU) performs Instructions
Data
Information
Storage
Devices
arithmetic, comparison,
and logical operations
Also called the
processor
119. PROCESS
OR
What are multi-core processors?
• A dual-core processor is a single chip that contains
two separate processors
• A quad-core processor is a single chip that contains
four separate processors
• A multi-core processor is a chip with two or
more separate processors
• Each processor on a multi-core chip generally runs at
a slower clock speed, but increase overall performance
120. WHAT IS A MACHINE
CYCLE?
Four operations of the CPU comprise a machine
cycle
Step 1. Fetch
Obtain program instruction
or data item from memory
Memory
Processor
Step 2.
Decode
Translate
instruction into
commands
Step 4. Store
Write result to memory
Control Unit
ALU
Step 3. Execute
Carry out command
121. DATA REPRESENTATION
Most computers are digital
Recognize only two
discrete states: on or off
Use a binary system to
recognize two states
Use Number system with
two unique digits: 0 and
1, called bits (short for
binary digits)
122. WHAT IS A
BYTE?
Eight bits grouped together as a unit
Provides enough different combinations of 0s and 1s
to represent 256 individual characters
Numbers
Uppercase
and lowercase
letters
Punctuation
marks
123. What are two popular coding systems to represent data?
DATA REPRESENTATION
ASCII—American Standard Code for Information
Interchange
EBCDIC—Extended Binary Coded Decimal Interchange
Code ASCII Symbol EBCDIC
00110000 0 11110000
00110001 1 11110001
00110010 2 11110010
00110011 3 11110011
124. MEMORY
What is memory?
Electronic components that store instructions, data,
and results
Consists of one or more chips on motherboard
or other circuit board.
Each byte stored in unique location called an
address, similar to seats in a concert hall
125. WHAT IS RANDOM ACCESS MEMORY
(RAM)?
Memory chips that can be
read from and written
to by processor
Also called
main memory
or primary
storage
Most RAM is
volatile, it is lost
when computer’s
power is
turned off
The more RAM a
computer has, the
faster it responds
126. MEMORY
Where does memory reside?
memory slot
memory chip
Resides on small circuit
board called memory
module
Memory slots on
motherboard hold memory
modules
127. What is access time?
Amount of time it takes processor to read data
from memory
Measured in nanoseconds (ns), one billionth of a
second
It takes 1/10 of a second to blink your eye; a computer
can perform up to 10 million operations in same
amount of time
Term Speed
Millisecond One-
thousandth of a second Microsecond One-
millionth of a second Nanosecond One-
billionth of a second Picosecond One-
trillionth of a second
128. EXPANSION SLOTS AND ADAPTER
CARDS
What are PC cards, flash memory cards, and USB Flash Drives?
A PC card adds memory, storage, sound, fax/modem,
communications, and other capabilities to notebook
computers
A flash memory card allows users to transfer data
from
mobile devices to desktop computers
A USB flash drive is a flash memory storage device
that plugs into a USB port on a computer
p. 147 Figs. 4-19 – 4-
20
129. PORTS AND
CONNECTORS
What are ports and connectors?
Port connects external devices to system unit
Connector joins cable to peripheral
130. PORTS AND CONNECTORS
What is a serial port?
Transmits one bit of data at a
time
Connects slow-speed devices,
such as a mouse, keyboard, or
modem
131. PORTS AND CONNECTORS
What is a parallel port?
Connects devices that can
transfer more than one bit at a
time, such as a printer
132. PORTS AND CONNECTORS
What are USB ports?
USB (universal serial bus) port can connect
up to 127 different peripherals together
with a single connector type
Single USB port can
be used to attach
multiple peripherals
using a USB hub
PCs typically have
six to eight USB ports
on front or back of
the system unit
The latest version of
USB is called
USB 2.0
133. PORTS AND CONNECTORS
What are FireWire ports?
Connects multiple types of devices that require
faster data transmission speeds
Allows you to connect up to 63 devices
together
134. PORTS AND
CONNECTORS
What are special-purpose ports?
Allow users to attach specialized peripherals or transmit data
to wireless devices
MIDI (Musical Instrument Digital Interface) port
Serial port
Electronic Keyboard
SCSI (small computer system interface) port
Disk Drives, Printers
IrDA (Infrared Data Association) port
Smart phone, PDA, keyboard
Bluetooth port
Uses radio-waves
Cell Phones
135. PORTS AND CONNECTORS
What is a bus?
Channel that allows devices inside
and attached to the computer to
communicate with each other
Bus width (size) determines
number of bits transmitted
at one time
64-bit common type
2 Types:
1. System bus connects
processor and main
memory
2. Expansion bus allows
processor to communicate
with peripherals.
136. PORTS AND CONNECTORS
What is a bay?
Open area inside
system unit used
to install
additional
equipment
Drive bays
typically hold disk
drives
137. POWER
SUPPLY
What is a power supply?
Converts
AC Power
(115 to 120
volts)
into
DC Power
(5 to 12
volts)
Fan keeps
system unit
components
cool
External peripherals
might use an AC
adapter, which is an
external power supply
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