Transcript Slide 1

BA 1306
Information Systems and
Programming
Asst. Prof. Engin Kucukkaya
BA 1306 Spring 2007
Introduction
Lecture Outline:
 The
Big Picture
 Hardware
 Data Communications
 The Internet
 Classification of Computers
 Software
BA 1306 Spring 2007
The Big Picture
The computer systems have three main
components: Hardware, software and people.
The equipment associated with a computer system
is called hardware.
The programs, or step-by-step instructions that run
the machines, are called software.
Computer programmers write programs for
users, or end-users — people who purchase and
use computer software.
BA 1306 Spring 2007
Hardware
A computer is a machine that can be
programmed to process data (input) into
useful information (output).
A computer system requires four main
aspects of data handling:
●
●
●
●
Input
Processing
Output
Storage.
BA 1306 Spring 2007
Hardware: The basic components
●
Input is data to be accepted into the
computer
●
●
Common input devices are keyboard,
mouse, joystick, and scanner.
Storage devices and communication
devices can also be used for input.
BA 1306 Spring 2007
Input

A keyboard is a common input device that
may be part of a personal computer or a
terminal connected to a remote computer.

A mouse is an input device with a ball on its
underside, whose movement on a flat surface
causes a corresponding movement on the screen.

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Moving the mouse allows you to reposition the pointer,
or cursor, an indicator on the screen that shows where
the next interaction with the computer can take place.
Mouse technology is now shifting towards
optical mouse, where light beams emitted
by the mouse are used to capture the
movement.
BA 1306 Spring 2007
Input

A trackball is like an upside-down mouse—the
ball is rolled with the hand.
 A touch pad invokes a command with finger
movement.
BA 1306 Spring 2007
Input
A
scanner converts text, drawings and
pictures into computer-recognizable
form
 Types of scanners
Flatbed
 Sheetfeed
 Handheld
 Overhead
 Drum

Overhead
Handheld
BA 1306 Spring 2007
Sheetfeed
Input
 Voice
input, or speech recognition, is
the process of presenting input data to
the computer through the spoken word.
 Speech recognition devices convert
spoken words into a digital code that a
computer can understand. The two main
types of devices are
BA 1306 Spring 2007
Input
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Input can be given directly to a computer
via a touch screen; a finger touching the
screen interrupts the light beams on the
monitor edge, pinpointing the selected
screen location.
A user can deliver input to a computer by
looking at a screen, assuming electrodes
are attached to the skin near the user's
eyes so that their signals can be read by
the computer system.
BA 1306 Spring 2007
Hardware: The basic components
The processor, or central processing unit (CPU),
processes raw data into meaningful, useful
information.
The CPU interprets and executes program instructions and
communicates with the input, output, and storage devices.
Main Memory, or primary storage, is connected
with the central processing unit but is separate from it.
Memory holds the input data before processing and also
holds the processed data after processing, until the data is
released to the output device.
BA 1306 Spring 2007
CPU

The CPU interacts with memory (not a part of
CPU), i.e. the primary storage, to get instructions
and data
 Secondary storage holds permanent data on
some external medium
INPUT
CPU
Control
Unit
OUTPUT
Arithmetic/
Logic
Unit
Memory
BA 1306 Spring 2007
SECONDARY
STORAGE
How does the CPU work?
 Control
unit directs the movement of
instructions and data between memory,
ALU and secondary storage
OUTPUT
INPUT
Control
Unit
Arithmetic/
Logic
Unit
Memory
BA 1306 Spring 2007
SECONDARY
STORAGE
Components of CPU

Control Unit: directs the entire
computer to carry out the program
instructions. It does not actually
execute instructions, it makes other
parts to do so.
–
–
–
•Arithmetic/Logic Unit: –
It executes all arithmetic –
–
and logical operations.
–
–
–
–
addition (+)
subtraction (-)
multiplication (*)
division (/)
equal to (=)
less than (<)
greater than (>)
less than or equal to (<=)
greater than or equal to (>=)
less than or greater than (< V >)
BA 1306 Spring 2007
Components of CPU
Registers are:
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temporary storage locations for instructions or data
not parts of memory, but parts of CPU
very fast
under the control of the control unit
Registers
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accept, hold, transfer instructions or data
hold data about immediate operation being executed, as
compared to the memory that holds data about near
future
BA 1306 Spring 2007
Speed and Power
 Execution
of an instruction on a slow
computer is measured in milliseconds
 Now we are at the age of nanoseconds
(one billionth of a second)
 MHz: millions of machine cycles per sec.

133 MHz SDRAM : 7.5 nanoseconds per cycle
 GHz:
billions of machine cycles per sec.
BA 1306 Spring 2007
Memory
Memory is the part of the computer that
holds data & instructions for processing
Main memory holds the
instructions and relevant data
of an application as long as it
is in operation
BA 1306 Spring 2007
Data Representation
 Data
is represented in
two states: electricity
high and low
 This is called the binary
system
 Each 0 or 1 is a bit, this
is the basic unit for
storage
BA 1306 Spring 2007
Data Representation
Bits are put together to a group called
byte. There are usually 8 bits in a byte
 Notation:
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210bytes = 1024 bytes = 1 Kbytes

220bytes = 1024 Kbytes = 1 Megabytes

230bytes = 1024 Mbytes = 1 Gigabytes
BA 1306 Spring 2007
Data Representation

ASCII: American Standard Code for
Information Interchange
 8 bits for each character
 Therefore, 256 (28)characters
exists in ASCII-8
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A: 0100 0001
B: 0100 0010
C: 0100 0011
D: 0100 0100
…
BA 1306 Spring 2007
Storage Locations and Addresses

A memory location can only hold fixed
amount of data
 The location in memory for each instruction
and piece of data is identified by a memory
address
 Memory Address of a location remains the
same, but the contents may change
 In programming, you need not worry about
the physical memory locations, instead we
use symbolic addresses
BA 1306 Spring 2007
Chips in your PC
Memory Types (RAM)

SIMM: Single in-line memory module
 DRAM: Dynamic RAM
 SRAM: Static RAM
 SDRAM: Synchronous dynamic RAM
 DDR SDRAM: Double Data Rate
 SoDIMM: Small outline dual inline memory module
(used in portable computers)
BA 1306 Spring 2007
Speed and Power

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Cache is a relatively small block of very fast
memory that is designed to speed up the
internal transfer of data and instructions
Internal Cache: built into the processor
External Cache: built on separate chips
RISC: Reduced instruction set computer
Parallel processing: a method of using several
processors at a time, this is the ultimate speed
solution used on servers
BA 1306 Spring 2007
Hardware: The basic components
Output, which is raw data processed
into usable information, is usually in
the form of words, numbers, and
graphics.
Users can see output displayed on a screen (also
known as monitor), or use printers to display
output on paper.
BA 1306 Spring 2007
Output

The monitor is a device that receives video signals from the
computer and displays the information for the user. It supports
high-resolutions when compared to regular TV screen.

The digital copy of a file that can be seen on a screen or that
can be stored on a storage media is known as soft copy
because it is intangible and temporary, unlike hard copy,
produced by a printer on paper, which is tangible and can be
permanent.
BA 1306 Spring 2007
Output
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A computer display screen that can be used for
graphics is divided into dots that are called
addressable because they can be addressed
individually by the graphics software.
Each screen dot is called a pixel.
The more pixels, the higher the screen resolution, or
clarity.
Dot pitch is the amount of
space between the dots on a
screen.
BA 1306 Spring 2007
Output
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CGA (Color Graphics Adapter)
2 colors at a resolution of 640x200.
EGA (Enhanced Graphics Adapter)
resolution of 640x350 with up to 256 colors.
VGA (Video Graphics Array or Video Graphics Adapter)
640x480 display showing 16 colors.
SVGA (Super-VGA)
resolution of 800x600 with support for 256 colors or 1024x768
with 16-color support.
XGA (eXtended Graphics Array or Extended Graphics Adapter)
resolution of 1024x768 in 256 colors or 640x480 in high (16-bit)
color.
SXGA (Super XGA)
A screen resolution of 1280x1024 pixels
UXGA (Ultra XGA)
A screen resolution of 1600x1200 pixels.
BA 1306 Spring 2007
Output
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Printers produce printed paper
output.
 Printers can be classified as either
impact printers, dot matrix, which form
characters by physically striking the
paper, or
 Non-impact printers, laser and ink-jet
printers, which use a non-contact
printing method.
Today's laser printers print usually at 600
dpi (dots per inch), producing extremely
high-quality results.
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BA 1306 Spring 2007
Storage and Multimedia
Secondary storage provides additional
storage space separate from memory.
The most common secondary storage devices
are magnetic disks
Hard disk
Flash Disk
and optical disks
CD-ROM
DVD
BA 1306 Spring 2007
Secondary Storage
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Secondary storage is the type of storage that is
separate from the processing
By using secondary storage, software and data can
be stored on a permanent or semipermanent basis.
Secondary storage is necessary because memory, or
primary storage, can be used only temporarily and it
has limited capacity.
Advantages of secondary memory
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space,
reliability,
convenience
economy
BA 1306 Spring 2007
Magnetic Disk Storage

Diskettes and hard disks are magnetic media,
 Magnetic data storage is based on a technology
of representing data as magnetized spots on the
disk.
BA 1306 Spring 2007
Magnetic Disk Storage

A hard disk is a metal platter coated with
magnetic oxide that can be magnetized to
represent data.
BA 1306 Spring 2007
Optical Disk Storage

Optical disk technology uses
a laser beam to enter data as
spots on the disk surface.
 To read the data, the laser
scans the disk, and a lens
picks up different light
reflections from the various
spots.
1 bit
0 bit
BA 1306 Spring 2007
Optical Disk Storage

CD-ROM (compact disk read-only
memory) has a disk format identical to that of
audio compact disks.
 Regular CD-ROMs can hold up to 700
megabytes per disk.
 CD-RW technology permits writing on optical
disks.
 DVD-ROM, for digital video
disk, has astonishing storage
capacity, up to 17GB if both
layers and both sides are used.
BA 1306 Spring 2007
Flash Memory

Flash Memory: An electronic circuitry that
offers a nonvolatile and rewritable type of
memory.
BA 1306 Spring 2007
Flash Memory
• Flash memory is durable,
operates at low voltages,
and retains data when
power is off.
• Flash memory cards are
used in digital cameras,
cell phones, printers,
handheld computers,
pagers, and audio
recorders.
BA 1306 Spring 2007
Data Communications

Data communications is the transfer of data between
separate computing devices at various locations using
telephone lines, microwave and/or satellite links.
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The process of data communications consists of three
main operations:
 transmission of data
 reception of data
 validation of data
BA 1306 Spring 2007
Data Communications

A network is a group of stations (computers,
telephones, or other devices) connected by
communications facilities for exchanging
information.
 Connection can be permanent, via cable, or
temporary, through telephone or other
communications links.
BA 1306 Spring 2007
Data Communications

The basic components of a data
communications system are
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a sending device,
a communications link,
and a receiving device.
BA 1306 Spring 2007
Data Transmission

Computers produce digital signals, but most
types of communications equipment use analog
signals.
 Digital transmission sends data as distinct on
or off pulses.
 Analog transmission uses a continuous electric
signal in a carrier wave
having a particular
amplitude* and
frequency.
*amplitude:
The maximum height of a wave.
BA 1306 Spring 2007
Data Transmission

Digital signals are converted to analog signals by
modulation (change) of the amplitude of the
carrier wave.
 Demodulation is the reverse process
(conversion from analog to digital).
 Both tasks are performed by a device called a
modem.
BA 1306 Spring 2007
Data Transmission
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Simplex transmission allows data to move in only
one direction (either sending or receiving).
Half-duplex transmission allows data to move in
either direction but only one way at a time.
With full-duplex transmission, data can be sent and
received at the same time.
BA 1306 Spring 2007
Data Communications
Often organizations use a network of
personal computers, which allows users to
operate independently or in cooperation
with other computers, exchanging data
and sharing resources.
Such a setup is called a local area
network (LAN).
BA 1306 Spring 2007
Data Communications
Users who connect their computers need some
type of equipment to transfer the data.
Connecting to a LAN is usually realized by the use
of a network adaptor (NIC) card.
Users who connect their computers via the phone
lines must use a hardware device called a modem
to reconcile the inherent differences between
computers and the phone system.
For wireless connections, a WIFI adaptor, or a
Bluetooth adaptor can be used.
BA 1306 Spring 2007
Local Area Network
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A local area network (LAN) is a network of personal
computers and other equipments such as printers and
scanners that share hardware, software, and data,
typically within a building.
The nodes on some LANs are connected by a shared
network cable or by wireless transmission.
• A network interface card
(NIC) is inserted into an
expansion slot to handle sending,
receiving, and error checking of
transmitted data.
BA 1306 Spring 2007
Local Area Network

If two LANs are similar, they can send messages
among their nodes by using a bridge.

A gateway is a collection of hardware and
software resources that connect two dissimilar
networks and performs protocol conversion
when necessary.
BA 1306 Spring 2007
Local Area Network
A router is an equipment that directs
network traffic when several networks are
connected together.
 Most of the networks that have adopted
the Internet protocol (IP) use IP switches,
which are less expensive and faster than
routers.

BA 1306 Spring 2007
Local Area Network
A Firewall is an
equipment which
limits network
access between
two or more
networks.
BA 1306 Spring 2007
Client-Server LANs

A client/server arrangement involves a
server, a computer that controls the network.
 The server has hard disks holding shared files
and often has the highest-quality printer.
 A file server transmits the entire file to the
node, which does all its own processing.
BA 1306 Spring 2007
Peer-to-Peer LANs

In a peer-to-peer arrangement, all computers
have equal status; no one computer is in
control.
 With all files and peripheral devices
distributed across several computers, users
share each other's data
and devices as needed.
BA 1306 Spring 2007
Network Topologies

If we have to connect several computers, we
have many options to do so.
 The physical layout of a network is called a
topology.
 A node usually refers to computers and
peripheral devices such as
printers connected to
a network.
Internet Mapping Project
http://research.lumeta.com/ches/map/index.html
BA 1306 Spring 2007
Network Topologies
• A star network has a central computer, the
hub, through which all traffic passes.
• A ring network links all nodes together in a
circular manner.
• A bus network has a single line, to which all
the network nodes and peripheral devices are
attached.
Bus
Star
BA 1306 Spring 2007
Ring
LAN Protocols

Ethernet is a network
protocol that runs on
bus topology.
• A Token Ring network
controls access to the
shared network cable by
using token passing.
BA 1306 Spring 2007
WLAN and WiFi

Wireless Local Area Network
(WLAN) is a local area network
that uses high frequency radio
signals to transmit and receive
data over distances of a hundred
meters at most.
 It is based on the IEEE 802.11
family of standards.
 Wireless Fidelity (WiFi) is a
WLAN using the IEEE 802.11a/b/g
specifications
BA 1306 Spring 2007
Bluetooth

Bluetooth describes how
mobile phones, computers
and PDAs can easily
interconnect with each other
and with home and business
phones and computers using
a short-range (10 m.) wireless
connection.
BA 1306 Spring 2007
Virtual Private Network (VPN)

Virtual Private Network a network
in which some of the parts are
connected using the public Internet,
but the data sent across the Internet
is encrypted, so the entire network is
"virtually" private.
• A typical example would be a company network where
there are two offices in different cities.
• Using the Internet the two offices merge their networks
into one network, but encrypt traffic that uses the
Internet link.
BA 1306 Spring 2007
The Internet
The Internet, sometimes called simply "the Net",
connects users worldwide.
To access the Internet, a user's computer must
connect to a computer called a server, which has
special software called TCP/IP (for Transmission
Control Protocol/Internet Protocol) that allows
different types of computers to communicate with
one another.
The supplier of the server computer, often called an
Internet service provider (ISP), charges a fee
based on the amount of service provided.
BA 1306 Spring 2007
The Internet
Using software called a browser, a user can use a
mouse to point and click on screen icons to explore
the Internet, particularly the World Wide Web (the
Web), an Internet subset of text, images, and
sounds linked together.
Each different location on the Web is called a web
site or, more commonly, just a site.
A home page is the first page of a web site, and is
accessed by internet users based on its address.
BA 1306 Spring 2007
Protocols & TCP/IP

A protocol is a set of rules for exchanging
data between a terminal and a computer or
between two computers.
 The protocol that makes Internet universally
possible is Transmission Control
Protocol/Internet Protocol (TCP/IP), which
permits any computer at all to communicate
with the Internet.

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TCP does the packeting and reassembling of the
message
IP does the addressing.
BA 1306 Spring 2007
What is Internet?

An internet is the collection of networks
interconnected by a set of routers which
allow them to function as a single, large
network.
• The Internet is a worldwide system of
computer networks in which any one
computer can get information from/or talk to
any other connected computer using the
TCP/IP protocols.
BA 1306 Spring 2007
IP Addresses / Domain Names
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Whenever a computer is connected to the
Internet, it is given a personal identification :
the IP address (Dynamic IP).
The IP address is made up of 4 series of
numbers from 0-255
e.g.: 194.133.117.3
No two computers in the world can share the
same IP address at the same time.
When you connect to Internet, your ISP
assigns an IP address to your computer.
Upon disconnecting, your IP address becomes
available for use by someone else.
BA 1306 Spring 2007
IP Addresses / Domain Names
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However, server computers need to have a
fixed addresses.
Consider that you want to access the web site
of our university. Its address has to be unique,
so that you get to the correct site.
The address of METU home page is
144.122.144.160.
Do you have to memorize this number? No!
Instead we use the domain name:
www.metu.edu.tr
BA 1306 Spring 2007
IP Addresses / Domain Names

The method of assigning understandable
names to IP addresses is called Domain
Name System (DNS)
 The mapping of domain names and addresses
are held on servers that are called as Domain
Name Servers.
 Everytime that you want to access
www.metu.edu.tr, the browser first “resolves”
the address by asking it to a Domain Name
Server.
 The main DNS Server in Turkey is operated by
METU.
BA 1306 Spring 2007
IP Addresses / Domain Names
www.metu.edu.tr
indicates that
this is the
address of a
site on the
Web
is the name of
the site, usually
the name of the
organization
• COM: commercial
organizations
• ORG : non-profit
organization.
• EDU: educational
institutions
• MIL: military
organizations
• GOV: government
entities
BA 1306 Spring 2007
represents the
name of the
country in which
the site is
located.
World Wide Web

(WWW or "Web") - A system of Internet
servers that uses HTTP to transfer specially
formatted documents.
 The documents are formatted in a language
called HTML (HyperText Mark-up Language).
Dr. Tim Bernes-Lee
 HTML supports links to other documents, as who developed the
concept of WWW and
well as graphics, audio, and video files.
wrote the first web
browser
 One can jump from one document to another
simply by clicking on hyperlinks.
BA 1306 Spring 2007
HTML

HTML: Hypertext Markup Language
 The coding language used to create Hypertext
documents for use on the WWW.
 Basically it is a set of ‘markup’ codes inserted in a file
that tells the Web browser how to display a Web page’s
words and images for the user.
 The "hyper" in Hypertext comes from the fact that in
HTML you can specify that a block of text, or an image,
is linked to another file on the Internet.
 HTML files are meant to be viewed using a "Web
Browser".
BA 1306 Spring 2007
HTML
<html>
<body bgcolor="yellow">
The content of the body element is
displayed in your browser.
<p>Paragraph elements are defined by the
p tag.</p>
<hr>
<h1 align="center">This is heading 1</h1>
<h2>This is heading 2</h2>
<h3>This is heading 3</h3>
<h4>This is heading 4</h4>
<h5>This is heading 5</h5>
<h6>This is heading 6</h6>
<b>This text is bold</b>
...
<big>This text is big</big>
<br>
<em>This text is emphasized</em>
<br>
<i>This text is italic</i>
<br>
<small>This text is small</small>
<br>
This text contains<sub>subscript</sub>
<br>
<br>
<strong>This text is strong</strong>
<br>
...
This text contains <sup>superscript</sup>
<br>
<a href=“http://www.metu.edu.tr”>This is
a link to our university web site</a>
This is the HTML code for... </body>
</html>
BA 1306 Spring 2007
HTML
... this web page.
BA 1306 Spring 2007
Plugins
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A plugin is a program that is integrated into
another application. The program plugs into the
application.
Plugins often provide additional functionality
that isn't available in the application.
They add functionality to a web browser.
Shockwave is the most popular plugin that
allows the use of sound and graphics (Flash
Animations) that the browser can't handle.
Quicktime is another plugin that allows
watching movies, and RealPlayer is a plugin
for audio files.
BA 1306 Spring 2007
E-Mail
BA 1306 Spring 2007
E-Mail

POP3 stands for Post Office Protocol version 3 and is
used to handle email between Email Server and our
Local Email Client (like Outlook or Eudora).
 Use of POP3 protocol is activated when we click on
"Receive" button in our email client. Until this
happens our email will stay on the “Email Server”.
 SMTP (Simple Mail Transfer Protocol) is used to
deliver email from our Email Client to the recipient's
Email Server.
 The email will stay on the recipient's Email Server
until it is explicitly requested to be downloaded by the
recipient's Email client over POP3 protocol.
BA 1306 Spring 2007
Software
Software:
●
●
1.
2.
3.
Telling The Machine What To Do
Some Task-Oriented Software
Software in The Business Environment
Computers and People
BA 1306 Spring 2007
Software: Telling the machine what to do
Software is the planned, step-by-step set of
instructions required to turn data into information.
Software is what makes a computer useful.
A subset of systems software is known as an
operating system, the underlying software found
on all computers.
The operating system serves as an intermediary
between the applications software and the
hardware.
BA 1306 Spring 2007
Operating System
Operating systems perform
basic tasks, such as:


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

recognizing input from the
keyboard,
sending output to the
display screen,
keeping track of files and
directories on the disk,
controlling peripheral
devices such as disk drives
and printers
running and controlling the
application programs
BA 1306 Spring 2007
Application Software
Applications software can be used to solve a
particular problem or to perform a particular task.
Applications software may be either custom or
packaged.
Computer programmers are people who design,
write, test, and implement software.
Organizations may pay computer programmers to
write custom software, software that is
specifically tailored to their needs.
BA 1306 Spring 2007
Acquiring Software
Software is considered to be in the public domain if it is
free to all; software in the public domain is sometimes called
freeware.
Software called shareware is also given away free; the
maker hopes for voluntary payment.
Copyrighted software costs money and must not be copied
without permission from the manufacturer.
Making illegal copies of copyrighted software is
called software piracy and is punishable under
the law.
BA 1306 Spring 2007