Transcript Fundamental of Computers

Introduction to Computer
Engineering
ENCE200
Engineers and Computers
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Storage, and manipulation of data
Communication over networks (e-mail, web)
Desktop publishing (desktop publishing is the process of
using the computer and specific types of software to
combine text and graphics to produce documents such as
newsletters, brochures, books, etc.)
Numeric, symbolic computations
Building software applications
Computer System
A computer is a machine that manipulates data according
to on a set of instructions.
System Elements:
Computing Elements:
 Central Processing Unit, CPU.
 Disk spaces,
 Input devices: keyboard, sensors
 Output devices: monitors, printers
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Main parts of a computer
Processor
• ALU
• Control
Memory
• RAM
• ROM
Devices (I/O)
• Input
• Output
Processor Units
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The Central Processing Unit (CPU) or the processor is
the part that carries out the instructions of a computer
program.
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ALU: Is a digital circuit which performs the arithmetic and
the logical operations.
Control Unit: It controls the flow of information through
the processor, and coordinates the activities of the other
units within it.
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Processor Specifications
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Cache: Cache operates as a temporary storage area
where frequently accessed data can be stored for rapid
access. (6 MB)
Clock Speed: The number of data transfers it performs
per clock cycle. (2.2 GHz)
Bus Speed: The clock speed of the bus.(1333 MHz)
Number of Cores: the number of processing cores. 2 Duo
Hardware Model of a Personal Computer
Central Processing Unit
Busses
Busses
Input/Output
Keyboard
Monitor
Ports
Mass Storage
Hard Disk
CD-ROM
DVD
Data
Instruction
Data
Instruction
Random Access
(RAM)
Data Memory Instruction
Data
Instruction
Read-Only Memory (ROM)
Zoom-in a System Component [1]
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Voltage Range of Binary Signals[1]
5.0 Volts
HIGH (1)
HIGH (1)
4.0 Volts
3.0 Volts
2.0 Volts
1.0 Volts
LOW (0)
LOW (0)
0.0 Volts
INPUT
OUTPUT
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Rapid change in Computer Technology
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Processor
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Memory
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logic capacity: about 30% per year
clock rate:
about 20% per year
So… advanced functions (e.g., multimedia functions in some Pentiums)
and high-speed features (multiple pipelines, larger caches)
DRAM capacity: about 60% per year (4x every 3 years)
Memory speed: about 10% per year
Cost per bit: improves about 25% per year
So… larger memory => more challenging applications (e.g., atmospheric
modeling, astrophysics modeling)
Disk
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capacity: about 60% per year
So … huge disk capacities => large data storage (video, music files, large
data for various applications)
Some Definitions:
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Bit: A variable that can have only two possible values.
Byte: A byte (B) consists of a grouping of eight binary digits ("bits"), and is
typically considered the smallest addressable unit of data.
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RAM: (Random Access Memory) RAM is used to run certain basic
programs and functions that your computer needs to operate correctly,
and functions only while the computer is receiving power.
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ROM: (Read Only Memory) : a type of unchangeable memory residing in
chips on motherboard. ROM contains the bare minimum of instructions
needed to start your computer.
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Hard Disk Drive: The mechanism that controls the positioning, reading, and
writing of the hard disk.
Basic Data Types
Data Type
Contains
Default
Size (bit(s))
Range
boolean
True or False
false
1
N.A.
char
Unicode Char
/u0000
16
\u0000 to
\uFFFF
byte
Signed integer
0
8
-128 to 127
short
Signed integer
0
16
-32768 to 32757
Int
Signed integer
0
32
-2147483648 to
2147483648
long
Signed integer
0
64
9223372036854
775808 to
9223372036854
775807
float
IEEE 754 floating 0.0
point
32
-1.4e-45 to
3.402e+38
double
IEEE 754 floating 0.0
64
-4.9e -32 to
Table for Quantifying Storage
Term
Abbreviation
Number of Bytes/bits
Byte
B
8 bits
Kilobyte
KB
1024= 2^10
Megabyte
MB
1,048,576=2^20
Gigabyte
GB
2^30
Terabyte
TB
2^40
Operating System
Operating System (OS.) is an interface between hardware
and user which is responsible for the management and
coordination of activities and the sharing of the resources
of a computer.
Examples:
Linux
Mac Os X (Unix based)
Microsoft Windows
Solaris
Services Provided from OS.
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Facilities for storing, manipulating data
Facilities for running software applications
Facilities for Communication with others
“It allows you to use the computer without any
knowledge of coding. Without an operating system, the
hardware would not work until you write your own
code.”
Operating Systems (continued)
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Earliest OS were designed for single user
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Extensions: Multiple user in small connected networks
could share information
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Now: The computers across World Wide Web (internet)
are able to communicate
Computer Networks
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When 2 or more computers are connected, through
electronic circuits or wireless transmissions of various
designs and technologies for the purpose of exchanging
data or communicating information between them.
Types of Networks by their size:
LAN: local- area network: covering a small physical area,
like a home, office.
WAN: Covers a broad area (i.e., any network whose
communications links cross metropolitan, regional, or
national boundaries [2]
Network Architecture
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There are two common architecture for computer networks:
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Client- Server networks:
Client-server computing or networking is a distributed
application architecture that partitions tasks or work loads
between service providers( servers) and service requesters,
called clients.
Peer-peer networks: P2P, a distributed network architecture
composed of participants that make a portion of their
resources (such as processing power, disk storage or network
bandwidth) directly available to other network participants,
without the need for central coordination instances (such as
servers or stable hosts).
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Client- Server Approach
Wired Technologies for Computer Networks
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Twisted –pair :The most widely used medium for
telecommunication. Twisted-pair wires are ordinary
telephone wire.
Data Transmission Speed: from 2 million bits per second
to 100 million bits per second.
Coaxial cable: are widely used for cable television
systems, office buildings, and other worksites for local
area networks.
Data Transmission Speed: from 200 million bits per
second to 500 million bits per second
Wired Technologies for Computer Networks(
continued)
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Fiber optic: consist of one or more thin filaments of
glass fiber wrapped in a protective layer.
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Data Transmission Speed: The speed of fiber optics is
hundreds of times faster than coaxial cables and
thousands of times faster than twisted-pair wire.
Different Types of Networks
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Intranets :A set of networks, using Internet protocols, and
IP based tools such as web browsers and file transfer
applications, under a control of administrative entity.
extranets: is a network limited to a single organization or
entity.
Internet: The a global system of interconnected
governmental, academic, public, and private computer
networks.
Network Hardware Components
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Network Card: A piece of computer hardware to allow
communication between computers.
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Repeater: The device that clean the signals from noises,
transmits it at a higher power level.
Routers: It forwards packets between networks.
Switches: This is distinct from a hub in that it only forwards
the frames to the ports involved in the communication rather
than all ports connected
Hub: When a packet arrives at one port, it is copied
unmodified to all ports of the hub for transmission. The
destination address in the frame is not changed to a broadcast
address
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Issues with Computer Networks
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Develop techniques for computers to communicate
(software/hardware)
Especially important for multimedia communication made
through protocols
Reliability is especially important –ensure data received
successfully
Need for mathematical modeling
Internet
Internet
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The world’s largest computer network. It means the
network of networks.
History: 1969 the DOD project on building an Advanced
Research Projects Agency Networks (ARPANET), how to
keep U.S. military sites in communication in case of war.
1994: It has 20 million users in more than 50 countries
2004: 800 million users
Internet (Continued…)
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1968 - DARPA (Defense Advanced Research Projects Agency) contracts
with BBN (Bolt, Beranek & Newman) to create ARPAnet
1970 - First five nodes:
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UCLA
Stanford
UC Santa Barbara
U of Utah, and
BBN
1974 - TCP specification by Vint Cerf
1984 – On January 1, the Internet with its 1000 hosts converts
en masse to using TCP/IP for its messaging
Common Definitions
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IP: An Internet Protocol (IP) address is a numerical label
that is assigned to devices participating in a computer
network that uses the Internet Protocol for
communication between its nodes.
IPv4 addresses are usually represented in dot-decimal
notation (four numbers, each ranging from 0 to 255,
separated by dots, e.g. 208.77.188.166).
IP address
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Browser: A web browser is a software application for
retrieving, presenting, and traversing information
resources on the World Wide Web.
Host: ( internet node) is a computer node, that is
connected to the internet.
Server: A host that host information resources as well as
application software for providing network services, is a
server.
URLs: Stands for "Uniform Resource Locator." A URL is
the address of a specific Web site or file on the Internet.
It cannot have spaces or certain other characters
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Router: Is an electronic device used to connect two or
more computers or other electronic devices to each
other, and usually to the Internet.
Firewall: A Hardware or software, or a combination of
both that blocks an unauthorized access.
Proxy: In computer networks, a proxy server is a server
(a computer system or an application program) that acts
as an intermediary for requests from clients seeking
resources from other servers.
Internet Service Provider: (ISP) Is a company that
provides
Modem
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A modem (modulator-demodulator) is a device that
modulates an analog carrier signal to encode digital
information, and also demodulates such a carrier signal to
decode the transmitted information.
Cable Modem (1999)
600-1500 kbits/sec
DSL (2004)
1.5 Mbits/sec
WLAN-Wireless Local Area Network
Protocols
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A set of rules which is used by computers to
communicate with each other across a network. A
protocol is a convention or standard that controls or
enables the connection, communication, and data transfer,
data formatting between computing end points.
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The Institute of Electrical and Electronics Engineers or
IEEE is a non-profit, professional organization for the
advancement of technology related to electricity.
Common Internet Protocols
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ISO
TCP/IP
HTTP
SSH
Telnet
FTP
Transmission Control Protocol (TCP)/
Internet Protocol (IP)
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IP: How the data are to be physically transmitted from one
computer to another.
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TCP: Ensures that data being using IP are received without
errors.
Note: TCP/IP form the foundation of many other high level
application-oriented protocols.
Examples:
FTP: file transfer protocol
Telnet
SSH: Secure shell
Http: Hypertext Transfer Protocol is used for retrieving the
hypertext
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OSI
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Open System Interconnection Reference Model
Is an abstract description for layered communications and
computer network protocol design.
Network layers
Connection in TCP/IP
TCP/IP VS. OSI
Number of Hosts on the Internet
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Host: Any computer connected to the internet- or any
type of data network. A network host can host
information resources as well as application software for
providing network services.
Date
No. of hosts
Date
No. of hosts
Aug 81
213
Jan. 89
80,000
May. 82
235
Oct. 90
313,000
Aug. 83
562
Oct. 91
617,000
Oct. 84
1024
Oct. 92
1,136,000
Nov. 85
1,961
Oct. 94
2,056,000
Dec. 86
5,089
Oct. 95
3,864,000
Jul. 88
33,000
Jul. 96
12,881,000
What is Happening on the Web
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Sending packets of information (like sending a letter)
Delivery address: The location of the internet provider.
Return address: The location of your home.
Internet Domain Names and Addresses
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Domain name : A name that identifies one or more IP
Addresses, they are used in URLs to identify particular
Web pages.
Example1 : umd.edu represents about a dozen IP
addresses.
Example 2: in URL https://mail.umd.edu/ mail.umd.edu is
the domain name.
Internet is based on IP addresses, not domain names,
every web server requires Domain Name System (DNS)
server to translate domain names into IP addresses.
Email addresses
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Email addresses follow a three-part format:
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Person’s UserID@ domain name of the computer.
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[email protected]
[email protected]
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Top Level Domains( TLD)
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Every domain name has a suffix that indicates which top
level domain (TLD) it belongs to. There are only a limited
number of such domains.
gov - Government agencies
edu - Educational institutions
org - Organizations (nonprofit)
mil – Military
com - commercial business
net - Network organizations
ca – Canada
th - Thailand
Domain Names and Address Resolution
Internet Services
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Basic Services the World Wide Web is providing:
E-mail: Sending and receiving Electronic messages
Telnet: The Telecommunication Network allows user to
remotely login to computers over the network.
File Transfer: The File Transfer Protocol enables copying
files from one computer to another computer in the
network.
Examples of the Internet Services
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http:// www.ence.umd.edu/welcome.html
Connects to an HTTP server and retrieves an HTML file.
ftp://rtfm.mit.edu/pub/usenet
Opens an FTP connection to the usenet frequently asked
questions stored at rtfm.mit.edu
Hypertext and Hypermedia
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Hypertext: The same as regular text - it can be stored,
read, searched, or edited - with an important exception:
hypertext is text with pointers to other text.
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Hypermedia: is a superset of hypertext. Hypermedia
documents contain links not only to other pieces of text,
but also to other forms of media - sounds, images, and
movies.
Uniform Resource Locators
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The Web employs called Uniform Resource Locators( URLs)
to represent hypertext, hypermedia links to network services
within Hypertext Markup Language (HTML) documents.
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URL format:
First part: The method of accessing (http is the most common
one)
Second part: is the address of the computer where the data or
service is located.
Further parts: Specify the names of files, the port to connect,
or the text to search for in a database.
http://www.ence.umd.edu/welcome.html
Web Search Engines
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A web search engine is simply a computer program that
allows users to make queries for information residing in a
database.
The URLs for some of the good search engines are as
follows:
Search Engine
Uniform Resource Locator
Yahoo
http://m.www.yahoo.com/
Alta Vista
http://www.altavista.digital.com
google
http://www.google.com/