ملخصات لمادة الانكليزي units : 27,28,29

[Golden man]

بسم الله الرحمن الرحيم


يوجد على الرابط التالي ملخصات للوحدات المطلوبة في المذاكرة الأولى لمادة الانكليزي :

Infotech Unit : 27,28,29 (http://www.100hla.com/up/uploads/d2bf6ee961.rar)

و هي من إعداد الأساتذة جمال عبد الله و نبيل زكريا جزاهم الله خيرا.

[snoop]

الله يعطيكوم العافيه مشكووووورين ياشباب :)

[ملك التصميم]

يسلموا كثير أخي Golden وشكرا لأحلى طلاب الأستاذ نبيل والأستاذ جمال
والله يوفقنا غدا ولا تنسوا ياشباب تستغلوا الساعات الأربع الفاضية بالدراسة ولا تضيعوها بالقيل والقال وإذا ما فهمت بعض الأمور قبل المذاكرة فاسآل أحسن ما تفوت على المذاكرة وما تفهم بعض الأمور بالمادة - ووقتها لا ينفع الندم -
وبالتوفيق للجميع

تحياتي..

[mahmoud]

Unit 27 Electronic communications


Glossaries:
Fax : a document or image that is transmitted in digitized electronic form over telephone lines and reproduced in its original form on the receiving end.
E-mail : a system that allows text-based messages to be exchanged electronically.
Teletext : a system of broadcasting news and other information in written form that can be viewed on specially equipped television sets, superimposed on, or in place of, the picture.
BBS : an online forum used to exchange e-mails, chat, and access software.
Commercial online service: to access massive databases containing all kinds of information, or to be connected with an airline reservations service.
Telecommunication: the transmission of encoded sound, pictures, or data over distances, using radio signals or electrical or optical lines.
Modem : an electronic device that connects computers via a telephone line, allowing the exchange of information. It consists of a modulator to convert computer information into a telephone signal and a demodulator to convert it back again.
ISP : a company that provides access to the Internet, it charges a flat monthly or annual fee that gives you unlimited access. Some large providers offer users a wide range of news, information, and entertainment services.

Questions:
What is sysop?
It’s acronym of system operator, the person who administrate the BBS.

What can you do with a modem?
1)Exchanging e-mail and files with your friends.
2)Accessing the Web, and searching for information about the stock market, current affairs, entertainment, etc.
3)Participating in newsgroups and live conversations.
4)Making bank transactions and buying things from the comfort of your home.
5)Accessing to your office from your computer at home of your laptop in a hotel room.

What do you need to telecommunicate?
1)PC.
2)Modem.
3)Telephone line.
4)Communication software.

What an ISP give you when make an account?
1)Software package
2)Username.
3)Password.
4)Access phone number.

Name three of companies that provide commercial online services and what they differ from ISPs?
America Online, CompuServe, and the Microsoft Network.
They differ from ISPs in two ways:
1)Commercial online services use a smooth, easy-to-use interface
2)They have extra services for members only. For example, they offer airline reservations, professional forums, etc.
3)They charge higher prices.

Acronyms (abbreviations):
MODEM : MOdulator/DEModulator
BBS : Bulletin Board System
sysop : system operator
FTP : File Transfer Protocol
IRC : Internet Relay Chat
fax : facsimile machine
kbps : kilobits per second
Unit 28 Internet Issues

Glossaries:
Hacker: a computer user who gains unauthorized access to a computer system or data belonging to somebody else.
Cookie : a computer file containing information about a user that is sent to the central computer with each request.
The server uses this information to customize data sent back to the user and to log the user's requests.
Certificates : files that indentify users and Web servers on the net, like digital identification cards.
Encryption : to convert computer data and messages into something incomprehensible using a key, so that only a holder of the matching key can reconvert them.
Decryption : to transform an encoded message into an understandable form.
Firewall : a software and hardware device that allows limited access to an internal network from the Internet. This prevents intruders, hackers, from stealing or destroying confidential data.
Virus : a computer program which attaches itself to an application or file. Once you run an infected application, the virus quickly spreads to the system files and other programs. Some viruses can delete files or destroy the contents of hard disks.
Trojan horse : a computer program containing a hidden function that causes damage to other programs while appearing to perform a valid function


Worm : a computer program that invades computers on a network, replicates itself to prevent deletion, and interferes with the host computer's operation.

Questions:
What is the only way to protect your message on the Internet?
It’s to encode your message with some of encryption.

What is name of system designed to send e-mail privately? Who wrote it?
It name is Pretty Good Privacy, written by Phil Zimmerman.

What is the most common methods of protection for network?
1)Passwords for access control.
2)Encryption and decryption systems.
3)And firewalls.

From where viruses could enter your PC? How can protect your PC from them?
Viruses can enter a PC through:
1)Files from disks (e.g. CDs, DVDs, Floppies…etc)
2)Internet.
3)BBSs (Bulletin Board Systems).
To protect you PC from them:
1)Set all security alerts to high on your web browser.
2)Delete cookies.
3)Make sure your bank uses digital certificates.
4)Don’t open e-mail attachments from strangers.
5)Take care when downloading files from the Web.
6)Remember to update your anti-virus software as often as possible, since new viruses are being created all the time.

Acronyms (abbreviations):
SET : Secure Electronic Transactions.







Unit 29:LANs and WANs

Definitions:
Network: is a group of devices (PCs, printers, etc.) or 'nodes' connected by communications circuits so that users can share data, programs and hardware resources.
Protocols: the rules which determine the formats by which information may be exchanged between different systems.
Software (in network): the 'language' that they use to 'talk' to one another over the network.
Transceiver: the hardware that sends and receives network signals.
Architecture: the physical distribution of nods and their circuits Or, that cables and transceivers that allow computers to 'hear' on another,
Enumeration:
What is the main element of network?
1.Physical structure. (That links elements.)
2.Software. (That allows communication.)

What are the considerable advantages of fiber-optic?
1.The cables require little physical space.
2.They are safe because they don't carry electricity.
3.They avoid electromagnetic interference.
Questions:
What is the network 'topology' or 'architecture'?
The physical distribution of nodes and their circuits.
What is the most widely used transceiver ?
Token Ring, Ethernet and LocalTalk.
What is the speed of transceiver?
The Token Ring adapters transmit data at a speed of 16 megabits per second.
The Ethernet adapters transmit data at a speed of 100 megabits per second and the newest version, Gigabit Ethernet , supports data rate of 1 Gb per second.
What the Ethernet provides?
Ethernet provides a very robust, trouble-free architecture with good levels of performance.
Why the LocalTalk is cheapest of all transceiver?
Because they directly included in each Macintosh.
Why the most Macs come with built-in Ethernet?
Because the LocalTalk a bit slow.
How the Token Ring avoids the possibility of collisions?
To transmit data, a workstation needs a token, and as there is only one token per network, holding one guarantees sole use of the network.
Why TCP/IP is the most useful?
It allows different operating systems to communicate with each other.
What is the protocol used by LocalTalk network?
They use AppleTalk Protocols.
What is the work of gateway ?
It's help to manage communications and control traffic on large network.
How gateways work?
They change the data to make it compatible with the protocols of different networks.
How network can be linked together ?
By either telephone lines or fiber-optic cables.
What are ISDN and ADSL ?
They are an international stander for transmitting digital text, sound, voice and video data over the telephone lines.


What is FDDI?
(Fiber distributed data interface ) is an optical-fiber network. It transmits data at great speed 100 megabit per second.
Why in telecommunication use fiber-optic cable?
Because data can be transmitted at a very high speed through the extremely wide bandwidths of glass fibers.
How the fiber system operates ?
By transmitting light pulses at high frequencies along the glass fiber.
Abbreviation:
LANs: local Area Networks.
WANs: Wide Area Network.
Transceivers: transmits and receivers
MbPS: megabit Pear Second .
GbPS: Gigabit Per Second
TCP/IP: Transmission Control Protocol / Internet Protocol.
ISDN: Integrated Service Digital Network.
ADSL: Asymmetric Digital Subscriber Line.
FDDI: Fiber Distributed Data Interface.