1Lecturer: Dalia Mirghani Saadabi. 2 A set of computers connected together so that they can...

Lecturer: Dalia Mirghani Saadabi

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Computer for Health Sciences

COMP101


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Communication software and the

internet

Lec. (6)


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Networks• A set of computers connected together so that they

can communicate is called a computer network. • This involves installing network cards in each

computer.• Each computer is then connected through cabling to

a central device called a hub.• Operating systems contain components that are

dedicated to the task of enabling computers to communicate over a network. This software makes use of special rules of communication called protocols.

• The most commonly used protocol for establishing and maintaining communication across a network is called TCP/IP or Transmission Control Protocol / Internet Protocol.


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Client-server and peer-to-peer networks

There are two types of network interconnection:

• 1) Networks on which all computers have equal status are called peer-to-peer networks.

• 2) Certain computers provide services to other computers, they are called servers.

• The computers that make use of the services or servers are called clients.

• A network such as this is called a client server network.

Dr. Dalia Mirghani Saadabi

5Dr. Dalia Mirghani Saadabi


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Types of networks1. LAN

A LAN or Local Area Network is a group of computers within the same building, or within a group of buildings that are in close proximity, that are connected together.

2. WANA WAN or Wide Area Network is a group of widely dispersed computers that are connected together. These could be across the same town, or across a country or even across the world.


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• InternetThe internet is the collection of all computers across the world which can access each other in some way. The links between computers might include telephone, fiber optic cable, radio, microwave or satellite.

Some of its main uses:• Provide access to and share information and

databases.• Transfer and share files between computers.• Facilitate business transactions.• Share resources.• Promote scientific co-operation between research

institutions.• Provide a communications channel for the military.

The Difference Between the Internet and Intranet


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• IntranetAn intranet is similar to the Internet in operation. However, it is limited to an organization. Users may browse computers within an intranet using a browser but will usually not be able to access the wider Internet. An intranet can be thought of as a private Internet.


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The Difference Between the Internet and World Wide Web• The World Wide Web, or simply Web, is a way of

accessing information over the medium of the Internet.

• It is an information-sharing model that is built on top of the Internet.

• The Web uses Hypertext Markup Language or HTTP protocol, which is the only language that spoken over the Internet to transmit data.

• The Web also utilizes browsers, such as Internet Explorer or Firefox, to access Web documents called Web pages that are linked to each other via hyperlinks.

• Web documents also contain graphics, sounds, text and video.

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Modems• A modem is a device connected between a

computer and a telephone line. • Its function is to convert the digital signals of

the computer into a form suitable for transmission over a telephone line.

• It must also do the reverse and convert the telephone line signals into a form suitable for the computer.


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Cards and Adapters• A special device is needed to move the data from

the computer or mobile device through the transmission media to the access provider.

• Some computers have wireless and network cards built into them instead of modems:

1. A wireless card:Is used to provide connectivity via mobile computers.

2. A network card: Which is installed into a computer, enables a

direct connection to a network. 3. USB cellular modem:

Is a wireless adapter that connects a laptop to a cellular telephone system for data access and transfer.



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A wireless card

A network card

USB cellular modem

Using the world wide web

Using Web browser:A web browser is the software program that is used to display Web pages on the World Wide Web, as Internet explorer and Firefox.

Internet search engine: Is an application, which helps users to locate Web sites containing useful information and references. To search Information :

A user types the description of the information using the user interference of the search engine.

The search engine then searches the requested information on the WWW and returns the results to the user.


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• This section will focus on a specific search engine such as Google chrome.

• Enter your URL into your web browser location bar.• Press Enter or click Search.

• The secret of using a search engine such as Google in choosing the best key words or phrases to locate useful web sites.


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Some Popular Internet Search Engines

Special Medical Search Engines…


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Medical Search Engines:

Medical search engines are search engines which are specialized in medical information, researches, news and so on.

Here are some examples of the most popular medical search engines…

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1- iMediasearch 2- pogofrog.com



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3- OmniMedicalSearch


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Most Popular medical website:


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Online Encyclopedia & Libraries

www.thecochrane.com www.oxfordhandbooks.com


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www.medicinenet.com (Medical dictionary)

http://www.medicinenet.com/


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Information Security• Information security refers to all the

procedures which are used to protect information for deliberate or accidental misuse or dissemination

• Technically, it refers to the maintenance of the integrity of information.

• There are a number of procedures companies and persons can take to protect their information.


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1. Security procedures:• Information should be classified on the basis of

its sensitivity. • Access rights to this information should be

limited to those who need to know.2. Physical procedures:• Physical access to mainframes should be

restricted to operators and systems administrators.

• Desktop and laptop computers are very vulnerable to theft. A simple procedure is to only allow authorized people access to offices.

• The use of security cameras can also act as a deterrent.


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3. Software procedures:• Information can be stolen, altered or deleted

without the computer being physically removed. The information may even be accessed across the Internet.

a) Firewalls:• It is a computer program that is installed on a

computer that connects a network to the Internet.• The firewall analyses the packets that pass in and

out of the network.

b) Access rights:• Access rights can refer to both physical and

software.• Software rights refer to the level of access

different users have to different levels of data and information.


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c) Password policies:• They can be required for access to a computer

system or a group of files or a single file.


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Computer Viruses• A computer virus is a program that is

deliberately created to cause annoyance or alter or delete data.

• Trojan: A Trojan (or Trojan horse) is a virus that hides itself inside another legitimate program. When the program is used, the virus is released and can begin its work of replication and annoyance or damage.

• Worm: A Worm is a program that replicates itself over and over in the computer's memory until the computer can barely function. One of the signs of invasion by a worm is the slowness of computers.


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• Spread of computer viruses:Viruses are spread in a number of ways:– Downloads from the Internet.– Pirated software.– Exchange of diskettes.– In attachments to emails and in emails

themselves.– In documents.


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• Anti-virus software:

• Anti-virus software scans files for pieces of code, called signatures, which it recognizes as part of a virus.

• Updating anti-virus software mostly involves updating the signatures file.

• When a virus is detected, the software will attempt to remove the virus. This is called cleaning or disinfecting.

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Exercise (3)• Refer to your text book, study chapter (9) and

answer the following question:

• List the equipment and software that needed to access the internet?

Please send answers to the e-mail

[email protected]


mailto:[email protected]


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