Fall semester 2011 Day 2: types of software, computing environments Professor: Giuseppe Sindoni ( [email protected]) Microcomputer applications This material is distributed under the “Creative Commons “Attribution – NonCommercial – Share Alike 3.0” , available at http://creativecommons.org/licenses/by-nc-sa/3.0/
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Allows users to input instructions to use the system.
Command line interface (CLI): the original interface mode, still in use for complex tasks. Based on text commands.
Graphical User Interface (GUI): graphics-based interaction to enable less expert users to use the computer. Usually based on an analogy of a working environment (Desktop, Folders, Trash, Notes, etc.).
Operating systems and their user interface: DOS, Windows, Linux, Mac OS, Android, iOS.
Application software - 2 Browsers: Internet Explorer, Mozilla Firefox,
Chrome, Safari Email clients: Outlook (Express), Mozilla
Thunderbird. Desktop Publishing Computer Aided Design (CAD) Enterprise Resource Planning (ERP) Media Players Graphics programs for drawing and retouching
photos, programs for composing music, editing film, etc
Computer games And many others...
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Algorithms
Algorithms solve problems by tackling them in a systematic way. Examples include recipes and search engines.
In IT, algorithms are methods to solve problems that can be implemented as programs.
A procedure is a series of steps (sequence) implementing an algorithm.
A flowchart provides a graphic representation of the algorithm (procedure). Broadly speaking, flowcharts are a graphic modeling language to represent algorithms.
Computers in everyday life Computers are used in the office and at home, for work and
leisure. Services available on the Internet and the Web:
• E-commerce: transactions for selling goods and services between producers (supply) and consumers (demand).
• E-banking: management of bank accounts and financial transactions.
• E-government: IT-enabling of Public Administration (PA) services, aimed at optimizing organizations’ work and providing users (members of public and businesses) with newer, faster services (e.g. websites).
• E-learning: learning over the Internet by long-distance access to teaching materials and tools.
• Teleworking: use of ICT to overcome office boundaries and enable staff to work from home. Teleworking has both benefits and limitations.
• Leisure time services…
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Your health and the environment Ergonomics. Suggestions for protecting the
health of computer users:-Pay attention to back, wrist and eye discomfort;-Use a suitable chair (adjustable seat height, armrests, lower back support, 5-pedestal base);
-Right keyboard position, wrist support;-Screen: straight in front of you, eliminate reflections, don’t stare at it too long, use a big screen;
-Take frequent breaks: alternate computer and paper work as much as possible.
Environmental protection:-Reduce use of paper and toner/cartridges. Recycle waste where possible;
-Use low-energy devices and energy saving options (PC configuration parameters).
Security encompasses 3 aspects:- Confidentiality: data, services and devices can be
accessed by enabled users only.
- Integrity: security of data, services and devices; tracking every change.
- Availability: those who have the right to use data, services and devices must be able to do so.
User identification is crucial. Authentication: general rules for creating
passwords. Identification and personal data: each country
has specific laws on protection of privacy.
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Data security
Many causes of data and information loss or damage:
- Failure of mass storage devices (e.g. hard disks);
- Intrusion of external agents (e.g. viruses);
- Theft (laptop, PDA, smartphone).
Many precautions to prevent data loss:
- Backups. Compression techniques;
- Firewalls and modern antivirus programs;
- Mechanical blocking devices, disk encryption.
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Computer viruses
Viruses are programs containing potentially harmful instructions. Main types:
True viruses: portions of a program which are activated when the program is executed. They can reproduce and cause trouble.
- Worms: programs which exploit the net to infect other computers. They propagate via email and the Web.
- Trojans: programs behaving in unexpected ways or opening doors to the “enemy”.
Where they hide:- Infected programs; they also spread as email attachments or are
downloaded from “fake” websites.- Infected documents (MacroVirus).
Defence:- Antivirus programs. Keep them and operating systems updated. - Defence systems limiting access to local resources (e.g. Firewall).- Common sense: do not open email attachments if you are not sure of
their content; do not download software from unsafe websites.
ICT history in a nutshell1946 ENIAC, the first electronic computer: valve technology,
programs written in machine code, physical connections between circuits.
1959 First transistors.1965 IBM introduces 360 mainframe series: integrated circuit
technology.1969 ARPA-Net, the precursor of the internet.1977 First Apple II microcomputer.1981 First IBM Personal Computer with MS-DOS and Intel 8088.1984 Apple Macintosh, mouse and graphical environment, laser
printers.1991 First Linux version.1992 Microsoft Windows 3.11994 World Wide Web. First version of Netscape. Intel Pentium
processor.1998 AMD Athlon processor.2001 Windows XP, rise of Linux.2004 Rise of Google and spread of ADSL.2006 Web 2.0: Wikipedia, Flickr, YouTube, Facebook, etc.2007 iPhone2008 Android
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Local computing
So far… PC as a self-contained world Software seen as something aimed at
making a single PC work
Principle… One person, one PC, a bunch of
dedicated software programs running on it
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Computer networks
Connect computers (millions of them). Communication network: a system of
computers, telephones or other connected devices, able to communicate with each other and share applications and data. Main types:
- Local or LAN: Local Area Network. WLAN (Wireless LAN);
- Geographic or WAN: Wide Area Network. MAN (Metropolitan Area Network);
What is the Internet? The largest computer network. Created in the 60s from an USA ARPA-DoD project. A network of networks, based on the TCP/IP (TCP, IP, UDP,
FTP, NNTP, HTTP). They are public and open. The original objective was to share and exchange data
between research laboratories. 1969: first connection between two computers (UCLA-
Stanford). The oldest services are email, file and document
transmission (ftp), newsgroup (nntp), remote control (telnet).
Modern services include web, chat, voip, etc. Main internet organizations: ICANN, ISOC, IETF, IESG and
W3C, managed by companies, selected users and nations. Internet technologies in the business world: Intranet and
Internet history in a nutshell1969: ARPANet, initially connecting 4 American universities with remote connection
services and file exchange. Originally also the backup for the US military network. 1971: First email service.1972: ftp protocol: ARPANet connects 37 hosts (nodes)1982: ARPANet adopts the Tcp/Ip protocol and recommends use of Unix.1983: The “military” part of ARPANet spins off and becomes MilNet.1984: ARPANet offers the first DNS services, creation of NSFnet (56Kbps).1989: ARPANet closes down. 100,000 hosts on NSFnet.1990: Internet starts spreading in Europe.1992: Public release of the WWW at CERN, Geneva. Rise of the internet society (Isoc).1993: Mosaic, the first graphical browser.1995: Non-USA nodes amount to 50% of the total. New backbone carrying 155 Mbps.
Creation of Netscape.1997: One million hosts on the Internet1999: Backbone upgraded to 2.5 Gbps. European backbone: 1 Gbps2004: Continental backbones beyond 10 Gbps, national ones beyond 2.5 Gbps2009: 43 million hosts and more than a billion Internet users2011: 2,100,000,000 Internet users and rising…
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The World Wide Web (web) 1989: Web project began at CERN, Geneva, led by Tim
Berners-Lee Goal: promote collaboration among scientists by exploiting
the Internet. Web standards:
- HTTP: hypertext document transfer protocol on Internet.
- HTML: web document format (tag language).- URL: standard protocol to assign a unique address to
each web document. 1993: Mosaic, the first browser with graphic color display of
photos, text, images, etc. developed by Marc Andreesen of NCSA (Illinois). Mosaic was the precursor of Netscape, itself the precursor of Mozilla, which became Firefox.
What is the Web? A distributed hypertext network. Hypertexts differ from other texts in the way information is
accessed by users: each page provides links to other pages, which can be accessed in whatever order the user prefers.
No page sequences: a concept can be explored or expanded with just a click.
In a hypertext network each hypertext links to other, related hypertexts.
Called a distributed network because hypertexts are located in various computers, connected through the Internet.
Hypertext links (URLs) on the WWW are network addresses pointing to web documents or pages (usually in HTML format), transmitted from a server to a browser via the HTTP protocol.
Web pages contain hypertext and much more: images, video, music, etc.
- http protocol: base protocol for the Web. - Domain name (www.w3.org): the name assigned to a
computer that is permanently connected to the Internet. Formed by 3 parts:
www: world wide web w3: organisation/company/institute name org: organization type, top level domain. Other domains: com
(commercial); edu (university and research); gov (governments); mil (military); net (ICT networking organizations). National domains: it, uk, fr, jp. European: eu.
- File path (/TR/html401/intro/intro.html), with file name: intro.html
- Fragment identifier (#section3): name of a part of a document
Chat: first internet applications for real time text message exchange between several users.
VoIp (Voice Over IP): use of internet data connection to transmit voice. Microphone needed.
Instant Messaging (IM) programs are currently very popular. They integrate chat (and video from a webcam), email and vocal communication: ICQ, Skype, MSN and Yahoo! Messenger.