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Computer/IT SS 3
Theme 1 Information and Communications Technology
Theme 2 Computer Applications
Theme 3 Problems – Solving Skills
Theme 4 Coding Systems in Computer
Theme 5 Computer Ethics
Computer networks are interconnected systems that allow computers and other devices to communicate, share resources, and exchange information. These networks come in various types, each suited for specific purposes and scales. Here are some common types of computer networks:
Computer networks are classified according to organizational structure, usage patterns, and operational coverage. These encompass:
A LAN is a network that spans a relatively small geographic area, such as a single building, office, or campus. LANs are typically used to connect devices like computers, printers, and servers. Ethernet cables or wireless connections are commonly used to establish LANs.
WANs cover larger geographical areas, often connecting LANs across cities, countries, or continents. The internet is the most well-known example of a WAN. WANs use routers, switches, and communication lines like leased lines, fiber optics, and satellite links to connect distant locations.
MANs are larger than LANs but smaller than WANs, covering a city or a metropolitan area. They are often used by organizations that need to connect multiple offices within a city.
CANs are networks that cover a campus or a large university. They provide connectivity between various departments and buildings on the campus.
A PAN is the smallest type of network, typically connecting devices within a short range, like personal devices (e.g., smartphones, laptops, and tablets) using technologies such as Bluetooth or infrared.
A WLAN is a type of LAN that uses wireless technology (such as Wi-Fi) to connect devices within a specific area, eliminating the need for physical cables.
A VPN is a network that creates a secure and encrypted connection over a public network (usually the internet). It allows remote users to access a private network as if they were directly connected to it, ensuring data privacy and security.
An intranet is a private network that functions similarly to the internet but is restricted to a specific organization. It enables employees to share resources, collaborate, and communicate within the organization.
An extranet is an extension of an intranet that allows authorized external users, such as partners, suppliers, and clients, to access certain parts of an organization’s internal network.
In this network model, one or more powerful servers provide services and resources to client devices. Clients request and use services, while servers manage and deliver those services.
In a P2P network, devices, or nodes, communicate directly with one another without relying on a central server. P2P networks are often used for sharing files and resources between users.
Cloud networks leverage cloud computing services to deliver resources and services over the internet. Users can access applications and store data remotely, without the need for local infrastructure.
These networks are used in industrial environments to connect and control machinery, equipment, and processes. They are essential in sectors such as manufacturing, energy, and transportation.
Sensor networks consist of interconnected sensors that gather and transmit data from the environment. They are used in applications like environmental monitoring, healthcare, and home automation.
HANs are designed to connect devices within a household. Smart devices like thermostats, lights, and appliances can be part of a HAN, allowing remote control and automation.
A SAN is a high-speed network dedicated to connecting storage devices, such as disk arrays and tape libraries, to servers. SANs are commonly used to enhance storage capacity and performance in data centers.
An overlay network is created on top of an existing network infrastructure to provide additional functionality or features. Virtual private networks (VPNs) and content delivery networks (CDNs) are examples of overlay networks.
GANs connect multiple networks across the world, often using satellite and terrestrial wireless communication. They are used for global communication and coordination in sectors like military and international organizations.
This type of network is established within an organization and is designed to facilitate secure communication and data sharing among its various branches, departments, and offices.
Cellular networks provide wireless communication for mobile devices like smartphones and tablets. These networks use a system of cell towers to provide coverage and allow users to access voice and data services.
Satellite networks use communication satellites to transmit signals between ground stations and satellite dishes. They are used for various purposes, including television broadcasting, internet access, and global positioning systems (GPS).
A MANet is a network that covers a specific area within a city or municipality, often providing free public Wi-Fi access to residents and visitors.
A hybrid network combines different types of networks, such as LANs, WANs, and cloud services, to create a unified and versatile communication infrastructure.
A mesh network consists of interconnected nodes, where each node can communicate with several other nodes directly. Mesh networks are highly resilient and self-healing, making them suitable for scenarios where network reliability is crucial.
Blockchain networks are decentralized and distributed ledgers that use cryptographic techniques to secure transactions and information. They have applications in secure data sharing, cryptocurrencies, and smart contracts.
These are examples of the many types of computer networks that exist. The choice of network type depends on factors like the geographical scope, connectivity requirements, security needs, and the purpose of the network.
Workstation/Client: Each computer within a network is commonly referred to as a workstation or client. Clients are the machines capable of accessing shared network resources made available by a server.
Server: A server offers shared resources and data across a network. It typically entails a high-performance microcomputer with multiple drives, often possessing substantial storage capacity and potentially a few CD-ROM drives. Servers permit all microcomputers to access an external network through the network communication system.
Media: The interconnection of computers relies on hardware components such as cables (UTP, STP, coaxial, and fiber optics).
User: An individual who employs a client to access network resources.
Resources: These encompass files, printers, modems, or other items employable by network users. Resources can manifest as hardware or software entities.
Protocol: Protocols denote prescribed rules employed for communication. They represent the language computers employ to interact within a network, examples being TCP/IP and AppleTalk.
Topology characterizes the physical arrangement of computers within a network. Networks can be structured in diverse ways, such as:
In this configuration, multiple small computers link to a central resource, often termed a host computer or file server. The star arrangement is common for connecting microcomputers to a mainframe, establishing a time-sharing system. This design offers heightened security as communication between workstations transpires through the central node (servers).
A shared cable links all network computers. The cable is typically terminated at each end, with one or more stations acting as the file server. Ethernet is an example of a bus system.
Workstations are connected in a ring-like arrangement using a single network cable. Ring networks offer less security, as data for a specific machine might traverse other machines before reaching its destination.
A specialized bus topology wherein terminals resemble branches on a tree. Extending the network is straightforward, and failure of a branch can be easily rectified.
The World Wide Web (WWW or simply the Web) is a system of interconnected documents and resources that are accessed over the Internet using web browsers. It’s a part of the broader internet and allows users to navigate through a vast collection of web pages, multimedia content, and other resources linked by hyperlinks. The web is based on the use of URLs (Uniform Resource Locators) to locate and access specific web pages, and it enables users to view text, images, videos, and other types of media from around the world.
The World Wide Web was invented by British computer scientist Tim Berners-Lee in 1989 while he was working at CERN, the European Particle Physics Laboratory. He proposed the concept of a hypertext system that would allow researchers to share information across the internet. In 1991, Berners-Lee published the first web page and released the first web browser. This marked the beginning of the web as we know it. Over the years, the web has evolved significantly, leading to the development of multimedia-rich websites, social media platforms, online commerce, and a wide range of applications that shape modern digital life.
Cables and connectors are essential components in various industries, particularly in technology, telecommunications, and electronics. They play a crucial role in transmitting signals, data, and power between different devices and systems. There are various types of cables and connectors designed for specific purposes, each with its own characteristics, compatibility, and use cases. Here’s an overview of common types of cables and connectors:
These are just a few examples of the many types of cables and connectors available. The choice of cable and connector depends on factors like the type of data or signal being transmitted, the distance involved, compatibility with devices, and the intended use case.
A database is an application utilized to systematically store information. It comprises a structured collection of data or records.
A database management system (DBMS) is a compilation of computer software that empowers users to establish, generate, and uphold a database. Functioning as a computer application, a DBMS interacts with users, other applications, and the database itself to capture and analyze data.
The primary objective of a database management system (DBMS) is to facilitate the creation, definition, querying, and administration of a database. It serves as an intermediary between the database and end users or application programs, ensuring consistent organization and easy accessibility of data. Database Administrators oversee the database system, including access and security aspects.
A DBMS enables users to generate, modify, and update data in database files. Its functions encompass:
Diverse types of database management systems are available, including:
To establish a computer-based database with MS Access.
Initiating MS Access involves the following steps:
Creating a Database
Creating a File
In the “Save As” dialog box, input the desired table name (e.g., Student Table) in the “Table Name” text box and confirm by clicking “OK.”
Database tables on a computer are structured with rows and columns. An MS Access table is organized into rows and columns, similar to the presented screen.
Each row holds records or different fields, determining the number of records in the table. In the example screen, the student table contains six records.
Columns usually represent fields within a database table, specifying the type of information stored. The shown screen includes three fields (data fields): REG. No., Surname, and First Name.
Fields are designated names relevant to the stored information. These field names are assigned data types, which govern the type of data they can accept. For instance, in the MS Access table above, the “Surname” field only accepts alphabetic characters, not numeric inputs like 10 or 500 as surnames.
To set the data type for a field in MS Access, follow these steps:
In the provided screen, the field “ID Number” would be assigned the “Number” data type, considering its numeric nature. Similarly, the “Surname” and “First Name” fields would both be assigned the “Text” data type.
A table incorporates a unique identifier, often referred to as a KEY. In MS Access, the initial field is usually set as the default primary key. To designate another field as the primary key, right-click the respective cell and select “Primary Key.”
Note: The key symbol should appear beside the field after setting it as the unique identifier. If it doesn’t appear, repeat the prior steps.
Creating a Database
In general, creating a database using any DBMS involves the following fundamental steps:
The structure specifies the preferred database organization. For a relational form, this includes RDBMS, table structure, row and column count, keys, and relationships.
When crafting a database, each field must accept a specific type of input, known as a data type. This prevents incorrect input, ensuring database integrity. Data types may differ across DBMS, but they generally fall into categories like alphanumeric/text, numeric, date, boolean, memo, currency, AutoNumber, hyperlink, attachment, and OLE object.
Computer Graphics refer to visuals that are generated using computers and encompass the creation, representation, and manipulation of image data through computational means.
Title Bar:
The title bar displays the name of the active CorelDraw file and facilitates window repositioning.
Menu Bar:
With 11 pull-down menus, the menu bar contains all command options.
Rulers:
Rulers aid in positioning and sizing, optionally toggleable, and guidelines can be dragged off for assistance in drawing.
Scroll Bars:
Horizontal and vertical scroll bars allow shifting of the page view.
Drawing Windows:
The primary drawing area is the large white screen space, with a shadowed rectangle representing the printable page.
Roll-up Windows:
The Transform (Position) roll-up, situated on the left, offers dynamic control over CorelDraw operations, serving as a quicker alternative to invoking standard menu dialog boxes.
Status Bar:
The status bar showcases fill patterns, outline location, object movement, and absolute coordinates of selected objects.
Color Palette:
The colour palette enables swift application of coloured fills or outlines. Expanding the palette offers an extended range of colours.
Page Counter:
CorelDraw supports multi-page drawings, displaying the total page count along with navigation arrows.
Standard Toolbar:
The toolbar provides convenient access to commonly used features, many of which can also be accessed through the Menu Bar. CorelDraw offers various customizable toolbars, with the option to add buttons for frequently used commands.
Note: Keyboard shortcuts can often expedite actions more than toolbar usage. Once memorized, they streamline tasks:
“`
FOR i = 1 TO 10
PRINT i
NEXT i
“`
“`
WHILE condition
‘ Code to be executed
END WHILE
“`
Now, let’s write a BASIC program to calculate the area of 10 different rectangles using both the `While… End` loop and the `For… Next` loop.
Using For… Next Loop:
“`basic
DIM length(10)
DIM width(10)
DIM area(10)
FOR i = 1 TO 10
INPUT “Enter length of rectangle ” + STR$(i) + “: “, length(i)
INPUT “Enter width of rectangle ” + STR$(i) + “: “, width(i)
area(i) = length(i) * width(i)
NEXT i
FOR i = 1 TO 10
PRINT “Area of rectangle ” + STR$(i) + “: “; area(i)
NEXT i
“`
Using While… End Loop
“`basic
DIM length(10)
DIM width(10)
DIM area(10)
i = 1
WHILE i <= 10
INPUT “Enter length of rectangle ” + STR$(i) + “: “, length(i)
INPUT “Enter width of rectangle ” + STR$(i) + “: “, width(i)
area(i) = length(i) * width(i)
i = i + 1
END WHILE
i = 1
WHILE i <= 10
PRINT “Area of rectangle ” + STR$(i) + “: “; area(i)
i = i + 1
END WHILE
“`
Both versions of the program will calculate and display the areas of 10 rectangles using different types of loops. The choice between `For… Next` and `While… End` depends on the specific needs of the program and the desired looping behavior.
A high-level programming language is a type of computer programming language designed to be human-readable and relatively easy to understand by programmers. High-level languages abstract away much of the complexity of computer hardware and provide more intuitive and user-friendly syntax for writing code.
They allow programmers to express algorithms and logic in a way that is closer to natural language, making it easier to develop software without dealing with the intricacies of the underlying machine architecture.
Some examples of high-level programming languages include:
In summary, high-level languages strike a balance between human readability and machine execution, making them a powerful choice for a wide range of programming tasks, from web development to system programming.
Number bases refer to ways of counting numbers. Counting started way back in the ancient times when began counting first, with his fingers. He counts in tens maybe because he has ten fingers and this is called decimal system of counting. There are different bases of counting,
Different number bases/system
Binary system
Octal system
Denary/decimal system
Hexadecimal system
The word BI means two, so binary combination means numbers made up of a combination of only two numbers. It also refers to numbers in base 2. The available digits in a binary system where 0 means off and 1 means ON.
This is counting in eight i.e. base 8. It has 0,1,2,3,,4,5,6,7 digits.
This is counting in tens. They are also called decimal system. The decimal system has the following digits 0,1,2,3,4,5,6,7,8,9
This system deals with numbers in base 16. It has the following digits 0,1,2,3,4,5,6,7,8,9,A,B,C,D.E,F (A=10, B=11, C=12, D=13, E=14 and F=15).
To convert a number in decimal system to other bases, the method of continuous division of the number by the new base number is used.
Convert 17ten to base 2
2 17
2 8 r 1
2 4 r 0 17ten = 100012
2 2 r 0
2 1 r 0
0 r 1
Convert 58ten to base 2
2 58
2 29 r 0
2 14 r 1
2 7 r 0 58ten = 1110102
2 3 r 1
2 1 r 1
0 r 1
Convert 248ten to octal
8 248
8 31 r 0
8 3 r 7 248ten = 370eight
0 r 3
Convert 312ten to base 16
16 312
16 19 r 8
16 1 r 3 312ten = 13816
0 r 1
Convert 935ten to hexadecimal
16 935
16 58 r 7
16 3 r A 935ten = 3A716
0 r 3
To convert numbers in other bases to denary system, expand the given number in powers of its base and evaluate.
Examples
1) Convert the following numbers to base ten
(i) 10012 (ii) 255eight (iii) 35416
(i) 10012 = 1 x 23 + 0 x 22 + 0 x 21 + 1 x 20
= 1 x 8 + 0 x 4 + 0 x 2 + 1 x 1
= 8 + 0 + 0 + 1
= 9ten
(ii) 255eight = 2 x 82 + 5 x 81 + 5 x 80
= 2 x 64 + 5 x 8 + 5 x 1
= 128 + 40 + 5
= 173ten
(iii) 35416 = 3 x 162 + 5 x 161 + 4 x 160
= 3 x 256 + 5 x 16 + 4 x 1
= 768 + 80 + 4
= 852ten
To convert from a number system to another one (not denary), it is usual to convert to base ten and then convert the base ten number to the new base number.
However, binary numbers can be converted to octal and hexadecimal numbers because of the fact that 23 = 8 and 22 = 16.
Examples
(1) Convert 110110two to base 8, base 16
(note 23 = 8 and 24 = 16)
(i) 1101102 = (1102) (1102)
= 66eight (1102 = 6ten)
(ii) 1101102 = (00112) (01102)
= 36hex (00112 = 3ten)
2) Convert 1110110two to base 16
1110110 = (01110110)two
= 7616
3) Convert 1000101two to base eight
1000101two = (001)(000)(101)
= 103eight
4) Convert 62eight to base two
62eight = 6 2
110 010
= 110010two
5) Change A0316 = A 0 3
1010 0000 0011
= 10100000011two
Data representation is the way in which information or data is encoded and stored in a format that computers can understand and manipulate. Since computers work with binary systems (1s and 0s), data from the real world needs to be translated into these binary values for processing. Data representation encompasses various methods and techniques to represent different types of data, including numbers, text, images, audio, and more.
ASCII is a character encoding standard that assigns unique numerical values to various characters used in the English language and some control characters. The ASCII standard uses 7 bits to represent each character, allowing for a total of 128 possible characters. The ASCII character set includes:
These characters are assigned specific numeric values, which are then represented in binary form. For example, the ASCII value for the uppercase letter ‘A’ is 65, which in binary is 01000001. This binary value is what computers use to internally represent and process the character ‘A’.
Data representation methods like bits, BCD, EBCDIC, and ASCII are crucial for enabling computers to handle various types of data in a standardized and consistent manner. ASCII, in particular, provides a way to represent characters in a format that is widely understood and used across different computing systems.
Security refers to the protection of computer systems, networks, and data from unauthorized access, attacks, and damage. It involves measures and practices that aim to ensure the confidentiality, integrity, and availability of digital assets. Ethical considerations come into play when making decisions about security practices. Ethical behaviour in the context of security involves respecting privacy, avoiding harm, and adhering to laws and regulations. For instance, ethical hacking involves testing systems for vulnerabilities with the permission of the owner to help improve security.
Viruses, worms, and Trojans are types of malicious software that can lead to security breaches:
An ICT (Information and Communication Technology) policy outlines guidelines and rules for using technology in an organization. A poorly implemented or lacking ICT policy can lead to security vulnerabilities. Without clear guidelines, employees might engage in risky behaviours, use unauthorized software, or ignore security practices. A well-defined policy helps prevent security breaches by providing a framework for secure technology usage.
Various preventive measures are in place to address security concerns:
Overall, a combination of technical measures, policies, ethical considerations, and legal frameworks is crucial to maintaining security, protecting user privacy, and preventing various forms of cybercrime.
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