Introduction to information technology and information systems (Notes)
What is information technology
The study, design, development, implementation, support or management of computer based information systems, particularly software applications and computer hardware. IT deals with the use of electronic computers and computer software to convert, store, protect, process, transmit, and securely retrieve information.
The combination of telecommunication and computer science for the capture, storage and transmission of information to every nook and corner of the world is said to be IT. Information Technology is the technology (hardware and software) required for the processing of data and other information.
What is an information system
An information system is an arrangement of people, data, processes and interfaces that are integrated for the purpose of supporting the day to day operations in a business. Information systems transform data into useful information.
Data:
Data are the facts arising out of operation of concern. They are raw facts abut the organization and it business transactions.
Types of data
> Alphanumeric – numbers, letters, symbols etc.
> Images-graphic images, pictures
> Audio-sound, noise, tones
> Video-moving pictures
Information:
Is data that has been refined and organized to become useful. It is a collection of data organized in such a way that they have additional value beyond the value of the facts themselves.
What is a Computer?
An electronic device for storing and processing data, typically in binary form, according to instructions given to it in a variable program.
A computer is an electronic device which is capable of receiving the inputs (data from the user), storing it for a desired period of time, manipulating it according to the set of instructions (called program) and producing the output to the user in desired form. It performs a variety of operations in accordance to the set of instructions.
The main types of computers are classed to differentiate between them as follows:
1. Mainframe
A mainframe now referred to as a ‘large server’ offers the ultimate in processing power and storage capabilities. It is big in size and more expensive. It has a large memory capacity high processing speed of information. Is used in large scale organization to process a bulk of information
2. Super computer
A supercomputer is a computer that leads the world in terms of processing capacity, particularly speed of calculation
3. Personal computer
A personal computer (PC) is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals. A personal computer can be:
> Laptop computer- A laptop computer is a personal computer for mobile use. A laptop integrates most of the typical components of a desktop computer, including a display, a keyboard, a pointing device (a touchpad, also known as a trackpad or pointing stick) and speakers into a single unit. A laptop is powered by electricity via an AC adapter, and can be used away from an outlet using a rechargeable battery.
> Palmtop computer
A small computer that literally fits in your palm. Compared to full-size computers, palmtops are severely limited, but they are practical for certain functions such as phone books and calendars. Palmtops that use a pen rather than a keyboard for input are often called hand-held computers or PDAs. (personal Digital Assistant)
Because of their small size, most palmtop computers do not include disk drives. However, many contain PCMCIA slots in which you can insert disk drives, modems, memory, and other devices.
> Desktop computer
A desktop computer is a personal computer (PC) in a form intended for regular use at a single location, as opposed to a mobile laptop or portable computer. Early desktop computers are designed to lay flat on the desk, while modern towers stand upright. Most modern desktop computers have separate screens and keyboards.
> Network computer
A computer allows you to connect two or more computers together. Allows sharing of resources. Example, instead of each PC requiring its own Printer, you can have single printer shared amongst, many network PCs
Advantages of using computers
1. It helps you automate various tasks that you can not do manually.
2. It helps you organize your data and information in a better way.
3. It has much more computing and calculating power then an ordinary human.
4. It may help your work to be a lot easier.
5. It may be the storage of your important data and files.
6. It may be your handy book.
7. It may help you solve problems faster than an ordinary human being can do.
8. It has speed, storage, reliability, consistency and communications.
9. It helps you to find useful information using the Internet.
10. It helps in businesses, factories, offices, schools and homes.
Disadvantages of using computers
1. It can potentially destroy your social life and interactions with humans if you do not maintain the balance.
2. It may effect to the destruction of your eye sight due to radiation.
3. It may cause pimples and wrinkles.
4. It may damage your studies and life.
5. Too much time in front of monitor may adverse effect your eye sight and can also make you fat.
6. The way it distracts and can deviate our thoughts and activities towards unproductive activities.
7. It could cause violation of privacy, impact on labor force, health risks, impact on environment, distraction from work, and possible antisocial influences.
8. Getting away from their real life and getting into bad lines
For a computer to be able to perform all these functions it needs the necessary hardware and software.
Computer hardware
A computer hardware is a physical part of the computer, including the central processing unit (CPU) and related microchips and micro circuitry, keyboards, case, monitors etc.
Computer hardware is made up of the equipment used to make up you computer unit. These parts include your monitor, central processing unit (CPU), keyboard, mouse, printer, and modem.
Peripheral - Any equipment that is connected externally to a computer. For example, printers, scanners and modems are peripherals.
The computer is an electronic machine that performs the following four general operations:
> Input
> Storage
> Processing
> Output.
Input Devices
The input hardware allows you to enter data and instructions into the computer. The primary devices used are the keyboard and mouse.
Keyboard - The keyboard looks like the typewriter. A numeric keypad is located to the right of the keyboard. Numeric keys have the same placement as a 10-key calculator, which allow the operator to enter data rapidly.
Mouse - The mouse is a device that allows you to control the movement of the pointer on the screen. The operator places the palm of the hand over the mouse and moves it across a mouse pad, which provides traction for the rolling ball inside the device. Movement of the ball determines the location of the pointer on the computer screen. You can also click the mouse and activate icons or drag to move objects and select text.
There are other input devices, such as touch screen, joystick, scanner, and microphone
Processing devices
The central processing unit or (CPU) is the "brain" of your computer. It contains the electronic circuits that cause the computer to follow instructions from ROM (read only memory) or from a program in RAM (random access memory). By following these instructions information is processed. The CPU contains the following parts.
1. Arithmetic Logic Unit - ALU is where the "intelligence" of the computer is located. It can add and compare numbers. To multiply 2 x 4 the computer would add 2 + 2 + 2 + 2. The ALU makes decisions by determining if a number is greater, less, or equal to the other number. Processing is completed in nanoseconds, which is a billionth of a second.
2. Control Unit - This is the part of the unit, which directs information to the proper places in your computer, such as calculation of information by the ALU unit or to store and print material.
When you choose a CPU, you should consider its speed.
The speed of a CPU is determined by 2 main factors.
> Clock frequency (measured in hertz)
> Amount of cache memory
The higher the value , the faster the CPU will be.
Output Devices
Output devices such as a monitor or printer make information you input available for you to view or use.
A monitor's front is called a screen with a cathode ray tube (CRT) attached to the screen. Portable computers use a (LCD) liquid crystal display. Today's super video graphics array (SVGA) monitors display 256 sharp and clear colors.
Printers used with computers fall into the following categories, dot matrix printers, print by contact against a ribbon making imprint on paper. Inkjet printers print images by not touching the paper. Ink jet printers spray ink onto the page while a laser printer works like a copying machine. Laser printers print a higher quality product but cost from $500 to $10,000 whereas an ink jet produces better quality than a dot matrix and can be purchased from $150 to $300. The personal computer user most commonly purchases an ink jet printer for home use.
Storage devices:
These are used to store data either temporary or permanent
1.Temporary memory
i.e. RAM (Random Access Memory) where information to be processed is held and the instructions on how to process that information is also held
NOTE: anything store in RAM will be lost when the power is turned off.
RAM is also known as Volatile memory.
2. Permanent Memory
Is where the processed information is held.
We have the Read Only Memory(ROM) where the startup information is held permanently and you can not change and we have other permanent storage devices like
> Hard disk Hard Drive - hard disk located inside the computer case is made of a stack of rotating disks, called platters. Data is recorded on a series of tracks that have been divided into sectors. Most computers have one hard drive, located inside the computer case. If a computer has one hard drive, it is called drive C. If a computer has additional hard drives, they are called drives D, E, and so on. A hard drive stores your programs. When you buy a new program, you must install the program files to your hard drive before you can use the program. A hard drive stores your data files such as documents spreadsheets, and graphics.
> Compact Disks, floppy disks(old tech) their drive is labelled as drive A DVDs, external hard disks, Flash disks etc.
> Disk drive
A machine that reads data from and writes data onto a disk. A disk drive rotates the disk very fast and has one or more heads that read and write data.
There are different types of disk drives for different types of disks. For example, a hard disk drive (HDD) reads and writes hard disks, and a floppy drive (FDD) accesses floppy disks. A magnetic disk drive reads magnetic disks, and an optical drive reads optical disks a USB drive for flash disks.
Disk drives can be either internal (housed within the computer) or external (housed in a separate box that connects to the computer).
A computer stores data in units called bits and bytes. Computer chips called integrated circuits have one of two states, off or on. Therefore, a system was developed that used only two numbers, 0 and 1. Zero representing off and 1 representing on. You can think of this as a sort of light switch. Each switch is called a bit.
Bits are grouped together in sets of eight. Each set of eight bits is called a byte. Setting different combinations of those eight "on and off" combinations can be developed to stand for letters numbers, spaces, and symbols. For practical purposes, think of a byte as one character. When computers refer to memory or storage they refer to terms using the following forms of measurement.
> 8 bits = 1 byte
> 1024 bytes = 1 Kilobyte (K)
> 1024 Kilobytes = 1 Megabyte (MG)
> 1024 Megabytes = 1 Gigabyte (GB)
> 1024 Gigabytes= 1 Terabyte(TB)
> 1024 terabytes=1 Petabyte(PB)
Today's hard drives are usually Three or more gigabytes of memory.
Computer software
Computer productivity is determined by programs/software which are step by step instructions telling the computer how to process data. Software can be divided into two groups, system software and application software.
System software - The operation of your computer is controlled by system software.
System software control all actions which are taking place in the computer. i.e. the action of computer hardware and application software
Examples are Operating Systems and ROM BIOS
- Examples of Operating Systems are WINDOWS 95/98/ME,2000/XP/ Vista windows 7 (which use a graphical user interface (GUI) that provides visual clues (icons) to help the user.) and Linux DOS, UNIX ( which are text based and not user friendly. )
As you boot the computer, the system software is stored in the computer's memory which instructs the computer to load, store, and execute an application
Application software
Programs designed to do a specific task they are designed mainly for users.
Professional programmers write a variety of application software to satisfy needs of the public who wants to perform specific tasks on their computers. The basic types of application software are word processing, database, spreadsheet, desktop publishing, and communication
A computer viruses is a destructive program that is buried within an existing program. They are written by people with programming skills who want to cause widespread problems for computer users.
To protect data against viruses, always know the source of your software. When downloading software from the Internet always save it and viruses check it before running it. Antivirus utilities are available and are a good ‘insurance’ investment
Computer virus is a software program written with malicious intentions. There are number of computer viruses that can impede the functioning of your computer system. Let us see what are the different types of computer viruses.
Computer Virus is a malicious software program written intentionally to enter a computer without the user's permission or knowledge. It has the ability to replicate itself, thus continues to spread. Some viruses do little but replicate, while others can cause severe harm or adversely affect program and performance of the system. A virus should never be assumed harmless and left on a system. Most common types of viruses are mentioned below:
Different Types of Computer Viruses
There are different types of computer viruses which can be classified according to their origin, techniques, types of files they infect, where they hide, the kind of damage they cause, the type of operating system or platform they attack etc. Let us have a look at few of them.
- Resident Virus
This type of virus is a permanent as it dwells in the RAM. From there it can overcome and interrupt all the operations executed by the system. It can corrupt files and programs that are opened, closed, copied, renamed etc. Examples: Randex, CMJ, Meve, and MrKlunky.
Direct Action Viruses
- The main purpose of this virus is to replicate and take action when it is executed. When a specific condition is met, the virus will go into action and infect files in the directory or folder that it is in as well as directories that are specified in the AUTOEXEC.BAT file path. This batch file is always located in the root directory of the hard disk and carries out certain operations when the computer is booted. Examples: Vienna virus
Overwrite Viruses
- Virus of this kind is characterized by the fact that it deletes the information contained in the files that it infects, rendering them partially or totally useless once they have been infected. The only way to clean a file infected by an overwrite virus is to delete the file completely, thus losing the original content. Examples: Way, Trj. Reboot, Trivial.88.D.
Boot Sector Virus
- This type of virus affects the boot sector of a floppy or hard disk. This is a crucial part of a disk, in which information of the disk itself is stored along with a program that makes it possible to boot (start) the computer from the disk. The best way of avoiding boot sector viruses is to ensure that floppy disks are write-protected and never starting your computer with an unknown floppy disk in the disk drive. Examples: Polyboot.B, AntiEXE.
Macro Virus
- Macro viruses infect files that are created using certain applications or programs that contain macros. These mini-programs make it possible to automate series of operations so that they are performed as a single action, thereby saving the user from having to carry them out one by one. Examples: Relax, Melissa.A, Bablas, O97M/Y2K.
Directory Virus
- Directory viruses change the path that indicate the location of a file. When you execute a program file with an extension .EXE or .COM that has been infected by a virus, you are unknowingly running the virus program, while the original file and program is previously moved by the virus. Once infected it becomes impossible to locate the original files. Examples: Dir-2 virus.
Polymorphic Virus
- Polymorphic viruses encrypt or encode themselves in a different way (using different algorithms and encryption keys) every time they infect a system. This makes it impossible for anti-viruses to find them using string or signature searches (because they are different in each encryption). The virus then goes on creating a large number of copies. Examples: Elkern, Marburg, Satan Bug and Tuareg.
File Infector Virus
- This type of virus infects programs or executable files (files with .EXE or .COM extension). When one of these programs is run, directly or indirectly, the virus is activated, producing the damaging effects it is programmed to carry out. The majority of existing viruses belong to this category, and can be classified depending on the actions that they carry out. Examples: Cleevix and Cascade.
Companion Viruses
- Companion viruses can be considered as a type of file infector viruses like resident or direct action types. They are known as companion viruses because once they get into the system they 'accompany' the other files that already exist. In other words, in order to carry out their infection routines, companion viruses can wait in memory until a program is run (resident virus) or act immediately by making copies of themselves (direct action virus). Some examples include: Stator, Asimov.1539 and Terrax.1069
FAT Virus
- The file allocation table or FAT is the part of a disk used to store all the information about the location of files, available space, unusable space etc. FAT virus attacks the FAT section and may damage crucial information. It can be especially dangerous as it prevents access to certain sections of the disk where important files are stored. Damage caused can result in information losses from individual files or even entire directories.
Multipartite Virus
- These viruses spread in multiple ways possible. It may vary in its action depending upon the operating system installed and the presence of certain files. Examples: Invader, Flip and Tequila
Web Scripting Virus
- Many web pages include complex code in order to create an interesting and interactive content. This code is often exploited to bring about certain undesirable actions.
Worms
- A worm is a program very similar to a virus; it has the ability to self-replicate and can lead to negative effects on your system. But they can be detected and eliminated by anti-viruses. Examples of worms include: PSWBugbear.B, Lovgate.F, Trile.C, Sobig.D, Mapson.
Trojans or Trojan Horses
- Another unsavory breed of malicious code are Trojans or Trojan horses, which unlike viruses do not reproduce by infecting other files, nor do they self-replicate like worms. In fact, it is program which disguises itself as a useful program or application.
Logic Bombs
- They are not considered viruses because they do not replicate. They are not even programs in their own right but rather camouflaged segments of other programs. They are only executed when a certain predefined condition is met. Their objective is to destroy data on the computer once certain conditions have been met. Logic bombs go undetected until launched and the results can be destructive.
Besides, there are many other computer viruses that have a potential to infect your digital data. Hence, it is a must that you protect your data by installing a genuine quality anti-virus software.
How do you get a virus in your computer
These are 3 common ways that your computer may get infected by viruses:
> Email: You get an email from a person that contains one or more viruses. If the attachment is opened, the viruses may infect files in the computer. The viruses might also send emails to people from your email address book or email folders automatically. So, you should not open unknown attachments in emails or do a virus scanning after opening them.
> Internet: If you download an exe file or a data file from the Internet or other shared networks, viruses might be transferred to your computer. Sometimes the free software programs on the Internet have viruses especially if downloading from sources such as Torrent or Usenet news groups. Therefore, if necessary, you should download files from trusted resources.
> Peripheral devices: The devices such as MP3 player, USB thumb drive, Memory card or CD Rom are also means for spreading viruses. So, remember to do a virus scan for them after they are connected to your compute
Symptoms of virus infection:
These are some of symptoms which may indicate virus activity:
> Your computer has unusual activity (e.g. programs crashing a lot or running slowly).
> Messages or images (unrelated to your current task) come up unexpectedly. • A program may start up unexpectedly.
> Your firewall informs that a certain application is trying to connect to the Internet (unrelated to what you are working on).
> Your friends say that they get emails from you but you did not send any to them.
> You receive many system error announcements. (Note: This may also come from another activity such as a hardware problem or genuine system error)
> Windows does not run when you start up your computer. (Note: This may also come from a hard disk problem)
> You realise that folders and files are removed or changed.
> You find that there's an access to your hard disk (one of the small light is blinking) even though there are no programs running.
> Your web browser has abnormal indications, for example it opens an unknown web page or you cannot close the browser tabs.
> Advertising pages pop up, desktop wallpaper changes.
> Exe files occur and have the same names as the folders.
> On the right corner of your computer, there is a small symbol written "Your computer is infected" or "Virus Alert" etc.
> When you open an USB thumb drive, unknown files such as Autorun.inf, New Folder.exe etc. appear.
> Cannot press Control + Alt + Delete (Task Manager) and you are warned that Administrator banned it.
> Folder Options disappears.
> Your computer keeps restarting when you try to shut it down.
> You cannot log in your Windows account with the right logon details
Measures to take against computer viruses
1. Make backups on a regular basis.
Should note that there is no absolutely safe way of protection. Virus creator will always find loopholes in the new computer products for use to infect their computer systems. Some viruses are malicious enough can damage data files or even delete the entire file system. Make regular backups of your data files to separate storage device. Try to save on a separate hard drive, flash card, compact disc or other storage device file that you select. To ease the procedure, you can use some automatic backup software. And be prepared if the system will die because of a viral infection.
2. Ready to reinstall your system if damaged by a virus.
Prepare your operating system software and distributives software you use and keep them together, for example, OS and drivers CD computer and other equipment drivers. In this case if virus infection will cause a system failure can be restored quickly reinstall your media to your computer system.
3. Protect your network connection with a firewall.
A firewall is a software which blocks suspicious connections and prevent the virus to penetrate your network into the system. Windows XP system is too simple but reliable built-in firewall. You can activate it in the following manner.
- In the Control Panel, double-click Networking and Internet Connections, and then click Network Connections.
- Right-click the connection you want to activate the firewall, and then click Properties.
- On the Advanced tab, click the Windows Firewall Settings box
- When the Windows Firewall window appears, click option On (Recommended)
- If you need more flexible control of its network connection, you can get and install software more sophisticated firewalls such as Norton Personal Firewall or Outpost firewalls. When you use this software you have the capability to allow or block certain connections and to monitor network activity.
4. Use antivirus software.
Installing antivirus software will scan your system for and remove viruses on a regular basis. Leader in antivirus software products for Windows systems are Norton Antivirus, McAfee, Kaspersky Anti-Virus and PC-cilin.
5. Regularly update your operating system.
Windows has a built-in auto update service. Regular contacts Microsoft server to find updates and notifies you if updates are ready to be installed. Important updates because hackers regularly find the holes in the operating system often used by virus creators (Very useful for those of you who use Windows Original).
6. Do not install and run software suspicious.
Check out the new programs that will install with your anti-virus software. Do not download software from suspicious sites. To download website software creators are always looking for software or authorized distributor. Do not use applications that are received via email from strangers.
7. Restrict access to your computer.
Protect with a password into the system, i.e with a user password in order when you go into windows system should log the user name and password
8. If you are using Internet Explorer, try moving to another browser.
Because IE is the browser most often been the target or the use the creator of the virus is actively using the flaw in the security system to infect your computer. Infection may arise if you are going to visit a Web page that contains malicious code invisible. You are more secure if you are using a browser that is not known simply because virus makers are not much attention on those brows. IE browser's main competitor is Firefox and Opera are now providing the same convenient interface and range of services to work on the Web.
9. Use spam protection.
Viruses are often distributed through email. Activate the spam filter in your email box to block received spam. If you need assistance with the use of filters, you can ask your email provider.
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