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File Types

Because files can have different purposes, they have different types. The file type is best identified by its file structure. For example a text file would have a very different structure than a file than can be executed. An executable file must have a specific structure to be able to be run. The file structure is used to determine its MIME type. The word MIME stands for multipurpose internet mail extension and is used as a standard to identify various file types.

File Extensions

In operating systems such as Microsoft Window systems, Linux, and Unix, a file extension is used to help identify the type of file. On Microsoft Windows systems, many file types are associated with a particular program which can read the file. For example a file with a .pdf extension can be read by the Adobe Acrobat application program.

Files are actually identified by what is called a MIME type. This can be done because files that are executable have a different structure than a data structure. Therefore file extensions are not the only way to identify a file type nor are they the most accurate. Apple MacIntosh computer systems do not use a file extension to identify file types.

Executable File Types

The most important file type to be aware of are executable file types. This is because if you accidentally run an executable file on your system, it may install a virus or some other unwanted software program. Executable file types include:

.com
.exe

What Files Are

Files are a collection of data onto a permanent storage structure. They are stored on a permanent storage media such as a computer hard drive, CD ROM drive, floppy disk drive or sometimes even a tape drive. Files take a certain amount of room to store. For example if you have two text files and one file has one sentence in it while the other file has 200 sentences in it, the file with 200 sentences will use more room on the storage media.

File Functions

Different files have different purposes. Files are used to do one or more of the following functions:

Provide machine executable code which is used to run application programs and the operating system.
Store application program or operating system configuration information.
Store data used by the user such as Microsoft Word document files.

Therefore there are three types of information that files contain:

Executable code.
System or program configuration information.
User data.

These files are read by an application program or the operating system.

File Characteristics

Files have the below characteristics:

Name
Optional extension name - Part of the name, it is used by Windows operating systems to identify an associated program that can be used to read it
Size - Shows the space the file requires for storage normally showed in kilobytes (Kb) which is 1000 bytes
Type - Indicates the program used to access the file. The next section will talk more about file types.
Date Modified - Shows the last date the file was created or changed.
File structure - This characteristic is not viewable by the computer user but some programs can examine file structure to determine the type of file it is even when the file extension is changed.

The main items to remember include the facts that all files take a certain amount of room on their storage media and all files have a type which indicates whether they can be run by your computer. The file extension is one indication of the file type but not the only way to determine type.

If you are browsing your files using "My Computer" and click on "View" and "Details" you will see a window showing the file characteristics like the one below. Folders only take a little room on the hard drive and do not normally take as much room as files.

http://www.comptechdoc.org/basic/basictut/

Computer Data

To help understand computers it is best to first learn about computer data. Computer data is information required by the computer to be able to operate. It is used to:

Run programs - This is the actual executable program data that the computer will execute to run the program such as Microsoft Word.
Store program or system configuration information.
Store information that the computer user needs such as text files or other files that are associated with the program the computer user is running. A common example of a program the computer user is running is the Microsoft Office suite of products which include Microsoft Word, Microsoft Excel, and others. These programs are also known as applications.

Data Structure

Computer data is in what is called binary format. This means that it is always a 0 or a 1. It only has these two states and must be in one of them.

There are several fundamental data units which include:

Bit - A data unit which must be in one of the two binary states described above. It is the smallest data unit that exists.
Byte - 8 bits of data which has a possible value from 0 to 255.
Word - Two bytes or 16 bits of data with a possible unsigned value from 0 to 16535.

Data transmission

Data transmission is the act of sending data from one place to another. Data is transmitted both inside and outside your computer. There are two fundamental methods of data transmission.

Serial - Data is sent on a single line and one bit is sent at at a time. This is similar to a line which one item must come one after another.
Parallel - Data is sent on more than one line at a time. This may be any number of bits at a time, but is usually one word at a time (two bytes) or possibly three bytes at a time.

http://www.comptechdoc.org/basic/basictut/

Applications

What is an application

Applications are programs that are installed. on computers to give users the ability to do specific tasks. For example, Microsoft Word® is a program that gives the user the ability to write documents. Some program packages come in a set with multiple programs included to provide multiple capabilities such as the Microsoft Office® suite of programs. This suite of programs also includes Microsoft Outlook® which is used to send and receive e-mail. It also includes other programs with more capabilities.

How Application Programs Work

Application programs are written in a text based computer language as mentioned in the section about hardware and software. Once written, they are compiled into a binary language the computer understands. The application programs use function calls (as described in the section about operating systems) to interface to the various computer peripherals such as your keyboard, mouse, screen, printers, and other devices. Most of these function calls are provided by the operating system so the application programs are usually compiled for a specific operating system such as Microsoft Windows 2000®, Microsoft Windows XP®, or Microsoft Windows 98®.

Application Problems

An application program is a computer program. It is written by human programmers who make mistakes. Therefore there can be errors in the code even though there may be some testing before the product is released. Application programs vary widely in the quality of the code. Errors in code are referred to as "bugs". Bugs can cause unpredictable results including system crashes, inability to perform expected functions, or providing an exploit for an attacker who wants to gain control of your system.

Application Acquisition and Installation

You get applications several ways. The most common way is to purchase it in a store and you will brind a CD home and install it on your computer system. The ways you may get applications include:

Purchase of a program from a store.
Download a purchased program on the internet.
Download a shareware program on the internet.
Download a free program on the internet.

Whether purchasing a program or downloading one for free on tHe internet, you should be aware of the quality of the product you are placing on your computer system. Ask yourself the following:

Do I know who made this product and are they a trustworthy source?
If the product is free, do I know why it is free?
Is there some hidden purpose for the product?
What is the reputation of the maker of the product?
What problems do users of the product have?

Before downloading a product or purchasing a product you should always spend at least a few minutes researching it. You should at least do a quick search on the Gigablast search engine using the product name and the name of the product producer. You should perform a Gigablast internet search and possibly Google groups search to find out where discussions about the product have taken place. There are also many product evaluation sites that can be used to obtain reviewers and users ratings of the product before you buy or install it. Downloading and install the wrong products can not only seriously impede the performance of your computer system, it can also cause your privacy to be invaded.

Bad Applications

There are many types of applications that can cause problems on your computer system.

Applications with serious bugs.
Applications that come with unwanted programs. Some applications come with additional software that you may not really want but is installed by default. Normally this is only annoying and may slightly slow your system down when it boots because some ot these items will load every time you start your computer.
Adware - Most adware comes with programs that may be purchased or downloaded for free on the internet. Adware will cause advertising popups to appear nn your computer. Besides being annoying, they will slow your ability to access the internet. Many times these programs will download other ad programs. These programs are very difficult to remove from your system because they are usually hidden on your system very well. Many times it requires an expert to remove these programs but later I will give you some tips on how you can either remove them or render them ineffective, but to be able to do this you must have reasonable knowledge aboutyour system. There are some programs written to remove adware programs which I will discuss later.
Spyware - This usually comes with some free programs and it will monitor your internet activity and send information to some corporation. This type of program is not normally seriously harmful but most people do not want to have their activities monitored. There are also programs to remove spyware but it is best to not install it in the first place.

If you do your research before installing applications you will avoid most problem applications. It is best to ask your IT support personnel about an application before you install it. In fact many corporate IT policies are set so users cannot install programs on their systems. This is because installation of the wrong programs on corporate systems can jeopardize computer security for the entire organization.

Application Files

Applications have a variety of files they use for three basic purposes.

Executable files
Configuration files
Data files used by the user such as Microsoft Word® document files.

http://www.comptechdoc.org/basic/basictut/

Operating System Functions

Is the Operating System?

The operating system is the core software from your computer. which perform many functions and, in very basic terms, an interface between your computer and the outside world. In the section about the hardware, the computer is described as part consisting of several components including monitor, keyboard, mouse, and other parts. The operating system provides an interface for this part using what is called a "driver". This is why sometimes when installing a new printer or other piece of hardware, the system will ask to install more software called drivers.
What to do?

Drivers are programs written specifically to understand the operation of the device interface for it, such as printers, video cards, sound cards or CD ROM drive. This translates commands from the operating system or the user into commands understood by the computer's components with. It also translates the responses from the computer component back to the responses that can be understood by the operating system, application programs, or users. The diagram below provides a graphical representation of the interface between operating systems and computer components.

Operating System Functions
The operating system provides several other functions including:

System tools (programs) that are used to monitor computer performance, debug problems, or keep parts of the system.
A set of libraries or functions that can be used to program certain tasks primarily related to interfacing with computer system components.

The operating system makes these functions interact with other functions operate smoothly and functions is largely transparent to users.

Operating System Concerns
As mentioned earlier, an operating system is a computer program. Operating system written by human programmers make mistakes. Therefore there can be errors in the code even though there may be some testing before the product was released. Some software companies have better quality control and testing than others so you might see varying levels of quality of the operating system to operating system. Errors in the operating system causes three main types of problems:

    System crashes and instability - this can happen because of software bugs in the system operating normally, although the computer programs that run on the operating system can make the system more stable or may even crash the system itself. This varies depending on the type of operating system. A system crash is the action of the clotting system becomes unresponsive and that will cause users to need to reboot.
    Security flaws - Some software errors left the door open for the system to be broken into by unauthorized intruders. Because of these shortcomings are found, the unauthorized intruder can try to use it to gain illegal access to your system. Patching these flaws often will help keep your computer systems secure. How this is done will be explained later.
    Sometimes errors in the operating system will cause the computer not work properly with some peripheral devices like printers.
Type of Operating System
There are many types of operating systems. The most common is the suite of Microsoft's operating system. They include from newest to oldest:

    Windows XP Professional Edition - A version used by many companies on the workstation. He has the ability to become a member of a company's domain.Windows XP Home Edition - A lower cost version of Windows XP for home use only and should not be used on business. Windows 2000 - A better version of the Windows NT operating system that works well both at home and as a workstation in the business. This includes technology that allows hardware to be automatically detected and other enhancements of Windows NT.
    Windows ME - An upgraded version of Windows 98 but has been historically plagued with programming errors that may be frustrating for home users.
    Windows 98 - is produced in two main versions. The first version of Windows 98 interrupted by a programming error but Windows 98 Second Edition that comes out later is much better with lots of errors resolved.
    Windows NT - a version of Windows intended for business offering better control over the workstation capabilities to help network administrators.
    Windows 95 - The first version of Windows after Windows 3.x version offers a better interface and better library functions for the program.
There are other valuable types of operating systems not made by Microsoft. The biggest problem with this operating system lies in the fact that not many application programs written for them. But if you can get this type of application program you are looking for, one of the systems listed below can be a good choice.

    Unix - A system that has existed for many years and are very stable. This key is used to be a server instead of workstation and should not be used by anyone who does not understand the system. It can be difficult to learn. Unix usually have to run a computer made by the same company that produces software.
    Linux - Unix Linux is similar in operation but it is free. It also should not be used by anyone who does not understand the system and can be difficult to learn.
    MacIntosh apples - the most recent version is based on Unix but has a good graphical interface so that both are stable (no crashes frequently or has a software problem as many other systems as possible) and easy to learn. One drawback of this system is that it can only run on Apple hardware is produced.

http://www.comptechdoc.org/basic/basictut/

What is the Internet

The word internet is used to describe a network of networks which incorporate a very large and complicated set of equipment. To understand the internet, there are three areas of discussion which are very helpful. These include the various services provided across the internet, the functions that enable the internet to work, and the various organizations that are part of the internet.

Internet Services

The main services used on the internet include:

Web browsing - Supported by the HTTP protocol, this functions allows users to view web pages using a web browser.
E-mail - Allows people to send and receive electronic messages.

Other lesser used services include telnet (allows remote login to computers), FTP (Allows quick file transmission to remote computers), and gopher (An early form of text based form of reading internet documents which is rarely used today).

Internet Functions

The internet provides for the following two functions which support communications. Without the communications support mentioned below, the internet could not function. These two functions are provided by internet service providers listed below under the "Internet Organizations" header.

Physical lines that data is sent across.
Routing of data - There are special machines on the internet called routers, that determine where data needs to go to get from the sender of the data to the receiver of the data.

Internet Organizations

ISPs (Internet Service Providers) - They provide the connection to the internet for users and also provide routers that direct internet traffic.
Corporations or Web hosting providers with mail servers and web servers - They provide the information posted on the internet and virtual data connections to other mail servers.

There are also other organizations that regulate the internet, providing communication standards and designing new communication standards for improvements. These communication standards are also known as protocols.

Summary

So the internet is a collection of organizations that provide equipment that support the internet functions and services. The internet connects many corporate and organizational private networks together thus enabling all these organizations to easily communicate.

Accessing the Internet

People use an internet browser to access web pages that are available across the internet. Internet browsers include Microsoft Internet Explorer, Netscape Navigator, Mozilla, and others.

Web pages are created in a marked up form of text file called HTML (Hyper-Text Markup Language). The markup within the text indicates document structure showing where paragraphs begin and end, what items are in a list, headers, tables and other document structure.

When people are browsing of surfing the internet, they usually go from place to place by clicking on links. These links are locations for specific pages and indicate the three things:

Protocol being used such as http or ftp
The domain that the web page is found on. This will point to a specific organization's or company's web server.
The location of the page on the server including the directory path and file name.

An example link is "http://www.comptechdoc.org/basics/bastutorial/osintro.html". In this case http is the protocol being used, the comptechdoc.org domain indicates where the organization's web server is, and the "/basics/bastutorial/osintro.html" part of the string indicates the folders the file is in and the name of the file.

These links are sometimes called hyperlinks or URLs (Uniform Resource Locators)

http://www.comptechdoc.org/basic/basictut/

What is a Network

The word network can be used to describe a very large and complicated set of equipment. In its most accurate and simplest definition a network refers to the cables and electronic components that amplify the signals going through the cables. The amplifying equipment is necessary to ensure accurate communication and make the signal stronger if it needs to go long distances.

Broader Definition

When many people talk about a network, they are talking about a network using a very broad concept. For instance if someone cannot get to their email, they may say "the network is down". Likewise they may say this if they cannot surf the internet or get to their files. They may not stop to think that in each specific instance there is a single piece of equipment that may provide the capability which they are trying to use. Most people who work on a corporate or organizational network think about the network in component parts. The three main parts are:

The cabling and amplifiers mentioned in the first paragraph.
The workstations which most members of the organization use to access resources.
Higher powered computers called servers - These are the machines that provide what network administrators call services. Services include the functions that most people try to use such as email, reading and writing files, printing, and getting to the internet. Whenever a user is trying to do something on the network, there is a service or machine providing the capability to do so. This even includes times when someone is trying to get to network resources from their home.

http://www.comptechdoc.org/basic/basictut/

Software and Hardware

Hardware

The term hardware describes the physical parts of your computer which you can physically touch or see such as your monitor, case, disk drives, microprocessor and other physical parts.

Software

The term software describes the programs that run on your system. This includes your computer operating system and other computer programs which run. Software is written in a computer language (such as Basic, C, Java, or others) by programmers. The computer language is in a text format and can be read by a person although if you do not understand the structure and rules of the language you may not understand it very well. Once a program is written, an operation is performed on it which is called compiling. Compiling is the process of changing the textual written language into a binary language which can be understood by the computer.

Writing these text files and converting them to computer readable files is the way operating systems and most application programs are created.

BIOS (Basic Input/Output System)

BIOS is a low level program used by your system to interface to computer devices such as your video card, keyboard, mouse, hard drive, and other devices. What BIOS programs provide in the computer are very simple function calls or small subprograms which can be used by higher level programs to perform simple operations on computer devices. For example a BIOS program would provide the ability to write a character to memory on a video card.

BIOS is normally written in a low level computer language and is permanently or semi-permanently written into the computer system. This type of computer program is commonly referred to as firmware since it was historically written permanently into computer systems. Although BIOS is a program, because of its permanent state, it was not quite considered to be software so the term firmware is used to describe it. Historically BIOS programs were written into a type of memory called ROM (read only memory). This type of memory would not lose its data when the computer lost power thus ensuring these BIOS programs would always be available. There were different variants of ROM memory some of which could be written multiple times but this memory could not normally be changed or re-programmed once the computer system was sold to the customer. Once ROM memory was written to, it could not be written to again and could only be read when in the possession of the customer. In more recent years a more flexible form of memory was developed called flash ROM which allows ROM memory to be written to after the computer system is in possession of the customer.

http://www.comptechdoc.org/basic/basictut/

Computer Hardware

The term computer hardware refers to the various electronic components that are required for you to use a computer along with the hardware components inside the computer case. As you know your computer equipment is made of several common components. These include:

The main computer box.
A monitor - Looks like a television screen.
A keyboard.
A mouse.
Speakers.
An optional printer

The main computer box is the main component of the computer. It has computer hardware parts inside that perform the following functions:

Temporary storage of information (known as data in more technical terms) - This function is done by memory.
Permanent storage of information - This function is done by a hard disk, floppy disk, or CD ROM.
Manipulation or processing of data - Used to determine where data is stored and perform calculations which support operations that the user is doing.
Interfacing to the outside components or to the outside world - This supports the ability for the user to communicate with the computer and know how the computer is responding to commands which are done primarily through the monitor, keyboard, and mouse along with their interface components in the main computer box.
A power supply which provides the electrical power to the components in the computer box.

The Main Computer Box

The main computer box is made of several computer hardware components and subcomponents which include:

The case - The outside component which provides protection for the parts inside and provides a fan and power supply which are used to both cool the working parts inside and provide power to them.
The motherboard - Hold the following computer hardware subcomponents:
- Memory - Used to provide temporary storage of information as discussed earlier.
- Microprocessor - Used to provide the processing of data function as discussed earlier.
- Video interface card which is also called the video card - This card is an interface between the computer monitor and the motherboard and its subcomponents such as the microprocessor and memory. This card may be included as part of the motherboard or it may plug into a card slot on the motherboard.
- Sound card is an interface between the computer speakers and the motherboard and its subcomponents such as the microprocessor and memory. This card may be included as part of the motherboard or it may plug into a card slot on the motherboard.
One or more permanent storage devices some of which may be optional:
- Hard disk - Most computers today have a hard disk (sometimes called hard drives) which is the component most commonly used to provide permanent storage of data. Hard disks are usually permanantly installed in a computer.
- CD ROM drive or DVD drive - Used to provide permanant storage of data but this type of drive is used to bring information into the computer more commonly than it is used to store information from the computer. Sometimes this type of drive is used to back up data from the hard drive so data is not lost if a hard drive breaks. A DVD drive holds more data than a CD ROM drive and DVDs have enough storage capacity that they may be used to play or store movies. The storage media, the CD ROM or DVD may be removed from the computer.
- Floppy Drive - A low capacity storage device which can be written to as easily as it is read. The floppy disk may be easily removed from the computer. It is called a floppy because the part of the media that holds the data is on a material that is not rigid but it is enclosed in a more rigit case to give it durability.

There are also other minor computer hardware components inside the case which include cables which may be used to hook other internal parts together along with connecting an interface to the case for printers and other devices such as a high speed serial bus called USB. (A serial bus simply refers to the fact that data is sent in a stream which is like sending one bit at a time.

The Case

The drawing below shows a typical case. It may help you understand where your connections for your monitor, keyboard, mouse, and other devices are if you should need to hook them up. For more specific information you should refer to your computer owner's manual.

The drawing below shows a typical layout of the components inside your computer case.

http://www.comptechdoc.org/basic/basictut/

Computer Data

To help understand computers it is best to first learn about computer data. Computer data is information required by the computer to be able to operate. It is used to:

Run programs - This is the actual executable program data that the computer will execute to run the program such as Microsoft Word.
Store program or system configuration information.
Store information that the computer user needs such as text files or other files that are associated with the program the computer user is running. A common example of a program the computer user is running is the Microsoft Office suite of products which include Microsoft Word, Microsoft Excel, and others. These programs are also known as applications.

Data Structure

Computer data is in what is called binary format. This means that it is always a 0 or a 1. It only has these two states and must be in one of them.

There are several fundamental data units which include:

Bit - A data unit which must be in one of the two binary states described above. It is the smallest data unit that exists.
Byte - 8 bits of data which has a possible value from 0 to 255.
Word - Two bytes or 16 bits of data with a possible unsigned value from 0 to 16535.

Data transmission

Data transmission is the act of sending data from one place to another. Data is transmitted both inside and outside your computer. There are two fundamental methods of data transmission.

Serial - Data is sent on a single line and one bit is sent at at a time. This is similar to a line which one item must come one after another.
Parallel - Data is sent on more than one line at a time. This may be any number of bits at a time, but is usually one word at a time (two bytes) or possibly three bytes at a time.

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Basic Computer Tutorial

This basic computer tutorial is written for those who do not know very much about computers. The purpose of this basic computer tutorial is to help the reader better understand how to use their computer more effectively and safely. It will help the reader understand:

What files and file types are.
How to copy files.
Where your files are stored.
What the parts of your computer are.
What an operating system is.
What a computer program is.

Security and Performance

With the above basic information, this tutorial will explain methods that you can do to make your system more secure, keep your data safe by backing it up, and avoid most performance degredation caused to bad applications and SPAM.

How some file types can be used by third parties to gain control of your computer.
How to modify your file view settings so you are not as easily fooled by e-mails containing viruses.
How to prevent viruses and worms.
How to reduce SPAM.
How to back up your files.
How to reduce or eliminate unwanted programs that could reduce your system performance.
What to do if you receive a virus or worm.
What to do if you receive an e-mail telling you that an e-mail you sent contained a virus.

This basic computer tutorial gives some basic information about hardware, operating systems, and programs in the first half to help the reader understand later information about files, e-mail and computer security practices. Depending on the reader's level of knowledge, some of the basic information may be skipped and the reader may refer to the terms page if they do not understand some of the terms.

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File Extensions

Executable File Types

File Functions

File Characteristics

Data Structure

Data transmission

What is an application

How Application Programs Work

Application Problems

Application Acquisition and Installation

Bad Applications

Application Files

Internet Services

Internet Functions

Internet Organizations

Summary

Accessing the Internet

Broader Definition

Hardware

Software

BIOS (Basic Input/Output System)

Computer Hardware

The Main Computer Box

The Case

Data Structure

Data transmission

Basic Computer Tutorial

Security and Performance

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