• Introduction
• The Outside of your Computer
• The Inside of your Computer
• The individual parts of your computer
  • Computer Case
  • Motherboard
  • Central Processing Unit
  • Power Supply Unit
  • Hard Disk Drive
  • Optical Disk Drives
  • Cooling Devices
  • Sound Card
  • Video Card
  • Memory
  • Expansion Cards
  • External Ports
• Conclusion

Introduction

When you look at your computer what you are seeing is actually the computer case. Inside the case are all of the individual components that when connected together create your computer. On the outside of the case you will see various external ports that you can plug devices into as well as the ability to access your optical devices such as your CD and DVD drives.

Front of a Dell Inspiron Desktop	Back of a Dell Inspiron Desktop

Figure 1. Front and Back of a Computer Case

On the front of the computer you will commonly find a CD or DVD drive that can be opened by pressing a small button near the door of the drive. This will eject the drive tray where you can place a CD or DVD disk. When you press the button again, the tray will slide back into your computer so that you can access it from within your operating system.

On the front of the case, you will also typically find USB ports and media readers. A USB port is a small opening on the front of your computer that allows you to plug a USB device or cable into it. You can usually determine if a port on your computer is USB as it will have the logo next to it. Common devices that you would plug into USB ports are iPod and iPads, flash drives, and external hard drives. The other common ports that you can find are for camera memory media. These media readers allow you to remove the memory card from your camera and insert it into the computer so you can access the images stored on it.

On the back of the case are connectors that are typically only used when you assemble your computer for the first time. These connectors allow you to connect external devices such as your printer, monitor, mouse, keyboard, and speakers. The back connections will also include an Ethernet port that will allow you to connect your computer to your network. Last, but not least, there will also be more USB ports available in the event that you need more USB connections than are available on the front of your computer.

The Inside of your Computer

Now that you know how to connect your various external components to your computer case, let's take a look at the inside of a computer as this is where the magic really happens. To open your case, you will need to typically unscrew a side panel or press a button on the bottom of the computer to open the computer like a clamshell. Once you can see inside a computer, you will see various individual components connected via cables or plugged directly into a large board attached to the side of the case. This board is the motherboard and is used to connect all the individual devices inside your case into a single computer. These individual devices and the motherboard they plug into can be seen in the image below.

Figure 2. Inside of a computer

As you can see from the image above, there are various components all connected to each other. Every device must be connected to the power supply unit, which provides electricity to various components. The add-on cards, each performing their own function, are inserted to the motherboard so that they can communicate with it. When all of these components are properly connected to each other, they can then communicate with each other and the computer will operate properly. In the next section we will discuss each individual component and what function they serve.

The individual parts of your computer

As already stated, a computer is nothing more than various individual hardware components connected to each through cables and the motherboard. These devices are then given electricity by the power supply unit so that they can function. In this section we will discuss the individual components and the function that each performs.

Computer Case

The computer case, also called a chassis, houses and protects other core parts of the computer.  Computer cases come in different sizes and shapes in order to accommodate the various environments that they will be stored in. These shapes are:

• Tower - A tower case is vertical and usually sits on the floor. A tower case comes in a mini, mid, and full size, with the larger sizes being able to hold more components.
• Desktop - A horizontal case that is designed to rest on a shelf or sit on your desk with the monitor on top of it.
• Rackmount - Rackmount cases are horizontal and are typically used for servers. These servers will then mount in a rack so that there are stacks of computers in one computer rack.

HAF 932 AMD Limited Edition Full Tower Case	iStarUSA E3M8 Rackmount Case

Figure 3. Computer Cases

Computer cases also need to support the largest component that resides inside it, which is typically the motherboard. The motherboard can come in many different shapes and sizes, called form factors, and the specifications on a computer case will state which form factors can fit inside it.

• Power switch
• Indicator lights such as disk activity or network activity.
• Back panel that contains holes to expose external ports.
• Metal framework to house the PSU and hard disk/optical drives
• Mounting points to secure the motherboard
• Vented panels to allow airflow through the case
  

Depending on the model, some cases have other features as well such as headphone jacks or USB ports.


Motherboard

The motherboard, or mobo for short, is perhaps the most critical piece of the computer.  It is a relatively large, rectangular board filled with various circuits, chips , and slots that you plug things into The motherboard serves two functions.  First, the motherboard is home to a number of chips that dictate how the various components of the computer will talk to each other. It also has special slots that allow you to plug expansion cards in that add new or improved functionality to your computer.  Secondly, and perhaps most importantly, the motherboard is the connecting point for all of the other pieces of the computer.  Without the motherboard, the different parts cannot communicate with each other, and the computer cannot function.

Figure 4. Computer Motherboard

Motherboards come in a variety of sizes, or form factors, such as ATX or microATX.  Generally speaking, the larger the form factor the more devices can be attached to it.  Motherboards connect with the other devices in your computer using a set of special slots and connectors called ports that are located on the top and back edge of the motherboard.  The ports on the back edge of the motherboard protrude out of the back panel of the computer case and allow you to connect external devices to the computer.  Virtually all modern motherboards have one or more USB ports and an Ethernet port mounted externally to allow connection to the internet and external devices.  Additionally, all modern motherboards contain at least one IDE or SATA port to allow the connection of a hard drive.

Central Processing Unit

The central processing unit, or CPU, is at the core of every computer.  Functioning as the "brain" of the computer, the CPU performs basic mathematical and logical functions as instructed by a computer program.  The CPU is located on the motherboard and is connected to it through a special port called the CPU socket. When the CPU is in use it generates heats, which must be transferred away from CPU chip so that it is not damaged. This is accomplished through the use of a heat-sink and fan which draws the heat out of the CPU chip and transfers it into the case instead.

Figure 5. A computer's CPU or Processor

A CPU has a maximum speed at which it can safely process instructions.  This speed is called the clock rate and is measured in hertz (Hz).  Some CPUs will allow a user to raise the clock rate beyond the speed at which the CPU is safely rated.  This is called overclocking, and can provide increased computer performance at the cost of  potential system instability or damage.  Due to the complexity of overclocking and the potentially destructive side effects it can cause, overclocking is a technique not recommended for average or professional computer users.

A relatively recent development in the field of CPUs is the multi-core processor.  Having many processing cores in the CPU effectively multiplies its potential by allowing the CPU to simultaneously process as many instructions as it has cores.  However, the OS must be designed to make use of multiple cores for this ability to take effect.  The CPU of a modern PC will likely have anywhere from two to eight cores


Power Supply Unit

All parts of a computer require electricity in order to operate.  The part of the computer that provides this electricity is called the power supply unit, or PSU.  The PSU receives electricity from an external source, which is usually a wall outlet, and changes it into power that the other parts of the computer can use. 

Figure 6. Power Supply

A PSU is necessary for two reasons.  First, computers require direct current, or DC, power.  However, electricity is supplied by power companies in alternating current, or AC, form.  The PSU takes the AC electricity and converts it into a DC form so that the computer can use it.  The second reason is that computer components use electrical power of relatively low voltage, while the electricity that comes out of a wall socket is of a significantly higher voltage.  The PSU converts the higher voltage energy into a low voltage form that the computer can properly use.

Power supplies are classified by the maximum amount of watts, such as 500 or 650 watts, which can be supplied to your computer system.  The amount of electricity that is required to power a computer depends on what components the computer is using.  For example, if you are using a high-end processor and a high-end video card your power you may need a more powerful PSU to support these power hungry devices. Therefore, when buying new components for a computer you should always look at the specifications for these devices to determine how much power they need and whether or not your PSU can support it.

Hard Disk Drive

The hard disk drive, or HDD, is the primary source of secondary storage in modern computers.  Secondary storage is any device where information is stored when it is not needed for immediate use.  An HDD uses magnetism to record information on a rotating disk of magnetic material.  It uses a moveable arm containing a device called a drive head to read from and write to different portions of the disk..  Since the disk remains magnetized even after power is removed, information is not lost when you turn off the computer.  One downside of HDDs is that they are very slow compared to other devices in the computer.  This is because the drive must position the arm and disk in the correct position in order to retrieve a particular piece of information. 

Figure 7. Hard Disk Drive

Modern HDDs have three major variables.  The first is the drive capacity.  This is how much information the drive can hold.  Drive capacity is measured in either gigabytes (GB) or terabytes (TB).  One terabyte is equal to one thousand gigabytes.  The second variable is the rotation speed.  This is how quickly the disk inside the HDD can rotate, and is measured in rotations per minute (RPM).  The faster the disk spins, the more quickly information can be retrieved from it.  The final variable is the type of interface the HDD uses.  The interface is the part of the HDD that connects to the motherboard and is how the HDD sends and receives information.  Most modern HDDs use SATA or SAS interfaces, although HDDs using IDE interfaces are still somewhat common.  It is important to know which interfaces your motherboard supports when purchasing a new HDD.

A recent addition to the personal computer market is a technology called a solid state drive, or SSD.  While not technically an HDD, SSD's fill the same functions.  The difference between HDDs and SSDs is that while an HDD uses a spinning disk to store data, an SSD uses special microchips.  Due to this, SSD's are less susceptible to physical shocks such as impacts and falls compared to a HDD.  Additionally, SSDs run silently and can access data more quickly.  However, SSDs have a higher cost per gigabyte than their HDD cousins do.

Optical Disk Drives

An optical disk drive is a component that uses a laser to read from or write to an optical disk.  Examples of optical disks include CDs, DVDs, and Blu-Rays.  An optical disk drive writes to a disk by using a laser to etch tiny grooves into the surface of the disk.  The disk is read by using a different, low-power laser to detect those grooves.  Modern optical disk drives usually have reading and writing (burning) capability.  Additionally, most optical drives are backwards compatible, which means that a new technology can read the media from an older technology. For example, a Blu-Ray drive can also play DVDs and CDs.

Figure 8. Optical Drive

Optical disk drive speed is measured differently than HDD speed.  While HDD speed is measured in the number of RPMs, optical drive speed is measured by the maximum rate at which data can be read from the disk.  For each technology (CD, DVD, Blu-Ray) there is an industry-wide standard data rate that serves as a benchmark by which drive speeds are measured.  The speed listed is put in terms of multiples of that base speed.  For example, the base speed for Blu-Ray technology is 6.74 megabytes per second.  Therefore, a drive rated at 52x can read data at a maximum rate of 52 x 6.74 = 350.48 megabytes per second.

Cooling Devices

As a computer runs, it generates a lot of heat.  One or more cooling devices are part of any modern computer in order to keep the machine from overheating.  The two types of cooling devices that are in almost every modern computer are heat sinks and cooling fans.  Heat sinks are small metal structures that conduct heat well.  They function by absorbing the heat produced by a component and efficiently releasing it into the air, or a liquid in certain special situations, similarly to how the radiator in your car works.  Cooling fans work by removing warm air from components or heat sinks and pulling in cool air to replace it.  Fans are available in a variety of sizes that determine how much air they can move within your case.  When adding a fan, it is important to ensure that you purchase a fan that is compatible with your motherboard, since different fans have different kinds of power connectors.

Figure 9. CPU Heat Sink and Fan

Some extremely high-end PCs have liquid cooling systems which use tubes of flowing water or coolant instead of or in addition to cooling fans.  These systems are more effective, quieter, and more efficient than air cooling systems.  However, they are complex, expensive, and carry the danger of a coolant leak which can damage the system.  For a typical PC, air cooling systems are sufficiently effective.

Memory

Random Access Memory, or RAM, is the part of the computer where information is stored while it is being used by the computer's processor, operating system, programs, and other devices on your computer.  RAM is designed so that any of the information stored on it can be read in any order without losing performance.  This makes RAM faster and more efficient to store data compared to slower devices such as an HDD or CD-ROM. 

Figure 10. Computer Memory

When you are using your computer it copies information that it is currently using, such as parts of the operating system or currently running programs, into RAM so that it can work faster.  The more RAM that the computer has, the less often it needs to get information off of the much slower HDD.  To use a comparison, think of your HDD as a well.  The information on the HDD is the water in the well, and the RAM is a bucket.  The bigger your bucket, the fewer trips you have to make to the well to get the water you need.

One characteristic of RAM is that it is volatile.  This means that when you turn off the computer, any information in the RAM is erased.  To protect against loss of information, an operating system will copy any data that it needs to the HDD so that it is available the next time you start the computer.

RAM comes in different speeds and types.  When you upgrade your computer's memory, it is important that you ensure that you choose a speed and type of RAM that is compatible with a computer's motherboard.  A great tool for finding out what kind of memory your computer uses is Crucial's Memory Advisor. 

Expansion Cards

An expansion card is a device that is inserted into special slots on the motherboard and provides the computer with additional functions, resources, or features.  There are a number of different kinds of expansion cards available; two of the most common being video cards, which provide increased graphics processing ability, and sound cards, which enhance the audio ability of the computer.  Some expansion cards such as video cards also include their own processor, memory, and even cooling devices such as fans or heat sinks.

When purchasing expansion cards there are a number of important factors to consider.  First and foremost is the type of connection that the expansion card requires.  There are a number of different standards for expansion slots, and motherboards have only a limited number of each kind of slot.  Before purchasing you need to ensure that your motherboard has the required slots available for use.  Another important factor is the size of the expansion card.  The card needs to be able to fit inside your computer case, and should not make contact with any other parts of the computer except for the motherboard.  Finally, you should ensure that your PSU can output enough power to support all your connected expansion cards.  If the PSU cannot supply the computer with enough electricity then one or more of your devices will fail to function.

Two common types of expansion cards are sound and video graphic cards, which are described below.

Sound Cards

Sound cards are a kind of expansion card which deals with audio input and output. Sound cards generally fill two functions. First, sound cards enhance the sound processing capability of the computer, allowing for the creation and output of more complex sounds. Secondly, sound cards often possess input and output ports that allow for other audio devices such as microphones or speakers to be connected to it.

Figure 11. Sound Card

Video Cards

A video card is a type of expansion card which increases the computer's ability to handle different kinds of visual output. Video cards have two main functions. First, while nearly all modern motherboards have some basic graphics capabilities built in, a video card can handle graphics issues much more effectively than the graphic chips built into the motherboard.

As a result, a video card allows for the creation and display of more complex and detailed images without putting an additional strain on the CPU. Additionally, since many video cards have their own memory, this leaves more of the general computer memory available for other purposes. Second, many video cards add additional functions to the computer such as video capture, a TV-tuner which allows you to watch TV on your computer, or the ability to connect multiple monitors to the computer.

Figure 12. Video Graphics Card

External Ports

As mentioned above in the motherboard section, a number of connectors on the motherboard are accessible from the back panel of the computer case.  These connections are called external ports because they can be accessed from outside the computer case.  There are a number of different kinds of connections available that include:

• VGA or DVI Connector- These ports are used for connecting a monitor or other display device to your computer.
• Ethernet Port - This port allows you to connect your computer to a network or the Internet.
• HDMI - Allows you to connect your computer a High Definition display or TV.
• eSATA - These ports allow you to connect an external SATA hard drive to your computer.
• USB Port - A common connector for external devices. More information about USB ports can be found below.

Figure 13. External Ports on the back of a computer

Virtually every modern PC also includes one or more USB, or Universal Serial Bus, ports.  There are two primary kinds of USB ports in use right now: USB 2.0 and USB 3.0.  USB 3.0 ports can move data much more quickly than USB 2.0 ports.  However, the connected device must be designed to take advantage of USB 3.0 technology in order to use the increased speed. 

USB ports and devices are both backwards and forwards compatible.  This means that you can plug any standard USB device into any standard USB port, and the device will function.  However, if the USB version of the device and the port do not match then the device can only transfer data to and from the PC at a maximum rate set by the lower of the two versions.  For example, if you connect a USB 3.0 device to a USB 2.0 port, the device will only transfer data at a maximum rate of 60 megabytes per second, which is the maximum rate for USB 2.0 technology.

When purchasing an external device such as a monitor, keyboard, mouse, or printer it is important to ensure that you have the correct kind of port available for use.  Otherwise you will be unable to use the device.

Conclusion

As you can see, a computer is more than that box sitting on the side of your desk. In fact it is a very complex machine comprised of numerous parts, cables, and devices that all need to properly work together in order for the computer to operate correctly. Having this basic understanding of the parts of your computer is important for any computer user. Whether you need to purchase a new one, upgrade an existing one, or repair a broken one, you now have the knowledge to understand what you are looking at.

1. Introduction
2. How to change file association by right-clicking on a file in Windows 8
3. How to change file association through the Set Associations Control Panel in Windows 8
4. How to set the default programs for an unknown extension in Windows 8

Introduction

When you double-click on a file in Windows 8, Windows will automatically open that file using a program that has been associated with that file's extension. There may come a time, though, that you wish you to use a different program to open a file rather than use the one that is set as the default in Windows. This tutorial will discuss how to assign a different program to a file extension so that it will become the default program for that file type. This tutorial will also explain how to assign a default program to a file extension that Windows does not already know about.

How to change file association by right-clicking on a file in Windows 8

To change the default program a file type is opened with, from the Windows 8 desktop search for the file you wish to change and right-click on it to bring up the file menu as shown below.

At the above menu, please select the Open with menu option. You will then be presented with a screen similar to the one below that shows the available programs that you can open the file with.

To change the default program that this file is opened with, please click on the Choose default program... option. You will then be shown a dialog asking how you want to open this type of file as shown below.

In this screen you will see a list of programs that Microsoft recommends you use when dealing with the particular type of file. To see other possible choices, you should click on the See all... option. This will bring up a screen that shows a larger list of choices that you can choose from as shown below.

If you see the program you wish to use by default, then put a check mark in the check box labeled Use this app for all .extension files and then select the program. The file will then be opened by this program and all other files that contain this extension will use this program as well going forward.

If you do not see the desired program, though, you should then put a check mark in the check box labeled Use this app for all .extension files and then click on the Look for an app on this PC option to open a window where you can browse to the program you wish to use. You will now be presented with the Open with window where you can browse to the executable that you want to set as your default. Once you have found the executable, select it by left-clicking on it once so it becomes highlighted and then click on the Open button. The file should now have been opened using the program you selected and these types of files will now automatically be opened by this program.

How to change file association through the Set Associations Control Panel in Windows 8

This method will allow you to change the default program for a particular extension using the Set Associations control panel. This control panel contains a listing of all known file extensions and the default programs that are assigned to them.

From the Windows 8 Start Screen, click on the Control Panel app. When the Control Panel opens, scroll down and then click on the More Settings option. This will open the classic Windows Control Panel screen as shown below.

Click on the Programs category as shown by the arrow above. This will open the Programs category of the Control Panel.

Now click on the Make a file type always open in a specific program option as shown above. You will now be at the Set Associations Control Panel, which shows all the extensions that Windows knows about and the associated program that is set to open these types of files.

To change the default program for a file in Windows 8, just scroll through the list of extensions until you find the one you want to change. Then click once on it once to select it and then click on the Change program... button. This will open a screen that displays the programs that Windows recommends you use to open this type of file as shown below.

To see other possible choices, you should click on the See all... option. This will bring up a screen that shows a larger list of choices that you can choose from as shown below.

If you see the program you wish to make the default for this particular type of file, then put a check mark in the check box labeled Use this app for all .extension files and then select the program you wish to use. The file will then be opened by this program and all other files that contain this extension will use this program as well.

If you do not see the program in this list, though, you should then put a check mark in the check box labeled Use this app for all .extension files and then click on the Look for an app on this PC option to open a window where you can browse to the file you wish to use. You will now be presented with the Open with window where you can browse to the executable that you wish to use to open these types of files. Once you have found the executable, select it by left-clicking on it once so it becomes highlighted and then click on the Open button.

You will now be back at the Set Associations Control Panel, but now the extension will show the new program that you have associated with it. When you open a file in the future that has this extension it will now use the new program.

How to set the default programs for an unknown extension in Windows 8

At times you may have files that have a file extension that is not know to Windows. Therefore, when you attempt to open them, Windows will not know what program to use and you will see a dialog box that states Windows can't open this file. This section will explain how to assign a default program to this new file type so that it can be opened automatically with the program of your choice when you double-click on it.

To assign a program to an unknown extension, simply double-click on the file that you wish to assign the program to. When you double-click on it, Windows will display a dialog box that states it can't open this file.

At this point you have two choices. If you do not know which program to use, you can select the Look for an app in the Store option, which will allow you to search for an app in the Microsoft Store that may be able to open that type of file. The other option is to use a program on your hard drive to launch the program. To find a program already on your hard drive, please click on the See all... option.

This will bring up a screen that shows a larger list of choices that you can choose from as shown below.

If you see the program you wish to make the default for this particular type of file, then put a check mark in the check box labeled Use this app for all .extension files and then select the program you wish to use. The file will then be opened by this program and all other files that contain this extension will use this program as well.

If you do not see the program in this list, though, you should then put a check mark in the check box labeled Use this app for all .extension files and then click on the Look for an app on this PC option to open a window where you can browse to the file you wish to use. You will now be presented with the Open with window where you can browse to the executable that you wish to use to open these types of files. Once you have found the executable, select it by left-clicking on it once so it becomes highlighted and then click on the Open button.

The file should now have been opened using the program you selected. Windows has also been configured to use this program to open files that contain this new extension in the future. If you have any questions regarding these steps, please feel free to ask in the Windows 8 forum.

1. How to change file associations by right-clicking on a file in Windows XP
2. How to change file associations through the Set Associations Control Panel in Windows XP
3. How to set the default programs for an unknown extension in Windows XP

When you double-click on a file in Windows XP, the operating system will automatically open the file using a program that has been is associated with the file's extension. It is possible, though, to change the default program that is opened when you click on a file. This tutorial will explain how to change the default program that is associated with an extension as well as assigning a program to an extension that Windows does not know about.

How to change file associations by right-clicking on a file in Windows XP

To change the default program a file type is opened with, search for the file you wish to change and right-click on it to bring up the file menu as shown below.

At the above menu, please select the Open with menu option. You will then be presented with a screen similar to the one below that shows the available programs that you can open the file with.

To change the default program that this file is opened with, please click on the Choose Program... option. You will then be shown the Open with dialog as shown below.

In this screen you will see a section called Recommended Programs that contains known programs that can properly open and manipulate the file in question. This does not mean, though, that there are not other programs on your computer that can properly manipulate the file as well. To change the default program to one of these unlisted programs, simply click on the Browse... button.

You will now be presented with a window where you can browse to the executable that you wish to use to open these types of files. Once you have found the executable, select it by left-clicking on it once so it becomes highlighted and then click on the Open button. You will now be at the Open With window, but should see other programs listed under the Other Programs list and the program you browsed to will be selected and highlighted as shown in the image below.

With the new program that you wish to use selected, make sure there is a check mark in the Always use the selected program to open this kind of file checkbox. Then press the OK button. The file should now have been opened using the program you selected and these types of programs will now automatically be opened by this program.

How to change file associations through the Folder Options Control Panel in Windows XP

This method will allow you to change the default program for a particular extension using the Folder Options control panel. This control panel contains a listing of all known file extensions and the default programs that are assigned to them.

First, click on the Windows XP Start button. This is the small rectangular button () in the lower left corner of your screen that has a Windows flag on it. When the Start Menu opens, click on the Control Panel menu option as shown by the black arrow in the image below.

When the control panel opens you may see the Control Panel in Category view as shown in the image below.

Please click on the Switch to Classic View option as designated by the black arrow above. This will change the display of the Control Panel to the classic view, which makes it easier to find the particular settings we would like to change.

Click on the control icon labeled Folder Options as shown in the image above. This will open the Folder Options control panel. When the Folder Options screen is open, click on the File Types tab. You will now see a screen similar to the one below.

Scroll through the list of file extensions till you find the extension that you wish to change the default program. When you find it, left-click on it once to select it and then click on the Change... button. In our example, we will be changing the .txt extension. You will then be shown the Open with dialog as shown below.

In this screen you will see a section called Recommended Programs that contains known programs that can properly open and manipulate the file in question. This does not mean that there are not other programs on your computer that can properly manipulate the file as well. To change the default program to one of these programs, simply click on the Browse... button.

You will now be presented with a window where you can browse to the executable that you wish to use to open these types of files. Once you have found the executable, select it by left-clicking on it once so it becomes highlighted and then click on the Open button. You will now be at the Open With window, but should see some new programs listed under the Other Programs list and the program you browsed to will be selected and highlighted as shown in the image below.

With the new program that you wish to use selected, make sure there is a check mark in the Always use the selected program to open this kind of file check box, and then press the OK button.

You will now be back at the Folder Options Control Panel, but with the new program associated with the .txt extension as shown in the image below.

Files that have the particular file extension that you changed will now automatically open with the new program when you double-click on them. You can now press the Close button to close the Control Panel.

How to set the default programs for an unknown extension in Windows XP

At times you may have files that have a file extension that is not know to Windows. Therefore, when you attempt to double-click on them to open them, Windows will not know what program to use and you will see a dialog box that states Windows can't open this file. This tutorial will explain how to assign a default program to this new file type so that it can be opened automatically with the program of your choice when you double-click on it.

To assign a program, simply double-click on the file that you wish to assign a program to. When you double-click on it, Windows will display a dialog box that states it can't open this file.

At this point you have two choices. If you do not know which program to use, you can select the Use the Web service to find the appropriate program option and click on the OK button. Windows will open up a web browser to a Microsoft web page that displays possible programs that you can download and install that will allow you to open these types of files.

On the other hand, if you know of a program that is already installed on your computer that can open these files you should click on the Select the program from a list and then click on the OK button. You will then be presented with the Open with screen as shown below.

In the above screen you should enter a description for this type of file in the Type a description that you want to use for this kind of file: field. When entering the description, try to offer information as to what program this file belongs to or contains. You should also see a list of programs that may be able to open the file. If the program you wish to use is listed, simply left-click on it once to select it. If it is not listed, then click on the Browse... button.

You will now be presented with a window where you can browse to the executable that you wish to use to open these types of files. Once you have found the executable, select it by left-clicking on it once so it becomes highlighted and then click on the Open button. You will now be at the Open With window, but should see other programs listed under the Other Programs list and the program you browsed to will be selected and highlighted as shown in the image below.

With the new program that you wish to use selected, make sure there is a check mark in the Always use the selected program to open this kind of file checkbox, and then press the OK button. The file should now have been opened using the program you selected and from now will be automatically be opened by this program as well.

The first thing you need to do is click on empty portion of your desktop so that the Finder is selected. Once it is selected, click on the Go button and select Utilities as shown in the image below.

The Utilities folder should now appear as shown in the image below.

Scroll through the list of apps till you find the Terminal icon, as shown by the arrow in the image above, and double-click on it. The Terminal utility should now open and you will be shown a prompt and rectangular cursor as shown in the screen below.

The Mac OS Terminal utilities allows you to enter commands by typing on your keyboard. In order to show hidden files within the Mac OS Finder, we need to first issue a command to enable the viewing of hidden files. To enter this command, simply type the following bold text on your keyboard defaults write com.apple.Finder AppleShowAllFiles TRUE and then press the Enter key on your keyboard. Once you have done this, your Terminal screen should look similar to the image below.

It is now necessary to restart the Finder so that these settings go into effect. To do this please type the following bold text on your keyboard killall Finder and then press the Enter key on your keyboard. Please note that you must capitalize the F in Finder or the command will not work. Once you have done this, your Terminal screen should now look similar to the image below.

After typing the killall Finder command, you should have seen the Mac desktop go away and then start again. This was the Finder restarting and enabling the new settings. You can now close the Terminal utility.

You will now be able to see all files, including hidden ones, when using the Finder on your Mac. In the future if you want to turn this setting off so that hidden files are not visible in the Finder, you can follow the same steps, but for the first command you should instead type the following bold text on your keyboard defaults write com.apple.Finder AppleShowAllFiles FALSE and then press the Enter key on your keyboard. You will then need to issue the killall Finder command to restart the Finder.

If you have any questions about this process please feel free to post them in our Mac OS Forum.

When the file menu opens, click on the Open With option as shown in the image above. This will open the Open With submenu as shown in the image below.

This submenu contains other programs that the Mac OS thinks could properly open the file and manipulate it in some way. If the program you wish to use is listed, then simply select it from this submenu and the file will open using that program.

On the other hand, if the program that you wish to use is not listed, then click on the Other... menu option. This will then open the Choose Application dialog where you can select a different application that you wish to use to open the file as shown in the image below.

As you can see from the image above, the Choose Application dialog will display a list of applications that you can choose to open this file with. By default, this dialog will only show Recommended Applications, which means that you will only be able to select the applications that are in bold. If you wish to select a different application than a recommended one, you can change the Enable option to All Applications. This will then allow you to select any application you wish.

Once you have determined the application you wish to use, select it by left-clicking on it once. If you want to make this application always open this particular file, then also put a check mark in the Always Open With check box. Then click on the Open button.

The file will now open with the selected application. If you have any questions about this process please feel free to post them in our Mac OS Forum.

Before changing a file extension back to its defaults, you should first enable your Mac to view file extensions so that you can find a file containing the extension you want to reset. To do this, please follow the instructions found in the tutorial How to show filename extensions on a Mac.

Once file extensions are visible on files, navigate to a file that is the type that you would like to reset back to the Mac OS defaults. Once you are at that file, right click on it and select the Get Info option as shown in the image below.

When you select the Get Info menu option, the file's information page will be displayed as shown below.

Expand the Open with: category as shown in the image above. You will now see the current program that this file type is configured to use when you double-click on it. In our example above, this means that if you double-clicked on the About Stacks.pdf file it would be open in Safari. To change it back to the default setting, you need to select the down/up arrow menu as shown in the image below.

In the drop down menu that appears you will see an application that contains the (default) phrase. This is the original default application in Mac OS for this type of file. Select it by clicking on it once. The Open With option should now be set to use the default application you selected.

Currently, only this individual file has been reset to use the default program. If you wish to make it so that all files of this type use the default application, you should now click on the Change All... button. Once you click on the Change All button, every file of this type will now be reset to use the default program. You can now close the Information screen.

The file extension has now been reset to the default program that was configured when Mac OS was installed. Now, if you double-click ona this type of file it will open with the default program that was configured when the Mac OS was installed.

If you have any questions about this process please feel free to post them in our Mac OS Forum.

First, you should navigate to the file that you wish to open. Once you have found this file, right-click on it to bring up the file's menu as seen below.

At the above menu, please select the Open with menu option. You will then be presented with a screen similar to the one below that shows the available programs that you can open the file with.

To open the file using a different program than the default one, simply select the available program that is listed and the file will open with that program instead.

If the program that you wish to use is not listed automatically, simply click on the Choose default program... menu option as shown in the image above. You will then be presented with a screen where further program recommendations are given. If you find that you still do not see the program you wish to use after browsing through the list, please click on the Browse button.

You will now be presented with a window where you can browse to the executable that you wish to use to open these types of files. Once you have found the executable, select it by left-clicking on it once so it becomes highlighted and then click on the Open button. You will now see the program you browsed to selected and highlighted in Open With screen.

With the new program that you wish to use selected, make sure the checkbox labeled Always use the selected program to open this kind of file checkbox is not checked as you do not want to make this new program the default one for this file type. When you are done, press the OK button. The file should now have been opened using the program you selected and these types of programs will now automatically be opened by this program.

This new program will now be added to the Open With list when you right-click on this file type in the future as shown in the image below.

1. Introduction
2. How to change file associations by right-clicking on a file in Windows 7
3. How to change file associations through the Set Associations Control Panel in Windows 7
4. How to set the default programs for an unknown extension in Windows 7

Introduction

When you open files that have a particular file extension, Windows will look at its configuration to determine what the default program should be in order to work with these files. The default program that is assigned to a particular extension, though, may not be what you want to use. Therefore, it is possible to change the default program that is launched when you double-click on a particular file type. This tutorial will discuss how you can open a file using another program or to assign a new program to extensions that have not been opened before.

How to change file associations by right-clicking on a file in Windows 7

To change the default program a file type is opened with, search for the file you wish to change and right-click on it to bring up the file menu as shown below.

At the above menu, please select the Open with menu option. You will then be presented with a screen similar to the one below that shows the available programs that you can open the file with.

To change the default program that this file is opened with, please click on the Choose default program... option. You will then be shown the Open with dialog as shown below.

In this screen you will see a section called Recommended Programs that contains known programs that can properly open and manipulate the file in question. This does not mean that there are not other programs on your computer that can properly manipulate the file as well. To change the default program to one of these unlisted programs, simply click on the Browse... button.

You will now be presented with a window where you can browse to the executable that you wish to use to open these types of files. Once you have found the executable, select it by left-clicking on it once so it becomes highlighted and then click on the Open button. You will now be at the Open With window, but should see other programs listed under the Other Programs list and the program you browsed to will be selected and highlighted as shown in the image below.

With the new program that you wish to use selected, make sure there is a check mark in the Always use the selected program to open this kind of file checkbox. Then press the OK button. The file should now have been opened using the program you selected and these types of programs will now automatically be opened by this program.

How to change file associations through the Set Associations Control Panel in Windows 7

This method will allow you to change the default program for a particular extension using the Set Associations control panel. This control panel contains a listing of all known file extensions and the default programs that are assigned to them.

First, click on the Windows 7 Start button. This is the small round button () in the lower left corner of your screen that has a Windows flag on it. When the Start Menu opens, type Show hidden in the search field as shown in the image below.

When you see the Make a file type always open in a specific program listing appear, as shown by the black arrow in the image above, click on it to open the Set Associations Control Panel.

When the control panel opens you will see a screen similar to the one below.

Scroll through the list of file extensions till you find the one that you wish to change the default program. When you find it, left-click on it once to select it and then click on the Change Program... button. In our example, we will be changing the .txt extension. You will then be shown the Open with dialog as shown below.

In this screen you will see a section called Recommended Programs that contains known programs that can properly open and manipulate the file in question. This does not mean that there are not other programs on your computer that can properly manipulate the file as well. To change the default program to one of these programs, simply click on the Browse... button.

You will now be presented with a window where you can browse to the executable that you wish to use to open these types of files. Once you have found the executable, select it by left-clicking on it once so it becomes highlighted and then click on the Open button. You will now be at the Open With window, but should see some new programs listed under the Other Programs list and the program you browsed to will be selected and highlighted as shown in the image below.

With the new program that you wish to use selected, make sure there is a check mark in the Always use the selected program to open this kind of file checkbox, and then press the OK button.

You will now be back at the Set Associations Control Panel, but with the new program associated with the .txt extension as shown in the image below.

Files that have the particular file extension that you changed will now automatically open with the new program when you double-click on them. You can now press the Close button to close the Control Panel.

How to set the default programs for an unknown extension in Windows 7

At times you may have files that have a file extension that is not know to Windows. Therefore, when you attempt to double-click on them to open them, Windows will not know what program to use and you will see a dialog box that states Windows can't open this file. This tutorial will explain how to assign a default program to this new file type so that it can be opened automatically with the program of your choice when you double-click on it.

To assign a program, simply double-click on the file that you wish to assign a program to. When you double-click on it, Windows will display a dialog box that states it can't open this file.

At this point you have two choices. If you do not know which program to use, you can select the Use the Web service to find the correct program option and click on the OK button. Windows will open up a web browser to a Microsoft web page that displays possible programs that you can download and install that will allow you to open these types of files.

On the other hand, if you know of a program that is already installed on your computer that can open these files you should click on the Select a program from a list of installed programs and then click on the OK button. You will then be presented with the Open with screen as shown below.

In the above screen you should enter a description for this type of file in the Type a description that you want to use for this kind of file: field. When entering the description, try to offer information as to what program this file belongs to or contains. You should also see a list of programs that may be able to open the file. If the program you wish to use is listed, simply left-click on it once to select it. If it is not listed, then click on the Browse... button.

You will now be presented with a window where you can browse to the executable that you wish to use to open these types of files. Once you have found the executable, select it by left-clicking on it once so it becomes highlighted and then click on the Open button. You will now be at the Open With window, but should see other programs listed under the Other Programs list and the program you browsed to will be selected and highlighted as shown in the image below.

With the new program that you wish to use selected, make sure there is a check mark in the Always use the selected program to open this kind of file checkbox, and then press the OK button. The file should now have been opened using the program you selected and from now will be automatically be opened by this program as well.

1. How to view file name extensions for all files on a Mac
2. How to view file name extensions for a individual file on a Mac

The default setting for Mac OS is to not display a file's extension. For those who want to view the full filename, rather than having the extension removed automatically , this tutorial will provide information on how to make it so you view the extensions for all files on your computer or for just an individual one.

How to view file name extensions for all files on a Mac

1. Close all programs so that you are at your desktop.
   

1. Click on the Finder menu as shown in the image below.
   
   
   
   
   
   
   
   When the menu opens, please click on the Preferences menu option.
   
   
2. The Preferences screen should now open in the General category as shown below.
   
   
   
   
   
   
   
   Now, please click on the Advanced button.
   
   
3. You should now be at the Advanced Finder Preferences screen as shown below.
   
   
   
   
   
   
   
   Put a check mark in the checkbox labeled Show all filename extensions.
   
   
4. Now click on the red X button to exit the Finder Preferences screen.

The Mac OS is now configured to show filename extensions for all the files on your Mac.

If you have any questions about this process please feel free to post them in our Mac OS Forum.

How to view file name extensions for a individual file on a Mac

1. Navigate to the file that you wish to be able to see its extension.
   
   
2. When you find your file, right click on it and select the Get Info option as shown in the image below.
   
   
   
   
   
   
   
   
3. When you select the Get Info menu option, the file's information page will be displayed as shown below.
   
   
   
   
   
   
   
   Expand the Name & Extension category as shown in the image above.
   
   
4. Under the file name field you should see a checkbox labeled Hide extension. Uncheck this box to have the Mac OS display this file's extension. If you wish to hide the file's extension then you can check this box.
   
   
5. When you are finished, click on the red X button to close the information screen.
   

The Mac OS has now been configured to display the filename extension for this particular file.

If you have any questions about this process please feel free to post them in our Mac OS Forum.

1. Introduction
2. How to change file association by right-clicking on a file in Windows 7
3. How to change file association through the Set Associations Control Panel in Windows 7
4. How to set the default programs for an unknown extension in Windows 7

Introduction

When you open files that have a particular file extension, Windows will look at its configuration to determine what the default program should be in order to work with these files. The default program that is assigned to a particular extension, though, may not be what you want to use. Therefore, it is possible to change the default program that is launched when you double-click on a particular file type. This tutorial will discuss how you can open a file using another program or to assign a new program to extensions that have not been opened before.

How to change file association by right-clicking on a file in Windows 7

To change the default program a file type is opened with, search for the file you wish to change and right-click on it to bring up the file menu as shown below.

At the above menu, please select the Open with menu option. You will then be presented with a screen similar to the one below that shows the available programs that you can open the file with.

To change the default program that this file is opened with, please click on the Choose default program... option. You will then be shown the Open with dialog as shown below.

In this screen you will see a section called Recommended Programs that contains known programs that can properly open and manipulate the file in question. This does not mean that there are not other programs on your computer that can properly manipulate the file as well. To change the default program to one of these unlisted programs, simply click on the Browse... button.

You will now be presented with a window where you can browse to the executable that you wish to use to open these types of files. Once you have found the executable, select it by left-clicking on it once so it becomes highlighted and then click on the Open button. You will now be at the Open With window, but should see other programs listed under the Other Programs list and the program you browsed to will be selected and highlighted as shown in the image below.

With the new program that you wish to use selected, make sure there is a check mark in the Always use the selected program to open this kind of file checkbox. Then press the OK button. The file should now have been opened using the program you selected and these types of programs will now automatically be opened by this program.

How to change file association through the Set Associations Control Panel in Windows 7

This method will allow you to change the default program for a particular extension using the Set Associations control panel. This control panel contains a listing of all known file extensions and the default programs that are assigned to them.

First, click on the Windows 7 Start button. This is the small round button () in the lower left corner of your screen that has a Windows flag on it. When the Start Menu opens, type Show hidden in the search field as shown in the image below.

When you see the Make a file type always open in a specific program listing appear, as shown by the black arrow in the image above, click on it to open the Set Associations Control Panel.

When the control panel opens you will see a screen similar to the one below.

Scroll through the list of file extensions till you find the one that you wish to change the default program. When you find it, left-click on it once to select it and then click on the Change Program... button. In our example, we will be changing the .txt extension. You will then be shown the Open with dialog as shown below.

In this screen you will see a section called Recommended Programs that contains known programs that can properly open and manipulate the file in question. This does not mean that there are not other programs on your computer that can properly manipulate the file as well. To change the default program to one of these programs, simply click on the Browse... button.

You will now be presented with a window where you can browse to the executable that you wish to use to open these types of files. Once you have found the executable, select it by left-clicking on it once so it becomes highlighted and then click on the Open button. You will now be at the Open With window, but should see some new programs listed under the Other Programs list and the program you browsed to will be selected and highlighted as shown in the image below.

With the new program that you wish to use selected, make sure there is a check mark in the Always use the selected program to open this kind of file checkbox, and then press the OK button.

You will now be back at the Set Associations Control Panel, but with the new program associated with the .txt extension as shown in the image below.

Files that have the particular file extension that you changed will now automatically open with the new program when you double-click on them. You can now press the Close button to close the Control Panel.

How to set the default programs for an unknown extension in Windows 7

At times you may have files that have a file extension that is not know to Windows. Therefore, when you attempt to double-click on them to open them, Windows will not know what program to use and you will see a dialog box that states Windows can't open this file. This tutorial will explain how to assign a default program to this new file type so that it can be opened automatically with the program of your choice when you double-click on it.

To assign a program, simply double-click on the file that you wish to assign a program to. When you double-click on it, Windows will display a dialog box that states it can't open this file.

At this point you have two choices. If you do not know which program to use, you can select the Use the Web service to find the correct program option and click on the OK button. Windows will open up a web browser to a Microsoft web page that displays possible programs that you can download and install that will allow you to open these types of files.

On the other hand, if you know of a program that is already installed on your computer that can open these files you should click on the Select a program from a list of installed programs and then click on the OK button. You will then be presented with the Open with screen as shown below.

In the above screen you should enter a description for this type of file in the Type a description that you want to use for this kind of file: field. When entering the description, try to offer information as to what program this file belongs to or contains. You should also see a list of programs that may be able to open the file. If the program you wish to use is listed, simply left-click on it once to select it. If it is not listed, then click on the Browse... button.

You will now be presented with a window where you can browse to the executable that you wish to use to open these types of files. Once you have found the executable, select it by left-clicking on it once so it becomes highlighted and then click on the Open button. You will now be at the Open With window, but should see other programs listed under the Other Programs list and the program you browsed to will be selected and highlighted as shown in the image below.

With the new program that you wish to use selected, make sure there is a check mark in the Always use the selected program to open this kind of file checkbox, and then press the OK button. The file should now have been opened using the program you selected and from now will be automatically be opened by this program as well.