Operating System

An operating system (OS) is a type of software. It is the first user-accessible software installed onto a computer, usually loaded by the manufacturer of the computer. Every desktop or laptop computer has an operating system; without an OS, a desktop or laptop is useless. An operating system organizes and controls a computer’s hardware and software to make the computer easy for a person to use.
Remember, computer refers to more than a desktop or laptop computer. These days, almost anything we turn on has some kind of computer. Not all products with computers have operating systems. Simple devices, such as microwaves, do not require operating systems; their computers run on low-level programs installed directly onto chips. However, more and more electronic devices, from MP3 players to cell phones to video game consoles, all contain computers running operating systems, many of which are specifically developed for a particular type of device. Hundreds of operating systems are available for special-purpose computers, including operating systems that control mainframes, robots, manufacturing equipment, and scientific instruments.
As an introduction to operating systems, let’s begin by discussing operating systems as they relate to desktop or laptop computers.

Operating Systems Tell Computers How to Work

When you turn a computer on, the first thing accessed is a firmware interface called the BIOS (basic input/output system). In simple terms, the BIOS configures your CPU, memory, hard drives, and peripheral ports (USB, FireWire, etc.) using settings that have either been preset by the manufacturer or configured by the computer’s operator. After the BIOS finishes, it accesses whatever has been defined as the computer’s system drive (usually C:), searches for the programs necessary to start up the operating system, and executes them. At this point, the computer functions are turned over to the OS.

Typical Desktop/Laptop OS Functions

Different operating systems offer different options and variations, but all have the following components in common:

  • Processor management: Single-core CPUs can perform only one task at a time. However, our computers often give the appearance of doing many tasks at the same time. It is the job of the OS to prioritize the tasks the CPU performs by beginning some tasks while ignoring others, sometimes switching tasks thousands of times a second. A multicore CPU can handle one task in each of its cores, and it’s the operating system’s job to prioritize tasks for each of those cores.
  • Memory storage management: The OS makes sure each task has enough memory to do what it needs to do. It also makes sure it does not run into the memory space of another task. The OS sets memory boundaries while ensuring different types of memory are used in the most efficient manner.
  • Device management: The OS manages the traffic of information between a computer and attached devices, such as a printer, an MP3 player, or a thumb drive. It regulates the transfer of data from the device to the computer and from the computer back to the device. This function is especially important when a number of processes are running and taking up processor time. If the CPU is being overtaxed, the OS may continue taking input from the device but hold the data in a “buffer.” Then, once the CPU is freed up, the OS releases the data to continue its journey through the CPU.
  • Application interface: Operating systems provide a stable, consistent way for applications to be loaded on and removed from the computer and for applications to work when the user is ready to access them. An application program interface (API) allows a software developer to write an application on one computer and have a high level of confidence that it will run on another computer with the same OS, even if variables such as amount of memory or quantity of storage are different on the two machines. For example, today’s operating systems work with thousands of different printers and other peripherals because the designers of these tools use the same set of specific guidelines (the API) defined by the OS.
  • Disk access and file systems: A computer’s OS allows a user to access files stored on the computer’s disks. The specific way files are stored on a disk is called the file system. The file system allows users to name and organize files in a hierarchy of directories or folders arranged in a directory tree.
  • Other functions: Most operating systems also determine the way computers communicate with each other via networks as well as the security controlling who can access these networks and when.

The OS and the User: Graphical User Interface (GUI)

The user interacts with the OS via a series of images and words, which represent different tasks. This is called the graphical user interface (GUI). Although not technically part of the OS, it allows users to easily organize and find their way around the computer. Most GUIs use a desktop metaphor, simulating on the monitor images, or icons, of items people find on their physical desks: folders, pieces of paper, and so on.
A GUI also may allow the user to customize, through a number of options or preferences, what his or her virtual desktop looks like and how it works. Here are some examples:

  • The size, color, and text size of objects
  • Background/screensaver images
  • How and where items are organized (on the desktop vs. in a directory or subfolder)
  • The applications that should be automatically launched at start-up
  • Speaker audio and monitor brightness level

In addition, the GUI provides easy access to system maintenance tools. These tools are used to do the following:

  • Back up data
  • Identify and remove system bugs
  • Monitor and diagnose problems related to use of the CPU, memory, disk, and other resources
  • Review file system operations and optimize disk space

Common Desktop/Laptop Computer Operating Systems

All non-server desktop/laptop computers have operating systems that are considered single-user, multitasking operating systems. This is the type of operating system that allows a single user to have several programs working at the same time. For example, your computer allows you to work on a school report while downloading a PDF from the Internet and printing the text of an email. The most common desktop OSs are as follows:

  • Microsoft Windows: Microsoft Windows is the name of several families of software operating systems by Microsoft. Microsoft Windows dominates the world’s personal computer market and is loaded on more than 90% of personal computers worldwide. Almost without exception, day-to-day work in the IT field requires the use of Windows, even if other operating systems are also used. Computers that run Windows are made by a variety of computer hardware manufacturers, including HP, IBM, Dell, and others. Windows 7 is currently the most dominant version of the Windows operating system in use today. Windows 8 was released in late 2012 but has been having trouble gaining wide acceptance because of the radical redesign of its user interface. A popular option for people who purchase Windows 8 is to disable many of Windows 8’s newer features and download free utilities to make the user interface look more like the Windows 7 desktop. Microsoft is due to release an updated version of Windows 8 (version 8.1) in fall 2013, to address some of these issues, including the ability to launch either in the icon mosaic mode or the more familiar Windows desktop mode.
  • Unix-based OSs: Unix-based operating systems (including System V, BSD, and Linux) are an alternative but important desktop/laptop OS option. Most of these are free and run on a wide variety of computers. Although Unix-based OSs run on fewer than 1% of personal computing desktops, many are found on workstations in creative, academic, and engineering environments and are used heavily for servers in business. However, the Android variant of the Linux OS has quickly come to dominate mobile devices such as tablets and smartphones, and it currently runs over 40% of tablets and over half of all smartphones.
  • Apple Macintosh: Apple Mac OS is the name of a family of software operating systems by Apple Computer. Mac OS is loaded on computers made by Apple Computer and does not work on any other computer hardware. The current version of the Mac OS is 10.8 (“ten point eight”), also known as Mountain Lion.


Every computer requires an operating system. An OS is a piece of software that does the following to tell a computer how to work:

  • Controls how the computer processes information
  • Organizes information
  • Ensures that users can work with a variety of applications
  • Provides a GUI so that people can interact effectively with the computer

It is important that you familiarize yourself with as many operating systems as possible. When you have the opportunity to use a different operating system, be sure to try it out. If you know one operating system well, learning a second or third one is much easier.

How Do I Manage My Files?

The Windows operating system, or Windows, allows you to create, store, rename, edit, sort, and delete files such as text documents, spreadsheets, pictures, and music. To keep all your data organized, you use Windows Explorer, a program built in to Windows. Note that Windows Explorer is not the same as Internet Explorer. Windows Explorer is the part of the operating system that manages files on your computer; Internet Explorer is a browser that you can use to access the Internet.
It’s easy to manage your files with Windows Explorer. First, you create folders, which are represented by icons that look just like real manila folders. Then, you move your files into the folders.

Opening Windows Explorer

Windows Explorer is not usually visible when you look at your computer’s desktop, because it runs in the background, “behind” the desktop. On a computer running the Windows XP operating system, you can open Windows Explorer by right-clicking the Microsoft Office icon or Start button, usually located in the lower-left corner of the screen, and then selecting Explore.

Exploring stored files in Windows XP

You can also launch Windows Explorer by clicking the My Computer icon on your desktop. A shortcut way to open Windows Explorer is to press the Windows key and the E key at the same time. Windows Explorer opens in a window named “My Computer.” It looks like a branching tree diagram, with folders on the left and files on the right. You might have to click the Folders button in the toolbar at the top to see all the files and folders.

Creating a New Folder

Windows provides some folders to get you started, such as My Pictures and My Music, but when you want to create your own folders, it’s important to use names that make sense to you. To stay organized, you can create subfolders under (within) other folders. To create a new folder, click the File menu in the Windows Explorer toolbar, and then click New, and then Folder.
Windows names the new folder “New Folder,” so you will want to rename it by right-clicking it and then clicking Rename. Sometimes, after you create a new folder, your cursor is already inside the label, next to the highlighted name “New Folder.” In this case, you only need to start typing the new name.

Renaming a folder

Type MyResumes (or whatever name you choose) over the words New Folder. Note: You don’t need to leave spaces between words in a file or folder name.
Your new MyResumes folder is now ready to store documents.

Moving a File into the New Folder

One way to move your files is to drag and drop them from the desktop into the folder. To do so, click a file you want to move and drag it with your mouse to the right side of Windows Explorer. Make sure that the folder you want to store the file in is highlighted (all you need to do is click the folder once to highlight it) before you start to drag the file.
Now your resume is moved to your MyResumes folder.

Selecting and Copying Files

Windows makes it easy to select files and then copy them. The following instructions show you how to copy the file you’ve already inserted into the folder. Windows does not allow you to store two files with identical names in the same folder, so you will have to rename the copied version of the file. First, right-click the file that you want to copy. In the drop-down menu that appears, click Copy.
Then, with your mouse pointer in the folder area where you want to save a copy, right-click with your mouse, and select Paste from the drop-down menu that appears.
Windows pastes your copied file into the folder and gives it a name starting with “Copy of.” Rename the file with a new name.

Deleting and Restoring Files

Delete files that you don’t want anymore by dragging them into the Recycle Bin, located on the desktop. Click the file and drag it into the Recycle Bin. Another way to delete a file is to right-click it and then select Delete from the drop-down menu that appears. This method also places the file in the Recycle Bin.
If you made a mistake deleting a file, you can restore it from the Recycle Bin. Open the Recycle Bin by double-clicking its icon on the desktop. Highlight the file that you want to restore; then, under Recycle Bin Tasks in the left pane, click “Restore this item.”
The file is restored to your original Windows folder.

Sorting Files in Folders

Sometimes you may have so many files in a folder that you’ll have to sort them to find the one you want. Often the most convenient way to sort Windows files is by the date they were last modified; that way, the latest file appears at the top of the list. You can also sort files by name, size, and type (such as document, picture, and so on) by clicking those words on the screen. To sort a file by date, click Date Modified in the file side of the Windows Explorer screen. If you want to re-sort, click Date Modified again, and the files will be sorted in the opposite order (with oldest files at the top).

Handling File Problems

If you encounter a problem while using Windows Explorer, the best place to get help is from the built-in help system. To access the help system, click the Help menu and then click Help and Support Center.
Type what you are looking for into the Search field in the help system. You can also search for a file in Windows Explorer, if you can’t remember where you saved it. If you’ve lost a file on your computer, use the Search tool by clicking Search on the toolbar at the top of the Windows Explorer window. If you don’t have a Search icon on your toolbar, you can click the Start button in the bottom left corner and then click Search.
You can enter the file’s name, part of the name, or even a date range of when you may have saved the file. Windows will scan your folders and files and show you where you might find the lost file.

How Do I Manage My Files?

Windows operating systems allow you to create, store, rename, edit, sort, and delete files such as text documents, spreadsheets, pictures, and music. It’s easy to manage your files with Windows Explorer in Windows 7. First, you need to create a folder, which is represented by an icon that looks just like a real manila folder. Then you can move your files into the folder.

Viewing Files on the Hard Drive

To view files already stored on a computer running Windows 7, click the Windows Explorer icon in the taskbar. It looks like a manila folder.
You can also click the Start icon and then select Computer, or you can click the Start icon and select Documents or Pictures, depending on the type of files you are looking for. Alternatively, you can click the Start icon, All Programs, Accessories, and Windows Explorer. A shortcut way to open Windows Explorer is to press the Windows Logo key and the E key at the same time.
If you click the Windows icon and select Computer, a window opens that shows your hard drives and the amount of free space remaining on each one, as well as any floppy and optical drives (DVD, CD, Blu-ray), and any USB thumb drives that are plugged in. Each device is represented by a unique identifier known as the drive letter. In a typical computer with one floppy drive, one hard drive, and one optical drive, the normal lettering would be A: or B: for the floppy, C: for the hard drive, and D: for the optical drive.
Double-click any of the drives to see the files and folders stored there.

Creating a New Folder

If you want to save a document or a picture to your hard drive, you first need to decide where you want to store that file. It’s important to save your files in a place that makes sense to you, so that you can find them again when you need them. After you decide where you want to save your file, create a new folder with a name that you will remember.
To create a new folder, click New Folder in the taskbar at the top of the window. This feature is new to Windows 7.
A new icon will appear in the list of folders and files in that partition, with a field where you can type in a new name for that folder. In this example, the new folder is named “MyResumes.”
Your new folder is now ready to hold files.

Moving a File into a Folder

One way to move your files is to drag and drop them from the desktop into the folder. To do so, click the file you want to move and drag it to the destination folder and drop the file there. You can also drag files from one folder to another.\ Windows 7 also lets you create what looks like a dual-pane Windows Explorer so that you can easily drag files from one folder to another. Try these four simple keystrokes:

  • Windows Logo + E to open Windows Explorer
  • Windows Logo + Left Arrow to snap Windows Explorer to the left side of your screen
  • Windows Logo + E to open another Windows Explorer
  • Windows Logo + Right Arrow to snap this Windows Explorer to the right side of your screen

Once you have the two windows open, you can easily copy files from one folder or drive to another.

Working with Files

When you right-click a file in Windows Explorer, a drop-down menu appears. From this menu, you can open, cut, copy, delete, or rename the file. You can also send the file to another person by fax or email, or you can compress it into a ZIP folder, which makes the file smaller and easier to send via email. And you can check the properties of a file by selecting Properties. This will show you the size of the file and when it was created, in addition to other details.
From this menu, you can also create a shortcut to the file. A shortcut is a link to a file; double-clicking the shortcut opens the file. Shortcuts help you keep access to files you use often in one place, such as your desktop or a library.

Using Libraries

Windows 7 introduced libraries, which are like folders, but they don’t actually store your files. A library holds files in one location for easy access even if they are stored in different places. For example, if you have music files in folders on your hard disk and on an external drive, you can use the Music library to access all your music files from one place.
Windows 7 gives you four default libraries: Documents, Music, Pictures, and Videos. You can add more libraries to help keep your files organized.

The Windows 7 Explorer Toolbar

The Windows 7 Explorer toolbar offers you many options. You can click the buttons in this toolbar to organize the contents of a folder and change the layout of the window. You can also include the folder in one of your libraries, or share it with certain people. If you click the E-mail button, Windows will generate an email with that folder as an attachment, ready to send. If you click the Burn button, Windows will ask you to put a writeable CD in your CD drive so that you can burn that file or folder to a CD.

Organizing Folders

You may have noticed that the navigation pane of Windows 7 doesn’t have a tree structure like that in previous versions of Windows. If you want easy access to certain folders from the navigation pane, you can drag the folder from the right pane to the navigation pane on the left, and you will then have a shortcut to that folder that stays in the navigation pane. The screenshot below shows a navigation pane where the student dragged a folder for each of his AOIT classes into the navigation pane for quick access.
You can also click Organize in the toolbar and select Folder Options and Search Options to organize your folders. Under “Navigation pane,” select both “Show all folders” and “Automatically expand to the current folder” to display a tree structure in the navigation pane.

Sorting Files in Folders

Sometimes you may have so many subfolders or files in a folder that you’ll have to sort them to find the one you want. Often the most convenient way to sort Windows files is by the date they were last modified; that way, the latest file appears at the top of the list. You can also sort files by name, size, and type (such as document, picture, and so on) by clicking those words on the screen. To sort a file by date, click Date Modified in the file pane of the Windows Explorer screen. If you want to re-sort, click Date Modified again, and the files will be sorted in the opposite order (with the oldest at the top).
Another way to find the file you are looking for is to use the Search box at the upper right of the Windows Explorer window. Select the folder you want to search and then type the word or phrase you are looking for. The window will display all the files that contain that word or phrase.

Changing the Way Files and Folders Appear

You can change the way files and folders appear in the window by clicking the “Change your view” button in the toolbar.
You can choose to see more or less information about each file, and you can change the size of the icons that appear for each type of file. To do so, click the “Change your view” button. From here you can change the view to match the setting, which can be Extra Large, Large, Medium, or Small Icons, as well as List, Details, Tiles, or Content. Click the arrow to the right of the “Change your view” button to see what the setting is or to choose another one. You can also move the slider up or down to fine-tune the size of the file and folder icons. You can watch the icons get bigger and smaller as you move the slider.
The Preview Pane button is on the right side of the toolbar. This button allows you to quickly and easily preview the contents of a file. You can also toggle the preview pane from the Organize > Layout menu.

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