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A+ Study Guide: Domain 3.0: Operating Systems - Operating System Basics

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What is an Operating System?
Introduction to Unix
Introduction to Linux
Introduction to OS X
Introduction to Windows

This section will provide a brief introduction to UNIX, Linux, Mac OS, and Windows operating systems. The A+ exams will focus mainly on Windows as will this guide.

What is an Operating System:
An operating system is a program that is loaded into the computer on boot up that is responsible for running other applications and provides an interface with which to interact with other programs. This interface can be mainly command-line based like Linux or Unix, or can primarily revolve around a Graphical User Interface (GUI) such as Windows and Macintosh operating systems.

Operating Systems can be divided into 2 groups: Single-process and multiprocess. Single process operating systems are capable of working on 1 task at a time while a multiprocess OS can work on several processes at once by breaking tasks into threads. There are several terms related to multiprocessing systems that you will need to know as follows:
  • Multitasking - This is the ability to work on several different tasks at a time. This is accomplished by switching back and forth between the tasks. There are a few different types of multitasking:
    • Task Switching - Allows for multiple applications to be run at the same time. The window that is in the foreground is the active window while the other applications run in the background. Used in Windows 3.0.
    • Cooperative Multitasking - Applications can control the system resource until they are finished. When the hourglass is displayed on the screen, you would be unable to perform any tasks until the system had finished the task that it was working on. If a task caused faults or other problems, it would cause the system to become unstable and force a reboot. Used in Windows 3.x.
    • Preemptive Multitasking - Applications are allowed to run for a specified period of time depending on how important the application is to the operation of the system(priority basis). This means that even though you may see an hourglass on the screen, you can still launch or use other application at the same time. If a particular task is causing problems or faults, that application can be stopped without the system becoming unstable. Used in Windows 9.x.
  • Multiuser - This is similar to multitasking and is the ability for multiple users to access resources at the same time. The OS switches back and forth between users.
  • Multiprocessor - Having multiple processors installed in a system such that tasks are divided between them.
Introduction to UNIX:
Originally developed in 1969 by AT&T employees, UNIX was the operating system of choice for decades and is the oldest of the bunch. Traditionally, it was command line based although newer versions do have a graphical user interface (GUI) like Windows. Solaris by Sun Microsystems is the most popular version of UNIX in use, although HP-UX and AIX still have some market share. UNIX is used as an operating system on servers and for specialty applications. It is not typically used for personal computing.

Introduction to Linux:
Linux is a UNIX-like operating system, that was invented by Linus Torvalds in 1991. Although it is a lot like UNIX, it is open source which means that the operating system and source code are freely available including most supporting applications which are freely licensed under the GNU public license. Because the source code is freely available, various organizations have modified the code and created their own variations known as "distributions". Some of the more common ones are Red Hat, SuSE, Debian, and Fedora Core. Linux has become a very popular platform for servers, particularly web servers. It also has a wide variety of GUIs that can be used for personal computing.

Introduction to OS X:
Macintosh computers produced by Apple are proprietary systems that run Mac OS operating systems. Mac OS X is the successor to the original Mac OS, which had been Apple's primary operating system since 1984. Unlike its predecessor, Mac OS X is a Unix-like OS based on BSD. Beginning in 2006, Macs began running on Intel CPUs for the first time instead of their own proprietary hardware.

Introduction to Windows:
Microsoft leads the operating system market with their Windows series of operating systems. At the time of this writing, Windows XP, Windows 2000, and Windows 2003 Server are currently the most widely used versions, although Windows Vista was recently released. The A+ exam probably will not test you on Windows vista. It is also doubtful that you will be tested on Windows 9x or NT with the exception of performing upgrades.

There are several major components that are essentially the same in most versions of Windows (2000/2003/XP) that you should know how to get to and use.

Windows Explorer is the utility used for file management functions in Windows operating systems. It can be used to move, copy, rename, delete files and browse through the directory. Explorer displays the file structure in a hierarchical tree. The figure below shows the explorer interface.

There are several ways in which explorer can be launched including right clicking "My Computer" and selecting explore or clicking the "Start" button and selecting run and type in "explorer". For the exam, you will need to know how to navigate and use Windows Explorer.

The "My Computer" icon is located on the desktop and allows you to browse through the file structure and set many of the file and folder properties. When My Computer is opened, you will see a window similar to the one shown below.

One of the most important parts of My Computer is the folder options that can be accessed from the view menu. Folder options has 3 tabs where various setting can be configured as follows.

The general tab allows you to configure how folders and files appear. The View tab allows you to set a variety of file and folder options. One of the most common of these is to check the "Show All Files" radio button in order to allow hidden files to be shown. You should be familiar with these settings for the exam.

The offline files tab allows you to configure the computer to synchronize files on a network. This is mostly used with laptop computers. The File Types tab allows you to control which applications open specific file types. This is otherwise known as associations which can also be controlled by using the WINFILE.EXE program in Windows 9x.

Shortcuts can be created when browsing the file system from the file menu and selecting "new" then "shortcut". They can also be created in Windows Explorer or by right clicking a file and selecting "Create Shortcut" from the drop down menu. New folders can be created in the same manners.

The Windows Control Panel is where most hardware, software and networking settings are configured. The Windows XP control panel is shown below. This is the default "Category View" that is new in Windows XP. Notice in the upper left side there is a link to switch to classic view which is the more familiar version found in previous Windows operating systems. You will need to be familiar with using the control panel for the exam and know the various ways to access them. For example, the Network control panel can also be accessed by clicking on the Network Neighborhood (called "My Network Places" in Windows XP) and selecting "Properties" and the Display control panel can also be access by clicking on the Desktop and selecting "Properties".

The System Properties control panel is one of the key control panels that is used to configure the systems hardware settings. Windows 95/98/2000/XP System Properties contain a portion called "Device Manager" that can be used to update device drivers, modify IRQ and I/O settings and troubleshoot hardware conflicts. A red "X" next to a device denotes that the device is either disabled or is experiencing a conflict. Windows NT did not include a Device Manager which is shown below. Windows NT/2000 system properties are where user and hardware profiles are configured.

device manager

Note that you can also get to the System Properties by right clicking on the "My Computer" icon and selecting properties. In Windows 2000 and XP, the Device Manager looks slightly different and can be accessed via the Computer Management Console. Device Manager can be navigated using the arrow keys if the mouse is not working. In the image above, you will also see the Performance tab. This is where file system, virtual memory and graphics settings can be configured.

The desktop is the first "screen" that you see after Windows loads. All of the icons on the desktop are shortcuts to other files and applications. You should be familiar with the Desktop and know that it is actually located in C:\Windows\Desktop for Windows 9x and C:\Documents and Settings\username\Desktop in Windows 2000 and XP. Below the desktop is the taskbar that contains toolbars, the start menu and displays active windows.

If you right click on the Desktop and select Properties, you will bring up the Display Properties for your system as shown below. From here you can customize Windows' colors and appearance, screensavers, screen resolution, default font sizes, and more.

device manager

The start menu is the starting point for most tasks that are performed on a Windows computer. The Windows XP default start menu is different than previous versions of Windows and is pictured below. Like many things in XP, the start menu can be switched to classic mode and will appear like previous start menus. In addition to changing the menu, this setting will also put the My Computer, My Network Places, and My Documents icons on your desktop.

Start Menu

You will need to know how to navigate the start menu and which items can be accessed from here. Also make sure that you know how to use the "Run" feature in the start menu and how to bring up a command or DOS prompt from here. In Windows 9x, you would type COMMAND and enter. For Windows NT/2000/XP the command would be CMD.

There are a number of keyboard shortcuts to know:
  • CTRL + ESC - Brings up the startmenu which can then be navigated with the arrow keys. Many keyboards have a Windows key that performs the same function.
  • ALT + ESC - Cycles through currently open windows.
  • ALT + TAB - Displays a menu of open applications that can be cycled through by continuing to hit the tab key.
  • SHIFT - Will bypass the autorun feature on a CD.
These are just some of the Windows basics, but there is too much to cover all of it here. You need to make sure that you know your way around Windows and where to find various features, customizations and tools.