Introduction to Operating Systems

Operating systems are the software that lets users, applications, and hardware interact. Without an operating system, a computer is just an expensive box of flashing lights that doesn't do much of anything useful.

*The operating system is your user interface; it handles your communication with any installed hardware and applications and accesses any connected data storage media.

*Before Windows, there was text-based MS-DOS, and macOS and Ubuntu Linux all had their predecessor, text-based operating systems, too. As you'll see, there's still a good amount of administration that technicians perform in a DOS-like, command-line interface (CLI), so don't be afraid of it.

However, the most important software for this exam is the operating systems (OS), both for workstations (meaning desktop and laptop computers) and mobile devices.

Common OS Functions

Each major OS handles tasks and operations differently, but they all offer the same fundamental set of functions.

Regardless of what tools and capabilities are offered, any OS you work with will do the following essential functions:

Provide a method for installed software to communicate with the machine’s hardware, including the underlying central processing unit (CPU) and its associated architecture.
Provide a user interface (UI), a visual artifice that allows the user to make sense of and interact with the data, applications, and hardware of the machine.
Allow users to enumerate the installed applications on the machine and execute, operate, and shut down those applications.
Allow users to add, move, and delete installed applications and data (whether it’s part of the applications or created by those applications).
Allow users to secure the data and the overall system from various threats.

User Interfaces

Windows

In the workplace, the most common OS is Microsoft Windows, so the major focus of the A+ study materials and exam is the Windows OS and associated products. Although many current users are more familiar with Windows 10, the current version, many large enterprises and corporations lag behind for security and support reasons, so technicians may be expected to be familiar with previous versions. Although the Start button and Start menu vary in appearance among Windows versions, the functionality of many aspects is the same across versions. Right-clicking on an icon or object provides a context menu, the taskbarshows applications that are currently running, and icons in the notification area, also known as the system tray, show programs running in the background.

macOS

Although not nearly as common in the workplace, technicians can expect to see computers running macOS, also often known as OS X, in their careers, particularly in businesses with a focus on creative work or media. In macOS, the primary feature on the desktop is called the Dock, which holds the most commonly used applications and runs across the bottom of the screen by default. Like the taskbar in Windows, it can be moved to any side of the desktop. Switching between open applications and windows can be done with Mission Control, which is accessed through the Mission Control key on the keyboard or by using CTRL + Up Arrow. macOS also supports multiple desktops, which are referred to as Spaces in macOS lingo.

Linux

It’s important to understand that unlike Windows or macOS, there isn’t one company that’s the canonical source of the Linux operating system. The source code of Linux is open source, which means that anyone can use it to create their own version of the OS for distribution, as long as it’s properly attributed in accordance with the license. As a result, there are many distributions of Linux in the wild from companies ranging from Red Hat to Sun and any number in between. Similarly, there are several UIs from which a Linux user might choose. One of the most popular ones currently is GNOME, which is used by default with current versions of Ubuntu.

Most distributions offer similar capabilities to Windows and macOS in terms of email clients, Web browsing, and file creation and usage, but many also offer the ability to create a bootable version that can be run from a USB stick or a DVD. This version, often known as a Live CD, allows users to boot to a fully capable version that can be run without destroying or changing the data on the hard drive, meaning you can take that version of Linux for a test run without changing anything.

File Structures and Paths

Virtually all OSs are fundamentally structured like a tree. The base of the tree is the core directory, often referred to as the root. This directory contains the folders and subfolders that hold the individual files, although individual files can be held in the root directory as well. The root directory is where the OS itself is installed.

In Windows, users generally use the File Explorer tool to parse the folder structures of the system. Depending on the View options set in the Explorer window, it will show the name of the file and may show the extensions (designating the type of file), association (which program the OS launches to open the file), the date it was created or last modified, and the file size. These and other options can be changed in the Folder Options menu.

Although the files and folders can vary widely from one Windows installation to the next, certain standard folder locations should be present in virtually all installations. In Windows, File Explorer will render these by default as [Drive Name (C:)] > [Folder Name] > [Subfolder], but the 1102 exam and your textbook provide these paths in standard folder formatting, as shown in the following list:

C:\Program Files: This is where most programs install their core files and folders. Often, the main folder for a program is named after the company, with folders denoting specific products within.

C:\Program Files (x86): The x86 designation is for 32-bit programs. Most machines currently use 64-bit architecture; on those machines, 64-bit software installations use C:\Program Files for their core directory, while 32-bit programs use this directory.

C:\Users\[User Name]: This is where files specific to one user are created and stored. Several subfolders will appear in this path, and the types of files stored there are reflected in their names:

C:\Users\[User Name]\Desktop: The files and shortcuts that appear on the user’s desktop are stored here.

C:\Users\[User Name]\Documents: Files created by the user in programs such as Microsoft Office are saved by default here.

C:\Users\[User Name]\Downloads: This is the default location for downloaded files.
C:\Users\[User Name]\Music: This is the default location for music files that are downloaded by various media applications.
C:\Users\[User Name]\Pictures: This is the default location for imported images.
C:\Users\[User Name]\Videos: This is the default location for downloaded and user-created video files.

For macOS and Linux, the file and folder organization is essentially the same; this isn’t surprising, as both OSs are fundamentally based on variants of UNIX, an older OS that’s still widely used. In macOS, the primary navigation tool is Finder, which opens by default to the Users folder for the logged-in user. This folder is accessible only to users with those specific credentials (or administrative-level credentials). Similar to Windows, there are default folders for documents, downloads, and so on. Linux uses the Home folder for the default and generally calls the navigation tool File Manager or something similar, depending on the distribution, but the differences end there.

Launch Points

There are certain commonly used launching points in each OS for utilities that technicians use frequently, so this section focuses on those utilities. Most of these utilities, particularly in Windows, can be reached through multiple pathways; this section focuses on the "standard" paths for access.

Windows

The major utility across Windows versions is the Control Panel, which houses most of the maintenance, upgrade, and configuration utilities for Windows. In Windows 10, press Start, type control panel in the Search field, and select the correct option from the results.

The 1102 exam assumes the Classic view, with large icons, for questions and simulations, so make sure you’re familiar with how to change that view. The programs in the Control Panel are known as applets. As a technician, you’ll become very familiar with these, particularly Device Manager, one of the main troubleshooting tools within Windows, and System Tools/System, which allows access to several common tools such as System Restore and Disk Defragmenter, depending on the OS version. System Tools/System is also available on the Start menu; you should be aware of how to find it and what it contains for the 1102 exam.

Another common utility across Windows versions is the command-line interface (CLI), which is a DOS-like shell that uses text-based commands to perform tasks and launch utilities. It may seem like something of a throwback to use the CLI. Still, there will be times when it’s simpler to use the CLI than try to perform the same task in the graphical user interface (GUI), and it can be quicker.

Additionally, if there are issues with the GUI, the CLI can sidestep those. To access the CLI, click Start, type cmd in the Search field, and hit Enter, or access the CLI from the Start menu, generally under Windows System, as Command Prompt. Later lessons delve into the various commands and utilities available in the CLI.

For Windows 10, accessing the Control Panel and the CLI is similar to the previous versions, but technicians will also need to be able to use the Settings applet. The Search field can be used, but a simpler approach is to select the Windows logo in the lower-left corner (hereafter referred to as Start) and choose the gear icon in the lower left. The resulting screen provides access to a wide variety of configuration and troubleshooting options.

macOS

The launch points in macOS are somewhat simpler in that there are two primary options instead of three. The first is System Preferences, which is accessed by pressing the Apple icon in the upper-left corner of the screen and selecting System Preferences. This is where you’ll find virtually all of the maintenance and administrative functions on a Macintosh machine. The second option is the Utilities folder, which is nested inside the Applications folder in Finder. Here, you’ll find system applications such as Activity Monitor (roughly equivalent to Task Manager in Windows) and Terminal, the macOS equivalent to the CLI. To access Utilities, open Finder, press Go, and select Utilities; alternatively, using Cmd-Shift-Uwill yield the same result.

Linux

As in macOS, Terminal is the utility that provides the CLI. Most distributions (referred to commonly as distros) use the Ctrl-Alt-T key combination to launch it, but not all do, so be sure that you can find it in the folder navigation tool as well. Other launch points can vary widely among distros, but some of the most common include All Settings and Kickoff.

64-bit versus 32-bit Processing

When referring to 32- or 64-bit, what’s being discussed is the width of the address bus, which essentially determines how much data can be utilized, or addressed, at any given time. There are definite ramifications to what type of system is being used. A desktop machine that uses 32-bit architecture can, for example, address only 232 bytes of memory, which sounds like an immense amount but translates to only about 4 GB of RAM. Any RAM above that amount is invisible to the computer. On the other hand, a 64-bit computer can address 264 bytes of memory, which is 16 exabytes (EB) of RAM.

That’s nice for hardware, but what does this mean for software? The major upshot is that performance is radically improved for applications that use large files, such as video editing. It also means that you have to pay attention to the OS and software being installed on a machine; 64-bit systems can run 32-bit software, but not vice versa. If you’re unfamiliar with whether a program is 32- or 64-bit, you can look at the directory for the software or—on Windows machines—the version of the Program Files directory where it’s installed. If it’s labeled x86 or is in the C:\Program Files (x86) directory, it’s a 32-bit program; if it’s labeled with x64, x86-64, or is in the C:\Program Files directory, it’s 64-bit.