CompTIA A_ Certification All-In-One Exam Guide, Seventh Edition - Michael Meyers [28]
Understanding the computer at this broad conceptual level—in terms of hardware, OS, and programs—can help you explain things to customers, but good techs have a much more fundamental appreciation and understanding of the complex interplay of all of the software and the individual pieces of hardware. In short, techs need to know the processes going on behind the scenes.
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NOTE The CompTIA A+ certification exams only cover the Windows operating system, so you won’t see much discussion of OS X or Linux in this book. Nevertheless, a good tech should possess a basic understanding of these two excellent operating systems.
Figure 3-2 Typical OS X, Linux, and Windows interfaces
From the CompTIA A+ tech’s perspective, the computer functions through four stages: input, processing, output, and storage. Knowing which parts participate in a particular stage of the computing process enables you to troubleshoot on a fundamental and decisive level.
Input
To illustrate this four-step process, let’s walk through the steps involved in a fairly common computer task: preparing your taxes. [Insert collective groan here.] February has rolled around and, at least in the United States, millions of people install their favorite tax software, TurboTax from Intuit, onto their computers to help them prepare their taxes. After starting TurboTax, your first job is to provide the computer with data: essential information, such as your name, where you live, how much you earned, and how many dollars you gave to federal and state governments.
Various pieces of hardware enable you to input data, the most common of which are the keyboard and mouse. Most computers won’t react when you say, “Hey you!”—at least not anywhere outside of a Star Trek episode. Although that day will come, for now you must use something decidedly more mechanical: a keyboard to type in your data. The OS provides a fundamental service in this process as well. You can bang on a keyboard all day and accomplish nothing unless the OS translates your keystrokes into code that the rest of your computer’s hardware understands.
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NOTE Some might argue that voice recognition, the ability for a computer to understand your voice, has been around for a long time. In my opinion, it doesn’t work well enough to replace my keyboard—yet.
Processing
Next, the computer processes your data. After you place information in various appropriate “boxes” in TurboTax, the computer does the math for you. Processing takes place inside the system unit—the box under your desk (see Figure 3-3)—and happens almost completely at a hardware level, although that hardware functions according to rules laid out in the OS. Thus again, you have a complex interaction between hardware and software.
The processing portion is the magical part—you can’t see it happen. The first half of this book demystifies this stage, because good techs understand all of the pieces of the process. I won’t go through the specific hardware involved in the processing stage here, because the pieces change according to the type of process.
Output
Simply adding up your total tax for the year is useless unless the computer shows you the result. That’s where the third step—output—comes into play (Figure 3-4). Once the computer finishes processing data, it must put the information somewhere for you to inspect it. Often it places data on the monitor so you can see what you’ve just typed. It might send the data over to the printer if you tell it, so you can print out copies of your tax return to mail