Computer systems include hardware, software, and firmware. Hardware is something you cantouch and feel—the physical computer and the parts inside the computer are examples of hardware.The monitor, keyboard, and mouse are hardware components. Software interacts withthe hardware. Windows, Linux, OS X, Microsoft Office, Solitaire, Google Chrome, Adobe AcrobatReader, and WordPerfect are examples of software.Without software that allows the hardware to accomplish something, a computer is nothingmore than a doorstop. Every computer needs an important piece of software called an operatingsystem, which coordinates the interaction between hardware and software applications. Theoperating system also handles the interaction between a user and the computer. Examples ofoperating systems include DOS, Windows XP, Windows Vista, Windows 7, OS X, and various typesof Unix, such as Red Hat and Mandrake.A device driver is a special piece of software designed to enable a hardware component. Thedevice driver enables the operating system to recognize, control, and use the hardware component.Device drivers are hardware and operating system specific. For example, a printer requiresa specific device driver when connected to a computer loaded with Windows 98. The same printerrequires a different device driver when using Windows XP. Each piece of installed hardwarerequires a device driver for the operating system being used. Figure 1.1 shows how hardware andsoftware must work together.Software applications are normally loaded onto the hard drive. When a user selects an application,the operating system controls the loading of the application. The operating system alsocontrols any hardware devices (such as the mouse, keyboard, monitor through the video adapter,and printer) that must be accessed by the application.
Firmware combines hardware and software into important chips inside the computer. It is
called firmware because it is a chip, which is hardware, and it has software built into the chip. An
example of firmware is the BIOS (basic input/output system) chip. BIOS chips always have
software inside them. The BIOS has startup software that must be present for a computer to operate.
This startup software locates and loads the operating system. The BIOS also contains
software instructions for communication with input/output devices, as well as important hardware
parameters that determine to some extent what hardware can be installed. For example, the
system BIOS has the ability to allow other BIOS chips that are located on adapters (such as the
video card) to load software that is loaded in the card’s BIOS.
The simplest place to start to learn about computer repair is with the hardware components
and their common names. A computer, sometimes called a microcomputer or a PC, is a unit that
performs tasks using software applications. Computers come in three basic models: (1) a desktop
model that normally sits on top of a desk; (2) a tower model that sits under a desk; and (3) a
laptop model, which is portable. Laptops are sometimes called notebooks; smaller versions are
called netbooks or nettops. A fourth type of computer is a handheld computer or palmtop computer.
These replaced the PDA (personal digital assistant). The palmtype computer is normally
incorporated into a cell phone. Figure 1.2 shows Apple’s iPhone, which has the ability to send and
receive phone calls and emails, view and listen to movies and songs, and take pictures.
A computer consists of a case (chassis), a keyboard that allows users to provide input into
the computer, a monitor that displays information, and a mouse that allows data input or is used
to select menus and options. Figure 1.3 shows a tower computer case, monitor, keyboard, and
mouse.
Once the case is removed from the computer, the parts inside can be identified. The easiest
part to identify is the power supply, which is the metal box normally located in a back corner of
the case. A power cord goes from the power supply to a wall outlet or surge strip. One purpose
of the power supply is to convert the AC voltage that comes out of the outlet to DC voltage the
computer can use. The power supply also supplies DC voltage to the internal parts of the computer.
A fan located inside the power supply keeps the computer cool, which avoids damage to
the components.
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