Whether the computer in question is housed in a desktop case, a tower case, a portable clamshell, or some other less common package, every Wintel computer (Wintel systems are designed around the Windows operating system and Intel processors) contains the same basic set of components. These components might take different physical forms, but they're always there. An important first step in understanding how a computer works is to know where to find and identify the parts that combine to make up the whole.
This chapter describes each of the essential components, including the power supply, the central processing unit (CPU), Random Access Memory (RAM), and the motherboard. It also briefly explains what each piece does and how it works with the other parts of the system. You can find more detailed explanations of most of these components later in this book.
The essential components that exist in every computer include:
Power supply: The power supply converts AC power from a wall outlet to well-regulated DC power for all the other components in the system.
Central processor (CPU): As the name suggests, the CPU, also known as the chip, is the computer's core data processing device. It accepts instructions (also called commands) from other components and responds to those commands by performing specific actions and sending the results of those actions to other components.
Chipset: The chipset includes one or more additional circuits that support the CPU by acting as an interface with the other components in the computer.
Random Access Memory (RAM): Memory modules store data and exchange commands and data with the CPU at high speed.
Basic input/output system (BIOS): The BIOS memory circuit contains the instructions that the computer uses to test itself and load the operating system software.
Motherboard: The motherboard holds the CPU, the chipset, the memory modules, the BIOS, and other electronic components.
Expansion cards: Expansion cards plug into the motherboard and add specialized features and functions (such as control of sound or a video display) that the motherboard does not provide.
Data storage devices: Storage devices are hard drives and drives for removable media, including compact disks and DVDs; older storage methods include floppy disks and tape cartridges.
Power cables: Power cables move electricity from the power supply to other components.
Data cables: Data cables transfer data between the motherboard and other devices.
Control cables: Control cables carry signals between the inputs and outputs on the motherboard and the switches and connectors on the case.
Fans and heat sinks: Fans and heat sinks are mechanical devices that move heat away from the CPU and other heat-sensitive components.
You might also find some additional components inside your computer, such as an antenna for a wireless data interface (in a laptop case) or acoustical insulation that reduces the amount of noise produced by the computer.
In this chapter, discussions of desktop cases refer to cases with the widest surface resting on a table, a shelf or the floor (as compared to tower cases that have a narrow surface on the bottom). In general usage, desktops and towers are both considered desktop computers, to differentiate them from portable systems or laptops. This is somewhat confusing, but in the world of computers, the word "desktop" has both meanings.