PC Hardware

The hardware of a personal computer is the set of physical components that together run software and store data. At its centre is the motherboard, the main circuit board that holds the processor, memory and the connectors for everything else. The processor, or CPU, carries out the instructions that make up a program, while the chipset and buses on the motherboard move data between the processor, memory and peripherals.

Memory in a PC comes in several forms. Random-access memory, or RAM, holds the programs and data the computer is actively using, and its contents are lost when power is removed. Read-only and programmable memory chips, such as ROM and EPROM, store firmware that does not change often, including the startup code. Caches are small, fast memories that keep frequently used data close to the processor to speed up access. Long-term storage, such as a hard drive or optical drive, keeps data when the machine is switched off.

Expansion buses such as PCI and the graphics-oriented AGP let additional cards extend a computer’s capabilities, for example with video or sound hardware. Input devices such as the mouse and keyboard, output devices such as the monitor, and the power supply that feeds all the components complete the system. Understanding how these parts fit together, and how the BIOS firmware starts them up, is the foundation for building, upgrading and troubleshooting a PC.

Frequently asked questions

What is the difference between RAM and storage?

RAM holds data the computer is currently using and is cleared when power is removed, while storage such as a hard drive keeps data permanently even when the machine is off.

What is a cache?

A cache is a small, fast memory that stores frequently used data close to the processor so it can be accessed more quickly than from main memory.

What are expansion buses such as PCI and AGP for?

They are slots and pathways on the motherboard that let add-in cards, such as graphics or sound cards, connect to and communicate with the rest of the system.