Intro to Computer Systems

Chapter 2: System Basics

A Computer System

A complete computer system is made up of a number of individual components, both internally (chips and circuit boards performing specific core functions) and externally (peripherals that allow data to be stored, printed, presented, and so on).

A computer system is made up of a processing unit, input devices (such as keyboards and mice), and output devices such as monitors and printers.
A computer system is made up of a processing unit, input devices (such as keyboards and mice), and output devices such as monitors and printers.

These components can be categorised as follows:

Core Components

The core components of a computer system are housed on circuit boards inside the computer case.
The core components of a computer system are housed on circuit boards inside the computer case.

The core components of the computer form its "backbone", so to speak. It provides the basic infrastructure that allows the computer to function, and for other peripherals to be connected to it.

These core components are usually grouped together on a circuit board known as the motherboard.

Internal Expansion

Internal expansion devices (such as disk drives and expansion cards) reside inside the computer case.
Internal expansion devices (such as disk drives and expansion cards) reside inside the computer case.

Attached directly to the motherboard are various internal (within the computer case) expansion devices. Components that are kept inside the computer are usually those critical to its function. This includes devices such as:

External Expansion

External expansion devices (such as external disks, monitors and printers) are in their own casings and connected via cable to the computer system.
External expansion devices (such as external disks, monitors and printers) are in their own casings and connected via cable to the computer system.

Ancillary devices that provide additional, non-core functionality are typically connected externally (i.e. in their own separate box, connected via cable to the computer system.)

This includes peripherals such as keyboards, mice, printers, modems, and so on. There are a number of different connection methods for these devices, which will be covered in the next chapter.