The components of a computer are divided into two areas: hardware and software. The hardware typically includes the housing, the motherboard, the processor, the hard disk, the graphics card, the monitor, the keyboard, the mouse, etc. These are divided into central processing units and peripherals.

The central unit

The minimum equipment of a computer is usually referred to as the central unit in order to be able to be regarded as a computer.

Input unit: The connections to all input devices are created via the input unit.

Output unit: The output unit forms the interface to all output devices.

Processor: The processor processes the commands and sends the result to the output unit.

Storage unit: The data that the processor processes are made available in the memory and the processor interacts with the memory through read and write access.

Bus system: So that all components are connected to each other, there is a bus system that is required for data transfer between each other. Because the most varied types of data are exchanged during data transfer, the bus system is divided into three parts, which are used depending on the data type. The data bus is for the transmission of information, the address bus for address data and the control bus for control data.

Consideration of the central unit in context

The mentioned minimum equipment of a computer has to be seen in the respective context and the opinions about what makes a computer vary greatly. For a user, for example, a monitor, keyboard and mouse are essential and are also part of a functioning PC. In the case of a chip developer, on the other hand, only the processor is viewed as the central unit and everything else as an input and output device.


Peripherals are all devices that are connected to the central unit. These are divided into input and output devices.

Typical input devices include:

  • keyboard
  • mouse
  • microphone
  • camera
  • scanner

Typical output devices are:

  • monitor
  • printer
  • projector

There are also devices that can be classified in both categories. For example, hard drives can be used to transfer data to the main memory and vice versa. Another device is the network card, which is used both for receiving and sending data and can therefore be classified in both categories.