The main system unit contains a number of devices namely:

1. The motherboard

2. The Central Processing Unit (CPU)

3. The memory (RAM)

4. Hard disk drive

5. DVD drive

6. CD Rom drive

7. Floppy disk drive

8. The Power Supply unit (PSU)

9. Adapters

10. Sound Card

11. Graphic cards

12. Network card

13. Modems

14. Heat sink

15. Fan

16. Cables

17. Case


The motherboard

The motherboard of a microcomputer has a printed circuit, and this motherboard is fitted into the microcomputer system case with other components mounted and plugged into it. These components include the central processing unit (CPU), the random access memory (Ram) and the Basic Input Output system (BIOS) memory.


The Central Processing Unit (CPU)

This is the main processing chip of the computer system and it is a silicon microchip. The CPU is sometimes referred to as the brain of the computer system or the ‘heart’ of the computer, and its job is to interpret and execute instructions sent to it. The general speed of the computer is also determined by the speed and design of this chip. An example of modern chips is the Pentium class chips.


The Memory (RAM)

This is a place in the computer that data needed by the computer is stored temporarily for quick retrieval by the CPU. This memory is also know has the ‘primary storage’. The full meaning of RAM is ‘random access memory’; it is volatile because the content of this memory can be destroyed; the memory does not exit after the computer has been switched off. The other type of memory that is non-volatile is the read only memory (ROM). In this case, the data continue to exits after the computer has been switched off.


Hard Disk Drive

The hard disk drive is the storage device used to store information and it is normally mounted inside the system unit. The drive is usually bought with a microcomputer and can hold several gigabytes of data. The hard disk can read in data, write a file as well as find files many times faster than the floppy disk.


DVD Drive

The DVD disk drives (digital versatile disc or digital video disc) are optical disks that are used to read digital data into the computer. They are commonly used for digital representation of movies and multimedia presentations that can combine sound and graphics. The DVD is similar to the CD-Rom but can store more data. Some DVD however can play CD-ROMs, and video CDs. DVD disk drive may be Read/write system or Read only systems.


CD-ROM

The CD ROM (Compact Disc-Read-Only Memory) is an optical disk that works like a CD player, but the difference is that the device can read digital data instead of audio data. Moreover, The device is capable of storing large amounts of data (as much as 1 GB). The CD-ROM can also be Read/write system or Read only system. Newer system units come with DVD drives rather than CD compatible drives.


Floppy Disk Drive

This device is used for inserting a floppy diskette. The floppy disk is normally 3.5 inches in size, and has a basic format of 720 kilobytes. Very few computers these days use floppy disk drives. People now use more of USB flash drives, memory cards, external hard drives and DVDs.


Power Supply Unit (PSU)

The power supply unit as the name implies is the component within the computer system unit that supply power to the computer. It is fitted in the computer system case.


Adapters

An Adapter is a printed circuit board or an expansion card that can be inserted into a computer system unit or already built into the motherboard. These adapters may include video adapters, or network work adapters, graphic cards, modem cards or sound cards. They give the computer added capabilities


Sound Card

The sound card is an expansion board device that enables the computer system to capture, decode play and edit digitised sound. The sound card is plugged into a slot on the motherboard and it has sockets for microphones and speakers.


Graphic Adapters

These types of adapters include video cards that give the computer display capabilities and graphic cards that increase speed of graphic-based applications.


Network Adapters

This adapter or card enables a computer to be linked to a network.


Modem cards

The modem card or adapter enables a computer to be connected to the Internet and also enables the transmitting and receiving of fax messages.


Heat Sink

The heat sink is a device that lowers the temperature of the system processor. This is achieved by dissipating heat into the surrounding air. When a heat sink is mounted with a fan, it is referred to an active heat sink, when it is without a fan; it is called a passive heat sink.


Fan

The fan is a component designed to lower the temperature of the processor. This is usually locked in place over the processor along with the heat sink.


Cables

The computer consists of cables that enable the hardware components to be connected together. These include multicoloured power supply cables running between the power supply and the motherboard, the cables going into the floppy and hard drives (black red and yellow), and the data cables (flat grey cables).


Case

The case houses the basic component of the computer system. The cases come with the power supply and the fan, and are available in different sizes. The type of case depend on the type of motherboard for example there are cases for AT and ATX boards which are available in mini-towers, towers and desktops.


See also

Main Component of the Computer Hardware


Further notes

Information technology has to do with the application of computer technology to information processing. Find out more...