System Unit
The "System unit" is the name given to the main PC box which houses the various elements which go together to make up the PC. Within the System unit is the computer system's motherboard, which contains all the main components, such as the CPU. The system unit also houses items such as the hard disc, the floppy disc and the CD ROM drives etc. System units come in two types, the tower version, or a desktop version, which is designed to sit on your desk with your monitor on top of the system unit.