The primary editing device of a computer is the system unit that houses the
central processing unit (CPU) and the disk drive. The CPU reads software
and directs the actions of the peripherals, and the disk drive electronically
stores and retrieves software and information.
The large box that encloses the CPU and the disk drive is called the system
unit. A horizontally oriented system unit lies flat on a desk top. A system
unit that stands upright is a tower unit. The system unit houses the
motherboard, the disk drives, the power supply, and the expansion ports.
Figure 3-5 shows a system unit.
Figure 3-5. The system unit.
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