 A desktop computer is a personal computer designed for regular use at a single location on or near the desk or table due to its size and power requirements. The most common configuration has a case that houses the power supply. Motherboard-apprinted circuit board with a microprocessor has the central processing unit CPU memory, bus, and other electronic components, disk storage usually one or more hard disk drives, optical disk drives, and in early models a floppy disk drive a keyboard and mouse for input, and a computer monitor, speakers, and, often, the printer for output. The case may be oriented horizontally or vertically and placed either underneath, beside, or on top of a desk.