tower or a so-called desktop configuration. A tower, as the name implies, stands vertically, measuring 15-18" high, 7-8" wide, and 18-24" deep. It encases the power modules, including the CPU, which is attached to one interior side wall of the unit with screws and/or clamps designed for the purpose. The interior of the CPU also houses circuit boards, or cards, that drive such hardware as scanners, sound cards, keyboard/mouse cards, printers and modems. One part of the card fits into performed electronic sockets, and another part, containing special plugs and sockets for external cabling, reaches through the rear vertical wall. Electronic sockets for printer and keyboard, which are attached to the CPU circuit board, protrude through the rear wall of the tower. The CPU also houses slots for memory- and storage-related hardware (q.v. below). Projecting through the front wall of the CPU are disk-drive slots. The current generation of units should come equipped with one 3.5" drive and one CD-ROM drive. Tower units, which are cable-connected to keyboard, mouse, and monitor, can be stored out of the way of keyboard and mouse--even on or under a desk, as long as disk drives are accessible.
The desktop configuration of a CPU has all of the features of a tower model. The only difference is logistical; components are arranged on a unit that measures 7-8" high, 15-18" wide, and 15-18" deep. The box configuration enables users who so desire to position their computer-screen monitors on top of the unit.
The CPU of a laptop computer is self-contained, of a piece with keyboard, cable outlets, and mouse. Typically, a laptop, aka notebook, computer flips up to reveal computer screen and keyboard in perpendicular relationship. A good laptop will have a minimum of two so-called PCMCIA slots, which accommodate credit-card-size circuit boards such as modems, sound cards, network hardware, or hard disks. Better laptops have sound cards already built i...