3.2 COMPUTER HARDWARE

4. PROCESSING DEVICES

Processing devices are the computer electronic components and chips housed in the system unit. The system unit is a box-like case that houses the motherboard, the disks and drives bays, the power supply, and the cooling systems. The components in the system unit are connected to the motherboard. Two major components on the motherboard are the CPU and internal memory. A drive bay is a rectangular opening that typically holds disk drives.

THE MOTHERBOARD

The motherboard is a single circuit board that provides the path through which the processor communicates with internal and peripheral devices. The motherboard is also called the system board. The components attached to the motherboard include the processor chip, memory chips, buses, and Expansion Slots for Adapter Cards.

BUSES

The BUS is a common electrical path that enables data flow between the various system components. A bus allows the various devices inside and attached to the system unit to communicate with each other. All buses consist of
two parts:

• The data bus which transfers actual data bits and
• The address bus transfers information about where the data should go in memory.

EXPANSION SLOTS AND ADAPTER CARDS

An expansion slot is a socket on the motherboard that can hold an adapter card. An adapter card also called an expansion card, is a circuit board that increases the capabilities of the system or provides connections to peripherals. Some motherboards include all necessary capabilities and do not require adapter cards. Adapter cards are used for many supplemental capabilities, such as more memory, higher quality sound devices, a modem, extra ports, or graphics capabilities.