CHAPTER 4

SYSTEM UNIT COMPONENTS

System Unit

•  The computer system unit is the enclosure for all the other main interior components of a computer. It is also called the computer case, computer chassis, or computer tower.

Components of system unit

• Drive bays
• power supply 
• sound card
• video card
• processor
• memory

Motherboard

The motherboard is the main circuit board of the system unit.

Processor

The processor, also called the central processing unit (CPU), interprets and carries out the basic instructions that operate a computer

• multi core
• dual core
• quad core

Data Representation

• Analog- signals that are continuous and vary in strength and quality.
• Digital- signals thatare in one of two states: on or off

Memory

Consists of electronic components that store instructions waiting to be executed by the processor, data needed by those instructions, and the results of processing the data.

• Volatile memory
• Non-volatile memory

Basic types of RAM chips

• Dynamic RAM (DRAM)
• Static RAM (SRAM)
• Magnetoresistive RAM (MRAM)

Ports and Connectors

• A port is the point at which a peripheral attaches to or communicates with a system unit (sometimes referred to as a jack)
• A connector joins a cable to a port.
• A USB port can connect up to 127 different peripherals together with a single connector.

Buses

• A bus allows the various devices both inside and attached to the system unit to communicate with each other
  –Data bus
  –Address bus

Example of buses

• PCI bus
• PC card bus
• USB and FireWire bus
• PCI Express bus
• Accelerated Graphics Port

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