CHAPTER 6: THE SYSTEM UNIT

System Unit

- System Chassis, System Board (Motherboard), Microprocessor, Memory, Socket, Bus Lines and Expansion Slots

System Unit Types:

• Desktop system units

• Notebook system units

• Tablet PC system units

• Handheld computer

• Media Center system units

• System Units

Two-state system or Binary System

• Off/On electrical states
• Characters represented by 0's (off) and 1's (on)
• Bits
• Bytes

Three types of binary coding schemes

• ASCII - American Standard Code for Information Exchange
• EBCDIC - Extended Binary Coded Decimal Interchange Code
• Unicode - handles languages with large numbers of characters

System Board

• Connects all components
• Allows communication between devices
• Main board or motherboard
• Circuit board components
• Sockets
• Slots
• Bus lines

Microprocessor Chips

• Central Processing Unit (CPU)
• measurement units for processing speed
• Two basic components
• Control unit
• Arithmetic-logic unit (ALU)
• Chip capacities are expressed in word sizes
• Two significant developments
• 64-bit processors
• become standard for most of today's desktop and laptop computers
• Multi-Core chips
• provide two separate and independent CPUs
• Parallel processing

Types of memory chips

• RAM - programs and data
• ROM - fixed start-up instructions
• Flash - flexible start-up instructions

Standard Ports

4 common ports

• VGA
• USB ports
• FireWire ports
• Ethernet ports

Legacy Ports

• Serial ports
• Parallel ports
• Keyboard and mouse ports
• Infrared data association (IrDA)
• Game ports

Specialized Ports

3 specialized ports

• Musical Instrument Digital Interface (MIDI)
• Sony/Philips Digital Interconnect Format (S/PDIF)
• High Definition Multimedia Interface (HDMI)

Cables

• used to connect external devices to the system unit via the ports
• one end of the cable is attached to the device and the other end has a connector that is attached to a matching connector on the port

Power Supply

• Computers require direct current (DC)
• DC power provided by converting alternating current (AC) from wall outlets or batteries
• Desktop computers use power supply units
• Notebook and handhelds use AC adapters