SYSTEM UNIT

Motherboard is main circuit board of computer.

  • a comp chip contains integrated circuits

Component

  • Buses
  • CMOS
  • Hard disc slots
  • Memory / RAM slots
  • PCI card slots
  • Ports
  • Power connector
  • Processor socket

Processor


  • called CPU ( central processing unit )
  • interprets & carry out basic instructions that operate comp


  • a Multi-core processor is single chip with 2 or more separate processor cores


Component


  • Control Unit
    [ directs & coordinates most of operation in comp ]


  • Arithmetic Logic Unit ( ALU )
    [ perform arithmetic, comparison & other ]


  • Registers
    [ hold data & instr temporarily ]
    [ eg: address register, storage register, accumulator ]


  • System clock
    [ control timing of all comp operations ]
    [ clock speed : megahertz(MHz) / gigahertz(GHz) ]

A processor repeats set of 4 basic operations :


  • Fetch - Decode - Execute - Store


  1. Control unit fetch calculations's data from memory
  2. Control unit decode calculation's instr & send to ALU
  3. ALU performs calculations on data
  4. Result of cal stored in memory

Leading manufacturer of PC processor chips are Intel & AMD

Processor generates heat could cause the chip malfunction / fail


Additional cooling

  • heat sinks
  • liquid cooling technology

DATA REPRESENTATION

Analog signals

  • continuous & vary in strength n quality

Digital signals

  • one of 2 states : on / off

Most comp are digital
Binary system use 2 unique digits (0&1)

  • Bits & bytes
  • 8 bits tgt as a byte ( single character in comp )

MEMORY

  • electronic components that store instr waiting to be executed by processor

3 BASIC CATE OF ITEMS

  • The operating system & other programs
  • Applications
  • Data being processed & resulting info
  • memory size : Gigabytes(GB) & Terabytes(TB)

VOLATILE MEMORY

  • loses content when power off
  • eg : RAM


NONVOLATILE MEMORY

  • doesnt lose content when power off
  • eg : ROM , flash memo & CMOS

RAM chips

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

RAM chips reside on memory module & inserted into memory slots.

ROM chips

  • memory chips storing permanent data
  • eg: Firmware

Flash Memory

  • can erase electronically & rewrite
  • CMOS provides high speed & consume little power

ADAPTERS

ADAPTER CARD

  • enhances func of a component of desktop / server system unit & provide connections to peripherals 外设
  • eg : sound card n graphics card

EXPANSION SLOT

  • socket on desktop / server motherboard that can hold an adapter card

With PLUG and PLAY, comp auto can recognize peripheral devices as we install them

Removable Flash memory device

  • USB Adapter
  • ExpressCard module

BUSES

  • allow various device both inside & attached to system unit to communicate with each other

  • eg: data bus , address bus


  • word size is no of bits the processor can interpret



3 TYPES OF BUSES

  • System bus
  • Backside bus
  • Expansion bus

POWER SUPPLY & BATTERY

  • convert the wall outlet AC power to DC power
  • mobile comp can run using either a power supply or batteries
  • battery typically are rechargeable lithium-ion

EXP of Peripherals :

  • modem
  • printer
  • scanner
  • keyboard

TYPES OF ADAPTER CARD


Bluetooth

  • enable bluetooth connectivity
    Sound
  • connect to speakers / microphone
    USB
  • connects to high speed USB ports