S4 CIT

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S4 CIT

• Computer Hardware

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Overview of Computer Hardware

• Motherboard
• CPU
• RAM
• Harddisk
• CD-ROM
• Floppy Disk
• Display Card
• Sound Card
• LAN Card

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Motherboard

• It is the main circuit board that links all the
  hardware components together.
• There are many chips or IC (Integrated Circuit)
  on the motherboard which contains millions of
  transistors.

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Bus Lines

• Bus line is a physical wiring that connects the
  components of the computer system on the
  motherboard.

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Types of Bus

• System Bus
• Data transmission between CPU and the main memory
  via System Bus. It is also known as the Front
  Side Bus (FSB).
• Peripheral Bus
• Data transmission between main memory and
  peripherals via Peripheral Bus.

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Bus Structure

• Data Bus
• It transfers actual data.
• Address Bus
• It transfers the information about the location
  of the data.
• Control Bus
• It indicates the direction of data transfer and
  coordinates the timing of events during the
  transfer.

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Bus Width

• It is the size of the bus lines.
• It determines the number of bits that the
  computer can transmit at one time (say, one clock
  cycle).
• eg a 32-bit bus can transmit 32 bits at a time.
• the larger the bus width, the faster the
  transmission.

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Examples of Peripheral Bus

• ISA Bus
• Old sound card
• Faded out already
• PCI Bus
• For most of the interface card like
• LAN Card
• MODEM
• Sound Card
• Capture Card

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Examples of Peripheral Bus

• AGP Bus
• Designed for Display Card only
• USB Bus
• For most of the peripheral
• MP3 Player, Digital Camera
• Keyboard, Mouse
• Printer, Scanner
• etc

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CPU (Central Processing Unit)

• It interprets and performs instructions of a
  computer program.
• The most determining factor in how powerful a
  computer is.
• A CPU in a common PC system is known as the
  microprocessor.

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A model of Computer
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CPU

• A CPU consists of two parts, the ALU and the CU.
• Both the ALU and the CU contains registers, which
  are
• high-speed memory
• temporarily hold data and instructions during
  processing.

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ALU

• ALU - (Arithmetic and Logic Unit)
• It performs
• arithmetic operations
• addition, subtraction, multiplication and
  division.
• logical operations
• comparison and decision.

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Registers in ALU

• ACC Accumulator
• temporarily holds the intermediate or final
  result of arithmetic and logical operations.
• Adder
• is the set of logic circuits that performs
  arithmetic operations

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CU

• CU Control Unit
• It
• interprets the instruction from the main memory
• tells the ALU how to perform an operation
• controls the overall operations of the computer
• directs and controls the operations of the
  peripheral devices.

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Registers in CU

• IR - Instruction Register
• holds the current instructions fetched from the
  main memory.
• Instruction Decoder
• a logic circuit which interprets the current
  instructions stored in the instruction register.
• PC - Program Counter
• a register which holds the address of the next
  instruction to be fetched
• automatically incremented by 1 to hold the
  address of the next instruction to be accessed
  after the current instruction has been fetched.
• some instruction may place new value into the PC
  instead of incrementing its value.

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Examples of how the CPU works
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Machine Cycle

• Machine Cycle
• the process of a CPU that executes an instruction
• it is repeated each time the computer executes an
  instruction

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CPU Performance depends on

• Clock rate
• the speed at which the CPU can execute an
  instruction.
• unit is Hertz (Hz).
• Word Size
• the number of bits that the CPU can manipulate at
  one time.
• a CPU with a larger word size can handle more
  data with each operation and therefore has higher
  performance.

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CPU Performance depends on

• Cache Memory
• memory that is placed inside the CPU.
• it is random access memory (RAM) that a
  microprocessor can access more quickly than it
  can access main memory.
• acts as an intermediate between registers and the
  main memory.
• it stores some frequently accessed data so it
  shorten the time of accessing the RAM.
• increasing the size of the cache memory will
  greatly improve the overall performance of the
  computer system.

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Different kind of CPU

• Intel
• Celeron
• Pentium 4
• Xeon
• AMD
• Duron
• Athlon XP
• Sempron
• Athlon 64

• Common features
• Clock rate gt 2GHz

• Differences
• Word Size
• Cache Memory Size
• Front Side Bus
• No. of transistors

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Main Memory

• Storage media installed on the motherboard
• store data and instruction to be executed by the
  CPU
• Main memory is classified into
• RAM
• ROM
• CMOS

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RAM

• RAM Random Access Memory
• RAM is volatile
• data is lost when the power to the computer is
  turned off
• The instructions and data for the job performing
  are written to RAM and read from it as needed.

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RAM

• Two operations of RAM
• Loading means copying data from the secondary
  storage to the main memory
• Saving means copying data from RAM to the
  non-volatile secondary storage.
• Types of RAM
• SRAM
• DRAM
• SDRAM
• DDR-RAM

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ROM

• ROM Read Only Memory
• ROM is non-volatile
• Data are stored permanently
• Data can only be read but cannot be changed
• Store instructions and tells the computer how to
  load the operations system when booting up
• Basic Input/Output System (BIOS)

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ROM

• Content can be changed in a special kind of ROM
• EEPROM (Electrically Erasable Programmable
  Read-Only Memory)
• can be erased and reprogrammed (written to)
  repeatedly through the application of higher than
  normal electrical voltage
• Now BIOS are stored in EEPROM for easier update
  of BIOS

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CMOS

• CMOS - Complementary Metal-Oxide Semiconductor
  Memory
• It has the characteristics of both ROM and RAM,
  ie
• it is non-volatile
• information in CMOS can be changed
• In computer, CMOS stores the configuration
  information about a computer like capacity of the
  hard disk and the current time and date.

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Access of Data in Memory

• For different storage method, there are different
  accessing method of data.
• Direct Access
• the CPU can retrieve or store a specific piece of
  data as long as the address is known.
• Eg knowing the file name and open the file
• Sequential Access
• If the address is unknown, data will be accessed
  one-by-one.
• Eg searching of a file named test.doc

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Secondary Storage

• CPU can only process data in RAM
• But RAM is volatile, processed data cannot be
  stored in RAM
• Secondary Storage device is needed
• It is a non-volatile storage media which has a
  big storage size.

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Secondary Storage
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Magnetic Media - Floppy

• Floppy
• 1.44 MB
• Plastic disk with magnetic coating
• Reading and writing speed is slow
• Data easily lost
• Some new kind of floppy called SuperDisk and
  ZipDisk have larger capacity, but need special
  drives to read the disk

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Magnetic Media Hard disk

• Hard disk
• Huge storage capacity
• A set of circular metal plates with magnetic
  coating
• Read/write head inside
• Rotate at a very high speed for faster data access

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Magnetic Media Hard disk

• Structure of Hard disk
• Track
• A track is a narrow recording band that forms a
  full circle on the disk surface.
• Sector
• Each track is divided into equal sections called
  sectors.
• Cylinder
• A group of tracks stacked vertically is called a
  cylinder.

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Magnetic Media Hard disk

• Data are stored in a certain number of sectors
  called clusters.
• Every track, sector and cylinder are named, so
  each sector has a unique address.
• When data is being saved or retrieve, the
  read/write head will go to the corresponding
  location to read/write data
• This is called Direct Access.

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Magnetic Media Magnetic Tape

• Usually 24GB, up to 72GB
• A strip of plastic with magnetic coating
• A large storage media with low price
• Tape drive is required to read/write data
• Accessing method of magnetic tape is Sequential
  Access.
• It is mainly used for
• long-term storage and backup.
• (About 10 years)

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Optical Media - CD

• CD Compact Disk
• Normally it can store 640MB data.
• It is cheap and durable.
• Data is stored by "burning" pits and lands on the
  metal coating.
• A laser beam is projected to the disc surface and
  the reflection will be read to detect the
  patterns of pits and lands.

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Optical Media CD-ROM

• The contents inside cannot be changed or
  overwritten once it is stored with data.
• Software publishers use them to distribute
  software program.

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Optical Media CD-R/CD-RW

• CD-R (CD Recordable) and CD-RW (CD Rewriteable)
• Both of them allow users to write data onto a
  CD-R or CD-RW disc.
• CD-R
• can be written only once
• CD-RW
• can be write and overwritten for many times.

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Optical Media - DVD

• DVD - Digital Versatile Disk
• 4.7GB 17GB
• It has the same diameter and thickness as a CD
  but have much higher capacity.

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Optical Media DVD-ROM

• It is similar to CD-ROM but its capacity varied
  from 4.7GB to 17GB.
• A DVD-ROM drive is needed to read data from a
  DVD-ROM.
• As its capacity is large, film companies use them
  to publish high quality film.

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Optical Media DVD R/DVD RW

• It is similar to CD-R and CD-RW, but has a much
  higher capacity.
• There are different standard
• DVDR, DVD-R
• DVDRW, DVD-RW
• DVD-RAM
• Different disc drives and different discs are not
  compatible
• Most DVD writers support ?RW standard
• DVD-R, DVD-RW seems to be the most popular
  standard

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Optical Media MO Disks

• MO - Magneto-Optical
• It combines the use of magnetic and optical
  methods to store data.
• large capacity (up to 9.1GB) similar to DVD but
  it is much more reliable (about 100 years)
• It is ideal for storing large amounts of data for
  backup
• More expensive than Magnetic Tape.

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Semi-conducting Media

• It is sometimes called flash memory, where it
  uses semi-conductor chips to store data.
• No mechanical movement involved in data transfer,
  so it is
• Quiet in operation
• Not easy to be damaged
• Used in portable devices such as
• PDA (Personal Digital Assistant)
• MP3 player
• Digital camera

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Semi-conduction Media

• CF card

• Flash Thumb Drive

• SD card

• Card Reader

• Memory Stick

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Comparison of memory
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Measuring SecondaryStorage device

• Access time
• The average time it takes the device to locate
  data on the storage medium and read it.
• Lower access time indicates higher speed. The
  unit is usually in ms.

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Measuring SecondaryStorage device

• Data Transfer Rate
• The amount of data that a storage device can move
  from the storage medium to the computer per
  second.
• Higher data transfer rate indicates higher speed.
  The unit is usually measured in MB/s.

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Measuring SecondaryStorage device

• Storage Capacity
• It is the maximum amount of data that can be
  stored on a storage medium.
• The unit is usually measured in KB, MB, and GB.

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Measuring SecondaryStorage device
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Input/Output Device

• It is the communication bridge between the
  computer and the user.
• Input
• any hardware that allows a user to enter data and
  commands into a computer.
• Output
• a hardware that presents digital information in a
  form that human being can understand.

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Input Device - Keyboard

• One of the most commonly used input device.
• The keyboard that we use nowadays is called the
  QWERTY keyboards.

Q Under what circumstances will we use the
keyboard as a input device?
A When we need to enter a large amount of data
into the computer.
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Input Device Pointing Devices

• It allows
• users to control the cursor or pointer on a
  Graphical User Interface (GUI)
• just like sending out a command to the computer.

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Pointing Devices Mouse

• It is the most common pointing device.
• It works by the Point-and-Click principle.
• In Windows environment, we can trigger some
  functions using mouse by a technique called
  Drag-and-Drop.
• There are two types of working mechanism
• mechanical mouse
• optical mouse

Q Under what circumstances will we use the
mouse as an input device?
A When there is a GUI which allows user to
control the computer using a mouse, we can use it
as an input device.
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Pointing Device Trackball

• It is like an upside-down mouse, which is
  stationary.
• User will rotate the ball to control the screen
  pointer.

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Pointing Device Joystick / Joypad

• It is used to control the actions of objects in
  computer games.
• It includes trigger buttons to perform certain
  actions.

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Pointing Device Graphics Tablet

• It is a flat electronic board that
• allows user to enter drawings and sketches into
  computer.
• detects the movement of a pen.
• It is used in inputting Chinese characters, with
  the use of a software known as handwriting
  recognition software
• It translate the scripts into
• Chinese character codes.

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Pointing Device Touch Screen

• It is a pressure sensitive display that allows
  users to select options with fingers or stylus
  instead of mouse.
• It is often used in information kiosk, PDA and
  tablet PC.

Q Is it a Input device or Output device?
A It is a device which got both the Input and
Output function.
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Scanner and Reading Device

• It transform source document into digital form
  without typing or pointing device.
• Then the data are analyzed and converting into
  useful format.

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Image Scanner

• It
• sends bright light on the document and detects
  the light reflected from the source document.
• detects data and convert them into a digital
  graphics.
• OCR (Optical Character Recognition) with the
  scanner to convert the digital graphics into text
  if the source is indeed a text document.

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Optical Reader OMR Reader

• OMR (Optical Mark Recognition) Reader
• read specific hand-drawn marks like crosses or
  rectangles on specially designed forms.
• Examples
• MC answer sheets
• Questionnaires
• Mark Six lottery
• tickets

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Optical Reader MICR Reader

• Magnetic Ink Character Recognition (MICR) reader
• Read text printed with magnetized ink
• Mainly used by bank for cheque processing

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Optical Reader Barcode Reader

• Books in library and goods in supermarket are
  given a unique bar code.
• A bar code reader will be used for check out.
• It is higher accurate and fast.
• Barcode contains a check digit.
• What is it for?

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Digital Camera

• It is just like a traditional camera but the
  photos are stored in digital format by a light
  sensitive chip
• Data is stored in flash memory like CF card and
  SD card.
• It contains a LCD display to view the taken image
  instantly.

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Digital Video

• It records videos in digital format, which can be
  stored in DV tapes or transmitted directly to a
  computer.
• A computer will ne ed a video capture card to
  input the recorded video into computer,
• video input or
• IEEE1394 (FireWire) port.

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Voice Input

• A user can use a microphone to input sound into a
  computer.
• The computer will store the sound in waveforms.
• A technology called voice recognition can be
  applied to analyze the speech into text.

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Output Device - Display device

• Visual Display Unit (VDU)
• commonly refer as monitor
• CRT monitor
• heavy and occupies a lot of desk space
• LCD monitor
• thinner in size but more expensive than CRT
  monitor
• used in notebook computer, tablet PC
• More and more desktop computer use LCD monitor

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Output Device - Display device

• LCD Projector
• It use strong light rays to project the computer
  display onto a large screen for a group of people
  to see.

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Output Device - Printer

• Impact Printer
• contains a printer head with small pins
• produces printed images by physically striking
  pins against an ink ribbon to leave dots on the
  paper.
• Examples Dot-Matrix Printer
• It uses continuous-form paper with holes in the
  margins on both sides

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Output Device - Printer

• Non-impact Printer
• It output information on a paper without
  physically striking the paper.
• It is quiet when printing.
• It use normal plain paper.

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Printer Non Impact Printer

• Ink-jet Printer
• It sprays tiny ink drops onto paper.
• Can produce low-cost colourful printouts.
• Colour printing quality can be increased if we
  use photo-quality paper as the printing medium.

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Printer Non Impact Printer

• Laser Painter
• laser beam to produce an electronically-charged
  image on a drum, causing toner to stick to the
  drum
• drum presses against the paper and a heating
  process follows which fixes the toner onto the
  paper.

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Printer Non Impact Printer

• Thermal Printer
• uses heat on heat-sensitive paper which react to
  heat by turning black
• Black and white, never run out of ink

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Output Device Audio Output Device

• It enables output from a computer that can be
  heard.
• Examples speakers and headsets.

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Ports and Interface Cards

• They are the interface between external
  peripheral devices and the computer.

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Ports

• A port is built on the motherboard.

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Interface Card

• An interface card is inserted into slots on the
  motherboard.

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Built-in Functions on Motherboard

• Sometimes, an interface card may become a
  built-in function on the motherboard.