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CHAPTER 2: COMPUTER HARDWARE, Printers, Memory, portable device, a digital…

- - - - Characteristics of and purchasing
        guidelines for desktops, laptops, tablets,
        smartphone, digital cameras,
        and portable media players
      - Handheld computers, servers, supercomputers,
        point-of-sale terminals, ATMs, self-service kiosks,
        e-book readers, game devices,
        embedded computers, and cloud computing
    - - The table below is categories of computers and mobile devices
  - - - A portable media player
      - An e-book reader
  - - - gamepad
      - joystick
      - pedals and wheels
      - dance pad
      - motion-sensing game controller
      - guitar
      - balance board
  - - - examples
        
        Tower server
        
        Blade server
        
        Rack server
      - Types of servers
      - Mainframe
        
        A large, expensive, powerful server that can handle hundreds of thousands of connected users simultaneously
      - Supercomputers
        
        The fastest, most powerful computer-also most expensive
    - - Limited processing power, enables user to send or receive data from or to a host
      - Limited capabilities and components
      - POS terminal
        
        Record purchases
        
        Process credit/debit card
        
        Update inventory
      - Self service kiosk
        
        Connects to a host computer through a network
        
        An ATM
- - - - A webcam is a type of DV camera that enables a user to :
        
        Capture video and still images
        
        Send email messages with video attachments
        
        Broadcasts live images or video over the internet
        
        Conduct videoconferences
        [ A videoconference is a meeting between 2 or more
        geographically separated people]
        
        Make video calls
  - - - Flatbet Scanner
        
        A flatbed scanner works in a manner similar to a copy machine except it creates a file of the document in memory instead of a paper copy
      - Optical Reader
        
        An optical reader is a device that uses a light source to read characters, marks, and then converts them into digital data that a computer can process.
        a) Optical Character Recognition (OCR)
        b) Optical Mark Recognition (OMR)
      - Bar Code Reader
        
        A bar code reader, also called a bar code scanner uses laser beams to read bar codes.
      - A QR code
        • A QR code stores information in both a vertical and horizontal direction
      - RFID
        • An RFID (radio frequency identification) uses radio signals to communicate with a tag placed in or attached to an object
        • An RFID reader reads information on the tag via radio waves
        • RFID can track :
        
        Tracking times of runners in a marathon
        
        Tracking location of people and other items
        
        Checking lift tickets of skiers
        
        Gauging temperature and pressure of tires on a vehicle
        
        Checking out library books
        
        Managing purchases
        
        Tracking payment as vehicles pass through booths on tollway systems
      - Magstripe readers
        • magstripes readers read the magnetic stripe on the back of cards such as:
        • Credit cards
        • Entertainment cards
        • Bank cards
        • Identification cards
        • Other similar cards
      - MICR
        • MICR (magneticink character recognition) devices read text printed with magnetised ink
        • An MICR reader converts MICR characters into a form the computer can process
        • Banking industry uses MICR for check processing
      - Data Collection Device
        • A data colection device obtains data directly at the location where transaction or event takes place
- - - - • A display visually conveys text, graphics, and video information
      - • A monitor is a display that is packaged as a separate peripheral device
      - Examples of displays output:
        
        quality of a display
        
        • The quality of a display depends primarily on its:
        
        – Resolution
        
        – Response time
        
        – Brightness
        
        – Dot pitch
        
        – Contrast ratio
        
        • Today’s monitors use a digital signal to produce a
        
        picture
      - Other output devices.
        
        Headphones
        
        Earbuds
        
        Speaker
        
        Interactive whiteboard
        
        Joysticks / game controller
- - - - Capacity is the number of bytes a storage medium can hold :
      - Kilobyte (KB) 1 thousand 210 or 1,024
        
        Megabyte (MB) 1 million 210 or 1,048,576
        
        Gigabyte (GB) 1 billion 230 or 1,073,741,824
        
        Terabyte (TB) 1 trillion 240 or 1,099,511,627,776
        
        Petabyte (PB) 1 quadrillion 250 or 1,125,899,906,842,624
        
        Exabyte (EB) 1 quintillion 260 or 1,152,921,504,606,846,976
        
        Zettabyte (ZB) 1 sextillion 270 or 1,180,591,620,717,411,303,424
        
        Yottabyte (YB) 1 septillion 280 or 1,208,925,819,614,629,174,706,176
    - - Figure 8-2 A screen display is considered volatile because its contents
      - disappear when power is removed. Likewise, most RAM is volatile. That
      - mobile device. Storage, by contrast, is nonvolatile. Its contents remain
      - when power is off.
      - state of computer
      - Screen Display Volatile
      - contents of most RAM
      - Contents of storage
      - is, its contents are erased when power is removed from a computer or
    - - – Measures the amount of time it takes a storage device to locate an item on a storage medium
        
        – Measures the time required to deliver an item from memory to the processor
    - - Faster transfer rate
        
        memory
        
        most RAM
        
        running programs and information they require; contents of screen display; commands sent between components of computer, such as the hard drive, processor, and video card
      - Slower transfer rate
        
        storage
        
        SSDs & Hard Disk
        
        Operating system; applications; user data and information, including photos, music, Storage
        and videos; backups
        
        USB Flash Drive & Memory cards
        
        Digital photos or files to be transported
        
        Optical discs
        
        Software, movies, music
  - - - Other RAID levels use striping; that is, portions of each drive are placed on multiple drives.
        
        In RAID level 1, called mirroring, a backup disk exists for each drive.
    - - Storage Area Network (SAN) is a high-speed network with the sole purpose of providing storage to other attached servers
      - A storage area network provides centralized storage for servers and networks
      - :
  - - - It has several advantages
        
        Faster access times
        
        Faster transfer rates
        
        Light weight
        
        More durable
  - - - Laser diode shines a light beam toward disc.
      - If light strikes a pit, it scatters. If light strikes a land it is reflected back toward diode
      - Reflected light sends digital signals of 1 to computer. Abssence of reflected light is read as digital signal of 0.
    - - A CD-ROM can be read from but not written to
      - A CD -R is an optical disc on which user can write once. but not erase
      - A CD-RW is an erasable multisession disc
      - A DVD-ROM is a high-capacity optical disc on which users can read
        but not write on or erase
        
        A DVD-R or DVD+R are competing DVD-recordable WORM formats,
        on which users can write once but not erase
        
        DVD-RW, DVD+RW, and DVD+RAM are competing DVD-rewritable
        formats that users can write on multiple times
  - - - Portable Flash Memory
        
        A memory card is a removable flash memory storage device
        
        Most computers have slots for memory
        cards.
        
        How SD Cards Work
        
        Insert SD Card in card reader, the metallic conducturs will make contact to allow the transfer of data.
        
        A notch on the side if the memory card prevent the card from slipping out of the card reader.
        
        Flash memory chips store lots of data, and when requested it will be transfered to the metallic conducturs.
        
        Some memory cards contain write-protect switches, which prevent you from erasing data on the flash memory chips.
  - - - Cloud storage
        
        Cloud storage is an Internet service that provides storage to computer or mobile device users
- - - - An adapter card enhances functions of a component of a desktop or server system unit and/or provides connections to peripheral devices
        
        Sound card and video card
        
        An expansion slot is a socket on a desktop or server motherboard that can hold an adapter card
      - Adapter cards
      - With Plug and Play technology, the computer automatically can recognize peripheral devices as you install them
      - A USB adapter enhances functions of a mobile computer and/or provides connections to peripheral devices
    - - The power supply or laptop AC adapter converts the wall outlet AC power into DC power
      - Mobile computers and devices can run using either a power supply or batteries
        
        Batteries typically are rechargeable lithium-ion batteries
  - - - A multi-core processor is a single chip with two or more separate processor cores
        
        Processors contain a control unit and an arithmetic logic unit (ALU)
    - - The arithmetic logic unit (ALU), another component of the processor, performs arithmetic, comparison, and other operations
    - - The system clock controls the timing of all computer operations
        
        The pace of the system clock is called the clock speed, and is usually measured in gigahertz (GHz)
    - - Require additional cooling
        
        Heat sinks
        
        Liquid cooling technology
        
        Cooling pads
  - - - Digital signals are in one of two states: on or off
        
        Most computers are digital
        
        The binary system uses two unique digits (0 and 1)
        
        Bits and bytes
  - - - Word size is the number of bits of processor can interpret and execute at a given time
    - - System bus
        
        Backside bus
        
        Expansion bus
- - - - Nonvolatile memory
        
        Does not lose contents when power is removed
        
        Examples include ROM, flash, and CMOS