4.7.4 External Hardware Devices

• What are the main categories of external hardware devices?

  Input and output devices, secondary storage devices
• What are the characteristics and purposes of input and output devices?

  • Characteristics: Functionality, compatibility, performance
  • Purposes: Data entry, data output, user interaction
• Why is secondary storage needed in a computer system?

  To provide permanent storage for data
• What are the main types of secondary storage devices?

  • Hard disk
  • Optical disk
  • Solid-state disk (SSD)
• How does a digital camera convert data?

  It converts analogue data to binary
• What is the role of sensors in a digital camera?

  Sensors store data for pixels
• How does a digital camera record color?

  It uses three sensors for RGB colors
• What type of memory does a digital camera use for storage?

  Removable flash memory
• How is image quality quantified in digital cameras?

  In megapixels
• What happens to image quality with lower resolution?

  Less accurate but smaller file sizes
• What file formats do digital cameras commonly use?

  RFF, JPG, PNG
• How does a barcode reader function?

  It measures light intensity reflected from an image
• What is the purpose of an ADC in a barcode reader?

  To convert analogue waveforms to digital
• What is the most common barcode format?

  UPC (Universal Product Code)
• How is encoded data linked to a POS system?

  It matches the code to a particular item
• What is RFID used for?

  Tracking items and valuable products
• What components are found in an RFID tag?

  A chip, modem, and antenna
• What is the typical range of RFID?

  1m to 100m
• How does a laser printer transfer toner to paper?

  By charging the paper with opposite charge
• What colors of toner are used in laser printers?

  Cyan, magenta, yellow, and black
• What is the advantage of main memory in a computer?

  High speed and direct access by location
• What is a disadvantage of main memory?

  It is expensive and volatile
• Why is secondary storage necessary?

  To provide high capacity and low cost
• What is a magnetic hard disk made of?

  Metal platter with magnetic coating
• How is binary data stored on a magnetic hard disk?

  As a series of polarized states
• What is a cluster in a magnetic hard disk?

  A group of sectors, smallest storage unit
• How does an optical disk store data?

  In pits and lands on a spiral track
• What is the function of the laser in an optical disk drive?

  To read and write data by altering light reflection
• What is a solid-state drive (SSD) used for?

  Storing files that are frequently read
• Compare the advantages and disadvantages of hard drives, optical disks, and SSDs.

  Advantages:

  • Hard Drive: Cheaper, higher capacity, portable
  • SSD: Faster access speed, no moving parts, less heat

  
  

  Disadvantages:

  • Hard Drive: Moving parts, more likely to fail
  • Optical Disk: Easily scratched, heat sensitive
  • SSD: Expensive, slower as they fill up