Topic 3: Computers

• Magnetic Storage: Data is stored on a magnetic disk or tape. It uses the magnetic field of a magnet to store data.

  
• Optical Storage: Uses lasers to read/write data onto optical disks such as CDs, DVDs and Blu-ray discs.

  
• Solid-State Storage: A type of secondary storage that uses flash memory chips instead of moving parts. For example: USB sticks and CD cards.

  A) Solid State Hard Disc

  B) Memory Stick

  C) Flash Memory

  D) Micro Flash Memory

  
• Advantages of Magnetic Storage: Can be easily accessed by computer, can hold large amounts of information, relatively cheap, reliable, durable, easy to transport, fast access times.
• Disadvantages of Magnetic Storage: Limited lifespan (can wear out), limited number of write cycles, slow transfer rates compared to other types of storage, fragile, prone to damage from physical shock.
• Advantages of Optical Storage: Large capacity, long life span, high reliability, low cost per gigabyte, no moving parts, resilient to electromagnetism.
• Advantages of Optical Storage: Large capacity, long life span, high reliability, low cost per gigabyte, no moving parts, resilient to electromagnetism, non-volatile, good durability, fast access time.
• Disadvantages of Optical Storage: Slow read/write speeds, susceptible to scratches, not suitable for storing frequently changing files, requires laser light source.
• Disadvantages of Solid-state Storage: Expensive, limited capacity, limited lifespan, risk of corruption if voltage levels are too high or low.
• Advantages of Solid-state Storage: No moving parts, small size, portable, rugged, quicker than hard drives, faster read/write speed, lower power consumption.
• Inside a hard disc is a stack of discs called platters made from hard materials, such as glass or ceramic.
• Inside a hard disc is a stack of discs called platters. The surface of each patter has a thin magnetic coating and it is divided into billions of tiny areas, each of which can be individually magnetised.
• Data is stored on the surface of a platter as a series of bits. An area that is magnetised represents a 1 and an area that is not magnetised represents a 0.
• Each platter has two tiny magnetic read-write heads one on each side of the disc.
• The computer's operating system maintains a map of the sectors showing which are occupied and which are available. When a computer wants to write a new file to the hard drive, it uses the map to find free sectors.
• CD, DVD or Blu-ray discs are made of several layers.
• A DVD writer will use two separate lasers one to write data into the disc and the other one to read the contents of the disc.
• Data on a disc is stored as a series of pits (bumps) and lands (flat areas) on the surface of the disc. A land represents the binary value 1 and the pit represents the value of 0.

  
• Operating System

  A program that controls and manages the hardware and all other software on a computer and provides a user interface or graphical user interface.

  
• Utility Software


  Programs that add functionality to a computer system or improve its performance in some way, such as disc repair, compression or anti malware

  
• Application Software


  Programs or apps developed for end users, such as web browsers, a spreadsheet, a console game, an e-mail client or a payroll application