Comp 1 Memory and Storage

MEMORY
1. RAM - Random Access Memory
  1. RAM is memory used for storing programs and data in use
  2. Features of RAM
    1. • volatile and so lost when the computer power is switched off
    2. • allows computer to read data quickly
    3. •allows computer to run applications
2. ROM - Read Only Memory
  1. Used for Firmware programs needed to boot up a device, referred to as Boot Strap and Start-up.
    1. Firmware is permanent software programmed into ROM.
  2. Features of ROM
    1. • is non-volatile and keeps its content when the computer power is switched off
    2. • allows computer to check hardware devices are working during start up it will report any errors
    3. • it stores the BIOS, Basic Input Output system and allows you to setup your computer
      1. • locates the operating system and passes control to it
3. Virtual Memory
  1. additional memory to a computer’s RAM, held on the storage device either a Hard disk or Flash memory. Volatile and it is used when the RAM is low on small and the computer wants to run additional processes.
    1. Disadvantages
      1. It is slower than RAM as data has to transfer between the CPU and the storage device
      2. If used extensively can lead to Disk Thrashing and possibly a Head crash, which could damage the hard disk and loose data
        Disk Thrashing - is when a computer's virtual memory subsystem is in a constant state of paging. This sometimes occurs if a CPU is attempting many processes at once
4. Flash Memory
  1. a type of non-volatile memory (that is it retains its data when the power is turned off). Data is stored in units called blocks.
    1. Advantages
      1. • It takes less space
      2. Transfer of data
      3. Being Solid State, they are more mobile
    2. Disadvantages
      1. • Cost more than traditional drives,
      2. • Less space than equivalent hard disks
      3. a Flash drive on a laptop might be 160 or 250 Mega Bytes but a Hard disk on a laptop might be 1 or 2 Terra bytes.
  2. E.g. -Smart phones, tablets and some laptops.
Storage
1. Input Output and Storage Devices
  1. An Input Device is used to enter of data. E.g. a Computer Mouse or Keyboard
  2. An Output Device is used to present information, the result of processing to the user. E.g. a Printer or a screen
  3. A Storage Device is some hardware to hold data in a binary format for processing later.
2. Computer Storage is somewhere to store electronic data. Data stored in random access memory or RAM and cache memory are referred to as Primary storage.
  1. Hard disks and other devices such as solid-state devices and optical drives are called Secondary storage.
    1. Secondary storage is used to store programs, data and other files that would otherwise be lost when the power is turned off
3. Types of Secondary Storage
  1. Magnetic hard disks- cheap, large capacity, slower than flash, commonly used within personal and commercial computers to store operating systems, and other files and programs.
  2. Optical disks (CD, DVD and Blue Ray) - distribute programs, videos and large data files as read only files. CD-RW and DVD-RW (RW is Read, Write) are used to store backup copies of files and to transfer files. Slow, inexpensive and have capacities of 700MB (CD), 4.7 GB (DVD) and 9GB (Blue Ray).
  3. Flash (Solid State) memory is very flexible and can store many GB of data in a small space. It has good access times, more expensive than Magnetic or Optical storage. It is used to store data in smart phones, cameras and tablets. The pen drive or USB stick is a very example of a Flash drive and is used extensively to transfer files and backup.

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Comp 1 Memory and Storage

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