Memory and Storage

• Primary Storage

  • Low-capacity, internal storage that can be directly accessed by the CPU
  • Program instructions must be copied from the hard drive into RAM to be processed by the CPU because primary storage access speeds are much faster than secondary storage devices such as the hard drive
• Types of Primary Storage

  • RAM: Stores all programs that are currently running. RAM also stores parts of the OS to be accessed by the CPU. RAM is volatile
  • ROM: Stores the boot program/BIOS for when the computer is switched on. The BIOS then loads up the operating system to take over managing the computer. ROM is non-volatile
• Volatile

  Data is lost when power is turned off
• Non-Volatile

  Data is saved in storage even when computer is not being powered
• Virtual Memory

  • If there is insufficient space in the RAM, the computer can use the Hard Disk Drive as an extension for RAM
  • If new data is needed to be stored in the RAM, then the unused data in the RAM is moved to the hard drive so the new data can be transferred into the RAM
  • When required, new data can be moved back from virtual memory into RAM. Using virtual memory allows users to run more programs simultaneously, with less system slow down
• Secondary Storage

  • Non-volatile storage used to save and store data that can be accessed repeatedly
  • Secondary storage is not directly embedded on the motherboard and so it is further from the CPU making it slower to access
• Storage Characteristics

  • Durability: The strength of the device
  • Capacity: The maximum amount of data that can be stored on the device
  • Portability: How easy it is to carry around
  • Access Speed: How quickly data on the device can be read/edited
  • Cost: The average price it costs to purchase the device
  • Reliability: The likelihood of the device continuing to perform well over time
• Common Types of Secondary Storage

  • Magnetic Storage: Large Capacity and Lower Cost compared to Solid State, Not Durable and Not Portable when power is on as it can damage the device, Slow Access Speed but faster than optical storage, Examples: Magnetic Tape, Floppy Disks
  • Optical Storage: Low Capacity, Not durable as discs are fragile and can break or be scratched easily, Discs are very Portable due to their thin size and are Cheap to buy in bulk, Have the slowest Access Speed, Examples: CD, DVD, Blu-ray
• Primary Storage

  Low-capacity, internal storage that can be directly accessed by the CPU
• Program instructions

  Must be copied from the hard drive into RAM to be processed by the CPU because primary storage access speeds are much faster than secondary storage devices such as the hard drive
• Types of Primary Storage

  • RAM
  • ROM
• RAM

  Stores all programs that are currently running. RAM also stores parts of the OS to be accessed by the CPU. RAM is volatile
• ROM

  Stores the boot program/BIOS for when the computer is switched on. The BIOS then loads up the operating system to take over managing the computer. ROM is non-volatile
• Secondary Storage

  Non-volatile storage used to save and store data that can be accessed repeatedly
• Secondary storage is not directly embedded on the motherboard and so it is further from the CPU making it slower to access
• Storage Characteristics

  • Durability
  • Capacity
  • Portability
  • Access Speed
  • Cost
  • Reliability
• Common Types of Secondary Storage

  • Solid State Storage
  • Magnetic Storage
  • Optical Storage
• Solid State Storage

  • High Capacity but More Expensive than magnetic
  • Durable, but USB sticks can snap/break
  • Very Portable as they are small
  • Highest Access Speed
• Magnetic Storage

  • Large Capacity and Lower Cost compared to Solid State
  • Not Durable and Not Portable when power is on as it can damage the device
  • Slow Access Speed but faster than optical storage
• Optical Storage

  • Low Capacity
  • Not durable as discs are fragile and can break or be scratched easily
  • Discs are very Portable due to their thin size and are Cheap to buy in bulk
  • Have the slowest Access Speed