Non Volatile
Retains data when the power is lost – Example ROM
Volatile
All information in the main memory is lost when power is lost. Examples RAM, Cache, Registers
RAM
Random Access Memory – Stores programs and data currently in use. Volatile Memory that can be read from and written to. Instructions are loaded into RAM from secondary storage
ROM
Read Only Memory – Non-Volatile Memory that can be read but not written.
Cache
Used to store frequently used data close to the CPU – the capacity of cache is not enough to store both programs and data.
Virtual Memory
Used as extra RAM, when the RAM is full. Stored on secondary storage
What is Secondary Storage?
Non-Volatile External data storage used to store data so that the computer can be switched off. This will be a Hard Disk Drive, a Solid-State Drive or Optical Disk.
What is Cloud Storage?
Uses magnetic, and increasingly solid state, storage at a remote location, backed up by the host. Users can access their data anywhere with an internet connection.
What is Magnetic Storage (HDD)?
Binary data is represented as magnetised dots representing 1’s and 0’s. Read write head moves to read/write data on block at a time. The platter (disk) spins around.
What is HDD Storage?
Traditional internal storage for PC’s and laptops that stores data magnetically.
What is an Optical Disk?
Disk rotates, Laser head moves across the disk and shines onto it. Laser burns pits and lands to store data (1’s & 0’s) in a spiral track onto the disk.
What is Optical Storage?
CD’s or DVD’s that can be written to and read from.
What is a Solid State Drive?
Uses flash memory with no moving parts, meaning it is robust & portable.
SSD’s degrade over time and have a limited number of read/write cycles.
What is Flash Storage?
Uses flash memory, examples include SSD, USB flash drive, SD card.
What is Local Storage?
Storage that is local to the computer system. EG: internal hard drive.
