What is primary, secondary and tertiary storage device?
Historically, memory and storage were respectively called primary storage and secondary storage. Primary storage, presently known as memory, is the only one directly accessible to the CPU. The CPU continuously reads instructions stored there and executes them. Any data actively operated on is also stored there in uniform manner. Secondary storage, or storage in popular usage, differs from primary storage in that it is not directly accessible by the CPU. Tertiary storage or tertiary memory, provides a third level of storage. Typically it involves a robotic mechanism which will mount (insert) and dismount removable mass storage media into a storage device according to the system’s demands; this data is often copied to secondary storage before use.
