Primary StoragePrimary storage, sometimes called primary memory or main memory, stores data and program instructions that needs to be accessed immediately by the Central Processing Unit (CPU). It is normally the Random Access Memory (RAM) of the computer and is retrieved by the CPU at the rate of 1-8 bytes at a time. The CPU cannot store or retrieve data from secondary storage because data on secondary storage is retrieved in bigger chunks, normally retrieved from 512 to 65536 bytes at a time, so data on secondary storage is usually written to primary memory and then used by the CPU. When it is time to save data or program instructions to secondary storage, the data/program instructions are stored to the device in big chunks again.
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Secondary StorageSecondary storage, also known as auxiliary storage, is external storage that holds information, data and program instructions and can also be used for backing up data and programs. Types of secondary storage include: USB flash drives, hard drives, floppy disks and magnetic tape. Secondary storage is generally cheaper than primary storage but is "slower in both read and write access." Secondary storage cannot be accessed directly by the CPU so the data must be first loaded into primary memory and then is sent to the processor. The RAM, the primary memory mentioned above, plays an important transitional role as it provides "faster data access speeds." Even though secondary storage is much slower than primary storage, it offers a greater storage capacity.
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