Modern computers employ a hierarchy of storage devices which may be broadly divide into two categories: ‘primary’ and ‘secondary’ systems. The CPU is the heart of the computer. It normally contains an arithmetic/logic unit, control unit and primary storage.
Primary storage refers to systems from which the processor is able to directly read instructions and data, and to which it is able to directly return the results of it compilation.
Primary storage or main memory is used to hold piece of programs, instructions and data that the computer is currently processing. However, the primary storage can hold information only while the computer system is on. Both main memory (RAM) and cache memory represents forms of primary storage device.
Since the mid-1980s, the primary storage device used by computers has been the hard disk drive. The limitation of primary storage is costly and volatile in nature – where the data are lost when the electricity is interrupted or computer is switched off. Another limitation of primary storage is that the storage requirements for programs and data on which it operate exceeds the capacity of a primary storage in all computer systems.
Primary storage
