Storage unit or Primary/main storage of a computer system is designed to store data and instructions so that they are available for processing as and when required. It provides space for storing data and instructions, space for intermediate results and also space for finall results.
Thus the main function of storage unit are −
To hold all data to be processed and instructions required for processing.
To store intermediate results of processing.
To store final results of processing before these results are released to output device.