Differentiate between the characteristics of Primary and Secondary storage of a computer system.

The primary storage also known as main memory, is used to hold pieces of program instructions and data, intermediate result of processing and recently produced results of processing of the jobs which the computer system is currently working on. These pieces of information are represented electronically in the main memory chips circuitry and while it remains in the main memory, the CPU can access it directly at a very fast speed. However, the primary storage can hold information only while the computer system is on. As soon as the computer system is switched off, the information held in the primary storage disappears. Moreover, the primary storage normally has limited storage capacity, because it is very expensive. The primary storage of modern computer systems is made up of semiconductor devices.

Whereas, the secondary storage also known as auxiliary storage, is used to take care of the limitations of the primary storage. That is, it is used to supplement the limited storage capacity and the volatile characteristic of primary storage. This is because secondary storage is much cheaper than primary storage and it can retain information even when the computer system is switched off. The secondary storage is normally used to hold the program instructions, data and information of those jobs on which the computer system is not working on currently, but needs to hold them for processing later. The most commonly used storage medium is the magnetic disk.