Difference between Primary Memory and Secondary Memory


Primary Memory: Primary memory is considered as the main memory of the computer system. Data and information are stored here as an internal storage. So frequently used programs can be fast accessed through primary memory. Primary memory is a volatile memory which means a when is a power failure occurs, data residing in this memory does not exist if it is not saved RAM, ROM, PROM, registers etc are examples of primary memory.

Secondary Memory: Secondary memory is considered as the external memory of the computer where data and information can be stored on a long-term basis. Here, at first data is transferred into main memory and after that it is transferred into main memory unit. Secondary memory is a non volatile memory which means when a power failure occurs, data residing in this memory remains intact. All external devices which are capable of storing high volumes of data are considered as secondary memory. Examples are hard drives, floppy disks, magnetic tapes, CDS etc.


Primary Memory Secondary Memory
1. CPU/Processor can directly access primary memory. 1. CPU cannot directly access secondary memory.
2. It is considered as main memory or internal memory. 2. It is considered as auxiliary memory, external memory or secondary memory.
3. Primary memory is temporary &volatile memory. 3. Secondary memory is permanent & non-volatile in nature.
4. Currently executing data or instructions are directly copied to the main memory. 4. Currently executing data can be permanently stored in secondary memory.
5. Data access is faster in primary memory. 5. Data access is slower in secondary memory.
6. Primary memory is often costlier/expensive than secondary memory. 6. Secondary memory is budget friendly than primary memory.
7. Primary memory is smaller in size. 7. Secondary memory is larger in size.
8. Primary memory is being executed by data bus. 8. Secondary memory is being executed by input-output channels.
9. Primary memory forms from semiconductors. 9. Secondary memory forms from magnetic and optical materials.
10. Capacity of primary memory is usually in 16 to 32 GB. 10. Capacity of secondary memory is usually from 200GB to terabytes.
11. In case of power failure data residing in primary memory does not exist. 11. In case of power failure data residing in secondary memory remains intact.
12. Slots can connect primary memory devices with the compiler. 12. Cables can connect secondary memory devices with the compiler.
13. Examples of primary memory are RAM, ROM, Cache memory, PROM, EPROM, Registers etc. 13. Examples of secondary memory are HDD, CD, Floppy disks, DVD, flash drives, magnetic tapes etc.
14. Storage capacities are limited in primary memory. 14. Storage capacities are scalable in secondary memory.


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Contributed By: Romana Rahman Ema