Comparing Different Types of Memories in Terms of Cost & Performance : The best way to measure the cost of a memory device is the purchase price of a complete unit of its. Let C be the price in dollars of a complete memory system with S bits of storage capacity. The cost c of the memory will be defined as follows,
The performance is determined by the rate at which data can be read or written from/ onto the device.When taking reading time the parameter will be called read access time. This will depend on the storage and access mechanism used by the device.
Low cost and high performance is always demanded. But these can not be obtained at once, as the performance will increase along with the cost and vice versa. Considering the following given figure. It indicates several types of memories arranged on a graph showing access time and cost at a time.
Here it can be seen that, faster memory RAM will take very little access time but with a higher cost. On the other hand slow storage medium magnetic tapes will cost a little. Thus based on the necessity one will have to choose the memories. Such as, main memories are attached with overall performance of the computer system, so one will have to have sufficient RAM in one’s system. When considering for secondary memory, based on necessity of the user that is if the user is in a need to store huge amount of data he will have to choose magnetic disks is large amount. On the other hand for the use of safe removal storage the optical disks are great choice.
So the comparison concludes that the better performance will demand greater cost and vice versa. But one thing that should be kept in mind that main and secondary memory should be chosen differently as because main memory serves the processor to perform where the secondary memory will serve the user for storage.