Memory Unit: It stores the programs and data. There are 2 types of storage classes Primary, Secondary

It is a fast memory that operates at electronic speeds.
Programs must be stored in the memory while they are being executed. The memory contains large no of semiconductor storage cells. Each cell carries 1 bit of information. The Cells are processed in a group of fixed size called Words. To provide easy access to any word in a memory,a distinct address is associated with each word location. ddresses are numbers that identify successive locations. The number of bits in each word is called the word length. The word length ranges from 16 to 64 bits. There are 3 types of memory. They are RAM(Random Access Memory)
Cache memory ,Main Memory

Memory in which any location can be reached in short and fixed amount of time after specifying its address is called RAM. Time required to access 1 word is called Memory Access Time.

The small,fast,RAM units are called Cache. They are tightly coupled with processor to achieve high performance.

The largest and the slowest unit is called the main memory.

 

Secondary Storage is used when large amount of data and many programs have been stored in frequently.