Some of them are inside CPU, which are known as register. Other bigger chunk of storage space is known as primary memory or main memory. The CPU can work with the information available in main memory only.

To access the data from memory, we need two special registers one is known as Memory Data Register (MDR) and the second one is Memory Address Register (MAR).

Data and program is stored in main memory. While executing a program, CPU brings instruction and data from main memory, performs the tasks as per the instuction fetch from the memory. After completion of operation, CPU stores the result back into the memory.

In next section, we discus about memory organization for our small machine.