We have already mentioned that digital computer works on stored programmed concept introduced by Von Neumann. We use memory to store the information, which includes both program and data.

Due to several reasons, we have different kind of memories. We use different kind of memory at different lavel.

The memory of computer is broadly categories into two categories:

• Internal and
• external

Internal memory is used by CPU to perform task and external memory is used to store bulk information, which includes large software and data.

Memory is used to store the information in digital form. The memory hierarchy is given by:

• Register
• Cache Memory
• Main Memory
• Magnetic Disk
• Removable media (Magnetic tape)