The memory storage device are of two types basically one is the primary memory which is a must in any computer system and the other is the secondary memory. The primary memory is also known as the temporary memory as it cannot hold the data when there is any a kind of disruption of power services. The primary memory is the volatile memory. This means that if the power is switched off or there is a power failure then the data in it is all lost. This is the temporary memory. The other one is the secondary memory or the hard disk, floppy disk or the CD, DVD discs etc. there are called as the non volatile memories or the permanent storage devices. The RAM is the example of the primary memory or the temporary storage media.

The temporary storage device stores the data only for a period of time. The primary memory or the main memory is a must in any computer system. The primary memory is initiated as soon as the computer is booted. The RAM may be of two types one is the Static RAM and the other is the Dynamic RAM. It is this memory that is actually recognized by the Ms DOS operating system as the base memory. This starts right from the base address.

The read mode is restricted to access only 1 mega bytes of the memory. Consider the booting up of the DOS operating system. The DOS as it boots up the machine, it occupies the first few locations of the base memory or the main memory for the storage of the DOS resident commands or the programs. It is also used for the storage of the vector address of the interrupt routines. After the system gets boot-up, the memory available within the area is called conventional memory. This is the memory that is available for the user to execute the programs. The area of the memory above the conventional memory is called as the upper memory area or the UMA. It is also referred to as the expanded memory. This memory is reserved for the usage of the memory that is reserved for the special use by the BIOS ROM, video and the other hardware devices like the display cards etc. Some of the memory above the conventional memory is empty and some is filled with the RAMs that are used by the adapters of the video terminals and some are filled with the ROMs that contain the low level drivers such as the hard disk controllers, LAN adapters, video adapters etc.

The memory area which is dedicated to the particular device RAMs and the ROMs are called as the reserved memory area. The expanded memory is a system of paging memory within the conventional memory by using the block of memory as a page frame in the expanded memory area. A page frame is an area of the memory map where the expanded pages can be switched in and switched out.

The EMS – Expanded Memory Specification is an alternative definition of the Lotus Intel Microsoft (LIM) standard. The RAM is now available starting from as low as 32 mega bytes to 2 giga bytes. The major manufacturers of the RAM are the Hyundai, and the Hynix. There are also some other brands that are available. This is the most fragile part of the computer that should be handled with care. They certainly increase the speed and the performance of the system.

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