Memory organisation

• Memory –group of letters to arrays bis

• Type of memories

It is used to increase the apparent size of the physical memory. The assumption is the address generated by the processor directly specifies physical location in the memory but the data may be stored in the physical memory location that have addressed different from those specified by process. The memory control circuiting translated the address specified by program into an address that can be used to access physical memory. The address generated by the processor is known as virtual/ logic add.

It is mapped on the physical memory where data is actually stored.

Characteristic of memory system

1 Storage capacity- internal memory can be expressed in words or byte.

2 Unit of transfer –number of bits read or written in a single RD/WR oppreation.

3 Location

--> CPU--> registers ,control unit

--> Internal –> RAM , cache

--> external—> SM

4 Access mode

-RAM – sequential - direct -associative

• Random: individual address identify location can we access directly access time is independent of location (Ram)

• sequential :start at beginning and through in order access time-- depends on location

• direct :individual blocks have unique address and access is done by jumping to vicinity plus sequential Research and access time depends on location and previous location (disk)

• associated :data is collected by comparison with content of a portion of the storage access time is independent of location previous axis and constant (cache)