05-12-2012, 01:32 PM
MEMORY ORGANIZATION
MEMORY.ppt (Size: 484.5 KB / Downloads: 21)
Main memory
Large , fairly fast external memory stores programs and data.It is physically separated from the CPU.
Access time is slower because of main memory’s large capacity and is physically separated from the CPU.
Secodary Memory
Much larger in capacity but also much slower than main memory.
Stores system programs ,large data files
Cache Memory
It is positioned between the CPU Registers and main memory .
It is faster in access speed but its storage capacity is less than that of MM.
It is much faster than MM because some or all of it can reside on the same IC as the CPU.
Random Access Memories
A storage unit is composed of a large number of addressable locations.
Each location stores a w bit word.
The address of the memory location to be accessed is transferred via the address bus to the address buffer.
The address is processed by the address decoder, which selects the required location.
The control line indicates the type of the operation to be performed – read or write
Cache and virtual memory
The cache memory and main memory resemble a single memory M to the software being executed.
Virtual memory is applied when the main memory and secondary memories appear to the user program like a single large memory.