UNIVERSITY OF SOMALIACollage of computer science & IT

Computer Organization

CACHE MEMORYTIME IS MONEY -- THE FASTEST MEMORY EVER

Lecturer: Eng Ahmed Ali Ahmed

WEE

K 8

Gmail:hormuud612@gmail.

01-01-2016

Friday8th class

CS13

Mohamed-Nur Hussein Abdullahi Hame

OUTLINE• CACHE MEMORY PRINCIPLES

– Cache Memory Principles• ELEMENTS OF CACHE DESIGN

– Cache Addresses– Cache Size– Mapping Function– Replacement Algorithms– Write Policy– Line Size– Number of Caches

CACHE MEMORY PRINCIPLES

• Small amount of fast memory• Sits between normal main memory and CPU• May be located on CPU chip or module

CACHE MEMORY PRINCIPLES

• Cache memory is intended to give memory speed approaching that of the fastest memories available

• At the same time provide a large memory size at the price of less expensive types of semiconductor memories.

• The cache contains a copy of portions of main memory.

CACHE/MAIN MEMORY STRUCTURE

CACHE OPERATION – OVERVIEW

• CPU requests contents of memory location• Check cache for this data• If present, get from cache (fast)• If not present, read required block from main

memory to cache• Then deliver from cache to CPU• Cache includes tags to identify which block of

main memory is in each cache slot

CACHE READ OPERATION

TYPICAL CACHE ORGANIZATION

TYPICAL CACHE ORGANIZATION

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