This document discusses cache memory principles and design. It explains that cache memory sits between the CPU and main memory to provide fast access to frequently used data. Cache memory is smaller and faster than main memory. When the CPU requests data, the cache is checked first. If the data is present, it is retrieved from the cache. If not, the block containing the data is copied from main memory into the cache before being sent to the CPU. The cache uses tags to identify which blocks of main memory correspond to each block in the cache.

1. UNIVERSITYOF SOMALIA
Computer Organization
CACHE MEMORYTIME IS MONEY -- THE FASTEST MEMORY EVER
Lecturer: Eng Ahmed Ali Ahmed
WEEK8
Gmail:hormuud612@gmail.
Friday
Mohamed-Nur Hussein Abdullahi Hame

2. 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

3. CACHE MEMORY PRINCIPLES
• Small amount of fast memory
• Sits between normal main memory and CPU
• May be located on CPU chip or module

4. 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.

5. CACHE/MAIN MEMORY STRUCTURE

6. 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

7. CACHE READ OPERATION

8. TYPICAL CACHE ORGANIZATION

9. TYPICAL CACHE ORGANIZATION

10. THANKS FOR LISTENING
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