Cache memory.12


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Cache memory.12

  1. 1. Cache Memory 1
  2. 2. Objective:On completion of this period, you would be able to understand: Cache memory used in computers. 2
  3. 3. Recap: What is meant by memory ? A space to keep information. It stores program, data results or any kind of information. 3
  4. 4. Cache Memory The word cache is pronounced as cash. Cache memory is placed between the CPU and the main memory. It stores instructions and data which are to be currently executed by the CPU. 4
  5. 5. Cache Memory (contd...)It is a semiconductor memoryIt is not accessible to users i.e. informationcannot be written into cache memory by users.It increases the speed of the computer up to15%. 5
  6. 6. Cache Memory (contd...) It consists of static RAMs. Its access time is 10ns which is much less than that of the main memory i.e. 50ns 6
  7. 7. Memory Hierarchy with cache memory Cache Primary SecondaryCPU Memory Memory Memory 7
  8. 8. Types Of Cache SchemesWrite-throughWrite-back 8
  9. 9. Write-through Cache memory is updated each time when the CPU writes into the cache. The advantage of the write through cache is that the main memory always contains the same data as the cache contains. 9
  10. 10. Write-back Only the cache memory is updated during a write operation. The updated locations in the cache are marked by flags so that later on when the word is removed from cache, it is copied into the main memory. 10
  11. 11. Write-back (contd) The words are removed from the cache time to time to make room for a new block of words. 11
  12. 12. Level of Cache Memory1. First level cache (L1).2. Second level cache (L2).3. Third level cache (L3). 12
  13. 13. Cache memory is placed at two or three levels (contd) The resident cache is called Level – L1 (internal). In addition to the cache memory built into the CPU, cache is also added to the motherboard. This motherboard- resident cache is often called Level – L2 (external). 13
  14. 14. Cache memory is placed at two or three levels (contd) Some computers contain L1 and L2 within the microprocessor. Cache memory within the processor is called internal cache. The cache outside the processor is called external cache. 14
  15. 15. Summary:In this class, we have learnt about  About cache memory. Levels of cache memory used in computers. 15
  16. 16. Frequently Asked Questions1. What is a Cache Memory?2. Explain levels of cache memory? 16
  17. 17. Quiz:1. Cache memory within the processor is called internal cache? a. Yes b. NoAnswer: a 17
  18. 18. Quiz:2. Cache consists of a. static RAMs. b. dynamic RAMsAnswer: a 18
  19. 19. Quiz:3. Cache is a a. magnetic memory b. semiconductor memory.Answer: b 19