6th Sem Notes By Irfan Rehman.

1. Memory Mappings in Cache
Architecture
Direct, Associative, and Set-
Associative Mapping
Your Name | Date | Course Info

2. Introduction
• Why Memory Mapping?
• - Improves access speed between CPU and
main memory.
• - Determines how cache memory stores and
retrieves data.

3. What is Cache Memory?
• Cache is a fast, small memory close to the
CPU.
• It stores copies of frequently accessed data.
• Memory mapping determines where data is
stored in the cache.

4. Direct Mapping
• Definition: Each block of memory maps to only
one possible cache line.
• Formula: Cache index = (Block address) MOD
(Number of lines)
• Pros: Simple, fast
• Cons: High conflict rate

5. Associative Mapping
• Definition: Any block can go into any cache
line.
• Search Method: Entire cache is searched using
tags.
• Pros: No conflict misses
• Cons: Slower and complex

6. Set-Associative Mapping
• Definition: Cache is divided into sets with
multiple lines each.
• k-way Set Associative: A block maps to one set
and any line in it.
• Pros: Balanced approach
• Cons: Moderately complex

7. Comparison Table
• Feature | Direct | Associative | Set-
Associative
• ------------------|------------|-------------|--------------
---
• Speed | Fastest | Slowest |
Moderate
• Flexibility | Low | High | Moderate
• Complexity | Low | High | Medium
• Conflict Miss | High | None | Low

8. Real World Use
• - Direct Mapping: Embedded systems
• - Associative Mapping: Research and
performance-critical parts
• - Set-Associative Mapping: Most modern CPUs

9. Conclusion
• - Mapping strategy depends on system needs
• - Set-Associative provides best balance
• - Critical for efficient cache utilization