LRU Replacement Policy in Fully Associative Cache

In a fully associative cache, each cache block can store any memory block from the main memory. The cache blocks are not assigned to specific memory locations, allowing for flexibility in mapping memory blocks to cache blocks.

The LRU (Least Recently Used) replacement policy is used in fully associative caches to determine which cache block to replace when a new memory block needs to be loaded into the cache. This policy replaces the cache block that has been accessed least recently.

Given Information:
- Fully associative cache with 8 cache blocks numbered from 0 to 7.
- Sequence of memory block requests: 4, 3, 25, 8, 19, 6, 25, 8, 16, 35, 45, 22, 8, 3, 16, 25, 7

Steps to Find the Cache Block for Memory Block 7:
1. Initially, all cache blocks are empty.
2. When a memory block is requested, we check if it is already present in the cache.
3. If the memory block is present, it is a cache hit, and the cache block containing the memory block is considered the most recently used.
4. If the memory block is not present, it is a cache miss, and we need to replace a cache block with the requested memory block.
5. In LRU policy, the cache block that has been accessed least recently is replaced.
6. We keep track of the order of memory block accesses to determine the least recently used cache block.
7. Let's go through the sequence of memory block requests and track the cache blocks.

Sequence of Memory Block Requests:
1. Request for memory block 4: Cache miss. Cache block 0 is filled with memory block 4.
Cache: [4, -, -, -, -, -, -, -]
2. Request for memory block 3: Cache miss. Cache block 1 is filled with memory block 3.
Cache: [4, 3, -, -, -, -, -, -]
3. Request for memory block 25: Cache miss. Cache block 2 is filled with memory block 25.
Cache: [4, 3, 25, -, -, -, -, -]
4. Request for memory block 8: Cache miss. Cache block 3 is filled with memory block 8.
Cache: [4, 3, 25, 8, -, -, -, -]
5. Request for memory block 19: Cache miss. Cache block 4 is filled with memory block 19.
Cache: [4, 3, 25, 8, 19, -, -, -]
6. Request for memory block 6: Cache miss. Cache block 5 is filled with memory block 6.
Cache: [4, 3, 25, 8, 19, 6, -, -]
7. Request for memory block 25: Cache hit. Cache block 2 is considered the most recently used.
Cache: [4, 3, 25, 8, 19, 6, -, -]
8. Request for memory block 8: Cache hit. Cache block 3 is considered the most recently used.
Cache: [4, 3, 25,