The algorithm which replaces the block which has not been referenced for awhile is called ……… ans. Random Replacement FIFO Optimal Page Replacement LRU

Break Down the Problem

1. Identify the algorithm being described in the question.
2. Recognize characteristics of each option provided.

Relevant Concepts

1. Random Replacement: Replaces a page at random.
2. FIFO (First In First Out): Replaces the oldest page in memory.
3. Optimal Page Replacement: Replaces the page that will not be used for the longest period in the future.
4. LRU (Least Recently Used): Replaces the page that has not been used for the longest period of time.

Analysis and Detail

• The question specifies "replaces the block which has not been referenced for awhile," which indicates that the algorithm focuses on the recently used status of pages.
• The LRU algorithm fits this description, as it tracks page usage and replaces the one that was least recently used.

Verify and Summarize

• Lifespan of Pages: LRU takes into account how recently pages have been accessed, making it suited for the description given.
• Looking at the other options, FIFO and Random Replacement do not specifically consider the time since last reference, and Optimal Page Replacement is primarily future-based, not historical.

Final Answer

The algorithm which replaces the block which has not been referenced for awhile is called LRU (Least Recently Used).