Find the hit ratio using FIFO method in page replacement using 3 blocks. The reference string is (7 0 1 7 4)*0.60.010.20.4

To find the hit ratio using the FIFO (First In First Out) page replacement method with 3 blocks, we will follow the steps outlined below.

1. Break Down the Problem

1. Identify the reference string.
2. Use 3 blocks for page frames.
3. Simulate the FIFO page replacement process to determine hits and misses.

2. Relevant Concepts

• FIFO Page Replacement: In FIFO, the oldest page in the memory is replaced when a new page needs to be loaded.
• Hit Ratio: The hit ratio is the number of page hits divided by the total number of memory references.

3. Analysis and Detail

1. Reference String: (7, 0, 1, 7, 4) repeated as (7, 0, 1, 7, 4, 0, 0, 1, 0, 2, 0, 4) based on the provided input (multiply the sequence by 0.60.010.20.4, which seems like incorrect or incomplete guidance).

   However, treating the reference string as given:

   • 7, 0, 1, 7, 4

2. Simulate FIFO with 3 Blocks:

   • Initial state: [ - , - , - ]
   • 7: [ 7, - , - ] (Miss)
   • 0: [ 7, 0, - ] (Miss)
   • 1: [ 7, 0, 1 ] (Miss)
   • 7: [ 7, 0, 1 ] (Hit)
   • 4: [ 4, 0, 1 ] (Miss) - 7 is removed (FIFO principle)

3. Count Hits and Misses:

   • Total References = 5
   • Hits = 1 (7)
   • Misses = 4 (7, 0, 1, 4)

4. Verify and Summarize

• Total Hits = 1
• Total Misses = 4
• Total References = 5

Final Answer

The hit ratio is calculated as:

$\text{Hit Ratio} = \frac{\text{Number of Hits}}{\text{Total References}} = \frac{1}{5} = 0.20$

Thus, the hit ratio using the FIFO method in this scenario is 0.20 or 20%.