Suppose in the First Come First Served Disk Scheduling Algorithm the order of request is (90, 150, 50, 140, 30, 20) and the current position of read/write head is 40, then the total distance covered by the disk ann would be

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Beltron Programmer 1 Oct 2023 Official Paper

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Answer 1

The correct answer is Option 3) 520.

Key Points

First Come First Served (FCFS) Disk Scheduling Algorithm serves the requests in the order they arrive.
Given:
- Initial head position = 40
- Request queue = (90, 150, 50, 140, 30, 20)
We calculate the total distance moved by the disk head step-by-step:

Additional Information

FCFS Characteristics:
- Simple to implement
- Processes requests in the order of arrival
- Does not optimize seek time
Other disk scheduling algorithms:
- SSTF (Shortest Seek Time First): Chooses the request closest to current head position
- SCAN: Moves head in one direction, servicing requests in order until end is reached, then reverses
- LOOK: Like SCAN, but stops at last request instead of going to the end of disk