A simple two-pass assembler does the following in the first pass:

The following page addresses, in the given sequence, were generated by a program:
1 2 3 4 1 3 5 2 1 5 4 3 2 3

This program is run on a demand paged virtual memory system, with main memory size equal to $$4$$ pages. Indicate the page references for which page faults occurs for the following page replacement algorithms.
(a) $$LRU$$
(b) $$FIFO$$

Assume that the main memory is empty initially.

A certain moving arm disk storage, with one head, has the following specifications.
Number of track/recording
Surface $$=200$$
Disk rotation speed $$=2400$$$$rpm$$
Track storage capacity $$=62,500$$ $$bits$$
The average latency of this device is
$$P$$ $$msec$$ and the data transfer rate is
$$Q$$ $$bits / sec.$$ Write the value of $$P$$&$$Q$$

The root directory of a disk should be placed: