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

A part of the system software, which under all circumstances must reside in the main memory is:

The details of an interrupt cycle are shown in Figure
Given that an interrupt input arrives every $$1$$ $$msec,$$ what is the percentage of the total time that the $$CPU$$ devotes for the main program execution.