Question 6880 – Operating-Systems

An operating system supports a paged virtual memory, using a central processor with a cycle time of one microsecond. It costs an additional one microsecond to access a page other than the current one. Pages have 1000 words, and the paging device is a drum that rotates at 3000 revolutions per minute and transfers one million words per second.Further, one percent of all instructions executed accessed a page other than the current page. The instruction that accessed another page, 80% accessed a page already in memory and when a new page was required, the replaced page was modi ed 50% of the time. What is the effective access time on this system, assuming that the system is running only one process and the processor is idle during drum transfers?

Correct Answer: B