Short attention span: a. Once the operating system identifies a page to remove from memory, what must be done before the frame in which the page is stored can be reused?

b. At one time, virtual memory system designers were advised to bias page replacement algorithms against modified pages in favor of those that have not been modified. The result of this suggestion was the unfortunate behavior of program code pages (which tend to be some of the only pages that are not modified) being kicked out of memory before other pages. Describe the rationale for the original suggestion of paging unmodified pages first.

c. Consider a fixed partitioning scheme with equal-size partitions of 216 bytes and a total main memory size of 224 bytes. A process table is maintained that includes a pointer to a partition for each resident program. How many bits are required for the pointer? Justify your answer.