Clock policy is a page replacement algorithm. It requires an additional bit with each frame, as the use bit.

When a page is first loaded into a frame in memory, the use bit is set to $1.$ Whenever the page is subsequently referenced, its use bit is set to $1.$ When a page is placed, the pointer is set to the next frame after the one just updated. When to replace a page, the operating system scans the cache to find a frame with use bit $0.$ Each time it encounters a frame with use bit $1,$ it reset that bit to $0$ and continues.

Consider the following string of page references: a ded beed be fe a fe c a de$.$ The main memory can contain FOUR frames. Show the detailed frame allocation using Clock policy. $(20$ points$)$

Use $*$ as the use bit $1.$ Use $>$ as the pointer. Mark F as the page fault.