title: Page table entries in Virtual Memory
body: <p>I have a simple question regarding page table entries. Suppose that we are given a 32 - bit Virtual address with 4 KiB page and a physical memory size of 2^28 bits. </p>
  
  <p>Since the page offset is 12 bits, we would have 2^20 page table entries which would be mapped to 2^16 physical frames. But how is it possible for 2^20 entries to map to 2^16 entries. There would run out of physical frame addresses. Suppose that the process uses the full 2^20 pages, then assuming that the whole RAM consists of memory from only this process, all the 2^16 frames in the RAM would contain this processes memory. Am i right to say that 2^4 of the page table entries would show that it maps to disk ?</p>
  
  <p>Also, if the process uses only one page table, then the remaining 2^20 - 1 page table entries would be invalid ? </p>