This Mano book seems to be more trouble than it's worth. Since the choice of course books is yours to make, can I recommend you shred this one and get something that actually explains things clearly without leaving you confused?


As I understand it a page fault is when the CPU tries to access something that was loaded into RAM but that has since been moved out to the page file.

So 6 is not a page fault because it hasn't been loaded into memory yet.

...a penny drops...

...that is, UNLESS 1-7 are pages that have been loaded into memory by previous operations, and that memory has been cleared (for example by 8 being loaded into memory and taking up all four pages, thus swapping all 1-7 out to swapfile). In that case then not only will 6 be a page fault but the preceding requests for 3, 2, 1, 5 (not 3 because it's already in RAM) will also be page faults.

So the answer to your opening question, now I know the full context, is Yes,

and in effect the complete sequence you're asking about is 1-7 iin whatever order, then the hypothetical 8a 8b 8c 8d, unload 8* (so RAM clear at this point), *THEN* 3, 2, 1, 5, 3, 6, 2, 1, 7, 4, 6, 2, 4.