UNIVERSITY OF HOUSTON
                 Department of Computer Science
          COSC 4330--Fundamentals of Operating Systems
                        FINAL EXAMINATION
                          May 16, 1994

This exam is closed book.  You can have one sheet of notes.

1.   A computer has 64 bit addresses and a virtual memory with  a
     page size of 4 Kbytes. (2X5 points)

     (a)  What is the maximum number of pages per process?

     (b)  How many bits are used to represent the page number ?

2.   What are the two major disadvantages of having a small  page
     size?  (2X5 points)

3.   Berkeley UNIX page replacement policy uses the valid bit  to
     simulate  an  non-existent page referenced bit.  What is the
     disadvantage of this  approach?   How  does  it  affect  the
     overall  system  performance?   (2X5 points) 

4.  How does VMS store (a) the system page table (5 points) and (b)
    user process page tables (10 points)?

5.   Which of the following statements apply to these  four  page
     replacement policies:

     FIFO, LRU, Clock, Denning's Working Set

     provides terrible performance:

     utilizes a page referenced bit:

     cannot be implemented efficiently:

     warns when the memory is overutilized: (20 points)

6.   What are the major advantage and the major  disadvantage  of
     UNIX delayed write policy? 2X5 points)

7.   What is an access control list? (5 points)   How  does  UNIX
     organize the access control lists of its files? (10 points)

8.   A UNIX file system has a block size of 2X5 points):

     (a)  using the block addresses stored in the i-node?

     (b)  with one additional level of indirection?


--IMPORTANT----IMPORTANT----IMPORTANT----IMPORTANT----IMPORTANT--
Please do not try to answer these questions by yourself BEFORE
having a clear idea of what's on the test for which you are
studying.

Materials covered in each test DO VARY from semester to semester
because the pace of the course can change, some materials are be
added and other deleted almost every semester.
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