UNIVERSITY OF HOUSTON
                 Department of Computer Science
                                
                  COSC 6360--Operating Systems
                       MIDTERM EXAMINATION
                          March 9, 1999
                                
     This exam is closed book.  You can have two sheets (i.e., four
     pages) of notes.

1.   UNIX is said to be a system using the toolkit approach.
     Why? (5 points)  What feature of the UNIX file system made that
     possible? (5 points)

2.   How would you simulate a page-referenced bit on an
     architecture lacking it but having (a) a missing bit set to one
     when the page is not in main memory and (b) an x bit in the page
     table that you can use as you want?  Be specific. (10 points)

3.   Compare and contrast the page replacement policies of VMS
     and Mach. (10 points).  Which one is the best suited for UNIX and
     why? (5 points)

4.   What are shared libraries? (5 points)   What is their major
     advantage?(5 points)
 
5.   What is partial-subblocking? (5 points)  What is its major
     advantage? (5 points)  Describe in some detail page table
     organization that would support partial-subblaocking with a
     blocking factor of 8? (10 points:  you will loose five points if
     your answer does not include a diagram)

6.   What is the difference between eager release and lazy
     release consistency? (10 points)

7.   Compare and contrast the ways Munin and Treadmarks interact
     with the underlying operating system. (10 points)

8.   What is the main purpose of a shuttle in the Spring Kernel?
     (5 points)

9.   What are the two basic components of an exokernel based
     system? (2×2 points)  What are their major functions?  (2×3
     points)