UNIVERSITY OF HOUSTON
                 Department of Computer Science
                                
                  COSC 6360--Operating Systems
                       MIDTERM EXAMINATION
                          March 8, 1996
                                
This exam is closed book.  You can have two sheets (i.e., four
pages) of notes.

1.   What are clustered page tables?  (5 points)  What is their
     major advantages over the traditional page table organizations?
     (2×5 points)  How do they interact with the TLB miss handling
     software? (5 points)

2.   What was the major reason for introducing symbolic links in
     Berkeley UNIX? (5 points)

3.   Describe the organization of Mach's address map? (10 points)

4.   What is the major purpose of Mach external pagers?  (5 points)

5.   What are the major functions of the two following MULTICS
     data structures:

     a)   active segment table (5 points)?  
 
     b)   known segment table? (5 points)

     THIS QUESTION WAS RELATED TO A PAPER THAT IS NOT ANYMORE IN THE
     READING LIST.  IT WILL BE NOT BE ASKED AGAIN.

6.   What did Babaoglu and Joy do to overcome the lack of a page
     referenced bit on the VAX? (5 points)  What was then the
     major drawback of their approach?  (5 points)  Is this issue
     still important today?  (5 points)

7.   How does MULTICS implement intersegment linking?  (5 points)
     What was the special problem raised by the linking of procedure
     segments?  (5 points)

     THIS QUESTION WAS RELATED TO A PAPER THAT IS NOT ANYMORE IN THE
     READING LIST.  IT WILL BE NOT BE ASKED AGAIN.

8.   According to Satyanarayanan et al., what was the main reason
     for insulating the recoverable virtual memory from the virtual
     memory subsystem?  (5 points)  What price did they have to pay
     for this decision?  (5 points)

9.   According to Anderson et al., what are the two significant
     inherent costs to managing threads in the kernel? (2×5 points)

10.  What are the purpose of the alternative command  in CSP?
     (5 points)?