COSC 4330                    FINAL       Name: _______________________

                                  
Closed Book.   You can have one sheet of notes.

1.   Answer the following questions in one or at most two sentences:
     (6*5 points)

     a)   What is the purpose of the dirty bit in virtual memory systems?
          
     b)   What is the major disadvantage of linked allocation for storing
          file blocks on disk?

     c)   What is the difference between little endian and big endian
          computer architectures?
          
     d)   Give one example of starvation without deadlock.

     e)   What is the major disadvantage of letting the kernel handle TLB
          misses?
          
     f)   What is the major limitation of semaphores?

2.   A computer has 256 Megabytes of main memory, 32 bit addresses and
     a page size of two kilobytes.  (2*5 points)
     a)   How many page frames are there in main memory? 
     
     b)   On the average, how much memory is lost to internal
          fragmentation?
          
          __________________________  per process
          
3.   Explain why deadlocks occurring in client/server systems cannot
     be prevented. (5 points)
     
4.   Describe the page replacement policies of VMS and Mach. (10
     points)  What are their respective strong points (2*5 points)

5.   Explain the differences between an access control list and a ticket
     (2*5 points) and give examples of both in the UNIX file system.
     (2*5 points)

6.   What is thrashing and what should we do to avoid it? (10 points)
     
7.   What is the difference between a notify and a signal? (5 points)

--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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