UNIVERSITY OF HOUSTON
                 Department of Computer Science
                                
           COSC 4330_Fundamentals of Operating Systems
                       MIDTERM EXAMINATION
                          March 1, 1995

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

1.              For each of the statements below, indicate in one
     sentence  whether the statement is true or false (2 points),
     and why (3 points).
     
     (a)  It  is  a  good  idea  to  assign  priorities  to
          interrupt requests.
     
     (b)  Busy  waits should be avoided because they  waste
          CPU cycles.
     
     (c)  A  UNIX process shares the address space  of  its
          parent.
          
     (d)  Every  system call occasions at least two context
          switches.
          
2.   What is the major difference between a monolithic kernel
     and  a microkernel? (5 points)  What is  the  major
     advantage of microkernels over monolithic kernels?(5 points)

3.   On  a process state diagram with all seven states properly  
     labeled  (5 points), explain all  the  transitions involving
     the  waiting_suspended  state   (that   is   all transitions
     coming from that state and all transitions going to that state)
     (15 points)

4.   What is the difference between user-level threads and 
     kernel-supported threads? (5 points) What is the  major
     disadvantage  of user-level threads? (5 points)   What  does
     AMOEBA do to solve this problem? (5 points)

5.   Using  the  round-robin scheduling policy  as an example           
     explain the trade-off between the two objectives of minimizing
     the  response  time  of  interactive  jobs   and maximizing the
     overall throughput of the system. (10 points)

6.   What is the difference between blocking sends and non-blocking 
     sends?  (5 points)   Which  ones   do  require
     buffering?  ( 5 points)  Which ones are the most  frequently
     utilized and why? (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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