COSC 4330                      QUIZ #2                  April 10, 1996

CLOSED BOOK.  You can have one sheet of notes.

1.   A pizza oven can contain twelve pizzas but the oven narrow
     opening allows only two cooks at a time to either put a pizza in 
     the oven or to take one out.  Given that there can be more than 
     two cooks preparing pizzas at any given time, complete the 
     missing lines in the following C procedure: (40 points)
          
          semaphore oven   = ______; // specify the initial value
          semaphore access = _______; // specify the initial value
          
          make_pizza(int size, int toppings)
          {
               prepare_dough(size);
               add_toppings(toppings);
               ______________________________________
               put_into_oven();
               ______________________________________
               wait_until_done();
               ______________________________________
               take_from_oven();
               ____________________________________
          } // make_pizza

2.   What is probably wrong with the following fragment of monitor
     procedure and why? (20 points)

     balance = read_balance(account_no);
     if (balance < MIN_VAL)
          small_account.signal;
     interest = balance*rate;
     write_balance(account_no, balance + interest);
 
3.   How can we prevent deadlock by denying the hold and wait
     condition?  (10 points)  What is the major disadvantage of 
     this solution?  (10 points)





4.  What causes external fragmentation? (10 points)  What can be
   done to correct it? (10 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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