CS 3733 Operating Systems, Spring 2005 Midterm 1 Comments

The grade distribution for the first midterm exams was as follows:

• 90-98: 9
• 80-89: 9
• 70-79: 16
• 60-69: 9
• 50-59: 5
• below 50: 2

Comments on particular problems

• 1. A directory entry contains exactly two pieces of information, while a file descriptor table entry contains only one. The other have lots of info, but you only needed to give two to get full credit.
• 3. For this problem it is important to be very careful to keep track of the values of c1 and c2.
• 4. Process A has its own copy of the file offset which processes B and C share a file offset. Reads of A are independent of the other processes so A always reads the first two characters of the file. The other two processes each read 2 of the first 4 characters of the file, and each gets two characters in alphabetical order. There are 6 possibilities.
• 5. This is identical to the problem assigned in class, except that the numbers are different. You will see a problem like this one again on a later exam.