Median = 5.0 X X X X X X X X X X X X X X X X X X X X X X X X _____X___X_X_X_X_X_X_X_X_X_X_X_X_X_X_____X___ 0 . 1 . 2 . 3 . 4 . 5 . 6 . 7 . 8 . 9 . 10 Grades? D C B A
Half of the credit for this problem was relocation, the other half was for redoing the problem from the first exam. 8 had perfect scores, 5 didn't do anything about relocation. Sadly, there were a significant number who could not correctly do the basic part of this problem from the first midterm.1 0000: 16 | B 22 2 0001: 22 |X: B #22 (3)0002: 01 | B X 4 |; commentary 5 0003: 0A | B Y (6)0004: 05 | B Z 7 |Y = 10 8 |Z: ; symbol table: X = #0001 Y = #000A Z = #0005
At least 14 students received no credit on the additional part of this problem, to identify the lines that would cause problems for relocation bases above about 256 (these line numbers are parenthesized above), while at least 6 did well on this.
a) 10 sectors long requires 10 disk accesses; 17 students knew this.
b) 100 sectors long requires 101 disk accesses; 16 students knew this.
c) 1000 sectors long requires 1009 disk accesses; 6 did well here, 5 more had "off by one" errors.
a) The directory manager needs to read 6 low-level files to open this file. Each of these low level files holds a directory. The names for these low level files are
b) The directory manager reads 6 i-nodes as it opens this file. The i-node for the root is already in the memory; the 5 i-nodes for the remaining low level files must be read, and the inode for the file itself must be read. 6 got this right, 6 were off by one.
c) Opening this file requires 18 disk reads. 1 for each i-node and 2 for each low-level file, since the low-level files are 2 sectors long. 5 got this right.
a) How long will it take to read the following sequence of disk addresses? All times are stated in 64ths of a second.
transfer number cyl sect begin time end time 1 0 0 0 1 2 1 3 11 12 3 5 4 28 29 4 4 5 37 38 5 0 1 57 5817 did well here (full credit was given to anyone who got the end time right; intermediate times were checked only for those who had errors on their start times). 10 had answers for which no credit could be assigned.
b) How many sectors will move past the head in the time it takes the head to seek n cylinders, for n = 1 to 7?
distance moved time distance moved time 0 0 4 16 1 8 5 ~18 2 ~12 6 ~20 3 ~14 7 ~2212 did well here. Off-by-one errors were accepted.
What minimal changes would you make to the code for the touch screen input driver and what code would you write for the asynchronous input interrupt service routine?
1 student gave a great answer to this question. 5 gave essentially no answer, 3 rambled on at great length giving no useful answer. 5 gave vague answers of variable quality that were not wrong and were penalized primarily by their degree of vagueness. 23 gave answers that focused in great detail on one or sometimes two issues, frequently peripheral to the central issues of the question while ignoring the big picture. 8 were penalized (mildly) for excessively long answers.