sample-midterm-solutions.txt

CSCI 237 Sample Midterm solutions

*********
Problem 1
*********
1-b 2-a 3-c 4-b 5-a 6-d 7-b 8-a 9-a 10-a    
11-b 12-a 
13-IA32: 1, 4, 4, 4 x86-64: 1, 4, 8, 8 
14-a 15-a 16-a 17-a 18-a 19-(ambiguous question) 20-a

*********
Problem 2
*********
Value	FP bits	Rounded value
  1       011 00    1      easy normalized, exact (1 pt)
  12      110 10    12     normalized exact (1 pt)
  11      110 10    12     round up to 12 (because 10 is odd) (1 pt)
  1/8     000 10    1/8    denorm, exact (2 pt)
  7/32    001 00    1/4    straddles norm/denorm boundary, round up 


*********
Problem 3
*********
Part 1:
abccddddeeeefXXX
gggg


Part 2:
There are multiple correct answers. In general, put
the largest data items first. E.g., 

ddddeeeeffffccab
fXXX

*********
Problem 4
*********
A. Clyde
B. Inky
C. Pinky
D. Blinky

*********
Problem 5
*********
Cases 210, 214, and 218 should have "break".

0x400590: 0x400470
0x400598: 0x40048a
0x4005a0: 0x40048a
0x4005a8: 0x400477
0x4005b0: 0x40047c
0x4005b8: 0x40048a
0x4005c0: 0x400482
0x4005c8: 0x40048a
0x4005d0: 0x400482
0x4005d8: 0x400487

*********
Problem 6
*********
A. (a) Call pushes the return address on the stack, jmp does not. 
   (b) Ret gets the return address from the top of the stack. 
B. x == 5
C. string "0123456" is stored at 0x80484d0
D. buf[0] = 0x33323130
   buf[1] = 0x00363534
   buf[2] = 0xffffd3e8
   buf[3] = 0x080483fc
   buf[4] = 0x080484d0
E. Value at %ebp is 0xffffd3e8
F. Value at %esp is 0x080483fc 
G. No segfault. "0123456" is only 8 bytes including '\0', and 
   int[2] can store 8 bytes.