Georgia State University
Department of Computer Science.
Spring Semester – 3/29/2011
CSC 2010
Test 3
Name:_____________________________
Grade:______________/100
Answer all of the following questions.
1. Do the following showing the entire procedure involved (use 8 bits to represent
each number): Use unsigned number. (4 pts)
125 – 14
125 → 01111101
14 → 00001110
....
01111101
00001110
---------------------01101111
2. Add the following using 8 bits to represent each number. Use unsigned number.
(4 pts)
231 + 16
231  11100111
16  00010000
--------------Answer: 11110111
Circle clearly the correct letter for questions 3 – 9. For Q3-Q8, each
question is 3 pts. For Q9, each sub question is 2pts.
Binary to Hex number
0000
0
0001
1
0010
2
0011
3
0100
4
0101
5
0110
6
0111
7
1000
8
1001
9
1010
A
1011
B
1100
C
1101
D
1110
E
1111
F
3. The Binary number for 25610 is:
a. 100100000
b. 111111110
c. 101010100
d. 100000000
Answer: d.
4. The Hexadecimal number for 8010 is:
a. 516
b. 5016
c. 616
d. 6016
Answer: b.
5. The decimal number (to base 10) of 11100110 is:
a. 189
b. 255
c. 345
d. 230
Answer: d.
6. The decimal number (to base 10) of 2AF16 is:
a. 688
b. 687
c. 777
d. 478
Answer: b.
7. The Hexadecimal number for 111100110001 is:
a. F4116
b. E4216
c. F3116
d. A5616
Answer: c.
8. The Binary number for AD716 is:
a. 110011001111
b. 101011110011
c. 101011010111
d. 111111000011
Answer: c.
9. Assuming that x = 1 and y = 2, circle the correct value for each of the following
Boolean expression: (2 pts each)
FALSE
(a) (x = 1) AND (y = 3).
TRUE
(b) (x < y) OR (x > 1).
TRUE
FALSE
(c) NOT [(x = 1) AND (y = 2)].
TRUE
FALSE
10. Compress the following text stream. (5 pts)
xxxzzzzAAxxxx
a. Show the run-length encoding (2pts)
(x,3) (y,6) (z,4) (A,2) (x,4)
b. What is the compression ratio? (3 pts)
19/10  1:1.9
11. Store the following number in the space provided using 16 bits – 1 each for the sign,
4 for the exponent and 10 for the mantissa. (7 points)
-133.75
a. binary value (2pt)
b. normalized value (1pt)
c. (4pt)
1
1000010111
0
1000
12. Draw a 3-8 decoder control circuit. (4 pts)
Inputs
0
1
2
3
8 outputs
13. Draw a multiplexor that has 2 selector lines only. (4 pts)
Inputs
0
1
2
1 output
3
A
B
Selector Lines
14. You found an old computer that has 3KB (kilobyte) of memory. In order to address
each byte of memory, what is the minimum number of bits needed in a memory
address? (3 pts)
12 bits
212 = 4096 just over 3000; 13 bits are too large, 11 bits are not enough
15. Describe any two important characteristics of RAM. (4 pts)
Volatile, unique address per cell starting from 0 to 2n - 1,
fixed size cell of 8 bits each,
can read or write one cell at a time,
randomly accessed.
16. Name the 4 major subsystems of the Von Neumann architecture. (4 pts)
Memory, Input/output devices, ALU and control unit
17. Using the following truth table derive the expression for case 1, case 2 and case 3
then, build the circuit using AND, OR and NOT gates. Make sure you give the algebraic
functions derived for case1 and case 2. (13 pts – 2 pts each for case 1 and case 2, 1 pts
to put case 1 and case 2 expression as one expression, and 8 pts for the circuit)
NOTE: To get full credit, you must use only 2-input AND and OR gates and 1input NOT gate.
A
0
0
0
0
1
1
1
1
B
0
0
1
1
0
0
1
1
C
0
1
0
1
0
1
0
1
Output
0
1
0
0
0
0
1
0
Cases
Case 1: ________________
1
Case2: _______________
Full Expression: __________________________
2
Circuit:
Case 1:
(not)A.(not)B.C
Case 2:
A.B.(not)C
Whole expression: (not)A.(not)B.C + A.B.(not)C
•
A
(not)A.(not)B.C
+
B
•
•
C
A.B.(not)C
•
18. Given the following partial table, fill in the empty columns with the values resulting
from the indicated operations. (14 pts – 2 for each column)
a
0
0
0
0
1
1
1
1
b
0
0
1
1
0
0
1
1
c
0
1
0
1
0
1
0
1
a.b.c a+b+c
0
0
0
1
0
1
0
1
0
1
0
1
0
1
1
1
not(a.b.c) not(a+b+c)
1
1
1
0
1
0
1
0
1
0
1
0
1
0
0
0
not(a)
1
1
1
1
0
0
0
0
not(b) not(c)
1
1
1
0
0
1
0
0
1
1
1
0
0
1
0
0
19. Assume that the variables v, w, x, y and z are stored in memory locations 200, 201,
202, 203 and 204, respectively. Using any of the machine language instructions in
the textbook, translate the following algorithmic operation into their machine
language equivalents. (10pts)
(LOAD, STORE, MOVE, ADD, SUBTRACT, JUMP, JUMPGT, JUMPEQ,
JUMPLT, JUMPGE, JUMPLE, JUMPNEQ)
a. Set v to the value of x-y-z
(2pts)
SUBTRACT 202,203,200
SUBTRACT 200,204,200
b. Set v to the value (w+x) – (y+z) (3pts)
ADD 201,202,200
ADD 203,204,201
SUBTRACT 200,201,200
c. While y>z do
Set y to the value (y+w+z)
Set z to the value (z+v)
End of the loop
(5pts)
1, COMPARE 203,204
2, JUMPGT 4
3, JUMP 8
4, ADD 203,201,203
5, ADD 203,204,203
6, ADD 204,200,204
7. JUMP 1
8. next instruction…
Q19 continues… Extra Credits (10pts)
d. If (v=w) then
set x to y
Else
Set x to z
(Use JUMPEQ)
(5pts)
1, COMPARE 200,201
2, JUMPEQ 5
3, MOVE 204, 202
4, JUMP 6
5, MOVE 203, 202
6. next instruction…
e. Rewrite question c without using JUMPEQ
(5pts)
1, COMPARE 200,201
2, JUMPNEQ 5
3, MOVE 203, 202
4, JUMP 6
5, MOVE 204, 202
6. next instruction…