Philadelphia University
Faculty of Information Technology
Lecturer
: Dr. M. Maouche
Coordinator
: Dr M. Maouche
Internal Examiner : Prof.Dr. M. Mahafzah
Marking Schema
Department of Computer Science
Course Name: Computer Design and Organization (750233)
Section: 1
First Exam
.
Question1: (8 marks)
1. CPU; Memory; I/O system. (2)
2. Stored program and data; sequential execution (fetch decode execute); single
datapath(2)
3. combinational circuits give always the same output values for the same input
values while for sequential circuits the output values depend not only on the input
values but also on last stored state of the circuit. (2)
4. Multiplexer (2)
Question2: (10 marks)
1.
57 = 32 + 16 + 8 + 1
so
111 0 0 1
(1.5)
0.55 : using successive multiplication by 2 gives: 100011
Final result:
2.
(1.5)
111001.100011
Converting -1.5 into binary gives : -1.1 x 20
(1)
Non biased exponent = 0 ; biased exponent = 127 + 0 = 127 (1)
IEEE representation: 1 01111111
3.
68:
34:
01000100
00100010
10000000000000000000000
-68: 10111100
-34: 11011110
------------10011010
Final result = -102 (correct result)
Carry out = carry in thus NO overflow
.
(1)
(two complement)
(two complement)
(1)
(1)
(1)
(1)
Question3 : (4 marks)
65 is the decimal ASCII code for the letter “A”;
code for the letter “a”.
97 is the decimal ASCII
1. (2)
65:
97:
100 |0001
110|0001
- same BCD value (0001) for both letters expressing that these are the
first letters of latin characters
- only one bit is different in their block parts (110 \100)
2. Switching from a capital letter to its corresponding small letter consists in
inverting the 6th bit of the ascii code and this is what the key CAPS LOCK do.
(2)