Mid-Term Exam (1)
Introduction to Computer Science
NCNU CSIE

Date: October 28th, 2009
Time: 14:10-16:00
Open book; turn off computer & mobile phone

1. (10%) What are the four major subsystems of a computer defined in the von Neumann model?
2. (10%) The EBCDIC codes of characters '0', '5', '9' are 240, 245, 249, respectively.
   • Write down the binary representation of these numbers (in "unsigned integer" format).
   • What are the ASCII codes of these characters?
   • Write down the binary representation of these ASCII codes.
   • For the same character '9', observe the binary representation of its ASCII code and EBCDIC code, what common/different property do you find?
3. (10%) Consider the following program. 
   
1. What will be its output?
2. If we delete line 90 and replace line 70 with "IF A(I)=0 OR I>50 THEN 130", what will be the output of this program?

   10 REM: ===== Prime Number =====
   20 DIM A(100)
   30 FOR I = 2 to 100
   40    A(I)=1
   50 NEXT I
   60 FOR I = 2 TO 100
   70   IF A(I)=0 THEN 130
   80   PRINT I;
   90   IF I>50 THEN 130
   100   FOR J=2 TO INT(100/I)
   110      A(I*J) = 0
   120   NEXT J
   130 NEXT I
   140 PRINT

4. (10%) Suppose we allocate 8 bits to store an integer. Write down the binary representation of 0 and -1 in one's complement.
   
5. (10%) Suppose we allocate 8 bits to store an integer. Write down the binary representation of -256 and -1 in two's complement.
6. (10%) If you input two numbers -84 and 16, what will be the output of the following program?
   
   10 REM: ===== gcd.bas =====
   20 REM: Greatest Common Divisor
   30 INPUT A, B
   40 A=ABS(A) : B=ABS(B)
   50 DO WHILE B>0
   60   A = A MOD B
   70   TEMP=A : A=B : B=TEMP
   80 LOOP
   90 PRINT A
   100 END
   
   
7. (10%) What will be the output of the following program?
   
   10 REM Sorting
   30 DATA 1, 3, 5, 7, 2, 4, 6
   40 K=7
   50 DIM A(K)
   60 FOR I=1 TO K
   70    READ A(I)
   80 NEXT I
   85 GOSUB 200
   90 FOR I=1 TO K-1
   100    FOR J=I+1 TO K
   110       IF A(I) > A(J) THEN TEMP=A(I): A(I)=A(J): A(J)=TEMP
   120    NEXT J
   125    GOSUB 200
   130 NEXT I
   150 END
   200 REM --- Print out the array ---
   210 FOR H=1 TO K
   220    PRINT A(H);
   230 NEXT H
   240 PRINT
   250 RETURN
   
   
8. (10%) One of your TA was born on November 10th, 1985.  What day is that day? Be sure to show your calculation in addition to your choice.
   0. Sunday
   1. Monday
   2. Tuesday
   3. Wednesday
   4. Thursday
   5. Friday
   6. Saturday
      
9. (20%) Convert 81.5625 to IEEE standard floating-point and represent it in binary and hexidemical notations.
   
10. (10%) Consider the following BASIC program:

    10 INPUT "N = "; N
    20 DO WHILE N<>0
    30    FOR I=N TO 1 STEP -1
    40       GOSUB 130
    50    NEXT I
    60    FOR I=    (1)    TO N
    70       GOSUB 130
    80    NEXT I
    90    INPUT "N = "; N
    100 LOOP
    110 END
    130 REM: --- subprogram ---
    140       W =    (2)    
    150       FOR J=1 TO I
    160      PRINT "*";
    170       NEXT J
    180       PRINT SPC(W);
    190       FOR J=1 TO I
    200      PRINT "*";
    210       NEXT J
    220       PRINT
    230       RETURN
    
    

    If we want to obatin the following results, what expressions should be filled into the two blanks, respectively?

    N = ? 5
    ***** *****
    ****   ****
    ***     ***
    **       **
    *         *
    **       **
    ***     ***
    ****   ****
    ***** *****
    N = ? 6
    ****** ******
    *****   *****
    ****     ****
    ***       ***
    **         **
    *           *
    **         **
    ***       ***
    ****     ****
    *****   *****
    ****** ******
    N = ? 0
    bwBASIC: