Question 1. What is the value in Accumulator B after the execution of the code below?
ORG $2000
XYZ DC.B 0, 1, 2, 4
ORG $8000
LDY #XYZ
LDAA #04
LDAB #02
BACK ADDB 0, Y
INY
DECA
BNE BACK
HERE BRA HERE
A. $04
B. $09
C. $07
D. $1009
E. None of the above
Question 2. The instruction “subb $100” will
A. subtract the content of Accumulator B from $100.
B. subtract $100 from Accumulator B.
C. subtract the content of memory at Address $100 from Accumulator B.
D. subtract the content of Accumulator B from the content of memory at Address $100.
Question 3.What will be the value in Accumulator A after the following program is executed?
ORG $2000
DATA1 DC.B $F8
ORG $8000
LDAA DATA1
LDAB #4
BACK LSLA
DECB
BNE BACK
HERE BRA HERE
A. $80
B. $08
C. 0
D. None of the above
Question 4.The MC9S12 instruction set has
A. only one multiply instruction: eight-bit signed.
B. both an eight-bit signed and eight-bit unsigned multiply instruction.
C. only one multiply instruction: eight-bit unsigned.
D. All of the above
E. None of the above
Question 5. In the following program, what is the largest number that Register B can take?
L1 CLRA
NOP
NOP
DECB
BNE L1
A. 255
B. 100
C. 0x200
D. 0x99
Question 6.For a 16-bit signed number, we can use a maximum of _____ bits for the magnitude of the signed number.
A. D7-D0
B. D14-D0
C. D16-D0
D. D15-D9
Question 7.Assume that PORTB has a value of 0x37. Which of the following gives us Unpacked BCD for 7?
A. PORTB= PORTB & 0x37;
B. PORTB= PORTB | 0x30;
C. PORTB= PORTB | 0x0F;
D. PORTB= PORTB & 0x0F;
Question 8. Fill in the blank to get 0x36 on PORTB.
unsigned char BCD_Byte = 0x67;
unsigned char x;
x= BCD_Byte & 0xF0;
_____;
PORTB = x | 0x30;
A. x=x>>4;
B. x=x>>2;
C. x=x<<4;
D. x=x<<2;
Question 9.The following program creates square wave pulses on PB0. What is the duty cycle?
ORG $8000
LDS #$4000
LDAA #$FF
STAA DDRB
BACK BSET PORTB,%00000001
JSR DELAY
JSR DELAY
JSR DELAY
BCLR PORTB,%00000001
JSR DELAY
BRA BACK
A. 33%
B. 66%
C. 75%
D. 25%
Question 10. Find the value for PORTB after the execution of the following code:
PORTB = 0xAA ^ 0x55;
A. PORTB = 0x05
B. PORTB = 0x0A
C. PORTB = 0x0F
D. PORTB = 0xFF