Answer the following questions which refer to the above PEP9 program. You must e

Question

Answer the following questions which refer to the above PEP9 program. You must express ALL of your answers in HEXADECIMAL using m-4 hexadecimal digits Assuming the STWA instruction at the label 'p1' has executed, the value stored from the A register to the variable RES will be: 1. 2. Assuming the STWA instruction at the label 'p2' has executed, the value stored from the A- register to the variable RES will be: Assuming the STWA instruction at the label p3' has executed, the value stored from the A- register to the variable RES will be: 3. Assuming the STWA instruction at the label p4' has executed, the value stored from the A- register to the variable RES will be: 4. 5. Assuming the STWA instruction at the label p5' has executed, the value stored from the A- register to the variable RES will be:

Explanation / Answer

1)

LDWA                        0x8002,i

ADDA                        0x7FFF,i

1000 0000 0000 0010

0111 1111 1111 1111

0000 0000 0000 0001 ADDA => This will return a carry 1 thus BRC p1 will be taken and value modes to RES would be 0001

2)

LDWA            0x7F00,i

SUBA 0x0001,i

0111 1111 0000 0000

0000 0000 0000 0001

0111 1110 1111 1111 SUBA => Since there is not overflow BRV will be false, next instruction executes is:

LDWA            22,i => RES has 22

3)

LDWA            0x4041,i         

NEGA             => negate the value in A

BRGE p3        => branch if greater than or equal to 0, which is false, Next instruction will be executed:

LDWA            23,i => RES has 23

4)

LDWA            -2, i

SUBA 1,i                    => A = -1

BRLT p4 => branch if less than 0, which is true => RES = -1

5)

LDWA            0x7FFF, i

ADDA            0x8001,i

0111 1111 1111 1111

1000 0000 0000 0001

0000 0000 0000 0000 ADDA => There is overflow

BRNE p5 => branch if not equal to 0, which is false since addition resulted in 0, next instruction:

LDWA            25,i      => RES has 25

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