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Author: Tran Minh Nhat (HCMUT)

LAB 1:

ALU Operations

1. Problem Statement

The numbers X and Y are found at locations x3100 and x3101, respectively. Write an LC-3 assembly language program that does the following.

• Compute the sum X +Y and place it at location x3102.
• Compute X AND Y and place it at location x3103.
• Compute X OR Y and place it at location x3104.
• Compute NOT(X) and place it at location x3105.
• Compute NOT(Y) and place it at location x3106.
• Compute X +3 and place it at location x3107.
• Compute Y −3 and place it at location x3108.
• If the X is even, place 0 at location x3109. If the number is odd, place 1 at the same location. The operations AND, OR, and NOT are bitwise. The operation signified by + is the usual arithmetic addition.

1.1 Inputs

The numbers X and Y are in locations x3100 and x3101, respectively

1.2 Instruction in LC3

    .ORIG x3000
    LD R4, ADDRESS
    LDR R1, R4, #0	;R1: FIRST NUM
    LDR R2, R4, #1	;R2: SECOND NUM
    ADD R3, R1, R2	;R3=R1+R2
    STR R3, R4, x2
    AND R3, R1, R2	;R3=R1 AND R2
    STR R3, R4, x3
    NOT R5, R1  ;
    NOT R6, R2
    AND R3, R5, R6
    NOT R3, R3
    STR R3, R4, x4
    STR R5, R4, x5
    STR R6, R4, x6
    ADD R3, R1, #3
    STR R3, R4, x7
    ADD R3, R2, #-3
    STR R3, R4, x8

    AND R5, R1, #1
    BRz EVEN
    AND R3, R3, #0
    ADD R3, R3, #1
    STR R3, R4, x9
    BR NEXT
EVEN
    AND R3, R3, #0
    STR R3, R4, x9
NEXT	HALT
    ADDRESS	.FILL x3100
    .END

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LAB 2:

Arithmetic functions

1. Problem Statement

The numbers X and Y are found at locations x3120 and x3121, respectively. Write a program in LC-3 assembly language that does the following:

• Compute the difference X −Y and place it at location x3122.
• Place the absolute values |X| and |Y| at locations x3123 and x3124, respectively.
• Determine which of |X| and |Y| is larger. Place 1 at location x3125 if |X| is, a 2 if |Y| is, or a 0 if they are equal.

1.1 Inputs

The integers X and Y are in locations x3120 and x3121, respectively.

2. Instruction in LC3

The steps taken during the execution of the instruction LDI R1, X

The steps taken during the execution of the instruction STI R2, Y

Decimal numbers with their corresponding 2’s complement representation

.ORIG x3000
LD R4, ADDRESS
LDR R1, R4, #0
LDR R2, R4, x1
NOT R3, R2
ADD R3, R3, #1
ADD R5, R1, R3	;R5=R1-R2
STR R5, R4, x2

ADD R1, R1, #0
BRzp	POSITIVE1
NOT R1, R1
ADD R1, R1, #1
POSITIVE1 ADD R1, R1, #0
STR R1, R4, x3

ADD R2, R2, #0
BRzp	POSITIVE2
NOT R2, R2
ADD R2, R2, #1
POSITIVE2 ADD R2, R2, #0
STR R2, R4, x4


NOT R5, R2
ADD R5, R5, #1
ADD R6, R1, R5	;R6=ABS(R1)-ABS(R2)
BRp	R1_LARGER
BRz	EQUAL
AND R3, R3, #0
ADD R3, R3, #2
STR R3, R4, x5
BR NEXT
R1_LARGER
AND R3, R3, #0
ADD R3, R3, #1
STR R3, R4, x5
BR NEXT
EQUAL	
AND R3, R3, #0
STR R3, R4, x5
NEXT	HALT

ADDRESS .FILL x3120
.END