Question

Implement a simple four function calculator in the LC3 assembly language that will run on the LC-3 simulator. The LC-3 computer only reads a character at a time but is capable of displaying a string of characters. This calculator program will use multiple subroutines that perform purposes such as reading multi-digit numbers, converting them to integers, performing addition, subtraction, multiplication, or division on these numbers, and displaying the result. The inputs to the calculator will not exceed 4 digits. The user interaction with the calculator is shown below in several example runs:

EXAMPLE RUN 1:

Enter the first operand (SRC1):     34

Enter the second operand (SRC2):    27  

Operation (+, -, *, /)?    +

Sum is: 61

Continue (Y, N)? Y

Enter the first operand (SRC1):     378

Enter the second operand (SRC2):    237

Operation (+, -, *, /)? -

Difference is: 141   

Continue(Y, N)? N

EXAMPLE RUN 2:

Enter the first operand (SRC1):     34

Enter the second operand (SRC2):    75  

Operation (+, -, *, /)? -   

Difference is: -41

Continue(Y, N)? N

EXAMPLE RUN 3:

Enter the first operand (SRC1):     24

Enter the second operand (SRC2):    18  

Operation (+, -, *, /)?    *

Product is: 432

Continue(Y, N)? N

Answer 1

;initializes all registers to zero
AND R0, R0, #0
AND R1, R1, #0
AND R2, R2, #0
AND R3, R3, #0
AND R4, R4, #0
AND R5, R5, #0
AND R6, R6, #0
AND R7, R7, #0

;this block will ask for user input then display it to the monitor

NEXTCHARACTER GETC
OUT
;reads input and determines whether or not it is a valid character
;Space?
LEA R0, PROMPT ;Save the location of the prompt
PUTS ;Print the prompt to the screen
GETC ;Store the character into R0