Basic subtraction program, MASM, written for x86 processors

subtractionAssembly.asm

; Simple Calculator
; Kurt Kaiser

INCLUDE Irvine32.inc

; .data is used for declaring and defining variables
.data
codeTitle		BYTE "  ---------  Math Magic  ---------  ", 0
directions		BYTE "Enter 2 numbers.", 0
prompt1			BYTE "First number: ", 0
prompt2			BYTE "Second number: ", 0
equals			BYTE " = ", 0
minus			BYTE " - ", 0
num1			DWORD ?
num2			DWORD ?
total           DWORD ?

; .code is for the executable part of the program
.code
main PROC
	; Output the title and author
		mov		edx, OFFSET codeTitle
		call	WriteString
		call	CrLf

	; Prompt for the first number
		mov		edx, OFFSET prompt1
		call	WriteString
		call	ReadInt
		mov		num1, eax

	; Prompt for the second number
		mov		edx, OFFSET prompt2
		call	WriteString
		call	ReadInt
		mov		num2, eax
	
	; Subtract the two numbers using the eax registry
		mov		eax, num1
		sub		eax, num2
		mov		total, eax
		
	; Print the total to the console
		; Print num1
		mov		eax, num1
		call	WriteDec
		; Print the minus sign
		mov		edx, OFFSET minus
		call	WriteString
		; Print num2
		mov		eax,  num2
		call	WriteDec
		; Print the equals sign
		mov		edx, OFFSET equals
		call	WriteString
		; Print out the total
		mov		eax, total
		call	WriteDec
		call	CrLf
		call	CrLf

	exit	
main ENDP
END main