;MODEL SMALL
;STACK 100h
;DATA
choice msg db 13,10,'Addition or Subtraction?',13,10,'$'
first_msg db 13,10,'Enter the first number:',13,10,'$'
second_msg db 13,10,'Enter the second number:',13,10,'$'
result_msg db 13,10,'The result is:',13,10,'$'
new_line db 13,10,'$'
val1 db ?
num2 db ?
num3 db ?
num4 db ?
ten db 10
.CODE ;where the code is written
start:
mov ax, @data ;Moves the address of the variables under .DATA into ax
mov ds,ax ;moves ax into ds. the two lines allow you to display string using the 21h interrupt sequence 9
mov ah,09
mov dx, offset choice_msg
int 21h ;displays the string in choice_msg
mov ah,01
int 21h ;copies a value into the al, using subfunction 01
mov val1,al ;moves the value in the al to the variable val1
cmp val1,'+' ;compares the entered value in val1 with "+"
je addition ;if the enterd value is "+" then it jumps to addition else it jumps to subtraction
addition:
mov ah,09
mov dx, offset first_msg
int 21h ;displays the string in first_msg
mov ah,01
int 21h ;copies a value into the al, using subfunction 01
sub al,48 ;subtracts 48 from the vaule in the al
mov num2,al ;moves the value in the al to the variable num2
mov ah,01
int 21h ;copies a value into the al, using subfunction 01
sub al,48 ;subtracts 48 from the value in the al
mov num3,al ;moves the value in the al to the variable num3
mov al,num2 ;moves the value in num2 into the al
mul ten ;multiplies the value in the al by ten
add al,num3 ;adds the value in num3 to the al, to get the two-digit number
mov num2,al ;moves the two digit value into
mov ah,09
mov dx, offset new_line
int 21h ;goes to the next line, i.e. "enter"
mov ah,09
mov dx, offset second_msg ;displays the string in second_msg
int 21h
mov ah,01
int 21h ;copies a value into the al, using subfunction 01
sub al,48 ;subtracts 48 from the value in the al
mov num3,al ;moves the new value in the al into the variable num3
mov ah,01
int 21h ;copies a value into the al, using subfunction 01
sub al,48 ;subtracts 48 from the value in the al
mov num4,al ;moves the new value in the al into the variable num4
mov al,num3 ;moves the value in num3 into the al
mul ten ;multiplies the value in the al by ten
add al,num4 ;adds the value in num4 to the al, to get a two-digit number
mov num3,al ;moves the value in the al into the variable num3
mov ah,09
mov dx, offset new_line
int 21h ;goes to the next line, i.e. "enter"
mov ah,09
mov dx, offset result_msg
int 21h ;displays the string in reslut_msg
; mov the value of num 3 into bl
mov bl, num3
add num2,bl ;adds num3 and num2 to form the sum
add num2,48 ;adds 48 to num2
mov al,num2
mov ah,02
mov dl, al
int 21h ;displays the value that was in the al
mov ah,09
mov dx, offset new_line
int 21h ; goes to next line, i.e. "enter"
mov ax,4c00h
int 21h ;ends the program
subtraction:
mov ah,09
mov dx, offset first_msg
int 21h ;displays the string in first_msg
mov ah,01
int 21h ;copies a value into the al, using subfunction 001
sub al,48 ;subtracts 48 from the value in the al
mov num2,al ;moves the value in the al into the variable num2
mov ah,01
int 21h ;copies a value into the al, using subfunction 01
sub al,48 ;subtracts 48 from the value in the al
mov num3,al ;moves the value in the al into the variable num3
mov al,num2 ;moves the value in num2 into the al
mul ten ;multiplies the value in the al by ten
add al,num3 ;adds the value in num3 to the al, to get a two-digit number
mov num2,al ;moves the value in the al into the variable num2
mov ah,09
mov dx, offset new_line
int 21h ;goes to the next line, i.e. "enter"
mov ah,09
mov dx, offset second_msg
int 21h ;displays the string in second_msg
mov ah,01
int 21h ;copies a value into the al, using subfunction 01
sub al,48 ;subtracts 48 from the value in the al
mov num3,al ;moves the value in the al into the variable num3
mov ah,01
int 21h ;copies a value into the al, using subfuntion 01
sub al,48 ;subtracts 48 from the value in the al
mov num4,al ;moves the value in the al into the variable num4
mov al,num3 ;moves the value in num3 into the al
mul ten ;multiplies the value in the al by ten
add al,num4 ;adds the value in num4 to the al, to get a two-digit number
mov num3,al ;moves the value in the al into the variable num3
mov ah,09
mov dx, offset new_line
int 21h ;goes to next line, i.e. "enter"
mov ah,09
mov dx, offset result_msg
int 21h ;displays the string in result_msg
mov bl, num3 ;move value of num3 to bl
sub num2,bl ;subtracts the value in num3 from the value in num2
add num2,48 ;adds 48 to the new value in num2
mov al,num2 ;moves the value in num2 into the al
mov ah,02
mov dh,al
int 21h ;displays the resulting value
mov ah,09
mov dx, offset new_line
int 21h ;goes to the next line, i.e. "enter"
mov ax,4c00h
int 21h ;ends the program
END
; Converts the integer value in AX to a string in
; decimal representation and prints it.
; The digits are placed in a string buffer in reverse
; order - i.e. for the value 123, '3' would be placed
; last in the buffer, then '2' before that, and '1'
; before that, so that we'd end up with the string "123".
print_int:
mov byte [buffer+9],'$' ; add a string terminator at the end of the buffer
lea si,[buffer+9]
mov bx,10 ; divisor
print_loop:
xor dx,dx ; clear dx prior to dividing dx:ax by bx
div bx ; AX /= 10
add dl,'0' ; take the remainder of the division and convert it from 0..9 -> '0'..'9'
dec si ; store characters in reverse order
mov [si],dl
test ax,ax
jnz print_loop ; repeat until AX==0
mov ah,9 ; print string
mov dx,si
int 21h
ret
buffer: resb 10
.MODEL SMALL
.STACK 100h
.DATA
choice_msg db 13,10,'Addition or Subtraction?',13,10,'$'
first_msg db 13,10,'Enter the first number:',13,10,'$'
second_msg db 13,10,'Enter the second number:',13,10,'$'
result_msg db 13,10,'The result is:',13,10,'$'
new_line db 13,10,'$'
val1 db ?
num1 db ?
num2 db ?
num3 db ? ; purely a buffer variable
ten db 10
t1 db 0
t2 db 0
result db 0
.CODE ;where the code is written
start:
mov ax, @data ;Moves the address of the variables under .DATA into ax
mov ds,ax ;moves ax into ds. the two lines allow you to display string using the 21h interrupt
sequence 9
mov ah,09
mov dx, offset choice_msg
int 21h ;displays the string in choice_msg
mov ah,01
int 21h ;copies a value into the al, using subfunction 01
cmp al,'+' ;compares the entered value in with "+"
jne subtraction ;if the enterd value is "+" then it jumps to addition else it jumps to subtraction
addition:
call read ;Read the input
call endl ;output new line
mov bl, num2 ;move the value of num 2 into bl
add num1,bl ;adds num2 and num1 to form the sum1
mov al, num1 ;mov num1 to al
mov result, al ;store the result of the sum in result
call write ;write the output
jmp exit
subtraction:
call read ;Read the input
call endl ;output new line
mov bl, num2 ;move value of num2 to bl
sub num1,bl ;subtracts the value in num2 from the value in num1
mov al, num1 ;move result to a register
mov result, al ;move the result of the subtraction to result
call write ;display result with write procedure
jmp exit
;-----------------------
;procedure declarations:
proc endl
mov ah,09
mov dx, offset new_line
int 21h ;goes to next line, i.e. "enter"
ret
endp
proc read
mov ah,09
mov dx, offset first_msg
int 21h ;displays the string in first_msg
mov ah,01 ;read char
int 21h ;copies a value into the al, using subfunction 01
sub al,48 ;subtracts 48 from the vaule in the al
mov num1,al ;moves the value in the al to the variable num1
mov ah,01 ;read second char
int 21h ;copies a value into the al, using subfunction 01
sub al,48 ;subtracts 48 from the value in the al
mov num2,al ;moves the value in the al to the variable num2
mov al,num1 ;moves the value in num1 into the al
mul ten ;multiplies the value in the al by ten
add al,num2 ;adds the value in num2 to the al, to get the two-digit number
mov num1,al ;moves the two digit value into
call endl
mov ah,09
mov dx, offset second_msg ;displays the string in second_msg
int 21h
mov ah,01
int 21h ;copies a value into the al, using subfunction 01
sub al,48 ;subtracts 48 from the value in the al
mov num2,al ;moves the new value in the al into the variable num2
mov ah,01
int 21h ;copies a value into the al, using subfunction 01
sub al,48 ;subtracts 48 from the value in the al
mov num3,al ;moves the new value in the al into the variable num3
mov al,num2 ;moves the value in num2 into the al
mul ten ;multiplies the value in the al by ten
add al,num3 ;adds the value in num3 to the al, to get a two-digit number
mov num2,al ;moves the value in the al into the variable num2
ret ;first number in num1, second in num2
endp
;The write procedure writes the decimal stored in result.
;by dividing by ten it seperates the two digits as quotient
;and remainder. Then it outputs the quotient and remainder
;in ascii form.
proc write
mov dx,offset result_msg
mov ah,09h
int 21h ;display the result_msg string
mov al,result ;move the result from add/sub to al
mov ah,00 ;initialize ah
div ten ;div al by ten, quotient is in al
;remainder is stored in ah.
mov dl,ah ;move the remainder to dl
mov t2,dl ;store the remainder in t2
mov dl,al ;move quotient into dl
add dl,48 ;add 48 to dl, to convert it to ascii
mov ah,02h ;char display interupt code
int 21h ;display char in dl register
mov dl,t2 ;move remainder to t2
add dl,48 ;convert it to ascii by adding 48
mov ah,02h ;display character in dl interupt code
int 21h ;diplays contents of dl
call endl ;output a new line
ret
endp
exit:
mov ax, 4c00h ;This is just a failsafe exit
int 21h
END
