Subtraction of Two Arrays and Stores Result in 3rd array and display the result on screen in Assembly language 8086 - arrays

Question

I have already written the code to add TWO arrays and Store the result in 3rd array. But the problem occurs while handling the NEGATIVE SIGN Numbers to display with (-) sign. Follow are the code listed below while subtracting the 6th element of array1 with array 2, result is GARBAGE value Need assistance immediately. After running executing's the code, all signed values are not displaying correctly.
org 100h
Array1 db 1,3,2,2,2,2,2,2,2,2
Array2 db 4,5,6,7,8,9,0,1,2,3
Array3 db 10 dup (?)
lea dx, msg1
mov ah, 9
int 21h
mov cx, 10
mov bx, 0
L1001:
mov al, Array1 [bx]
; Extend (unsigned) AL to AX (to print)
mov ah, 0
call printd
mov ah, 2
mov dl, 09 ;TAB Character
int 21h
inc bx
loop L1001 ;End Loop1
mov ah,2
mov dl,10
int 21h
mov dl,13
int 21h
; print msg2
lea dx, msg2
mov ah, 9
int 21h
; Use loop to print values of Array2
mov cx, 10
mov bx, 0
L1002:
mov al, Array2 [bx]
; Extend (unsigned) AL to AX (to print)
mov ah, 0
call printd
mov ah, 2
mov dl, 09 ;TAB Character
int 21h
inc bx
loop L1002 End Loop2
mov ah,2
mov dl,10
int 21h
mov dl,13
int 21h
; print msg3
lea dx, msg3
mov ah, 9
int 21h
mov cx,10
mov bx, 0
L1003: ; Main Addition
mov al, Array1 [bx]
sub al, Array2 [bx]
mov Array3 [bx], al
; Extend (unsigned) AL to AX (to print)
mov ah, 0
call printd
mov ah, 2
mov dl, 09 ;TAB Character
int 21h
inc bx
loop L1003 ; End of lOOP3
lea dx, pkey
mov ah, 9
int 21h ; output string at ds:dx
; wait for any key....
mov ah, 1
int 21h
mov ax, 4c00h ; exit to operating system.
int 21h
printd proc
; preserve used registers
push ax
push bx
push cx
push dx
; if negative value, print - and call again with -value
cmp ax, 0
jge L1
mov bx, ax
; print -
mov dl, '-'
mov ah, 2
int 21h
; call with -AX
mov ax, bx
neg ax
call printd
jmp L3
L1:
; divide ax by 10
; ( (dx=0:)ax / cx(= 10) )
mov dx, 0
mov cx, 10
div cx
; if quotient is zero, then print remainder
cmp ax, 0
jne L2
add dl, '0'
mov ah, 2
int 21h
jmp L3
L2:
; if the quotient is not zero, we first call
; printd again for the quotient, and then we
; print the remainder.
; call printd for quotient:
call printd
; print the remainder
add dl, '0'
mov ah, 2
int 21h
L3:
; recover used registers
pop dx
pop cx
pop bx
pop ax
ret
printd endp
printud proc ;Print Undecimal Numbers
push ax
push bx
push cx
push dx
mov dx, 0
mov cx, 10
div cx
cmp ax, 0
jne L4
add dl, '0'
mov ah, 2
int 21h
jmp L5
L4:
call printud
add dl, '0'
mov ah, 2
int 21h
L5:
pop dx
pop cx
pop bx
pop ax
ret
printud endp ;
ret
msg1 db "Array 1 = $"
msg2 db "Array 2 = $"
msg3 db "Array 3 = : $"
pkey db "press any key...$"

Answer 1

mov al, Array1 [bx]
sub al, Array2 [bx]
mov Array3 [bx], al
; Extend (unsigned) AL to AX (to print)
mov ah, 0
call printd
You say that your program is having trouble displaying the negative numbers, but your code is never feeding any negative number to the printd routine! Whatever the signed result of the subtraction in AL may be, the mov ah, 0 that follows will produce a positive number in AX and it is AX that printd processes...
You should replace mov ah, 0 by cbw.
But, what is terribly wrong is the placement of the 3 arrays. They can't be at the top of the program like that. The cpu is executing their bytes (data) as if it were instructions (code)!
Move those 3 lines towards the bottom of the source.
It surprised me to see these recursive solutions to display a decimal number. I believe they are correct with one exception though! If you feed printd the negative number -32768 then the program will fall into an infinite loop. This happens because the negation of that particular value is again -32768.
You might want to investigate Displaying numbers with DOS for info about the iterative solution that is surely faster (and could be improved further by outputting the digits all at once).