为什么数字总和显示错误

Question

我有5000和5001这样的数字，我需要将它们相加。我加了数字，但输出的结果是错误的。

s3       DW  5000
s4       DW 5001
s5       DW 0
mov ax, s3
add ax, s4
mov bx, 10
div bx
add dx, '0'
mov s5+3, dx
mov dx, 0
mov bx, 10
div bx
add dx, '0'
mov s5+2, dx
mov dx, 0
mov bx, 10
div bx
add ax, '00'
mov s5, ax
mov s5+1, dx
mov s5+4, '$'
LEA DX, s5
mov ah, 9
INT 21h

Answer 1

s3  DW 5000
s4  DW 5001
s5  DB '00000$'   ; Reserve space for 5 digits, $-terminated.
mov ax, [s3]   ; AX=5000.
add ax, [s4]   ; AX is now 5000+5001=10001, five decimal digits to display.
MOV DX, 0      ; Do not relay on undefined register contents.
mov bx, 10
div bx         ; AX=1000, DX=1.
add dx, '0'    ; DX=0x0031
; mov [s5+3], dx ; Wrong, the last (fifth) digit of the sum should go from DL to [s5+4].
MOV [s5+4],DL
mov dx, 0
; mov bx, 10     ; This is redundand, BX=10 unchanged.
div bx         ; AX=100, DX=0.
add dx, '0'
; mov [s5+2], dx ; Wrong, the fourth digit of the sum should go from DL to [s5+3].
MOV [s5+3],DL
mov dx, 0
; mov bx, 10     ; This is redundand, BX=10 unchanged.
div bx         ; AX=10, DX=0.
; add ax, '00'
; mov [s5], ax   ; Wrong, the third digit of the sum should go from DL to [s5+2].
ADD DL, '0'
MOV [s5+2],DL
MOV DX, 0
DIV BX          ; AX=1, DX=0.
ADD DL, '0'
; mov [s5+1], dx  ; Wrong, the second digit of the sum should go from DL to [s5+1].
MOV [s5+1], DL
ADD AL,'0'      ; The first digit of the sum should go from AL to [s5+0].
MOV [s5+0], AL
; mov [s5+4], '$' ; Wrong, this would overwrite the fifth digit of the sum.
LEA DX, [s5]
mov ah, 9       ; Display the sum at s5.
INT 21h
MOV AH,4Ch      ; Don't forget return to DOS.
INT 21h