汇编子程序ret不到正确的地址

assume cs:code,ds:data,ss:stack

data segment
x dw 1234
y dw 100 dup(?) ;存放数字的ASCII码
data ends

stack segment
dw 16 dup(?)
stack ends

code segment
start:
mov ax,stack
mov ss,ax
mov ax,data
mov ds,ax

mov dx,0
mov ax,x
mov si,0
call s

mov ax,4c00h
int 21h

s proc near
res:mov cx,10

push ax
mov ax,dx
mov dx,0
div cx
mov bx,ax
pop ax
div cx
mov cx,dx
mov dx,bx

push dx
add cl,30h
mov ds:[si+4],cl
pop dx
push ax
push dx
add ax,dx
jz goOut
pop dx
pop ax
inc si
jmp res

goOut:
pop dx
pop ax
mov dl,ds:[si+4]
mov ah,2
int 21h
cmp si,0
jz ok
dec si
jmp goOut

ok:
ret //这个地方使用ret回不到原来的地方，因为程序并未返回dos
;mov ax,4c00h //把ret直接改成返回dos就可以正常运行，请问是怎么一回事
;int 21h

s endp

code ends
end start