汇编语言关于2号功能函数的坑点

mov ah,2
int 21h

DATAS SEGMENT
    ;此处输入数据段代码  
DATAS ENDS

STACKS SEGMENT
    ;此处输入堆栈段代码
STACKS ENDS

CODES SEGMENT
    ASSUME CS:CODES,DS:DATAS,SS:STACKS
START:
    MOV AX,DATAS
    MOV DS,AX
    mov ax,3633H
    call print
    MOV AH,4CH
    INT 21H
print proc
    push dx
    mov dl,ah
    ;入口参数是ax
    mov ah,2
    int 21h
    mov dl,al
    mov ah,2
    int 21h
    pop dx
    ret
print endp
CODES ENDS
    END START

Category: DOS kernel
INT 21 - DOS 1+ - WRITE CHARACTER TO STANDARD OUTPUT

    AH = 02h
    DL = character to write
    （某些版本存在返回值）
Return: AL = last character output (despite the official docs which state
        nothing is returned) (at least DOS 2.1-7.0)
Notes:  ^C/^Break are checked, and INT 23 executed if pressed
    standard output is always the screen under DOS 1.x, but may be
      redirected under DOS 2+
    the last character output will be the character in DL unless DL=09h
      on entry, in which case AL=20h as tabs are expanded to blanks
    if standard output is redirected to a file, no error checks (write-
      protected, full media, etc.) are performed
SeeAlso: AH=06h,AH=09h