用汇编编写DOS下的内存驻留程序(3)：中断矢量

sp;   call dspace
    ;
    mov     al,dl                   ;move the interrupt number to AL
    mov     ah,35h                  ;Function is Get interrupt vector
    int     21h
    mov     dx,bx                   ;Move BX to DX so we can display
    call    ddword                  ;double-word in ES:DX
    call dEndFra
    call    dcrlf                   ;Display a newline
    ret
   dvector endp  
   ;----------------------------------------------------------------------------
   ;DS:SI points to ASCII string to be printed
   ;----------------------------------------------------------------------------
   dstring proc    near
    push    si
    push    ax
   dis:    mov     al,[si]                 ;Fetch the next character
    cmp     al,0                    ;If it''s zero,we are done
    je      disdone        
    call    dchar                   ;If not,point it
    inc     si                      ;Advance pointer to nest char
    jmp     dis
   disdone:pop     ax
    pop     si
    ret
   dstring endp
   ;----------------------------------------------------------------------------  
   ;ES:DX contains double word to be displayed
   ;----------------------------------------------------------------------------
   ddword  proc    near
    push    dx                 &nbs