11.asm

华工电信系汇编习题的编程实现

stack segment stack 'stack'
      dw 32 dup(?)
stack ends

data segment
     B1 db 0FBH
data ends

code segment 
begin proc far
      assume ss:stack,cs:code,ds:data
      push ds
      sub ax,ax
      push ax
      mov ax,data
      mov ds,ax

      mov al,B1
      and al,al
      JNS ZHENG
      and al,07FH
      NEG al
ZHENG:

      ret
begin   endp
code    ends
      end begin