B8255C EQU 300H 
  CNTL EQU 83H 
  MOV DX,B8255C+3
  MOV AL,CNTL 
  OUT DX,AL 
  MOV DX,B8255C+1 
  IN AL,DX 
  MOV DX,B8255C 
  OUT DX,AL 
  MOV DX,B8255C+2 
  IN AL,DX 
  AND AL,0FH 
  ROL AL,1
  ROL AL,1 
  ROL AL,1 
  ROL AL,1
  OUT DX,AL