org  100 h  ; This example starts the PS / 2 mouse and puts an O on the screen every time a button is moved or pressed  mov  ax , 0 C207h  ; Function to set the address of the mouse driver  mov  bx , offset  driver_mouse  ; We load in BX the offset of the mouse driver code  int  15 h  mov  ax , 0 C205h  ; We initialize the mouse  mov  bl , 8  ; We use 8 bytes of data in the mouse  int  15 h  mov  ax , 0C200h  ; We activate the mouse  mov  bh , 01 h  ; We activate the mouse (00h -> To deactivate it)  int  15 h  int  20 h  ; We  return  to MS-DOS driver_mouse: mov  ah , 0 Eh  ; Function to print character on screen  mov  al , ' O '  ; Print an O  int  10 h  retf  ; We exit the controller