Code utilisé dans Nebulus:

unsigned char *contraste(void) ;
asm("	contraste:
		move.w	%d0,-(%a7)
		move.w  #4,%d0
		trap    #9
		move.w (%a7)+,%d0
		rts"		) ;

void set_contraste (int value_contrast)
{
  unsigned char *contrast=contraste();
 	*contrast=value_contrast+1;
 	OSContrastDn ();
}