public link unit clock {}
driver.clock = clock;
public link unit char {}
driver.char = char;
public link void OS_init(){} = driver.OS_init;
public link void ShowYearMouthDay(bit n1,bit n2){} = driver.ShowYearMouthDay;
public link void ShowHourMinuteSecond(bit n1,bit n2){} = driver.ShowHourMinuteSecond;
