按下小键盘上的数字键，对应的数字显示在7段LED数码管上，显示的内容自动向左移动，按下小键盘上的A键，清楚键盘缓存区，显示全0；按下小键盘上的B键，删除输入的键值，显示内容自动向右移动。-Press the keypad number keys, the corresponding figures in the 7 LED digital tube, showing the contents of the auto to the left, press the A button on the keypad, clear the keyboard buffer to show all 0　press the small B key on the keyboard to delete the input key, display automatically move to the right.