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，清除键盘缓存区，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 number keys on the keypad, the corresponding figures show that in the 7-segment LED digital tube, showing the contents of the auto-shift to the left, press the A button on the keypad to clear the keyboard buffer to show the whole 0　press the small B keys on the keyboard to delete the input key, display the contents of automatic right.