利用AT89S51单片机来制作一个手动计数器，在AT89S51单片机的P3.7管脚接一个轻触开关，作为手动计数的按钮，用单片机的P2.0－P2.7接一个共阴数码管，作为00－99计数的个位数显示，用单片机的P0.0－P0.7接一个共阴数码管，作为00－99计数的十位数显示(To create a manual counter using AT89S51 microcontroller, in AT89S51 MCU P3.7 pin as a touch switch, manual counting button, P2.0 using microcontroller P2.7 with a common cathode digital tube, as a number of 00 - 99 count display, microcontroller P0.0 P0.7 received a total of Yin digital tube, as the 00 - 99 count ten digit display)