说明：  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
(AT89S51 Singlechip use to produce a manual counter, in the P3.7 pin MCU AT89S51 by one touch switch, the button as a manual count, using SCM after another P2.0-P2.7 total overcast digital tube, as a count of 00-99 single-digit display, with single chip after another P0.0-P0.7 digital tube were overcast, 00-99 count as ten-digit display)