电子选择器，是利用TND－MD教学系统实现的，用来作为特定场合投票机器统计使用。所用到的芯片主要有8253定时计数器、8255A并行接口电路芯片等。使用时，用户用键盘输入A，B，C，D这四个字母中的一个来作为已经选择的项目，程序将在屏幕上对应显示已经选择的“A,B,C或者D”，并且通过控制扬声器，发出对应的频率声音信号，同时相对应的LED灯也对应发光，以便于位于远处的计票员进行远程计票。-Electronics selector is the use of TND-MD teaching system implementation, and used as a specific occasion the use of voting machines and Statistics. Used by the main chip has 8253 regular counters, 8255A parallel interface circuit chips. When used, the user with keyboard input A, B, C, D in these four letters as a selection of projects has been, the program will display on the screen has been chosen corresponding to " A, B, C or D" , and through control speakers, the issue of the corresponding frequency of the voice signal, while the corresponding LED lights also light-emitting counterparts, so far located in remote tellers tellers.