此电路由AT89C51最小系统、四位数码管、蜂鸣器电路和按键模块组成。

运行原理：

        该抢答器电路可同时进行八路优先抢答。按键按下后，蜂鸣器发声，同时数码管
显示优先抢答者的号码，抢答成功后，再按按键，显示不会改变，除非按主持人键。
复位后，显示清零，可继续抢答。

二、运行效果图

三、部分代码

#include<reg51.h>
#define uchar unsigned char
#define uint unsigned int//按键扫描，判断哪个人抢答
void key()
{uint n, flag = 1;n=2200;	display(n);keep=1;if(key2==0){delay(5);if(key2==0){while(1){n=2202;display(n);if(flag){keep=0;			 //开启蜂鸣器delay(80);keep=1;			// 关闭蜂鸣器delay(80);flag = 0;}if(key9==0){delay(5);if(key9==0){keep=1;n=2200;	display(n);while(1)return;}while(!key9);delay(5);while(1);    }} }	 while(!key2);delay(5);}	  if(key3==0){delay(5);if(key3==0){while(1){n=2203;display(n);if(flag){keep=0;			 //开启蜂鸣器delay(80);keep=1;			// 关闭蜂鸣器delay(80);flag = 0;}if(key9==0){delay(5);if(key9==0){keep=1;n=2200;	display(n);while(1)return;}while(!key9);delay(5);while(1);    }}}					while(!key3);delay(5);	 }if(key4==0){delay(5);if(key4==0){while(1){n=2204;display(n);if(flag){keep=0;			 //开启蜂鸣器delay(80);keep=1;			// 关闭蜂鸣器delay(80);flag = 0;}if(key9==0){delay(5);if(key9==0){keep=1;n=2200;	display(n);while(1)return;}while(!key9);delay(5);while(1);    }} }					while(!key4);delay(5);	 }		if(key5==0){delay(5);if(key5==0){while(1){n=2205;display(n);if(flag){keep=0;			 //开启蜂鸣器delay(80);keep=1;			// 关闭蜂鸣器delay(80);flag = 0;}if(key9==0){delay(5);if(key9==0){keep=1;n=2200;	display(n);while(1)return;}while(!key9);delay(5);while(1);    }}}					while(!key5);delay(5);	 }if(key6==0){delay(5);if(key6==0){while(1){n=2206;display(n);if(flag){keep=0;			 //开启蜂鸣器delay(80);keep=1;			// 关闭蜂鸣器delay(80);flag = 0;}if(key9==0){delay(5);if(key9==0){keep=1;n=2200;	display(n);while(1)return;}while(!key9);delay(5);while(1);    }}}					while(!key6);delay(5); }	if(key7==0){delay(5);if(key7==0){while(1){n=2207;display(n);if(flag){keep=0;			 //开启蜂鸣器delay(80);keep=1;			// 关闭蜂鸣器delay(80);flag = 0;}if(key9==0){delay(5);if(key9==0){keep=1;n=2200;	display(n);while(1)return;}while(!key9);delay(5);while(1);    }}}					while(!key7);delay(5);	 }	if(key8==0){delay(5);if(key8==0){while(1){n=2208;display(n);if(flag){keep=0;			 //开启蜂鸣器delay(80);keep=1;			// 关闭蜂鸣器delay(80);flag = 0;}if(key9==0){delay(5);if(key9==0){keep=1;n=2200;	display(n);while(1)return;}while(!key9);delay(5);while(1);    }}}					while(!key8);delay(5);	 }	
}//  主函数
void main()
{while(1){key();  // 判断按键}
}