4．相关程序设计内容
（1． 行列式键盘输入及按键功能设定；
（2． 动态数码显示；
（3． 数码显示方式处理；
5．汇编源程序
（略）
6． C 语言源程序
#include <AT89X51.H>
unsigned char code dispcode[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,
0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71,0x00};
unsigned char code dispbitcode[]={0xfe,0xfd,0xfb,0xf7,0xef,0xdf,0xbf,0x7f};
unsigned char dispbuf[8]={0,16,16,16,16,16,16,16};
unsigned char dispbitcount;
unsigned char temp;
unsigned char i,j;
unsigned char key;
unsigned char keypos;
bit alarmflag;
void change(unsigned char *p,unsigned char count)
{
while(count>0)
{
*(p+count)=*(p+count-1);
count--;
}
}
void main(void)
{
TMOD=0x01;
TH0=(65536-4000) / 256;
TL0=(65536-4000) % 256;
TR0=1;
ET0=1;
EA=1;
while(1)
{
P3=0xff;
P3_4=0;
temp=P3;
temp=temp & 0x0f;
if (temp!=0x0f)
{
for(i=50;i>0;i--)
for(j=200;j>0;j--);
temp=P3;
temp=temp & 0x0f;
if (temp!=0x0f)
{
temp=P3;
temp=temp & 0x0f;
switch(temp)
{
case 0x0e:
key=7;
