中断做的时钟，怎么去掉字母、字符

ti

中断做的时钟，可以正常走，设置时间，但是怎么去掉字母、字符。看了不造从哪里设置条件。可以帮我改改吗

#include
#define uchar unsigned char
***it rd=P1^0;
***it wr=P1^2;
***it lcde=P1^1;
***it k1=P3^7;
***it k2=P3^6;
***it k4=P3^1;
***it k8=P3^0;
uchar code table1[]="2011-11-05";
uchar code table2[]="00:00:00";
uchar code table3[][3]={{"MON"},{"TUE"},{"WED"},{"THU"},{"FRI"},{"SAT"},{"SUN"}};       //定义了二维数组存放星期
uchar t,s1num;
char shi,fen,miao,week,nian;
uchar yue=1,ri=1;
void delay(uchar z)    //延迟zms函数
{
uchar x,y;
for(x=z;x>0;x--)
for(y=110;y>0;y--);
}

void write_com(uchar com)    //液晶写指令操作
{
rd=0;
wr=0;
delay(5);
lcde=1;
P2=com;
lcde=0;
}
void write_date(uchar date)       //液晶写数据操作
{
rd=1;
wr=0;
delay(5);
lcde=1;
P2=date;
lcde=0;
}
void write_sfm(uchar add,uchar date)    //更新时分秒
{
uchar shi,ge;
shi=date/10;
ge=date;
write_com(0x80+0x40+add);
write_date(0x30+shi);
write_date(0x30+ge);
}
void write_week(uchar i)          //更新星期
{
uchar j;
write_com(0x80+0x0b);
for(j=0;j<3;j++)
{
  write_date(table3[j]);

}
}

void write_riqi(uchar add,uchar riqi) //更新年月日
{
uchar shi,ge;
shi=riqi/10;
ge=riqi;
write_com(0x80+0x00+add);
write_date(0x30+shi);
write_date(0x30+ge);
}
void init()             //初始化函数
{
uchar i,j;

write_com(0x38);
write_com(0x0c);
write_com(0x06);
write_com(0x01);
write_com(0x80+0x00);
for(i=0;i<10;i++)
write_date(table1);
write_com(0x80+0x00+0x0b);
for(j=0;j<3;j++)
write_date(table3[week][j]);
write_com(0x80+0x46);
for(i=0;i<8;i++)
write_date(table2);
TMOD=0x01;             //定时器0工作方式1
TH0=(65536-50000)/256;       //设定定时器初值
TL0=(65536-50000)%6;       //12M晶振时50ms数为50000
EA=1;
ET0=1;
TR0=1;
}
void keyscan()          //键盘扫描函数
{
if(k1==0)             //按下k1键确定调时分秒
{
delay(5);
if(k1==0)
{
  s1num++;
  while(!k1)
  ;
  delay(5);
  while(!k1);
if(s1num==1)
{
TR0=0;                //暂停计时器
write_com(0x80+0x4d);    //光标在秒的位置闪烁
write_com(0x0f);
}

if(s1num==2)       //光标在分的位置
{
TR0=0;
write_com(0x80+0x4a);
write_com(0x0f);
}
if(s1num==3)       //光标在小时的位置
{
TR0=0;
write_com(0x80+0x47);
write_com(0x0f);
}
  if(s1num==4)       //光标在星期的位置
{
TR0=0;
write_com(0x80+0x0d);
write_com(0x0f);
}
  if(s1num==5)       //光标在日的位置
{
TR0=0;
write_com(0x80+0x09);
write_com(0x0f);
}
  if(s1num==6)       //光标在月的位置
{
TR0=0;
write_com(0x80+0x06);
write_com(0x0f);
}
  if(s1num==7)       //光标在年的位置
{
TR0=0;
write_com(0x80+0x03);
write_com(0x0f);
}
if(s1num==8)    //按下第8下时接着走时
{
s1num=0;
write_com(0x0c);
TR0=1;
}
  }
}
if(s1num!=0)
{
  if(s1num==1)
  {
  if(k2==0)          //按k2键秒加1
  {
delay(5);
  if(k2==0)
  {
while(!k2);
delay(5);
while(!k2);

miao++;
if(miao==60)
miao=0;
write_sfm(0x0c,miao);
write_com(0x80+0x4d);
  }
  }
}

  if(s1num==2)
  {
  if(k2==0)          //分加1
  {
delay(5);
  if(k2==0)
{
while(!k2);
delay(5);
while(!k2);
fen++;
if(fen==60)
fen=0;
write_sfm(0x09,fen);
write_com(0x80+0x4a);
}
  }
  }

  if(s1num==3)
  {
if(k2==0)          //时加1
  {
delay(5);
if(k2==0)
{
while(!k2);
delay(5);
while(!k2);
shi++;
if(shi==24)
shi=0;
write_sfm(0x06,shi);
write_com(0x80+0x47);
}
  }
  }
  if(s1num==4)
  {
if(k2==0)          //星期加1
  {
delay(5);
if(k2==0)
{
while(!k2);
delay(5);
while(!k2);
week++;
if(week==7)
week=0;
write_week(week);
write_com(0x80+0x0d);
}
  }
  }
  if(s1num==5)
  {
if(k2==0)          //日加1
  {
delay(5);
if(k2==0)
{
while(!k2);
delay(5);
while(!k2);
ri++;
if(ri==31)
ri=1;
write_riqi(0x08,ri);
write_com(0x80+0x09);
}
  }
  }

  if(s1num==6)
  {
if(k2==0)          //月加1
  {
delay(5);
if(k2==0)
{
while(!k2);
delay(5);
while(!k2);
yue++;
if(yue==12)
yue=1;
write_riqi(0x05,yue);
write_com(0x80+0x06);
}
  }
  }
  if(s1num==7)
  {
if(k2==0)          //年加1
  {
delay(5);
if(k2==0)
{
while(!k2);
delay(5);
while(!k2);
nian++;
if(nian==100)
nian=0;
write_riqi(0x02,nian);
write_com(0x80+0x03);
}
  }
  }

if(k4==0)  //判断k4是否被按下
{
  delay(5);
  if(k4==0)
  {
while(!k4);
delay(5);
while(!k4);
if(s1num==1)
{
miao--;       //秒减1
if(miao==-1)
miao=59;
write_sfm(0x0c,miao);
write_com(0x80+0x4d);
}
if(s1num==2)
{
fen--;       //分减1
if(fen==-1)
fen=59;
write_sfm(0x09,fen);
write_com(0x80+0x4a);
}
if(s1num==3)
{
shi--;       //时减1
if(shi==-1)
shi=23;
write_sfm(0x06,shi);
write_com(0x80+0x47);
}
  if(s1num==4)
{
week--;       //星期减1
if(week==-1)
week=6;
write_week(week);
write_com(0x80+0x0d);
}
  if(s1num==5)
{
ri--;       //日减1
if(ri==0)
ri=30;
write_riqi(0x08,ri);
write_com(0x80+0x09);
}
  if(s1num==6)
{
yue--;       //月减1
if(yue==0)
yue=12;
write_riqi(0x05,yue);
write_com(0x80+0x06);
}
  if(s1num==7)
{
nian--;       //年减1
if(nian==-1)
nian=99;
write_riqi(0x02,nian);
write_com(0x80+0x03);
}
  }
}
}
if(k8==0)       // 按下k8退出调时
{
  delay(5);
  if(k8==0)
  {
while(!k8);
delay(5);
while(!k8);
s1num=0;
write_com(0x0c);
TR0=1;
  }
}
}

void main()
{
init();
while(1)
{
keyscan();
}
}
void timer0() interrupt 1    //中断服务程序
{
TH0=(65536-50000)/256;       //设定定时器初值
TL0=(65536-50000)%6;       //12M晶振时50ms数为50000
t++;
  if(t==20)          //定时器中断20次为1秒
{
t=0;
miao++;
if(miao==60)
{
miao=0;
fen++;
if(fen==60)
{
  fen=0;
  shi++;
  if(shi==24)
  {
shi=0;
ri++;
week++;
if(week==7)
week=0;
write_week(week);             //刷新星期
if(ri==31)
{
   ri=1;
   yue++;
   if(yue==13)
   {
   yue=1;
   nian++;
   if(nian==100)
   nian=0;
   write_riqi(0x02,nian); //刷新年
   }
   write_riqi(0x05,yue); //刷新月
   }
  write_riqi(0x08,ri);  //刷新日
  }
write_sfm(0x06,shi); //刷新时
}
write_sfm(0x09,fen);    //刷新分
}
write_sfm(0x0c,miao);    //刷新秒
}
}