[求助]1秒內(nèi)燈閃10次

程序要求：1秒之內(nèi)燈閃10次，我編的程序A和B都不能實(shí)現(xiàn)這個要求，哪位熱心人幫幫我

A:

#include  <reg52.h>

#define uchar unsigned char
#define uint unsigned int
uchar a=0;
sbit LED=P0^0;
sbit P1_4=P1^4;
void delay(uint z);
void main()
{
   P1_4=0;
 a=0;
  TMOD = 0x01;
 TH0 = (65536-50000)/256;//50ms
 TL0 = (65536-50000)%256;
 EA = 1;
 ET0 = 1;
 TR0 = 1;
 while(1);
}

void Timer_0() interrupt 1
{
 TH0 = (65536-50000)/256;
 TL0 = (65536-50000)%256;
   a++;

    if(a == 1)
   {
     a=0;
     LED = ~LED;
 
  delay(689);
  TR0=0;
   }
}

void delay (uint z)
{
 uint x,y;
 for(x=125;x>0;x--)
 for(y=z;y>0;y--);
 }

B:

#include  <reg52.h>

#define uchar unsigned char
#define uint unsigned int
uchar a=0;
sbit LED=P0^0;
sbit P1_4=P1^4;
void delay(uint z);
void main()
{
   P1_4=0;
 a=0;
  TMOD = 0x01;
 TH0 = (65536-50000)/256;//50ms
 TL0 = (65536-50000)%256;
 EA = 1;
 ET0 = 1;
 TR0 = 1;
 while(1);

delay(689);

  ET0=0;
  TR0=0;

}

void Timer_0() interrupt 1
{
 TH0 = (65536-50000)/256;
 TL0 = (65536-50000)%256;
   a++;

    if(a == 1)
   {
     a=0;
     LED = ~LED;
 
     }
}

void delay (uint z)
{
 uint x,y;
 for(x=125;x>0;x--)
 for(y=z;y>0;y--);
 }