分析计时中断！！！！

mokang0421

#include <reg52.h>
#include <intrins.h>
#define uint unsigned int
#define uchar unsigned char
sbit SPK = P3^7;
uchar FRQ = 0x00;
void Delayms(uint ms)
{
  uchar i;
while(ms--)
{
   for(i=0;i<120;i++);
}
}
void main()
{
  P2 = 0x00;
TMOD = 0x11;
TH0 = 0x00;
TL0 = 0xff;
IT0 = 1;
IE = 0x8b;
IP = 0x01;
TR0 = 0;
TR1 = 0;
while(1)
{
   FRQ++;
  Delayms(1);
}
}
void EX0_INT() interrupt 0
{
  TR0 = !TR0;
TR1 = !TR1;
if(P2 == 0x00)
  P2 = 0xe0;
else
  P2 = 0x00;
}
void T0_INT() interrupt 1
{
  TH0 = 0xfe;
TL0 = FRQ;
SPK = ~SPK;
}
void T1_INT() interrupt 3
{
  TH0 = -45000/256;
TL0 = -45000%256;
P2 = _crol_(P2,1);
}
这三个计时器怎么工作的啊 指的是 何时开始工作，何时结束。中间是否发声了重叠部分
小弟看不懂了，仇高手！！！！