#include <reg51.h>
#include <absacc.h>
void MSDelay(unsigned int itime);
void main()
  {
    unsigned char value;
    XBYTE[0x4003]=0x80;	
    while(1)
      {
        value = 0x55;
        XBYTE[0x4000]=value;	
        XBYTE[0x4001]=value;
        XBYTE[0x4002]=value;
        MSDelay(100);
        value = 0xAA;
        XBYTE[0x4000]=value;	
        XBYTE[0x4001]=value;
        XBYTE[0x4002]=value;
        MSDelay(100);
      }
  }
void MSDelay(unsigned int itime)
  {
    unsigned int i, j;
    for(i=0; i<itime; i++)
      for(j=0; j<1275; j++);
  }