這個是電子琴加播放音樂的程序。。。

這個程序在播放音樂的過程中 ，，，如果按其他的鍵  沒反應   只能在放完音樂后才能實現彈奏功能，，，，誰能幫我改下使這程序它在播放的過程中按下按鍵時可以能實現彈奏的功能。。。，，最好能再加一首歌曲上去。。。

#include <reg52.h>
#define uchar unsigned char
#define uint unsigned int
void PlayMusic();
sbit a=P3^2 ;
sbit BEEP = P3^0;

uchar code DSY_Table[]=
{
  0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,0x88,0x83,0xc6,0xa1,0x86,0x8e,0xBF
};
uint code Tone_Delay_Table[]=
{64021,64103,64260,64400,64524,64580,64684,64777,64820,64898,64968,65030,65058,65110,65157,65178};
  uchar code SONG_TONE[]=
{
  212,212,190,212,159,169,212,212,190,212,142,159,212,212,106,126,129,169,190,119,119,126,159,142,159,0
};
uchar code SONG_LONG[]=
{
  9,3,12,12,12,24,9,3,12,12,12,24,9,3,12,12,12,12,12,9,3,12,12,12,24,0
};

void DelayMS(uint ms)
{
  uchar t;
 while(ms--)
 {
   for(t=0;t<120;t++);
 }
}
uchar KeyNo;


void Keys_Scan()
{
  uchar Tmp,k;
 P1 = 0x0f;
 DelayMS(2);
 Tmp = P1 ^ 0x0f;
 switch(Tmp)
 {
   case 1: k = 0; break;
  case 2: k = 1; break;
  case 4: k = 2; break;
  case 8: k = 3; break;
  default: return;
 }
 P1 = 0xf0;
 DelayMS(2);
 Tmp = (P1 >> 4) ^ 0x0f;
 switch(Tmp)
 {
   case 1: k+= 0; break;
  case 2: k+= 4; break;
  case 4: k+= 8; break;
  case 8: k+= 12;break;
  default: return;
 }
  KeyNo=k;
}

void Play_Tone() interrupt 1
{
  TH0=Tone_Delay_Table[KeyNo]/256;
  TL0=Tone_Delay_Table[KeyNo]%256;
  BEEP=~BEEP;
  }
void main()
{
  P0 = 0xBF;
 TMOD=0x01;
 IE=0x82;
 while(1)
 {
   if(a==0)
    PlayMusic();
  else
  {P1 = 0xf0;
  if(P1 != 0xf0)
  { Keys_Scan();
  
    P0 = DSY_Table[KeyNo];
   TR0=1;}
  else
  {
  TR0=0 ;
  }
  DelayMS(2);
   }
}
}
  void PlayMusic()
{
  uint i =0,j,k;
 while(SONG_LONG!=0||SONG_TONE!=0)
 {
   for(j=0;j<SONG_LONG*20;j++)
  {
    BEEP = ~BEEP;
   for(k=0;k<SONG_TONE/3;k++);
  }
  DelayMS(50);
  i++;
 }
}