Make simple music program with beep(freq, duration) with Pascal

Pascal is my first programing language when I have studied in high school. It was really exciting for me. :)

The Pascal programming language was created by Niklaus Wirth in 1970. It was named after Blaise Pascal, a famous French Mathematician. It was made as a language to teach programming and to be reliable and efficient. Pascal has since become more than just an academic language and is now used commercially.

I tried to make a simple music program by using Lazarus IDE on MS Window 7, 64-bit. It frustrated me a few times how difficulty to use Sound command to make a sound. Sound did not work on my compiler and my platform anymore. So far, I just could use beep(freq, duration) from window unit to implement my work.

Here is my code. ;)

program mysong;

uses
   Windows,
   crt;
const
  C: Integer = 512;    { x = A * EXP(LN(2)/12)}
  C_: Integer = 542;
  D: Integer = 574;
  D_: Integer = 608;
  E: Integer = 644;
  F: Integer = 682;
  F_: Integer = 723;
  G: Integer = 766;
  G_: Integer = 812;
  A: Integer = 860;
  A_: Integer = 911;
  B: Integer = 965;

  WHITE: Integer = 1600;        {x = B/2}
  BLACK: Integer =  800;
  SINGLE: Integer = 400;
  DOUBLE: Integer = 200;
  TRIPLE: Integer = 100;

procedure play(freq,duration: Integer);
begin
     Windows.Beep(freq,duration);
end;
begin
   { A Time For US }
   Clrscr;
   play(A, SINGLE);
   play(C*2, SINGLE);
   play(B, SINGLE);
   play(E, BLACK + SINGLE);

   play(E, SINGLE);
   play(G, SINGLE);
   play(E, SINGLE);
   play(A, BLACK + SINGLE);

   play(A, SINGLE);
   play(G, SINGLE);
   play(F, SINGLE);
   play(G, BLACK + SINGLE);

   play(G, SINGLE);
   play(F, SINGLE);
   play(E, SINGLE);
   play(D, BLACK + SINGLE);

   play(E, DOUBLE);
   play(D, DOUBLE);
   play(C, SINGLE);
   play(D, SINGLE);
   play(E, BLACK + SINGLE);

end.

I just chose frequency's Do note is 512. Next, I inferred the frequency of other notes by "afterNote = beforeNote * EXP(LN(2)/12)".

Reference:
[1]. http://kon-phum.com/tutors/pascal/programming_pascal_learn01.html
[2]. http://stackoverflow.com/questions/23249175/how-to-use-sound-in-pascal

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