BackPlay  --  A unit for playing music in the background.

  Version 1.00 --  9/24/1988 -- First version

  Copyright 1988 Scott Bussinger
  All rights reserved.

  Scott Bussinger
  Professional Practice Systems
  110 South 131st Street
  Tacoma, WA  98444
  (206)531-8944
  Compuserve [72247,2671]

  This unit allows you to play music in the background of your
Turbo Pascal 5.0 programs. In the background means that once you
start the music playing, you can continue on with the rest of
your program and the music keeps playing without any additional
effort on your part until the song is finished. You can use this
to provide special sound effects in your programs or just to add
a cute indication that your program is still working on
something.

  The unit accepts music files from Neil Rubenking's PianoMan
program version 4.0 and the code in this file is based on
information gained from his sample music playing routines.  You
can either play the .MUZ files off of your disks, or imbed the
the MUZ data directly into your program so the the file need not
be available at run time.  Neil's PianoMan is an excellent
shareware product and is available from many bulletin boards on
in the IBM Software forum on Compuserve. It allows you to play
your computer's keyboard like a piano keyboard and record and
edit music entered in real time or from sheet music.  There are
also many files of songs already entered that you can use. One
sample archive for instance contains over 50 sample songs.

     function PlayingInBackground: boolean;
          This returns true if there is still