Maybe this is not the one you mean, as if it really had a musical program which allowed one to play with keyboard or whatever another way.
I got sample tape with my new Toshiba HX-10 in ´87.
Tape itself was light grey coloured and there was same shiny silver coloured label attached on both sides, and label said:
TOSHIBA HOME COMPUTER HX-10
SAMPLE PROGRAM
CLOAD [RETURN] (5 PROGRAMS)
MSX PZA-525
MADE IN JAPAN
TOSHIBA CORPORATION
MSX is a registered trademark of MICROSOFT CORPORATION
Let me see, what I can remember, I still have that dear tape, but I don´t have time to check it more carefully (i.e. load and watch as programs are LONG, not to load, but long to watch!).
I may remember wrongly the order of the programs (who cares

)
first was somekinda greeting text which told what you can actually DO with your new computer TOSHIBA HX-10 ie play games, use it as office work etc and I remember it told about printers etc stuff and of course it explained how to USE these five programs.
second was LONG graphics demo, which showed all 255 characters and drew really neat screen 2 graphics!!
third one showed audio stuff and played notes from one, two and atlast three channels and played nice little melodies. but it could be that this part was included in graphics demo program, as there was subroutine that showed how you can alter SIZE of your drawings with DRAW command and it drew giant letter "E"s while playing long CAN-CAN!
it had program which allowed you to train yourself to master in ten fingers typing, and this program drew keyboard in screen2. That´s why I believe it maybe could have been same program as you had. You had to press flashing key as fast as you could, and it gave you rating at the end of each game how successfull you had been! that was really fun!
And last program had calculating Game, which had BIG numbers in screen (they were magnified 16x16 sprites!) and that looked really cool!!!! in the beginning of each game you could either choose addition or multiply.
ps.. As younger I examined those BASIC programs and between lines there were REM statements which said those programs were made by KNIGHTS COMPUTERS in UK, when running the demos, there were nothing about their work, just TOSHIBA.
So, was this same tape?
And I like to know more about other companies demo tapes!