Re: An interesting Apple II cassette ditty

["Michael J. Mahon" <mjmahon@aol.com>]

winston19842005@yahoo.com wrote:
> On Jan 16, 11:17 am, "Jayson Smith"
> <ihatespamratguynospample...@insightbb.spamsucks.com> wrote:
>
> > Hi,
> >
> >     Just wasting time this morning, I got to wondering what each of the 256
> > possible bytes sounds like when written to tape. Of course, in what I'm
> > about to show you, no tape was ever involved, rather, a digital wav
> > recorder. Anyway, I came up with the following Applesoft program.
> >
> > 0 a = 8192
> > 10 for b = 0 to 255
> > 20 for n = a to a+63
> > 30 poke n,b
> > 40 next n
> > 50 a = a+64
> > 60 next b
> >
> >     When I ran this little masterpiece, I went into the monitor and wrote
> > that data out to tape. And it actually sounds like a strange little ditty.
> > No, it almost certainly doesn't conform to any western scale, but you never
> > know! This might be the next big hit all the radio stations are playing!http://www.bluegrasspals.com/appleditty.mp3
> >
> >     It's interesting to say the least. No idea if that will actually load
> > into an Apple, being an MP3. However, it can be recreated on a real Apple by
> > running the above Applesoft program, going into the monitor, then executing:
> > 2000.5fffw
> > Jayson
>
>
> Is writing direct from the monitor bypassing any of the built-in
> cassette routines? The reason I ask is I did the same for my TI-99,
> and it doesn't sound all that fantastic - more like a regular cassette
> program. I did a program similar to yours that poked 0-255 into
> successive memory locations 12 times, then went to Easy Bug and did a
> S7000 to 7BFF after verifying the data was still there.
>
> Really isn't worth posting anywhere!

The Apple II cassette routines use a coding in which 1's take
twice as much time as 0's.  This means that the repetition rate
of a series of the same byte is determined by the number of 1's
it contains, and therefore the dominant audible frequency takes
on 9 different fundamental periods, with harmonic content determined
by the actual pattern of 1's and 0's.

If the coding method took a constant time for each bit, and therefore
for each byte, the results would not be nearly so interesting to the
ear.  Though the harmonic content (timbre) would shift with each byte
value, the dominant frequency would remain essentially constant.

"Daisy" covers a fair range of notes, so it would be difficult to
render accurately with the small palette available--but you could
probably come up with a sequence that was recognizable as "Daisy"
in an alternative tone scale.  ;-)

-michael

NadaNet and AppleCrate II: parallel computing for Apple II computers!
Home page: http://home.comcast.net/~mjmahon

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