Re: cassette interface data format?

["Jayson Smith" <nospamratguyspambegone@nospamplease.bellsouth.ihatespam.net>]

Hey, with this info, I bet somebody could write a Win/Linux program to take
any standard file and convert it to a .wav of a valid Apple II cassette dump
of that file.  That way you could transfer, say, ADT to an Apple via the
tape interface.  Or any other binary for that matter.  DOS, even?
I couldn't do it, but somebody probably could!  What would be the best
sample rate for such a wav?  What kind of frequency response does the
cassette hardware require?
Jayson.

"Benjamin Ketcham" <bketcham@drizzle.com> wrote in message
news:1097056634.892700@yasure...
> Michael J. Mahon <mjmahon@aol.com> wrote:
> >
> > The best "documentation" of cassette format is in the monitor
> > listing for the code that creates and decodes cassettes.  The
> > listing is in virtually all early Apple II Reference Manuals.
>
> Yes, I'd like to get my hands on a manual (again).  I had started
> to trace the monitor code, but the info you gave below sure saves
> me a lot of time and uncertainty.
>
> > There is a lead-in tone of 3.5 seconds of 770Hz, followed by
> > a 1-cycle "start" mark with two 400 microsecond half-periods.
> > Then data follows, most significant bit first, with two 250
> > microsecond half-periods for a "0" and two 500 microsecond
> > half-periods for a "1".  Following the data, there is a single
> > checksum byte, which is the EOR of all data bytes, seeded
> > with $FF.
> >
> > Applesoft BASIC files are preceded by a short record with
> > the length of the program and an "auto run" flag byte.
>
> Thank you very much for this info!  If it is available on the
> Web anywhere, I was unable to find it with my search attempts.
> I'd suggest that those who maintain Apple II FAQs (there seem
> to be more than one active FAQ) might want to include this
> info -- though I guess if I'm the only one who asked, it's
> not a very FA Q.
>
> --Benjamin
>