[Coco] .CAS file format

[Gustavo Ranaur Schoenaker]

Harry,

The tape format I have (from the TRS-80 Color Computer Technical Reference
Manual). I just need to know the CAS file format. One byte for each "byte
on the tape? Should I put the leads?

But thanks anyway!

On Sun, Dec 16, 2012 at 8:22 PM, Harry Hurst <hhos at st-tel.net> wrote:

> > I looking for the specification of the .CAS file format. I wrote in
> Octave
> > a cassete parser.
> > It`s in pre-zero-zero-alpha, it`s slow and difficult to use, but it`s
> > reading tapes (with checksum) that xroar was giving me IO ERRORs.
>
> Since you are talking about XROAR I guess you are talking about a Dragon's
> cassette output? Or does XROAR also do CoCo1/2? The reason I ask is that I
> did find a description of the CoCo cassette tape format. I have yet to
> find one for the Dragon. There is, BTW a program, called "cocotape", to go
> from tape to a wave file on your hard drive. The PC executable is on
> CoCo3.com if that would help.
>
> http://www.coco3.com/community/downloads/coconet-support-files/
>
>
>
>
> >
> > Now I need to generate the .CAS file.
> >
> > Does anyone have some docs for the format?
> >
>
>
> Here is the page from "The Facts for the TRS-80 Color Computer" that I
> found.
>
>
> ********************************************************************
>      G.  Cassette Interface - Cassette data is stored onto the tape
> using a format called Frequency Shift Keying (FSK ).  This means that
> two sine waves of differing frequency are used to store zeroes and ones
> on the tape.  A sîne wave of 24OO Hertz is used to store a one, and a
> sine wave of 1200 Hertz is used to store a zero.  These sine waves are
> generated by the computer with a lookup table and sent to the D/A
> converter (see Appendix A)
>
>      The table is scanned sequentially and the values are stored in the
> D/A converter.  The output of the D/A converter is then sent to the aux-
> îliary input of the tape recorder and stored on the magnetic cassette
> tape.  When the datȧ is to be read back into the computer, it is read
> back in through a circuit which detects when the input voltage has
> crossed zero and counts the time before it crosses zero again.  A high
> frequency sine wave will cross zero more often than a low frequency sine
> wave.  This fact is used to determine whether a zero or a one was stored
> on the tape.  It is a very sîmple method but works well.
>
>      The cassette motor is controlled by the computer through CA2 of
> PIA1.  The motor will be on if CA2 is high and off if CA2 is low.
>
>
>
>      CASSETTE TAPE FORMAT:  The normal Color Computer tape contains
> the following information:
> 1)  A leader of 128 bytes of $55
> 2)  Namefile block.
> 3}  Ab out 1/2 second of blank tape.
> 4)  128 bytes of $55
> 5)  Data blocks.
> 6)  End of File block.
>
>
>      The format for Data, Namefile or End of File blocks is:
> 1) One $55 byte.
> 2) One $3C sync byte.
> 3) Block Type byte: Namefile= OO, Data= 01, End of Fil e= $FF.
> 4) Block length byte, O to 255
> 5) Data, O to 255 bytes.
> 6) Checksum byte, the sum of all the data plus block type and block
>    length.
> 7) one $55 byte.
>
>     The Namefile block is a normal block with a length of 15 bytes as
> described below:
> 1) Eight bytes for the program name.
> 2) File Type byte; BASIC= OO, Data= 01 , Machine language= O2
> 3) ASCII flag byte; Binary= 00, ASCII= $FF
> 4) Gap flag byte; Continuous= 01, Gaps= $FF this byte is not used by the
> current versions of BASIC
> 5) Two.bytes for the start address of a machine language program.
> 6) Two bytes for the transfer address of a machine language program.
>
>     The End of File block is a normal block with a length of zero.
> ********************************************************************
>
>
> The Dragon structure may be the same. I will be watching for information
> on the subject, but I probably won't actively search for it any more for
> the present. Let me know if you need that, though, and I will start
> searching again.
>
> HH
>
>
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