[Coco] tape format and .cas file problems

[Roger Taylor]

At 05:01 PM 11/19/2008, you wrote:
>On 11/19/08, Roger Taylor wrote:
> > At 02:28 PM 11/19/2008, you wrote:
> >>
> >>Color Basic does not support muti-segment CLOADM files, but Extended
> >>Basic does add that capability. These multi-segment files must have
> >
> > Shows ya how much I clung to the tape format over the years.  I was
> > under the impression that no CoCo ROM supported multi-segment
> > CLOADMs, but I stand educated.  ;)
> >
> > So, where are the origin control bytes in those data blocks?  The
> > filename block has the initial load and exec addresses, ofcourse.
>
>
>The multi-segment tape format is identical to the disk format. The
>5-byte pre/postamble blocks are contained in the cassette file's data
>bytes. The initial load and exec address in the filename block are
>ignored for multi-segment files.

I suspected this.  There's really no other place for the addresses to go.



>The CAS files I have seen all use zeros for silence without any real
>way to diferentiate them from actual bytes of $00. I'm not sure how it
>was supposed to work.

Yea, kind of strange.  Maybe somewhere in the beginning of the file 
is a set of pointers that mark the start/length or end of the silence area(s)?

And then there's Vavasour's ROM format, etc. with the headers.







>My conversion utility does not try to replicate the CAS file exactly,
>but instead uses a state machine to translate the file. Initially, it
>starts in an "invalid" state and remains in that state until its sees
>enough sync bytes to move to the next one. It then looks for the
>logical block structures, etc... When it reaches the end of a block it
>returns to the "invalid" state.  The audio output contains silence
>gaps of a fixed duration. This won't work for every CAS file (like
>those that don't use the defined block format), but it has worked for
>everything I've needed to convert.
>
>Darren
>
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-- 
Roger Taylor

http://www.wordofthedayonline.com