[Coco] CoCo Emulator Floppy Images - JVC format

Eric J. Rothfus eric at rothfus.com
Thu Sep 2 13:15:56 EDT 2004


Thanks Tim.  I've downloaded a couple of your "section
H" examples.

What I meant by "deleted sector" is really a deleted
data mark within the JVC...meaning that the image is
using the extended "attributes" byte in the front of
each sector.  Have any of those types of images?  I
just haven't seen any "real" floppy images (made from
real floppies) that have used the extended features of
JVC.

I'm looking to excersize JVC reading code that I have.
This code is part of a larger project that I'm working
on.  The goal is to be able to run floppy images easily
on a physical vintage machine...including the CoCo.
The system currently supports DMK pretty well...just
wanted to make sure that it supports JVC correctly too.
(http://www.theSVD.com)

You mentioned in a previous posting the Diecom images
that you've run on the emulator.  But those are in DMK,
right?  In other words, JVC isn't expressive enough to
represent them.  Are there some images out there that
do make use of the extended features of JVC?

Thanks for the help Tim!

Eric


>> Does anyone have JVC-formatted floppy images that are
>> not of the "simple" kind?  For a quick explanation of
>> the JVC format take a look at (from Tim's site):
>> 
>>    http://home.netcom.com/~tlindner/JVC.html
>> 
>> All JVC-format images that I have are either 161,280 or
>> 184,320 bytes long, corresponding to 35 and 40 track
>> CoCo DD 18-sector images.  These images do NOT have the
>> JVC header, indicating that they are "simple" images
>> that use the default parameters.
>
> My web page above does contain a link to download some non standard
> (with header) disk images. They are under section H (Example files).
>
>> Does anyone have images that HAVE the header in them?
>> These JVC images would PROBABLY be (or thereabouts)
>> 161,915 or 161,285 bytes long for 35 track and 185,045
>> or 184,325 bytes for 40 track.  These images would
>> probably not use the default parameters and may have
>> deleted sectors or some form of copy protection.
>
> The JVC format does not support the concept of deleted sectors. You can
> only suppily the number (total count) of sectors. I suppose if you set
> the sector count to 17, then there is a missing sector at the end, but
> then all tracks have a missing sector at the end.
>
> You'll need to investigate the DMK format for more functionality.
>
> -- 
> tim lindner
> tlindner at ix.netcom.com                                            Bright




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