[Coco] Orchestra90-Dragon NEW version

Pere psergm at gmail.com
Sun Jul 17 04:21:02 EDT 2016

Hi all,
acording to the manual, XRoar supports these kind of disks:

The problem with the big disks with music inside is that they have been 
created to be
used with a Dragon compatible DOS, not by RSDOS.
The FAT is at the first/second sectors on the Directory track (#20) and the 
first 90 bytes
of each sector tell us the state of 8 sectors each (1 bit per sector)
In RSDOS the FAT is at the second sector of the Dir track (#17) and after 6 
control bytes
there are 68 data bytes that tell us the state of each granule (block of 9 
To complicate life a bit more, the directory entries in Dragon are nor 
linked one to
the next, instead they have a small internal table where you will find four 
entries and
this can be extended with a byte pointer to other entries.
The file headers are 5 bytes long for CoCo and 9 bytes for Dragon. CoCo has 
a 5 bytes
end of file that doesn't exist in Dragon.
As Orchestra works at low level with the drives, it controls the data 
structure of each
read sector, so no compatability between the two machines for drives.
This is the reason why I had to rewrite the whole disk access system for the 
version of the Orchestra.

This collection has been cretated from a big amount of ASCII files that we 
to CAS files with a perl scrit made by Tony Jewell. Next step was a 
conversion from
CAS to Dragon BIN format. This was done with a small java utility I built. 
Finally we used
the Dragontools utility (by Rolf Michelsen) to put lots of 160 files into a 
blank disk.
160 is the maximum number of files supported on the 16 directory sectors of 
DOS because each one accepts 10 entries ...


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Message: 5
Date: Sat, 16 Jul 2016 18:50:09 -0400
From: Bill Pierce <ooogalapasooo at aol.com>
To: coco at maltedmedia.com
Subject: Re: [Coco] Orchestra90-Dragon NEW version
Message-ID: <155f5e713ad-47b9-6bfb at webprd-a96.mail.aol.com>
Content-Type: text/plain; charset=utf-8

Barry, I think you'll have problems with VDK in DW4 and/or VCC. I have no 
idea whether Mess even supports VDK at all. I have had many problems with 
VDK in VCC as well as DW4.
VCC and DW4 both only have "limited" VDK support and will not read all forms 
of VDK. I may be wrong and those disk images may read fine, though I think 
the best bet would be to load the VDK images into XRoar and copy the files 
to a JVC format disk image.

XRoar originally only supported VDK and it's still the native format, but 
JVC support has been greatly improved on the later versions of XRoar.

In the end, VDK is actually a more "complete" disk image format, having the 
"between track" timing sections and such, but JVC with it's straight "raw 
file" format is just easier to work with and the reason they became the 
standard for VCC & DW4. Even the NitrOS9 repo produces JVC style disk 

Bill Pierce
"Charlie stole the handle, and the train it won't stop going, no way to slow 
down!" - Ian Anderson - Jethro Tull

My Music from the Tandy/Radio Shack Color Computer 2 & 3
Co-Contributor, Co-Editor for CocoPedia
Global Moderator for TRS-80/Tandy Color Computer Forums

E-Mail: ooogalapasooo at aol.com

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