[Coco] Flash updated Dragon DOS into SDC... help!

Rogelio Perea os9dude at gmail.com
Sun Mar 13 08:15:34 EDT 2016

Thanks for the follow up... now knowing a bit more on this :-)

-- RP

On Sun, Mar 13, 2016 at 4:26 AM, Pere <psergm at gmail.com> wrote:

> Hi Rogelio,
> I did try to use the updater VDK file as it is released but on the Dragon
>> DOS/SDC release I had on my card, the WRITE commands of the BASIC updater
>> program came off as unrecognized tokens, flagged by ! characters.
> The VDK updater disk will only work if you start the Dragon with an old
> extender
> version. If you satrt with the DOS/SDC version for CoCo or the one by
> Sixxie, then
> the commands I added will not be recognized at all, will show the '!' sign
> instead.
> I also tried to snoop out the BIN file LOADM address out of its preamble,
>> but being it a data file more than an executable binary program, I hinted
>> that the preamble calculated load address would be meaningless, the length
>> reported on the file with the 'preamble' read as is was even more out of
>> bounds than the 'load' address - the update BIN file did have the codes
>> for
>> characters D and K properly set on the first two bytes - a Disk ROM file.
>> More on this later...
> The BIN file in that disk, is really the ROM saved in XRoar to disk, so it
> has
> a std Dragon header (9 bytes) that contains:
> $55, $02, LoadAdrs, Length, Exec, $AA
> The LoadAdrs should be $3000 'cause it has the DOSPlus50 and the extender.
> Length should be $3F00 and exec the same as Load.
> So, loading it into the Dragon with simply:
> LOAD"UPD2503.BIN"     it will occupy from $3000 to $6F00
> Then you could issue WRITE MEM @bank without parameters and this will flash
> the chosen bank with default values ($3000, $C000,$3F00)
> Been playing with the Dragon setup all morning, no problems found on any of
>> the VDK images loaded. Now any updates should be a cinch to do using the
>> Dragon - heard 2504 is out... later.
> Now that you have the v0.25.03 you could use the Basic program UPD2504
> that comes in the VDK Updater disk to get the new v0.25.04 in any bank.
> I am not sure how the BIN updater file in the 2503 distribution VDK got
>> such padding at its start and end... MS Windows?
> This file is created by a batch file while compiling.
> The binary file has NO padding at the beginning, just the Dragon std
> header.
> It consists of the DOSPlus and then the extender, being rounded to a
> multiple of 256 bytes padding it right with zeros.
> The lowercase 'dk' is the signature for a DISK image, whilst 'DK' is the
> one
> for a DOS system ROM.
> My VDKs are DW4 compatible, so they have a header 256 bytes long that
> contain
> some 8 geometry bytes data and padded with zeros to the end.
> cheers
> pere
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