[Coco] HDBDOS >>DRIVE OFF

[Brett Gordon]

I believe Robert is correct.  The HDB variable that implements the "DRIVE
OFF" is setup via code in lower memory by HDB itself after booting.  I
don't think you can just "poke" the ROM easily... the setup code is in
different places in the ROM depending on which flavor of HDB your running,
and you'll have to modify HDB source and reassemble the HDB ROM.  -OR- you
can issue the "DRIVE OFF" command from within BASIC after booting.  It
would be nice if this variable had a straight forward ROM mirror as my
CoCoBoot project could set this up dynamically at bootup.

Sincerely,



On Mon, Oct 7, 2013 at 1:57 PM, Christopher Smith <csmith at wolfram.com>wrote:

> So you need to find the operation that initializes it from somewhere else,
> then?
>
> Chris
>
> ----- Original Message -----
> > From: "Chad H" <chadbh74 at hotmail.com>
> > To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
> > Sent: Saturday, October 5, 2013 10:55:31 PM
> > Subject: Re: [Coco] HDBDOS >>DRIVE OFF
> >
> > crap... was about to flash and realized that address is not part of
> > HC000 rom space ugh...
> >
> > Sent from my Asus Transformer Infinity
> >
> > Chad H <chadbh74 at hotmail.com> wrote:
> >
> > Well i may have found the "trick" I was looking for.  I wrote a quick
> > & dirty BASIC program to toggle DRIVE ON/OFF while scanning
> > addresses and looking for changes...started at drive table area in
> > the 65500 range going backwards.... should have started from 0
> > upwards LOL...
> >
> > key address seems to be at decimal 334.  poking a 0 here seems to put
> > in DRIVE ON mode (rom default).   poking a 4 here made it access
> > physical floppy just like DRIVE OFF.   These are the values returned
> > from PEEKing that address after issuing that command as well....
> >
> > Now time to test...  I will flash a modded HDBOS rom in my FD502
> > controller and see if it autoboots floppy..  crossing fingers...
> > Sent from my Asus Transformer Infinity
> >
> > Robert Gault <robert.gault at att.net> wrote:
> >
> > Chad H wrote:
> > > yea but that would only work with from DriveWire disk#0 which i'm
> > > trying to have the option of doing without... physical floppies
> > > only.  HDBDOS may have been made for hdd setups but it enhances
> > > the floppy experience as well.
> > >
> >
> > Hmmm, there was a function in RGBDOS that made drives 0-3 floppies if
> > a hard
> > drive was not present. Still AUTOEXEC.BAS was not automatically run
> > from floppy
> > drive 0.
> > HDBDOS for Drivewire will not even automatically switch to floppies
> > if Drivewire
> > is not running or there is no drive mounted in DW drive0.
> >
> >
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>
> --
> Christopher Smith
> Systems Engineer, Wolfram Research
>
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-- 
Brett M. Gordon,
beretta42 at gmail.com