[Coco] CocoSDC booting OS9

[Bill Pierce]

I run all my systems (real and emuled) the way Robert describes. Even my starter kits are set up this way (I modded the roms with the offset).
 I have been complaining for almost 4 years now that a 2nd set of hdbdos roms needs to be generated with the ofset at $5A000 and got nothing but flack. Now it's slowly coming back on everyone :-)
Even the stock Vcc 1.4.2 and it's accompanying vhd (which needs to be updated to NOS9 v3.3.0) is set like this. This is s atandard set by Alan deKok when he developed the emudsk driver for the Coco emulators.
SuperIDE uses a different offset, and needs to be sat different. It's the only odd case I know of.
If the roms could become available with the offset, then a copy of Robert's RGBDOS/HDBDOS Tools disk needs to accompany the roms as they allow you to use the auto boot feature to boot straight into OS9 or RSDOS.
 

Bill Pierce
"Today is a good day... I woke up" - Ritchie Havens
 

My Music from the Tandy/Radio Shack Color Computer 2 & 3
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-----Original Message-----
From: Robert Gault <robert.gault at att.net>
To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
Sent: Tue, Nov 18, 2014 8:52 am
Subject: Re: [Coco] CocoSDC booting OS9


Brett Gordon wrote:
><snip>
> Usually, I think most user partition there HD's with OS9 at the beginning,
> and HDBDOS *after* it.  With Boisey's Super Driver for OS9 you can
> partition the drive the other way around with HDBDOS drives taking the
> lower partition and OS9 the higher. If you format your HD this way, then
> you have the ability to create a bootdisk that is readable from HDBDOS (and
> the DOS command) solve the Bob's proposed dillema.
>
><snip>

Maybe you can place the Basic portion first and OS-9 last with the Super Driver 
but that would NOT be good. Further there is no reason to do that with HDBDOS.

RGBDOS and HDBDOS start in Disk Basic mode and read Basic disks based on the 
offset at $D938-$D93A in the Disk ROM. If you want just Disk Basic then the 
offset (stock I believe for HDBDOS) is $000000. The default for the emulators 
JVC, MESS, and VCC is $5A000.
You can backup a 35-track single sided NitrOS-9 disk to any of 256 drives after 
the $5A000 break and boot into NitrOS-9 from that disk. It just requires the 
correct Boot module and the program LINK.BAS to correctly set LSN0 in the 
NitrOS-9 portion of the .vhd drive.
There should not be any reason why the SDC can't work this way and be compatible 

with all other Coco installations including real hard drives with RGBDOS.
Also, if you don't like Disk Basic, you can have HDBDOS automatically boot into 
NitrOS-9 on startup with the use of only 1 or 2 Disk Basic "drives" on the hard 
disk.

With real hard drives, the offset is set by the user based on the size of the 
drive and the desire or lack of it for OS-9 or Disk Basic. The original code 
RGBDOS was written when drives were small; not like todays monsters. :)

Robert



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