[Coco] Question regarding OS-9 Default Drive (/DD)

[Gene Heskett]

On Saturday 08 November 2014 20:54:40 Nick Marentes did opine
And Gene did reply:
> I am wondering how OS-9 handles the default drive.
> 
> I always thought that the idea behind OS-9 is that regardless of your
> OS-9 hardware, the driver maps the hardware to a software "translator"
> (my terms because I don't know the official terms yet). This is the
> default drive (/dd)?
> 
> That way, whether you have a 40trk, 80trk, drivewire, SDC etc drive,
> the application program doesn't care because it talks to this
> "software/device translator".
> 
> So, what has me wondering is why, when I look at the NitrOS-9 software
> website (http://nitros9.sourceforge.net/latest/) there are so many
> files and many are just duplicates but configured for there respective
> loading device?
> 
> Seems messy, confusing and goes against what I thought was how OS-9
> works.
> 
> I would have thought that once one configures an NitrOS-9 to suit their
> setup, the single version of the application disk/s is all that is
> needed.
> 
> Does this mean that when a new program is added, a version of the same
> application needs to be created for each device?
 
No, as long as you have a dd, aka a default drive, the program should run 
from it just fine.  The concept of dd which is the real system 'master' 
drive but renamed, was invented decades ago precisely to put a stop to 
folks assuming the user had both a /d0 and a /d1 drive and hard coding the 
programs accordingly.

/dd can point at, and be a duplicate of any of those drive descriptors, 
just renamed internally to /dd so _all_ the programs can find it.

> Seems wrong and but I'm sure there is something I'm not understanding
> here.

Maybe this helps?  I hope so.

> Nick


Cheers, Gene Heskett
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