[Coco] CoCo SDC weirdness

[Tim Fadden]

On 3/3/2017 8:01 PM, David Ladd wrote:
> On Wed, Mar 1, 2017 at 1:47 PM, Tim Fadden <t.fadden at cox.net> wrote:
>
>> Don't get me wrong, this is not a complaint, I love me sdc cards.
>>
>> I have been having the following symptoms/features?
>>
>> I have two scsi drives attached, and use the floppy do boot into nitros9,
>> and the scisi is the /dd device.
>> This works, and I can use the floppies, SDC, and drivewire.
>>
>> So I was thinking it would be nice to be able to boot off of the sdc card
>> the same way.
>> I took a 40tk nitros9 dsk image and used deldir to clean off the files.
>> Then I used the custom build script/bootlists minus the format sdc doesn't
>> like that. :-)
>> Ok, the sdc dsk image gets created with no problem, and I am able to boot
>> from it.
>>
>> It changes over to the /dd (scsi partition) I can access the scsi, sdc and
>> drivewire.  But when trying
>> to access the floppies it accesses the sdc instead.  taking a look at the
>> device descriptors of
>> /do and /sd0 everything looks correct.
>>
> ​This is because you probably had the MPI switch set to the slot with the
> CoCoSDC rather than the slot with the real FDC.
Well, that is kinda required if you booting of the sdc disk image.
>
> The floppy disk drivers in OS-9 or NitrOS-9 are not aware of the slot the
> real FDC is in.  Since the CoCoSDC also emulates being a FDC that is why it
> responds to the FDC commands given by the floppy drivers.
>
> This is also why on all my CoCo setups I have always had my RGBDOS, HDBDOS,
> or other custom Disk Basic ROMs always in the FDC as to make sure I don't
> run into these issues.
I have HDBDOS in my fdc controller, but I don't use the hard drives for 
basic, only os9.
>
> I know for a lot of people this can also be a draw back to this.
>
> It has been brought up before with accessing the real FDC via a POKE from a
> AUTOEXEC.BAS program on your default RGBDOS/HDBDOS drive.  As far as
> default startup on CoCoSDC you will just have to manually enter the POKE or
> store a basic program on a disk image that does the POKE for you and call
> it every time you start up the system.
Everything I am talking about is via nitros9. It has has nothing to do 
with a poke.
I do NOT use an rgbdos drive although rgbdos is on the controller.
>
> Maybe if someone gets around to reproducing floppy controllers they could
> make a version that has flash chips so custom ROM's could be as easily
> updated on the FDC as it is on the CoCoSDC. :D
>
Normally I boot from floppy with the hard disk as my /dd.
so, as a test, I made a disk image of the same floppy, and booted it off 
of the SDC image.
That worked except that a dir /d0 looked at /sd0 instead.
After I unmount that image, and mount a different one /d0 and /sd0 work 
properly.

Ya I know I could just have everything on the SDC. but I have  15 or so 
scsi disks, and I like making the original hardware work.

Any how it appears no one else is using hard disks for os9 only from the 
what I have received back.

I know it is kinda confoluted and hard do explain in via email.

Thanks for your thoughts!  They are appreciated.
>> ​<cut>
>>
>>
>> ​
> +-----------------------------------------------------------------------+
> | David Ladd a.k.a. PacoOtaktay a.k.a. Drencor                          |
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> | G+:  https://plus.google.com/+DavidLaddPacoOtaktay                    |
> |                                                                       |
> | Do you have your CoCo 3 yet?                                          |
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>
> ​
>


-- 
Tim Fadden
"Hey Schmidt, don't forget about the six P's.
Proper Preparation Prevents Piss-Poor Performance!"