[Coco] OS-9/68K raw disk access syntax

[Joel Ewy]

On 01/01/2016 10:02 PM, Gene Heskett wrote:
> On Friday 01 January 2016 22:39:53 Joel Ewy wrote:
>
>> On 01/01/2016 07:34 PM, David Ladd wrote:
>>> ​​
>>> I might be wrong, but if memory serves me I think the MM/1's
>>> OS-9/68K formatted floppies sectors per track starts at 0 rather
>>> than 1 like some of the older floppy formats use to be.  So may have
>>> to take that into account.  Sadly I can't verify this at this time
>>> as my MM/1 is currently packed away.
>>>
>>> ...
>> You're right about that, as I've discovered.  I think that's causing
>> me a problem when trying to image the disks with 'dd' under LInux on a
>> PC.
>>
>> JCE
> Sadly, there are fdc chipsets built into some good motherboards that any
> attempt to read or write a coco's 256 byte sector will take the machine
> down, with the only recourse being the hardware reset button and a full
> reboot done.
>
> This machine, with a nearly $300 when new Asus M2N-SLI Deluxe mother
> board in it, is one such machine.
>
> Cheers, Gene Heskett
Well, fortunately the one I'm using for this doesn't have that problem.  
I was able to image a 720k CoCo disk with no problem using:
sudo setfdprm sect=18 hd ssize=256 cyl=80
sudo dd bs=256 if=/dev/fd0 of=720.dsk

So the 256 byte sector size isn't the hangup here.

JCE