[Coco] Connect CoCo Floppy drive to Windows PC

[Steven Hirsch]

On Mon, 19 Jan 2009, Gene Heskett wrote:

>> I'll add to that.  It's something I've noticed when moving disks back and
>> forth.  Once it's been formatted on a CoCo, my Linux box chokes on it.
>> Other way around works fine.
>
> And as you'll note, my experience has been the opposite.  What I think is
> wrong is that the linux formatter doesn't like sector 0's, on any track.  But
> that's just what I call a SWAG too.  I have not put a scope on it and
> compared them in that manner.

Are you quite sure that the CoCo writes a sector id of 0?

>>> FWIW Bill, I find that when I am doing nitros9 disk images here in this
>>> linux box, Fedora 8, generic kernel local build, that I must first format
>>> the disk on the coco in order for it to work correctly, otherwise dd gets
>>> a tummy ache a few sectors into the write and dumps out.  If anyone knows
>>> the secret of properly formatting a coco disk on linux, I would appreciate
>>> a hand. Software to use, command line to use, etc, please.
>>
>> Exactly the opposite from my experience.  I _can_ tell you that the disk
>> parms are incorrect on many systems.  Here's what I had to do on a Xubuntu
>> 7.04 box:
>>
>> Install 'fdutils'
>
> And what version does that install?   5.4 works mostly here, 5.5 has something
> wrong in its mediaprm parser from what I can get it to spit out.  It also
> ships with a broken mediaprm file, and an error in that file causes it to
> skip all entries below it.

I don't use Fedora, so I cannot comment one way or the other.  On a Ubuntu 
box, 'apt-get install fdutils' gets me a working copy.

>> Check the media descriptor in /etc/mediaprm.  On my box, COCO360 and
>> COCO720 used an extraneous 'zero-based' flag.  This is certainly incorrect
>> for 5.25" diskettes (haven't tried the 3.5 yet).
>
> That is another problem, that is not incorrect, but the parser thinks it is,,
> the coco (1793 family fdc's) are in fact a base zero sector numbering system,
> one of the very few, and only by beating a 765 based fdc about the brow
> forcefully, can you get it to accept 'track zero sector zero' numbering for
> write functions.

That comment puzzles me a bit.  In all my experience with FDC chips (and I 
had considerable exposure to this back in the day), the sector (and track) 
ids were purely a software notion.  I wrote code to build a complete image 
of the track in memory (complete with gap bytes and magic values per spec 
sheet) and used a chip intrinsic (write-track) to blast that on to the 
media.  The software then modifed the track id, stepped the heads (or 
switched sides) and proceeded.  I have heard that the NEC 765 chips have 
problems with SD diskettes, but that's the only incompatibility I've 
personally encountered besides the start-of-track timing already mentioned 
in this thread.

Are you claiming that the hardware itself has a fixation for zero origined 
sector numbers?  I just don't recall ever running into that.

Also, how would you explain the fact that 360k DSDD diskettes generated 
with 'dd' read correctly on the CoCo and appear uncorrupted?  This doesn't 
seem to support a zero-based sectoring scheme.  But, I have not 
specifically dug into it and perhaps you are correct.  Stranger things 
have happened.

> The repos have been cleaned out, this is an F8 system.  EOL for F8 support was
> a week ago. :(
~
If it were me, I would look for a new distro.  I've had my fill of RPM 
based package systems.  What a PITA.  After SuSE jumped into bed with the 
evil empire of Redmond a few years ago I switched to Ubuntu and never 
looked back.

> It may be on a dvd, I haven't looked.  Busy putting out other fires, like
> verizon's dns servers became inaccessible to anything but a ping about 7Pm &
> I've been battling with the typical morons in tech support on a Sunday since.
> They are incapable of groking that my OS of choice has absolutely zip to do
> with their failed dns setup. Finally a friend called and he got me setup to
> use the opendns servers.  And they are 10x faster than vz's have ever been.
> I won't convert back.

Been there.  Have the T-Shirt!  I had to do the same thing with Comcast. 
You must keep in mind that their technical support people are measured on 
the number of issues they close rather than how many folks actually 
receive help with problems.  Mentioning Linux gives them all the excuse 
they need to blow you off and dismiss the case.

Fortunately we are one of the 2% of cities in the US with municipal 
fiber-to-the-premises.  I now get IP TV + 5Mbs symmetrical internet 
service for about 2/3 the price of Comcast, so they and their support 
morons are a fading memory.  Burlington Telecom, while not "Linux 
friendly" will at least listen to polite reasoning and take action.

>> Adjust names to suit your system.  The important issue to always execute
>> setfdprm with the target disk in the drive.
>
> Yes, cuz all those config changes are nulled when the drive says the disk is
> gone.

We've got to get you a working copy of fdutils.  Have you tried building 
from source?

Steve


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