[Coco] Issues with 26-3022 interface

[Juan Castro]

I'm happy to inform Daniel used Jeff Vavasour's DSKINI MS-DOS program in an
old PC and now he's transferring images like there's no tomorrow. I'm sure
he can fill in more juicy details. Yo, Daniel! Manifest thyself!

And now an idea I had. Could it be possible to program the CoCo FDC to
format/read/write (a) additional tracks in the same side of the floppy, or
(b) side 2 of the floppy, or (c) both?

We could have four disks in one!

I remember way back at the CoCo clone company I worked, we did a hack to
interpret side two of the floppy as a second drive. IIRC, that involved
some slight change in DECB to program the FDC differently if drive 1 or 3
was being accessed.

On Wed, Feb 13, 2013 at 12:12 AM, Juan Castro <jccyc1965 at gmail.com> wrote:

> Your floppies have been formatted with 256 byte sectors. Each track has 18
> sectors of 256 bytes instead of 9 sectors of 512 bytes like in a 720KB PC
> disk. You'll need to (a) get a PC with a FDC old enough to read that, and
> (b) get some DOS software that can program the FDC and read/write a 256
> byte formatted disk. That will be a challenge. Anyone here has successfully
> done that?
>
>
> On Tue, Feb 12, 2013 at 1:26 PM, Daniel Campos <daniel.campus at gmail.com>wrote:
>
>> Hi Mark,
>>
>> I understand your point, as this subject have probably been talked on
>> this list many times over. But my main purpose is to pass disk images from
>> a PC (through emulator or some other program) and run them on the Coco. I
>> don't have any legacy 5 1/4 disks to worry about, so if I can do this work
>> on a 3 1/2 floppy, for me is the best choice.
>>
>> I will try now to transfer some images from the PC to this disks and
>> let's see how will it work...
>>
>> Thanks!
>> Daniel
>>
>> Em 12/02/2013 13:04, Mark Marlette escreveu:
>>
>>  Daniel,
>>>
>>> Understand the beast in which you are trying to tame.......... :)
>>>
>>> Go read what occurs and the differences between all of the disk formats
>>> and densities on a hardware and software level.
>>>
>>> You will then realize as it 'might' appear to have worked, you are in
>>> violation of the specs.
>>>
>>> This has been beat to death here. Follow the specs and it will always
>>> work.  You are flirting with diasater if you assume it is working, IMHO.
>>>
>>> Regards,
>>>
>>> Mark
>>>
>>> http://www.cloud9tech.com
>>>
>>>
>>>
>>> ______________________________**__
>>>   From: Daniel Campos <daniel.campus at gmail.com>
>>> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
>>> Sent: Tuesday, February 12, 2013 8:50 AM
>>> Subject: Re: [Coco] Issues with 26-3022 interface
>>>   Mark,
>>>
>>> Em 12/02/2013 11:56, Mark Marlette escreveu:
>>>
>>>> Daniel,
>>>>
>>>> This HD mod was created by Robert Brose of our computer club many years
>>>> ago.
>>>>
>>>> I have done this mod, it works. I also added a line from the controller
>>>> to the drive to automatically switch the transfer rate clock based upon the
>>>> sensors in the drive rather than just the descriptor.
>>>>
>>>> With that said...this is NO easy mod. Almost easier making a new
>>>> controller.
>>>>
>>> Yes, for what I saw from the document that Harry sent, it will be no
>>> easy task.
>>>
>>>  It requires a the MB8877A(??) memory loss ATM upgrade and then there
>>>> was also a speed issue running at 1.78MHZ as well. A chip that needed
>>>> replacing. Was pinged this past weekend on this at Cloud-9 and haven't had
>>>> the chance to look up my work in my project documentation book. I have it.
>>>>
>>>> The file was up on RTSI for a long time. ????
>>>>
>>>> Regards,
>>>>
>>>> Mark
>>>> http://www.cloud9tech.com
>>>>
>>>>
>>>>
>>>>  Ou of curiosity, I just attached today a 3 1/2 1.44M drive to the Coco
>>> and it worked flawlessly! It formated the disk (a HD disk with the role
>>> closed to make the drive understand it as 720Kb disk) and SAVEd and
>>> LOADed some programs. No errors ocurred during the format process!
>>> How can I check the disk to see if it was formated properly ?
>>>
>>> This drive is a Mitsumi D359M3D and was already configured to DS0,
>>> because I used it before with one of my MSX machines.
>>>
>>> Thanks!
>>>
>>> Daniel
>>>
>>>
>>>
>>>
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>>>
>>
>>
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>
>