[Coco] Good news: my CoCo 3 is back to life!

[Joel Ewy]

Mark Marlette wrote:
> Joel,
>
> Not sure what a WD-1791 is but you are right I almost forgot!!!!!!!!
>
> james?
>
> Mark
>
Ok, look what comes up at the top of a Google search on sy6591: 
http://five.pairlist.net/pipermail/coco/2004-March/005585.html

It's an interesting read.

So.  The SY6591 might not be pin compatible with the WD-1791 (though I
don't think that's really confirmed by the above) and the Fujutsu
MB8877A as you (Mark) and Marty Goodman suggest, is a 5V-only,
pin-compatible replacement for a WD 5V + 12V chip.  If the latter is
correct, then Mike Pepe and I were wrong in claiming that the 26-3022
was the only disk controller that required 12V.  In that case, 26-3029
units that shipped with the WD chip instead of the MB8877A would as well.

And I didn't even get past the first Google hit.

JCE
>
>
> Quoting Joel Ewy <jcewy at swbell.net>:
>
>> Mark Marlette wrote:
>>> Joel,
>>>
>>> MB8877A was a 5v drop in replacement for the +12v WD1793, otherwise
>>> you would need a MPI for that device.
>>>
>>> SY6591...that is it...No datasheet on that one at Cloud-9's
>>> repositiory... :(
>>>
>>> I knows there was a mod for the J&M to work on the CC3.
>>>
>>> Mark
>>>
>>     Well, the one I have I got second hand (in fact, it came to me in a
>> hacked-up standard full-length black plastic drive controller case with
>> a Hard Drive Specialist sticker which was about 1/3 torn off so somebody
>> could get to the screw.  So it's possible that it was modified before it
>> got to me.  But if so, it was a _very_ subtle modification, as I see no
>> jumper wires soldered on anywhere, and all the solder joints on the back
>> side look original.
>>
>> And just this morning I checked it out on a CoCo 3.  I used it to load
>> up a saved Sockmaster hi-color picture, and it worked like a charm.
>> Maybe the modification was for 2MHz operation.  I didn't check that out.
>>
>> As for a data sheet, I think the SY6591 may be a second source of the
>> WD-1791.  I bet James Daggett could confirm or refute that...
>>
>> JCE
>>> Quoting Joel Ewy <jcewy at swbell.net>:
>>>
>>>> L. Curtis Boyle wrote:
>>>>> On Mon, 05 Mar 2007 08:31:49 -0600, Boisy Pitre
>>>>> <boisy at boisypitre.com>
>>>>> wrote:
>>>>>
>>>>>> Gents,
>>>>>>
>>>>>> Not to put too fine a point on it, but FD-500 controllers will also
>>>>>> work at 5v.  I think it's a very older, specific model number of
>>>>>> disk
>>>>>> controller that requires 12v and hence, the MPI.
>>>>>>
>>>>>> Boisy
>>>>>>
>>>>>
>>>>> The very old, full size controllers that came with original full
>>>>> height, really long grey 35 track single sided drives were the 12V
>>>>> controllers.
>>>> FWIW, I have a 26-3029, a 26-3129, a J&M (says JFD-COCO rev.A on the
>>>> PCB), a Disto Super Controller, and a couple Super Controller IIs. 
>>>> They
>>>> all work on the CoCo 3 without an MPI.  (And none of them are an
>>>> FD-501
>>>> :) )  My 3029 has an MB8877 FDC with a WD9216 data separator.  The
>>>> controller in the J&M is an SY6591.  All the rest use the 28-pin
>>>> WD1773.
>>>>
>>>> Mike Pepe notes in an email on this list on 8/2/06 that the original
>>>> controller (the one that required 12V on the bus) was the 26-3022.  So
>>>> that should be the only one you would need to plug into the MPI to use
>>>> with the CoCo 3.
>>>>> Ironically, the only ones that could properly handle hi-density (1.2
>>>>> or 1.44 MB) drives with some modifications to the controller.
>>>>>
>>>> This fall Mike Pepe modified his  3029 for high-density and posted
>>>> a few
>>>> messages about it on this list.  Last I recall he still needed to
>>>> finalize the software/firmware modifications.  His notes are here:
>>>> http://www.doki-doki.net/~lamune/computers/coco/hd-floppy/
>>>>
>>>> JCE
>>>>>
>>>>> --L. Curtis Boyle
>>>>>
>>>>> -- 
>>>>> Coco mailing list
>>>>> Coco at maltedmedia.com
>>>>> http://five.pairlist.net/mailman/listinfo/coco
>>>>>