[Coco] 26-3022 Disk Controller Question

[Gene Heskett]

On Sunday 03 September 2017 00:01:43 Arthur Flexser wrote:

> I believe replacing the 1793 with an 8877A does work as you describe,
> and I'm almost sure it worked for me that way, long ago.  As I recall,
> I discovered this fact accidentally, having replaced with the Fujitsu
> chip because I couldn't find a 1793.
>
> Art

That is correct Art, the MB8877A does not need that funkity 12 volt 
adjustable bias circuit the WD1793 needed. I have a data sheet on the 
MB8877A around someplace in this midden heap, and IIRC, there is a B 
model that can run at 2x the clock and with some switching tom-foolery, 
should be able to make use of 1.44 megabyte drives as true 1.44 megabyte 
drives. But by the time I became aware of that, I had already setup a 
Maxtor 7120s 132 meg hard drive on a disto 4n1. All history now.
>
> On Sat, Sep 2, 2017 at 11:26 PM, Garrett Reynolds
> <greynolds86 at hotmail.com>
>
> wrote:
> > I picked up a Drive 0 1st generation (grey) single floppy drive and
> > controller.  The original label is missing but I assume this is the
> > 26-3022 as it is equipped with the WE FD1793B-02.  I understand this
> > controller is not very popular or reliable.  I've read that it will
> > not work on the CoCo2/3 (I have a CoCO3).  I believe this is because
> > it needs 12VDC to function which is not present on the later
> > computers or needed by the newer controllers (that's weird to say,
> > "newer controllers").
> >
> > Anyway, I've read that if you replace this DIP CHIP with a Fujitsu
> > MB8877A that it will then work with the CoCo2/3.  I found several of
> > these chipsets on ebay for around $10.  Does anyone have experience
> > with this controller, the modification that I speak of and any
> > recommendations as to making this controller work with my CoCo3?
> >
> > I did open the controller, seat the components, and cleaned up the
> > pins and confirmed that controller boots to DECB.  I did not attempt
> > to plug in the drive or access it pending answers to these
> > questions.
> >
> > I also read that if you have a multi-pak that this controller will
> > work without modification, but I do not have one.
> >
> > Your ideas/suggestions are graciously invited.
> >
> > Garrett
> >
> > --
> > Coco mailing list
> > Coco at maltedmedia.com
> > https://pairlist5.pair.net/mailman/listinfo/coco


Cheers, Gene Heskett
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