1771 floppy controller questions

From: Richard Erlacher <edick_at_idcomm.com>
Date: Tue Nov 20 10:36:39 2001

I don't know right offhand of any second sources, except for Intel, which did,
IIRC, make a 1771-equivalent/compatible for a time. They went the NEC route
when MFM became popular, however.

WD also made a 1781 which was M2FM capable, and, as some folks will tell you,
THAT's a hard modulation scheme to support.

As I mentioned before, it might be worthwhile to communicate with Tony Duell
regarding the expansion interface, as he recently admitted he'd actually made
the model-1 disk interface work as it was designed to work. A lot of folks
couldn't get reasonable reliability until they bought a third-party enhancment
for the floppy interface.

Dick

----- Original Message -----
From: "Tothwolf" <tothwolf_at_concentric.net>
To: <classiccmp_at_classiccmp.org>
Sent: Tuesday, November 20, 2001 8:51 AM
Subject: Re: 1771 floppy controller questions


> On Tue, 20 Nov 2001, Richard Erlacher wrote:
> > From: "Tothwolf" <tothwolf_at_concentric.net>
> > > On Tue, 20 Nov 2001, Richard Erlacher wrote:
> > >
> > > > What is it that makes you believe that the 1771 s the problem?
> > >
> > > Well, I accidentally plugged the chip in backward when troubleshooting the
> > > floppy interface right after I got it. It turned out that the floppy
> > > ribbon was bad, just due to age I guess. I don't think the chip let out
> > > its magic smoke, but it certainly does not work now ;)
> >
> > OK ... I can believe you'd reach that conclusion from what you describe.
I've
> > done that on one of those "late nights" on more than one occasion. It's
> > reasonable to assume the part is toast, given that there are several
supplies,
> > each of which has been applied to the wrong pins. Too bad ...
>
> I'm really not too worried about it, since the 1771 does seem to be
> available and I have the technical reference book for the expansion
> interface. I don't think there are any unusual or proprietary chips used
> in the expansion interface with the exception of the floppy controller. If
> it took out any other logic chips with it, I should be able to replace
> those easily.
>
> It appears that my local vendor may have just assumed the part he has in
> stock is a National, since I can't find any references to National ever
> manufacturing a 1771, and the -B01 is a WD suffix.
>
> -Toth
>
>
Received on Tue Nov 20 2001 - 10:36:39 GMT