20 Nov
2001
20 Nov
'01
2:36 a.m.
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(a)concentric.net>
To: <classiccmp(a)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(a)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