Tarbell is making me insane - test-drb@ccmp.vtda.org

14 Nov 2007

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Subject: Re: Tarbell is making me insane
   From: Grant Stockly <grant at stockly.com>
   Date: Tue, 13 Nov 2007 14:16:59 -0900
     To: "General Discussion: On-Topic Posts Only" <cctech at
classiccmp.org>

   One
little nasty.  The 1771 has a basic ability to do data seperation.
 I havent' looked at a tarbel board in a very long time but I do hope
 that they didn't do the TRS80 save a buck trick and try to use that
 internal seperator, it does NOT work.  It has zero jitter tolerence. 
Strange. I used an unmodified TRS-80 Model 1 EI for years and never had
any problems with the disk side of things. And that used the internal
data separateor of the 1771 IIRC. 
If that is the case, why would the Tarbell have so many extra 
chips?  Also, at the time the tarbell was manufactured, would they 
have even known that there was an issue with the 1771's data separation? 
Because the internal seperator sucked.  If the user never had problems 
it was just dumb luck.  Percom (and others) sold thousands of add on 
data seperator board to all the E1 users that couldn't make it work.

...
 Just wondering why...I'm not trying to second guess
anyone.  Just 
that if the extra ICs weren't required I can't imagine Tarbell using them???

Because they were needed. Even WD advised that it was not adaquate for 
many cases.  Tarbell wasn't stupid, they built protos and tested them
and the board they sold worked.

Allison

...
 Grant  