Advice wanted on Kennedy 9600 and PDP11/23

From: <(>
Date: Tue Jul 6 07:28:32 1999

>I have a Kennedy 9600 tape drive (cream and black, horizontal loading) on an
>11/23 via a third party card.

What is the third party card?

>A "backup/dev du1: ms0:" set at PE works fine. The same command with a /ver
>option also works fine. However, when I set NRZI, it looks like its backing
>up, the tape cycles much more slowly forward, but eventually I get an RT-11
>"output error". If the drive really doesn't support 800bpi, I would think it
>wouldn't even try writing NRZI. So - my question is (given the above info) -
>is the drive broke but only for 800bpi or am I doing something silly?

Well, the tape does need to be re-inited at the new density. Are you
doing the INIT before the BACKUP, or doing a BACKUP/INIT? Does the INIT
operation work OK? Can you do a DIR MS: after the INIT at 800 BPI?

Other than that, the -11 doesn't much care what density the tape is at, but the
controller card might. Try to identify it (maybe a Dilog DQ132? DQ133?
Emulex TC02? TC03? QT13?) and I'll see what I can figure out. Some
controller cards (the Dilogs in particular) might be expecting part of
the PE burst to come down the cabling.

I'm not awfully familiar with the Kennedy 9600, but if it's like the 9614
it supports 800, 1600, 3200, and 6250 BPI. Yours is the Pertec-formatted
(two 50-pin cables) interface?

I'll also point out that NRZI requires a lot tighter physical tolerances
on the alignment of the tape head (the reason why many drives don't support
800 BPI NRZI at all) than 1600 and 6250 BPI (which allow substantial skew
between the tape channels as part ofthe spec.) If at some point the head
in your transport had been replaced or knocked around without properly
being re-aligned you might see something like what you're seeing.

 Tim Shoppa                        Email:
 Trailing Edge Technology          WWW:
 7328 Bradley Blvd		   Voice: 301-767-5917
 Bethesda, MD, USA 20817           Fax:   301-767-5927
Received on Tue Jul 06 1999 - 07:28:32 BST

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