Advice wanted on Kennedy 9600 and PDP11/23

From: Jay West <jlwest_at_tseinc.com>
Date: Tue Jul 6 09:36:26 1999

Tim wrote...
>What is the third party card?


It's an Emulex. The card has silkscreened Assy TU0210401 REV C. One one of
the chips, it says Top Assy TC0210201-FSH, Sub Assy C6716 C. Two 50 pin
ribbon cables look pretty Pertec-ish to me. There's a 4 switch dip and LED
between the ribbon cables. There's also a 20 pin header (2 rows of 10) on
each side of the ribbon cable connectors. In the center of the board are two
10 position dip switches. There's 3 sets of wire wrap jumper pins as
follows: at the top A,B,C,D in the middle E,F,G, and at the bottom H,J,K,L.

On my board, the 4 switch dip SW1 has all switched towards the PCA (closed).
On the center two 10 position dips, SW2 is all down or off except #8; SW3
all are down or off except #1,3,7,8. On wirewraps, A-B, C-D,E-F. There
appears to be a few ECO wires added to the board too.

>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?


In my version of RT11 (5.04), /init isn't a valid option on the backup
command. But, when I do a backup/dev du1: ms0: it does ask if I want to
initialize, that seems to complete, then the backup goes on and finally an
output error. Once I get the tape controller reinstalled, I'll tell you for
sure.

>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?


Yup, pertec. It would appear to support 800 and 1600, because the density
switch toggles between PE and NRZI one at a time (plus a remote setting for
each).

>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.


Really! I didn't know that. When I got the tape drive, it had been in
storage and was immaculately clean. Other than usual wear on the door, it
looked in fantastic condition. What's involved in aligning the heads? I take
it I would need an alignment tape? 1600bpi seems to work great though, both
reading and writing.

Any help is most appreciated!

Jay West
Received on Tue Jul 06 1999 - 09:36:26 BST