Ethan's Retrocomputing Corner - DEC TK50 SCSI issues
classiccmp: DEC TK50 SCSI issues
Date: Wed, 21 Jul 1999 18:38:22 -0500 (CDT)
From: sms@antinode.org
To: "Discussion re-collecting of classic computers" <classiccmp@u.washington.edu>
Subject: Re: Using a TK50 tape on a TK70?
allisonp@world.std.com (Allison J Parent) wrote:
> Ah, I believe TK50 and TK70 tape is different media (magnetics). That
> is why the TK70 can only read TK50 formats.
The number of tracks is different, with more on the TK70 than on the
TK50 (not surprisingly). When a TK70 drive tries to read a TK50 tape,
it's easy enough to center a smaller (TK70) read head on a larger (TK50)
track. It is far more difficult (that is, practically impossible) for
the smaller write head to write a track which covers the larger track
well enough to satisfy the larger read head. _This_ is why a TK70 drive
can not write a tape which can be read by a TK50 drive.
The magnetic properties of the tapes may or may not be different. My
experience suggests that they're close enough. (Of course, also I've
used HD floppies as DD by taping over the hole, again, with no
problems. Please, let's not start that discussion here.) Regardless,
it's the difference in track configuration which is the fundamental
source of the problem. The same argument applies similarly to QIC tape
drives of various densities.
If anyone actually _knows_ about the magnetic properties of the two
types of tapes, I'd be pleased to learn of the differences, if any. I
could live happliy without additional uninformed speculation.
------------------------------------------------------------------------
Steven M. Schweda (+1) 651-645-9249 (voice, home)
1630 Marshall Avenue #8 (+1) 612-754-2636 (voice, work)
Saint Paul MN 55104-6225 (+1) 612-754-6302 (facsimile, work)
sms@antinode.org sms@provis.com (work)
Date: Fri, 6 Aug 1999 20:03:08 -0600 (MDT)
From: Clint Wolff (VAX collector) <vaxman@uswest.net>
To: "Discussion re-collecting of classic computers" <classiccmp@u.washington.edu>
Subject: Re: VaxStation 2000 and TK-50Zs
Hi Don and other ListErs,
I have been working on a similiar problem... I have the original DEC
distributions for a few things (including Ultrix 3.1, looking for
UWS 3.0), and I want to make archival copies of them...
I discovered the TK-50Z (both FA and GA) will work with FreeBSD and
an old Adaptec SCSI controller. This allows me to read (and copy) the
TK50 onto my PCs hard disk, but I haven't quite got the format right
to write a new tape (still playing with file marks)...
NOTE: I tried a 2940 and a 1535 and neither of them worked. I was
successful with a AHA-1542B scsi adapter.
I also have a SCSI adapter for my uVAX II, and have copied tapes
from TK50 to 4mm DAT, but it seems quite a waste to put 95MB on a
4GB tape.
Finally, if none of these options appeal to you (and you don't
have other success), I have a uVAX II with a TK70, TK50, SCSI
adapter for the 4mm DAT, and a 9-track tape drive, and can copy
them for you (contact me off list for this).
Laters,
clint
PS My 11/750 is up and running!!! The dead power supply turned out
to be two pins shorted on the backplane... Sometimes my debugging
skills leave something to be desired...
PPS What is a Fujitsu Eagle worth used? I am going to upgrade the
11/750 to a SCSI controller and 3.5" drive as soon as I get two
nickles to rub together :)
>
> I have been tinkering around with my VaxStation 2000 and a couple of
> TK-50Zs that I have. One is an FA and the other a GA so I am able to set
> them at differing SCSI node values.
>
> My thought was that I could use both on the VaxStation and use them to
> duplicate some tapes that are save_set(s). Apparently it cannot be done
> on the VS. Either unit is recognized when connected alone, but when both
> are connected the FA is always recognized as MUA0 and the GA is ignored.
> Does anyone have an explanation for this, or am I just doing it wrong?
>
> Assuming failure on the two tape approach, how might I make the duplicate
> tape(s) without wiping out the contents of my hard disk? It is at the
> moment fairly lightly loaded and may hold the save_set. The HD is an RD54
> by the way and I am running VMS 5.5.
>
> Thanks!
> - don
Date: Fri, 6 Aug 1999 20:30:49 -0600
From: "emanuel stiebler" <emu@ecubics.com>
To: "Discussion re-collecting of classic computers" <classiccmp@u.washington.edu>
Subject: Re: VaxStation 2000 and TK-50Zs
----- Original Message -----
From: Clint Wolff (VAX collector) <vaxman@uswest.net>
To: Discussion re-collecting of classic computers
<classiccmp@u.washington.edu>
Sent: Friday, August 06, 1999 8:03 PM
Subject: Re: VaxStation 2000 and TK-50Zs
> I discovered the TK-50Z (both FA and GA) will work with FreeBSD and
> an old Adaptec SCSI controller. This allows me to read (and copy) the
> TK50 onto my PCs hard disk, but I haven't quite got the format right
> to write a new tape (still playing with file marks)...
If you really have problems with that, I remember seeing a program, which
finds out, which blocksize, filemarks, ... a tape is been written.
> NOTE: I tried a 2940 and a 1535 and neither of them worked. I was
> successful with a AHA-1542B scsi adapter.
the adaptec 2940 works on linux & dos.
> Laters,
> clint
cheers,
emanuel
Date: Fri, 06 Aug 1999 23:00:51 -0700
From: Bruce Lane <kyrrin@bluefeathertech.com>
To: "Discussion re-collecting of classic computers" <classiccmp@u.washington.edu>
Subject: Re: VaxStation 2000 and TK-50Zs
At 22:08 06-08-1999 -0700, you wrote:
> Yep! Seems to be the case, and premised on some further testing it has to
> have an ID of 1. Hmmm! I didn't try 0, but it shows all ID positions as
> occupied in the T 50 display.
Whoa! All ID positions showing as occupied when you don't have actual
devices to match usually means a duplicate SCSI ID somewhere on the bus.
Check carefully! I'll bet a blueberry bagel that you've got two devices
set for the same ID.
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Bruce Lane, Owner and head honcho, Blue Feather Technologies
http://www.bluefeathertech.com // E-mail: kyrrin@bluefeathertech.com
Amateur Radio: WD6EOS since Dec. '77
"Our science can only describe an object, event, or living thing in our
own human terms. It cannot, in any way, define any of them..."
Date: Sun, 8 Aug 1999 23:46:53 -0400
From: allisonp@world.std.com (Allison J Parent)
To: "Discussion re-collecting of classic computers" <classiccmp@u.washington.edu>
Subject: Re: TK50 flavours
>> It's a TK50 in an external case with a single 50 pin D-sub connector and
>> no ID switch.
>
> A single connector? A D-sub 50 no less?
>
> Geez... that's downright psychotic. Ok, I'm baffled. Anyone else?
Sounds like a externally mounted TK50 for use with the usual Qbus M7546.
The companion was the externally mounted RD5x for use with the RQDXn and
the matching distribution card. Both are for those that had BA23s and
no place left for a disk or tape.
Allison
To Ethan's Home Page
Last modified:
09 August 1999
Compilation © Copyright 1999, Ethan Dicks
<erd@infinet.com>.
All Rights Reserved.