10 Feb
2016
10 Feb
'16
2:40 p.m.
From: Christian Corti
Sent: Wednesday, February 10, 2016 2:28 AM
On Tue, 9 Feb 2016, Pete Lancashire wrote:
> There are a few odd balls in 9-track as well, but
the 556 was a typo.
Really?
I actually *do* have a 9 track tape drive (HP 7970)
that has 200/556/800
bpi densities:
And it is a *9* track tape, I know for sure.
Actually, what you have is a *dual-density* tape drive, an HP7970E. It
will write 9-track tapes at 800bpi, or 7-track tapes at 200, 556, or 800.
See the manual for the 7970 drive family at
http://bitsavers.informatik.uni-stuttgart.de/pdf/hp/tape/7970/07970-90885_7…
Rich
Rich Alderson
Vintage Computing Sr. Systems Engineer
Living Computer Museum
2245 1st Avenue S
Seattle, WA 98134
mailto:RichA at LivingComputerMuseum.org
http://www.LivingComputerMuseum.org/
10 Feb
10 Feb
3:05 p.m.
Nice unit! Drool. Looks like this is a NRZI triple density tape, so 7970A or B. The later
7970E would have a 1600 PE density switch too. I have an E, but not with the multiple
density or 7 track options unfortunately. Thanks for the link to the series overview
manual Rich.
Marc
Sent from my iPad
On Feb 10, 2016, at 11:40 AM, Rich Alderson <RichA
at LivingComputerMuseum.org> wrote:
From: Christian Corti
Sent: Wednesday, February 10, 2016 2:28 AM
On Tue, 9 Feb 2016, Pete Lancashire wrote:
> There are a few odd balls in 9-track as well,
but the 556 was a typo.
Really?
I actually *do* have a 9 track tape drive (HP
7970) that has 200/556/800
bpi densities:
And it is a *9* track tape, I know for sure.
Actually, what you have is a *dual-density* tape drive, an HP7970E. It
will write 9-track tapes at 800bpi, or 7-track tapes at 200, 556, or 800.
See the manual for the 7970 drive family at
http://bitsavers.informatik.uni-stuttgart.de/pdf/hp/tape/7970/07970-90885_7…
Rich
Rich Alderson
Vintage Computing Sr. Systems Engineer
Living Computer Museum
2245 1st Avenue S
Seattle, WA 98134
mailto:RichA at LivingComputerMuseum.org
http://www.LivingComputerMuseum.org/
6:37 p.m.
From: Curious Marc
Sent: Wednesday, February 10, 2016 12:05 PM
Top-posting,
> On Feb 10, 2016, at 11:40 AM, Rich Alderson
<RichA at LivingComputerMuseum.org>
> wrote:
> From: Christian Corti
> Sent: Wednesday, February 10, 2016 2:28 AM
>> I actually *do* have a 9 track tape drive (HP
7970) that has 200/556/800
>> bpi densities:
>> And it is a *9* track tape, I know for sure.
> Actually, what you have is a *dual-density* tape
drive, an HP7970E. It
> will write 9-track tapes at 800bpi, or 7-track tapes at 200, 556, or 800.
Nice unit! Drool. Looks like this is a NRZI triple
density tape, so
7970A or B. The later 7970E would have a 1600 PE density switch too. I
have an E, but not with the multiple density or 7 track options
unfortunately. Thanks for the link to the series overview manual Rich.
Note that Christian Corti stated that his drive is capable of 9-track
operation. That's an E. (Apparently that will also write 9-track PE at
1600bpi, but it will write 9-track NRZI at 800bpi).
Rich
Rich Alderson
Vintage Computing Sr. Systems Engineer
Living Computer Museum
2245 1st Avenue S
Seattle, WA 98134
mailto:RichA at LivingComputerMuseum.org
http://www.LivingComputerMuseum.org/
11 Feb
11 Feb
12:55 a.m.
Nice unit!
Drool. Looks like this is a NRZI triple density tape, so
7970A or B.
Marc
Note that Christian Corti stated that his drive is capable of 9-track
(Apparently that will also write 9-track PE at
1600bpi, but it will write
9-track NRZI at 800bpi).
Rich
Interesting. So what model do you think he has? For example, from the manual
you listed, I see only two E models that can do dual 7/9 track with all the
lower speeds he has, the 7970E -164 and the -165 (a master and a slave). But
both of them are Read Only (because of the dual 7/9 track read head needed,
I suspect they did not have the space to put a double write head too). This
conflicts with his tape lacking a 1600 density button, and having a Write
Enable light. The latter strongly suggests it is a Read after Write tape,
not a Read Only one.
That's why I thought he had a 7970A or a 7970B (-136), that can read and
write 200, 556 and 800 NRZI. This would match all the front panel buttons we
see. However it looks like the 200/500/800 NRZI were only made in 7-track
guise. This conflicts with Christian saying his tape is a 9 track.
So I cannot find a model match for both what I see and what is said about
it. Christian, it would be nice to have a picture with the door closed and
confirm the model letter. If such a model exists (dual 7/9 track dual
read/write and dual NRZI/PE), I'd like to know which one it is (and get one
;-) ).
Marc
5:28 a.m.
New subject: Real tape drive densities
On Wed, 10 Feb 2016, CuriousMarc wrote:
It is not an E.
I would know that ;-)
Note that
Christian Corti stated that his drive is capable of 9-track
operation. That's
an E. (Apparently
that will also write 9-track PE at 1600bpi, but it will write
9-track NRZI at
800bpi). Interesting. So what model do you think he has? For
example, from the manual
[...]
That's why I thought he had a 7970A or a 7970B
(-136), that can read and
write 200, 556 and 800 NRZI. This would match all the front panel buttons we
[...]
I have a 7970B (-236) with options 127, 006, 007, 012 and 023.
More and better pictures are here now:
http://computermuseum.informatik.uni-stuttgart.de/pics/hp1000/7970/
Christian
12 Feb
12 Feb
3:45 p.m.
New subject: Real tape drive densities
Thanks for the details. Seems like the goldilocks unit, and of course one that I can't
find any documentation for. Can you confirm it can read and write 9 track formats in PE
1600 cpi?
Marc
On Feb 11, 2016, at 2:28 AM, Christian Corti <cc at
informatik.uni-stuttgart.de> wrote:
On Wed, 10 Feb 2016, CuriousMarc wrote:
It is not an E.
I would know that ;-)
Note that
Christian Corti stated that his drive is capable of 9-track
operation. That's
an E.
(Apparently that will also write 9-track PE at 1600bpi, but it will write
9-track
NRZI at 800bpi). Interesting. So what model do you think he has?
For example, from the manual
[...]
That's why I thought he had a 7970A or a
7970B (-136), that can read and
write 200, 556 and 800 NRZI. This would match all the front panel buttons we
[...]
I have a 7970B (-236) with options 127, 006, 007, 012 and 023.
More and better pictures are here now:
http://computermuseum.informatik.uni-stuttgart.de/pics/hp1000/7970/
Christian
13 Feb
13 Feb
7:20 a.m.
New subject: Real tape drive densities
On Fri, 12 Feb 2016, Curious Marc wrote:
Can you confirm it can read and write 9 track formats
in PE 1600 cpi?
Was there ever a 7970B with PE? I have the manual matching this unit
(serial number is marked on the cover page) and there's no mention of PE
AFAIK. It's the 1971 version of the 7970B/C manual, the drive is from
1971, too.
What I know is that I can read and write 800bpi 9 track tapes. I've not
tried the other densities, yet.
Christian
7:33 a.m.
New subject: Real tape drive densities
On Thu, 11 Feb 2016, Christian Corti wrote:
I have a 7970B (-236) with options 127, 006, 007, 012
and 023.
According to the HP 1000 Peripherals Selection Guide from 1982, page 16,
option 236 specifies an 800bpi master magnetic tape subsystem with one
drive and two-card 13181B interface.
And you can't mix 800 and 1600 bpi on the same interface for the HP 1000.
You need either the 13181 for NRZI, or the 13183 for PE.
So, apparently my NRZI 9 track drive has the density option included, and
I don't know if there were any other 200/556 bpi 9 track drives out
there. When we got the drive I had hoped it would be a 7 track drive, but
it isn't.
Christian
14 Feb
14 Feb
1:47 a.m.
New subject: Real tape drive densities
So, apparently my NRZI 9 track drive has the density
option included, and
I don't know if there were any other 200/556 bpi 9 track
drives out there.
When we got the drive I had hoped it would be a 7
track drive, but it
isn't.
Now I finally get it. NRZI, 200, 556 and 800 densities, but in 9 track all
the time. That's weird. You'd think the lower densities would be for 7
track. Could it be that it is a read-only for 7 tracks at lower density, but
a read/write at 800 for 9 tracks? If you looked at the head you might be
able to confirm if it has a dual 7 track / 9 track head.
Marc
5:08 p.m.
New subject: Real tape drive densities
On 2/13/2016 6:33 AM, Christian Corti wrote:
On Thu, 11 Feb 2016, Christian Corti wrote:
That makes sense: different formatters would be required.
I have a 7970B (-236) with options 127, 006, 007,
012 and 023.
According to the HP 1000 Peripherals Selection Guide from 1982, page 16,
option 236 specifies an 800bpi master magnetic tape subsystem with one
drive and two-card 13181B interface.
And you can't mix 800 and 1600 bpi on the same interface for the HP
1000. You need either the 13181 for NRZI, or the 13183 for PE.
So, apparently my NRZI 9 track drive has the density option included,
and I don't know if there were any other 200/556 bpi 9 track drives out
there. When we got the drive I had hoped it would be a 7 track drive,
but it isn't.
Christian
I have never heard of 200bpi or 556bpi for anything other than 7 track.
I cannot imagine why anyone would ever produce such a thing. The only
density I have ever heard of as being available on both 7 track and 9
track is 800BPI NRZI, from any manufacturer, and I have seen quite a lot
of them over the years. Nor have I ever seen a 9 track tape whose label
on the exterior claimed it had been written at 200 BPI or 556 BPI.
Your S/N has prefix 1124, so it looks like this manual is applicable:
http://bitsavers.trailing-edge.com/pdf/hp/tape/7970/07970-90886_7970drws_No…
Looking at this manual for the 7970B / 7970E I see that dual 7/9 track
heads did exist. Yours has a plate that claims it has option 127 (as
well as 6, 7, 12 and 23). The 127 implies a 9 track only head, but I
suggest you pull the head cover off to see if you can find a part
number. What the plate claims, and what the machine actually is can
differ for all sorts of reasons. And the sticker is coming off at the
edges as well - it may have been *moved* from one frame to another.
Wouldn't be the first time - particularly in a university setting.
The buttons clearly imply a NRZI drive (rather than 1600 BPI PE).
JRJ
6:36 p.m.
New subject: Real tape drive densities
On 02/14/2016 02:08 PM, Jay Jaeger wrote:
I have never heard of 200bpi or 556bpi for anything
other than 7
track. I cannot imagine why anyone would ever produce such a thing.
The only density I have ever heard of as being available on both 7
track and 9 track is 800BPI NRZI, from any manufacturer, and I have
seen quite a lot of them over the years. Nor have I ever seen a 9
track tape whose label on the exterior claimed it had been written at
200 BPI or 556 BPI.
That would agree with my own experience as well. 800 NRZI and 1600 PE;
6250 GCR. There may have been non-computer (e.g. data logging) drives
in 9-track with lower densities, but I've not run into any.
Some drives apparently *can* mix densities. I came across an AT&T
distro tape recently for SVR4 that started with 6250 GCR and then after
the first tapemark, switched to 1600 PE for the remainder of the tape.
I managed to read it in two passes--the first is the drive set to 6250
at loadpoint, then with the drive set to 1600 at loadpoint. All data
was complete, so it's a puzzlement.
--Chuck
9:13 p.m.
New subject: Real tape drive densities
On 2/14/2016 5:36 PM, Chuck Guzis wrote:
On 02/14/2016 02:08 PM, Jay Jaeger wrote:
Yes, some drives can - ones that are not "smart" with their own
microprocessor. My HP 9 Track drive is, unfortunately, "smart", and
looks for recording bursts at the beginning of the tape and sticks
doggedly to that.
Maybe some yahoo decided to write over the first file of that SVR4 tape
at higher density so as not to clobber the files after it. Smart, so as
not to clobber the other stuff, but crazy. Or it may have been just a
case of writing that first file, with no double-EOF EOT on it.
Or maybe someone wrote the first file and then went "OH SH*T that was a
DISTRO TAPE wasn't it..." ;)
Anyway, I doubt AT&T would have written the tape that way intentionally.
Curious: What processor was that distro for? Maybe donate the files to
PUPS?
JRJ
I have never heard of 200bpi or 556bpi for
anything other than 7
track. I cannot imagine why anyone would ever produce such a thing.
The only density I have ever heard of as being available on both 7
track and 9 track is 800BPI NRZI, from any manufacturer, and I have
seen quite a lot of them over the years. Nor have I ever seen a 9
track tape whose label on the exterior claimed it had been written at
200 BPI or 556 BPI.
That would agree with my own experience as well. 800 NRZI and 1600 PE;
6250 GCR. There may have been non-computer (e.g. data logging) drives
in 9-track with lower densities, but I've not run into any.
Some drives apparently *can* mix densities. I came across an AT&T
distro tape recently for SVR4 that started with 6250 GCR and then after
the first tapemark, switched to 1600 PE for the remainder of the tape. I
managed to read it in two passes--the first is the drive set to 6250 at
loadpoint, then with the drive set to 1600 at loadpoint. All data was
complete, so it's a puzzlement.
--Chuck
15 Feb
15 Feb
1:37 a.m.
New subject: Real tape drive densities
On 02/14/2016 06:13 PM, Jay Jaeger wrote:
Maybe some yahoo decided to write over the first file of that SVR4 tape
at higher density so as not to clobber the files after it. Smart, so as
not to clobber the other stuff, but crazy. Or it may have been just a
case of writing that first file, with no double-EOF EOT on it.
Or maybe someone wrote the first file and then went "OH SH*T that was a
DISTRO TAPE wasn't it..." ;)
Anyway, I doubt AT&T would have written the tape that way intentionally.
Well, the tape bears an AT&T label. The tape itself comes from UCB at
about the same time that "ernie" was in use, so VAX or PDP11. It could
be a copy of an AT&T distro tape with the duplicate label attached.
It's a 2,222,000 byte cpio file that starts out with:
# THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF AT&T
# The copyright notice above does not evidence any
# actual or intended publication of such source code.
#ident "@(#)mk::mk 1.10"
#
# Shell script for rebuilding the UNIX System
#
trap "exit 1" 1 2 3 15
if [ "$ROOT" = "" ]
then
PATH=/bin:/etc:/usr/bin; export PATH
fi
That's the 6250 GCR file; the 1600 PE file that follows is a 37,432,320
byte cpio file that starts out in exactly the same way. The 2MB file
was probably an "osh*t" file as it terminates prematurely at
"usr/src/cmd/bnu/bnu.mk".
I read it on my Fuji 2444 (Pertec interface). None of my SCSI drives
could handle the mixed density.
Just curious--
How many "smart" drives can handle multiple load points? Before the day
of autothreading drives, it was convenient to have a "universal
deadstart" tape to carry along, with various operating systems on it.
Just keep hitting the "load" button until you get to the one you want,
then push the button.
--Chuck
14 Feb
14 Feb
10:41 p.m.
New subject: Real tape drive densities
On 02/14/2016 05:36 PM, Chuck Guzis wrote:
On 02/14/2016 02:08 PM, Jay Jaeger wrote:
Well, that could be a malfunction. Some tape
drive-formatter sets cannot do this without hardware
problems. But, some had software-controlled density, and so
the software could override the detected density when the
tape was mounted. 800 NRZI had nothing recorded over the
BOT marker, 1600 and 6250 had distinct patterns written over
the BOT marker to ID the density. Once the density is
identified, it SHOULDN'T allow you to change it in the
middle of the tape.
Jon
I have never heard of 200bpi or 556bpi for
anything other
than 7
track. I cannot imagine why anyone would ever produce
such a thing.
The only density I have ever heard of as being available
on both 7
track and 9 track is 800BPI NRZI, from any manufacturer,
and I have
seen quite a lot of them over the years. Nor have I ever
seen a 9
track tape whose label on the exterior claimed it had
been written at
200 BPI or 556 BPI.
That would agree with my own experience as well. 800 NRZI
and 1600 PE; 6250 GCR. There may have been non-computer
(e.g. data logging) drives in 9-track with lower
densities, but I've not run into any.
Some drives apparently *can* mix densities. I came across
an AT&T distro tape recently for SVR4 that started with
6250 GCR and then after the first tapemark, switched to
1600 PE for the remainder of the tape. I managed to read
it in two passes--the first is the drive set to 6250 at
loadpoint, then with the drive set to 1600 at loadpoint.
All data was complete, so it's a puzzlement.
15 Feb
15 Feb
5:32 a.m.
New subject: Real tape drive densities
On Sun, 14 Feb 2016, Jay Jaeger wrote:
Looking at this manual for the 7970B / 7970E I see
that dual 7/9 track
heads did exist.
Yes, but only in read-only configurations.
Yours has a plate that claims it has option 127 (as
well as 6, 7, 12 and 23). The 127 implies a 9 track only head, but I
suggest you pull the head cover off to see if you can find a part
number. What the plate claims, and what the machine actually is can
I've added another picture of a closeup of the R/W head. In my opinion
it's a 9 track read-after-write head. The geometry and gaps are identical
to those of the adjacent 7970B 800bpi-only tape drive we have.
differ for all sorts of reasons. And the sticker is
coming off at the
edges as well - it may have been *moved* from one frame to another.
Wouldn't be the first time - particularly in a university setting.
I think it's the original sticker, the options listed on the manual
(hand-written by HP on the cover page) match, and the date codes (1971)
match, too.
Christian
10:49 a.m.
New subject: Real tape drive densities
On 2/15/16 2:32 AM, Christian Corti wrote:
I've added another picture of a closeup of the R/W head. In my opinion
it's a 9 track read-after-write head. The geometry and gaps are
identical to those of the adjacent 7970B 800bpi-only tape drive we have.
I have two
7/9 track HP drives, and a bunch of head stacks. There is no
erase head. The 7 and 9 track head stacks sit next to each other. I may
have time to dig them out and take pictures at some point this month.
11 Feb
11 Feb
1:06 a.m.
On 2016-Feb-10, at 3:37 PM, Rich Alderson wrote:
From: Curious Marc
Sent: Wednesday, February 10, 2016 12:05 PM
Top-posting,
Not sure whether you're intending a qualifier to the 9-track / E model association,
but 9-track drives in the 7970 series go back to the 7970A (I have a 7970A in the 9-track,
800BPI variant).
The HP 7970 B/E manual shows only 3 model-options with 200 & 556 bpi:
- 7970B-136 200/556/800 7-track
- 7970E-164 200/556/800/1600, dual-capability 7 & 9 track, READ-ONLY
- 7970E-165 200/556/800/1600, dual-capability 7 & 9 track, READ-ONLY
None of the dual-capability 7 & 9 track model-options listed in the manual are capable
of writing, nor is any model-option listed capable of writing 200/556 9-track.
An HP manual speaks of HP producing dual-capability 7&9 track heads but they are
read-only heads.
Photos in the manual show the dual-capability 7&9 variant with selector switches for
7&9 track and 1600 bpi (in addition to the 200/556/800 selectors).
The unit presented by Christian does not have the additional selectors.
The manual does mention that there are non-standard, "Special" variants.
The manual mentions 7970C as a 'special configuration' of the B but doesn't
say what the difference is.
If the unit presented by Christian is 9-track, it does not seem to be any of the standard
B or E variants.
I'd suggest resolution would require Christian to identify the model & option
(specific model label is on the inside in my unit).
> On Feb 10, 2016, at 11:40 AM, Rich Alderson
<RichA at LivingComputerMuseum.org>
> wrote:
> From: Christian Corti
> Sent: Wednesday, February 10, 2016 2:28 AM
>> I actually *do* have a 9 track tape drive
(HP 7970) that has 200/556/800
>> bpi densities:
>> And it is a *9* track tape, I know for
sure.
> Actually, what you have is a *dual-density*
tape drive, an HP7970E. It
> will write 9-track tapes at 800bpi, or 7-track tapes at 200, 556, or 800.
Nice unit! Drool. Looks like this is a NRZI
triple density tape, so
7970A or B. The later 7970E would have a 1600 PE density switch too. I
have an E, but not with the multiple density or 7 track options
unfortunately. Thanks for the link to the series overview manual Rich.
Note that Christian Corti stated that his drive is capable of 9-track
operation. That's an E. (Apparently that will also write 9-track PE at
1600bpi, but it will write 9-track NRZI at 800bpi).
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16 comments
8 participants
participants (8)
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cc＠informatik.uni-stuttgart.de -
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RichA＠LivingComputerMuseum.org