7 Mar
2023
7 Mar
'23
5:04 p.m.
I’m working on a project, and I need to know the age of various tape formats. For example
when were 6250bpi 700’ 9-Track tapes or DC600A cartridges introduced? Is there any good
resource online that documents this? Wikipedia is of some help, but the older you go, the
spottier it is.
Zane
7 Mar
7 Mar
5:23 p.m.
On 3/7/23 17:04, Zane Healy via cctalk wrote:
I’m working on a project, and I need to know the age
of various tape formats. For example when were 6250bpi 700’ 9-Track tapes or DC600A
cartridges introduced? Is there any good resource online that documents this? Wikipedia
is of some help, but the older you go, the spottier it is
Strictly speaking out of an orifice, I'd suggest that 9 track tapes in
NRZI and PE first came around with the IBM 2400 series tapes, GCR with
the 3400.
Prior to the S/360, tape drives were largely 7 track and used NRZI in
200, 556 and 800 bpi densities (IBM 700 series drives). Of course,
there are many outliers.
As far as QIC-24 (DC600A), the applicable standard dates from 1983.
https://www.qic.org/html/qicstan.html
FWIW,
--Chuck
5:32 p.m.
On Mar 7, 2023, at 8:23 PM, Chuck Guzis via cctalk
<cctalk(a)classiccmp.org> wrote:
On 3/7/23 17:04, Zane Healy via cctalk wrote:
Was IBM the first for each of these?
I'm a bit puzzled by "6250 700'" because the reel size has no bearing on
the format. 10 inch reels (1200 feet) were by far the most common but occasionallly the
smaller 600 foot ones would be seen. and in rare cases (the infamous DEC TS05 comes to
mind) 600' was all that they could handle.
I’m working on a project, and I need to know the
age of various tape formats. For example when were 6250bpi 700’ 9-Track tapes or DC600A
cartridges introduced? Is there any good resource online that documents this? Wikipedia
is of some help, but the older you go, the spottier it is
Strictly speaking out of an orifice, I'd suggest that 9 track tapes in
NRZI and PE first came around with the IBM 2400 series tapes, GCR with
the 3400. Prior to the S/360, tape drives were largely 7 track
and used NRZI in
200, 556 and 800 bpi densities (IBM 700 series drives). Of course,
there are many outliers.
I added the 14-track CDC drives to the Wikipedia article a while ago. And I've been
learning a bit about the oddball 10 track 1/2 inch tapes used on the Electrologica X1
(and, apparently, on the Eliott (UK) as well). The X1 tape is unusual in that it's
somewhat like DECtape -- it supports random rewriting but with variable length blocks
limited by a size limit set at format time rather than a single fixed block size.
paul
7:07 p.m.
On 3/7/23 17:32, Paul Koning wrote:
For 9 track tapes, definitely. 7 track, that would go back to the IBM
726, but that was only 100 bpi. Later members of the series increase
density. My experience is that with 7 track, the density matters mostly
with writing. A drive set to 800 or 556 bpi can easily read 200 bpi.
On Mar 7, 2023, at 8:23 PM, Chuck Guzis via
cctalk <cctalk(a)classiccmp.org> wrote:
On 3/7/23 17:04, Zane Healy via cctalk wrote:
Was IBM the first for each of these? I’m working on a project, and I need to know the
age of various tape formats. For example when were 6250bpi 700’ 9-Track tapes or DC600A
cartridges introduced? Is there any good resource online that documents this? Wikipedia
is of some help, but the older you go, the spottier it is
Strictly speaking out of an orifice, I'd suggest that 9 track tapes in
NRZI and PE first came around with the IBM 2400 series tapes, GCR with
the 3400. I added the 14-track CDC drives to the Wikipedia
article a while ago. And I've been learning a bit about the oddball 10 track 1/2 inch
tapes used on the Electrologica X1 (and, apparently, on the Eliott (UK) as well). The X1
tape is unusual in that it's somewhat like DECtape -- it supports random rewriting but
with variable length blocks limited by a size limit set at format time rather than a
single fixed block size.
There were several vendor-specific tape formats early on, generally not
interchangeable between vendor equipment, so I won't count those.
--Chuck
7:11 p.m.
New subject: Speaking of tapes....
I noticed in a Dectape 2 document that the tape drives are just DC100
models. Are there any specific documents on what kinds of signals should
be coming out or into them?
I'd like to fix this TU58.
CZ
On 3/7/2023 10:07 PM, Chuck Guzis via cctalk wrote:
On 3/7/23 17:32, Paul Koning wrote:
For 9 track tapes, definitely. 7 track, that would go back to the IBM
726, but that was only 100 bpi. Later members of the series increase
density. My experience is that with 7 track, the density matters mostly
with writing. A drive set to 800 or 556 bpi can easily read 200 bpi.
On Mar 7, 2023, at 8:23 PM, Chuck Guzis via
cctalk <cctalk(a)classiccmp.org> wrote:
On 3/7/23 17:04, Zane Healy via cctalk wrote:
Was IBM the first for each of these? I’m working on a project, and I need to know the
age of various tape formats. For example when were 6250bpi 700’ 9-Track tapes or DC600A
cartridges introduced? Is there any good resource online that documents this? Wikipedia
is of some help, but the older you go, the spottier it is
Strictly speaking out of an orifice, I'd suggest that 9 track tapes in
NRZI and PE first came around with the IBM 2400 series tapes, GCR with
the 3400. I added the 14-track CDC drives to the Wikipedia
article a while ago. And I've been learning a bit about the oddball 10 track 1/2 inch
tapes used on the Electrologica X1 (and, apparently, on the Eliott (UK) as well). The X1
tape is unusual in that it's somewhat like DECtape -- it supports random rewriting but
with variable length blocks limited by a size limit set at format time rather than a
single fixed block size.
There were several vendor-specific tape formats early on, generally not
interchangeable between vendor equipment, so I won't count those.
--Chuck
8:38 p.m.
New subject: Speaking of tapes....
On Wed, Mar 8, 2023 at 3:11 AM Chris Zach via cctalk
<cctalk(a)classiccmp.org> wrote:
I noticed in a Dectape 2 document that the tape drives are just DC100
models. Are there any specific documents on what kinds of signals should
be coming out or into them?
I'd like to fix this TU58.
The drive unit from a TU58 is just the head, motor, tacho sensor and a
couple of microswitches. It contains no electronics at all (unless you
count the LED and phototransistor in the tacho sensor). All the
electronics to handle the signals from those is on the controller
board. This consists of a simple 8085-based system (IIRC, 8085
processor, 8155 RAM/IO, ROM, serial interface, etc) and the analogue
read amplifier etc.
-tony
8:34 p.m.
On Mar 7, 2023, at 5:32 PM, Paul Koning via cctalk <cctalk(a)classiccmp.org> wrote:
I'm a bit puzzled by "6250 700'" because the reel size has no bearing
on the format. 10 inch reels (1200 feet) were by far the most common but occasionallly
the smaller 600 foot ones would be seen. and in rare cases (the infamous DEC TS05 comes to
mind) 600' was all that they could handle.
I’ll be the first to admit my question is a bit strange. Basically I’m trying to use the
date that various media types were first introduced to show the oldest possible date for a
bunch of media I’m trying to date. The 9-Track tapes have been inventoried as “700 6250
BPI”, and I know they’re the smaller reels. Doing some digging, it looks like 6250BPI
tapes date back at least as far as 1971 with the IBM 3400 series drives, I’d thought that
6250 came about in the 80’s.
Zane
9:22 p.m.
On 3/7/23 20:34, Zane Healy via cctalk wrote:
On Mar 7, 2023, at 5:32 PM, Paul Koning via cctalk
<cctalk(a)classiccmp.org> wrote:
10.5" 2400' reels were the lingua franca since at least 1953.
Companies bought them by the semi-trailer load. Quite often, just
wrapped and palletized. Smaller reels (e.g. 5" and 7") were often used
to economize (particularly when shipping; got a bunch of those). 2400'
on a 1.5 mil mylar base was the most common, but you could find 3600' on
1.0 mil base.
1/2 tape adoption was typically a lot slower than the "bleeding edge"
we're used to today. 7-track tapes were still common in the early
1980s, particularly if you were running older iron (CDC 6000/CYBER,
UNIVAC 1100). Fortunately, the tape doesn't really care what you put on
it, so long as the grain size of the oxide supported the recording
density. I've handled tapes recorded at 556 that were labeled as
6250-certified.
You have to appreciate the fact that tape was for many years, the
preferred interchange medium between different computers.
The IRS for years accepted tax returns prepared on 9 track tape, for
example.
I recall having to babysit the customer at McClellan AFB because the
tapes written on CDC 669 drives weren't being read on the customer's'IBM
3420 drives.
It turned out that the 669 when operating start-stop would "crowd" the
first few frames of a block; the drive wasn't quite at speed when those
were written. While the 669s could read them fine, the 3420s barfed.
It eventually meant flying in one of the firmware techs to tweak things.
"Never underestimate the bandwidth of a station wagon full of tapes
hurtling down the highway." Andrew Tannenbaum, Computer Networks, 3rd
ed., p. 83. (paraphrasing Dr. Warren Jackson, Director, University of
Toronto Computing Services (UTCS) circa 1985)
--Chuck
I'm a bit puzzled by "6250 700'" because the reel size has no bearing
on the format. 10 inch reels (1200 feet) were by far the most common but occasionallly
the smaller 600 foot ones would be seen. and in rare cases (the infamous DEC TS05 comes to
mind) 600' was all that they could handle.
I’ll be the first to admit my question is a bit strange. Basically I’m trying to use the
date that various media types were first introduced to show the oldest possible date for a
bunch of media I’m trying to date. The 9-Track tapes have been inventoried as “700 6250
BPI”, and I know they’re the smaller reels. Doing some digging, it looks like 6250BPI
tapes date back at least as far as 1971 with the IBM 3400 series drives, I’d thought that
6250 came about in the 80’s. 
8 Mar
8 Mar
8:42 a.m.
Speaking of compatibility, we had a 360/50 many ages ago,
and it was "permitted" to put the tape controller on the
multiplexer channel. This prevented long tape operations
from locking up the disk controller on the selector
channel. The model /50 only had one selector. But, if
there was too much traffic on the multiplexer, it could
cause data late issues. We tried to read some of those
tapes on our PDP-11, and the controller couldn't do it. I
got some Magna-See, and found that there were little gaps in
the data records.
These were quite obvious visually, so at least several
character spaces. Apparently, IBM's tape controller had a
2-character FIFO and would only start processing the end of
record after a LONG gap of at least 5-10 characters. Our
Datum controllers immediately looked for a CRC after a
2-char gap, and got a CRC/LRCC error when it hit those
little gaps. This would be on 800 BPI NRZI tapes, of course.
Jon
3:33 a.m.
-----Original Message-----
From: Zane Healy via cctalk <cctalk(a)classiccmp.org>
Sent: Wednesday, March 8, 2023 4:35 AM
To: General Discussion: On-Topic and Off-Topic Posts <cctalk(a)classiccmp.org>
Cc: Zane Healy <healyzh(a)avanthar.com>
Subject: [cctalk] Re: Age of Tape Formats?
On Mar 7, 2023, at 5:32 PM, Paul Koning via cctalk <cctalk(a)classiccmp.org>
wrote:
Our Honeywell H3200 had 1200BPI NRZI 7-track drives.....
http://www.bitsavers.org/pdf/honeywell/datapro/70C-480-01_7404_Honeywell_20…
page 13 onwards... Needed chrome tape....
Dave
I'm a bit puzzled by "6250 700'" because the reel size has no bearing
on the
format. 10 inch reels (1200 feet) were by far the most common but
occasionallly the smaller 600 foot ones would be seen. and in rare cases (the
infamous DEC TS05 comes to mind) 600' was all that they could handle.
I’ll be the first to admit my question is a bit strange. Basically I’m trying to use
the date that various media types were first introduced to show the oldest
possible date for a bunch of media I’m trying to date. The 9-Track tapes have
been inventoried as “700 6250 BPI”, and I know they’re the smaller reels. Doing
some digging, it looks like 6250BPI tapes date back at least as far as 1971 with
the IBM 3400 series drives, I’d thought that 6250 came about in the 80’s.
Zane
8:45 a.m.
On 3/8/23 05:33, Dave Wade G4UGM via cctalk wrote:
Our
Honeywell H3200 had 1200BPI NRZI 7-track drives.....
http://www.bitsavers.org/pdf/honeywell/datapro/70C-480-01_7404_Honeywell_20…
page 13 onwards... Needed chrome tape....
Dave
The reason NRZI topped out at 800 BPI on 9-track was skew.
If you ever adjusted the skew using a skew tape, you could
clearly SEE on a scope how close 800 BPI came to the limits
of tape weave (and it WAS close).
Jon
8:31 a.m.
On 3/7/23 22:34, Zane Healy via cctalk wrote:
I’ll be the first to admit my question is a bit strange. Basically I’m trying to use the
date that various media types were first introduced to show the oldest possible date for a
bunch of media I’m trying to date. The 9-Track tapes have been inventoried as “700 6250
BPI”, and I know they’re the smaller reels. Doing some digging, it looks like 6250BPI
tapes date back at least as far as 1971 with the IBM 3400 series drives, I’d thought that
6250 came about in the 80’s.
Wow! I'd love to see the 1971 vintage GCR tape controller,
it must have been the size of a 360 CPU! We had a GCR
controller from Storage Tech. in 1982 or so that was the
same size as a PDP 11/44 large cabinet. CDC Keystone drives
(92185) had it integrated into the 680x controller micro,
which I thought was pretty amazing.
Jon
11:03 a.m.
Wow! I'd love to see the 1971 vintage GCR tape
controller, it must
have been the size of a 360 CPU! We had a GCR controller from
Storage Tech. in 1982 or so that was the same size as a PDP 11/44
large cabinet. CDC Keystone drives (92185) had it integrated into
the 680x controller micro, which I thought was pretty amazing.
The IBM history pages seem to say that the initial 3420 offerings were
1600, in 1971, and that later models added GCR in 1973. The control
unit, 3803, was similarly sized to the 3420 drive, iirc a bit shorter,
but very roughly the same occupied square footage.
https://www.ibm.com/ibm/history/exhibits/storage/storage_3420.html
De
1:39 p.m.
On the subject of 1/2" open-reel tape, I note that the tapes initially
used with the IBM 726 drive (1952) used a cellulose acetate base. In
1956, a switch was made to Mylar. That's unfortunate, since early
existing 726 tapes have almost certainly rotted away due to vinegar
syndrome.
--Chuck
1:53 p.m.
On Wed, Mar 8, 2023 at 1:39 PM Chuck Guzis via cctalk <cctalk(a)classiccmp.org>
wrote:
On the subject of 1/2" open-reel tape, I note
that the tapes initially
used with the IBM 726 drive (1952) used a cellulose acetate base. In
1956, a switch was made to Mylar. That's unfortunate, since early
existing 726 tapes have almost certainly rotted away due to vinegar
syndrome.
I have what appears to be a stainless steel UNIVAC tape. It isn't
crumbling away into dust anytime soon.
Sellam
2:16 p.m.
On 3/8/23 13:53, Sellam Abraham via cctalk wrote:
On Wed, Mar 8, 2023 at 1:39 PM Chuck Guzis via cctalk
<cctalk(a)classiccmp.org>
wrote:
Heavy bugger,no?
Nickel-plated Vicalloy (a type of phosphor-bronze).
--Chuck
On the subject of 1/2" open-reel tape, I
note that the tapes initially
used with the IBM 726 drive (1952) used a cellulose acetate base. In
1956, a switch was made to Mylar. That's unfortunate, since early
existing 726 tapes have almost certainly rotted away due to vinegar
syndrome.
I have what appears to be a stainless steel UNIVAC tape. It isn't
crumbling away into dust anytime soon.
5:41 p.m.
On Wed, Mar 8, 2023 at 2:16 PM Chuck Guzis via cctalk <cctalk(a)classiccmp.org>
wrote:
On 3/8/23 13:53, Sellam Abraham via cctalk wrote:
1.76 pounds on the (aluminum?) reel. That doesn't seem like much, but it's
on a 6" reel, and it definitely feels dense when held.
Phosphor-bronze makes more sense. Thanks for the clarification.
Sellam
On Wed, Mar 8, 2023 at 1:39 PM Chuck Guzis via
cctalk <
cctalk(a)classiccmp.org>
wrote:
Heavy bugger,no?
Nickel-plated Vicalloy (a type of phosphor-bronze).
On the subject of 1/2" open-reel tape, I
note that the tapes initially
used with the IBM 726 drive (1952) used a cellulose acetate base. In
1956, a switch was made to Mylar. That's unfortunate, since early
existing 726 tapes have almost certainly rotted away due to vinegar
syndrome.
I have what appears to be a stainless steel UNIVAC tape. It isn't
crumbling away into dust anytime soon.
7:23 p.m.
On Mar 8, 2023, at 4:18 PM, Chuck Guzis via cctalk
<cctalk(a)classiccmp.org> wrote:
On 3/8/23 13:53, Sellam Abraham via cctalk wrote:
Heavy bugger,no?
Nickel-plated Vicalloy (a type of phosphor-bronze).
Yes, heavy. I have one too, from UNIVAC 1
Who can read them now? ;-)
cje
On Wed,
Mar 8, 2023 at 1:39 PM Chuck Guzis via cctalk <cctalk(a)classiccmp.org>
wrote:
On the subject of 1/2" open-reel tape, I note that the tapes initially
used with the IBM 726 drive (1952) used a cellulose acetate base. In
1956, a switch was made to Mylar. That's unfortunate, since early
existing 726 tapes have almost certainly rotted away due to vinegar
syndrome.
I have what appears to be a stainless steel UNIVAC tape. It isn't
crumbling away into dust anytime soon.
8:23 p.m.
On 3/8/23 19:23, Chris Elmquist wrote:
Who can read them now? ;-)
I suppose that you could rig something up as a streaming rig, but the
metal was murder on heads; the Univservo I interposed a thin plastic
tape between the metal and the head. Fortunately, the density was
pretty low.
Not easy--the contents would have to be special. But not gone forever.
--Chuck
9 Mar
9 Mar
12:11 a.m.
On 3/8/23 22:23, Chuck Guzis via cctalk wrote:
On 3/8/23 19:23, Chris Elmquist wrote:
The Univac 3 had nothing but Uniservo 3 tape drives, and continually did
things between drives in most installations. I read that most job steps
consisted of putting the OS and other stuff on a tape prior to doing
something, then preparing another drive with the next step and a copy of
the OS.
So any Uniservo U3 tape could have the OS and the job data on it. None
should be taken to have only data.
And most operations programmed variants, so different installations
tapes would have differ flavors of the OS to suit their styles and needs.
Not many had disk drives from what I saw, certainly none had Disk OS.
Some probably didn't run the software from the tape drives, but the tape
was the reason for the movies both fiction, bad TV and real machine
rooms in that era having so many drives.
I don't think the U3 had metalic tape, but won't swear. Didn't really
get a chance to look at the tape when i had access to the Univac 3.
My web page archived, and referenced by Wikipedia. Photos taken when we
had a Univac 3.
Bill Donzelli may have tapes and residue from the system.
Thanks
Jim
https://web.archive.org/web/20050901062918/http://jwstephens.com/univac3/pa…
Who can read them now? ;-)
I suppose that
you could rig something up as a streaming rig, but the
metal was murder on heads; the Univservo I interposed a thin plastic
tape between the metal and the head. Fortunately, the density was
pretty low.
Not easy--the contents would have to be special. But not gone forever.
--Chuck
1:42 p.m.
I'll toss a couple of old IBM magtape variations out:
The IBM 728, used on SAGE. 7 track, but not your daddy's 7 track. 3
data tracks either side of a central clock track. Different from either
of the pre- and post-series drives (727 and 729) that we have grown to love.
And, of course, the 7340 hypertape. Inch-wide cartridge tape, 10
tracks, circa 1961. The 7000 series (e.g. 7070, 7090) used only 8 of
the tracks. Does anyone know if the extra tracks were intended for use
by the 7030 STRETCH?
--Chuck
10:16 p.m.
I believe that this photo shows a Datamatic 1000 tape next to a standard
1/2" drive.
https://i.pinimg.com/564x/00/3e/7d/003e7d4e3a2478db0b9a7c94f2033252.jpg
--Chuck
11:30 p.m.
On 3/10/23 00:16, Chuck Guzis via cctalk wrote:
I believe that this photo shows a Datamatic 1000 tape
next to a standard
1/2" drive.
https://i.pinimg.com/564x/00/3e/7d/003e7d4e3a2478db0b9a7c94f2033252.jpg
--Chuck
Hub size looks small on the 1/2" for later style tapes. 2" tape? I
wonder if that was linear? Had to have impressive motors.
Our Ampex 1/2" 7 track data tapes which ran 200ips to get any sort of
bandwidth had huge motors on it. One of the 3/4ips to 200ips machines
with 10 push buttons, similar to the similar chart recorders with up to
that speed.
FWIW, OT, I visited a small TV production facility in Springfield Mo
(got some excess equipment), and they had the Betacam, 3/4" Umatic, and
a 1" machine for editing. Most has gone to digital storage. They had a
mirrored 22tb server, and used Mac and the like for production editing.
Most use was for a 3 camera studio, but could mostly do talking head
direct to digital.
Anyway never saw either a data or video 2" in person.
thanks
Jim
10 Mar
10 Mar
1:38 a.m.
On 3/9/23 23:30, jim stephens via cctalk wrote:
On 3/10/23 00:16, Chuck Guzis via cctalk wrote:
Noted! Possibly a H400 drive that uses 3/4" tape (10 channel).? Very
early in any case.
--Chuck
I believe that this photo shows a Datamatic 1000
tape next to a standard
1/2" drive.
https://i.pinimg.com/564x/00/3e/7d/003e7d4e3a2478db0b9a7c94f2033252.jpg
--Chuck
Hub size looks small on the 1/2" for later style tapes. 2" tape? I
wonder if that was linear? Had to have impressive motors.
6:14 a.m.
On Mar 10, 2023, at 2:30 AM, jim stephens via cctalk
<cctalk(a)classiccmp.org> wrote:
On 3/10/23 00:16, Chuck Guzis via cctalk wrote:
Early on the hub specs tended to vary. For example, the EL-X1 10-track 1/2 inch tape uses
1/2 inch instrumentation type reels (same as professional audio reels) which have a bigger
hub than the later standard 1/2 inch tapes, with 3 notches.
paul
I believe that this photo shows a Datamatic 1000
tape next to a standard
1/2" drive.
https://i.pinimg.com/564x/00/3e/7d/003e7d4e3a2478db0b9a7c94f2033252.jpg
--Chuck
Hub size looks small on the 1/2" for later style tapes. 2" tape? I
wonder if that was linear? Had to have impressive motors.
10:46 a.m.
On 3/10/23 06:14, Paul Koning via cctalk wrote:
As witnessed by some ijits rolling a 10.5" reel with 1/2" Ampex 456
audio tape down a road on a hill here a couple of weeks ago. It
apparently took them two tries to fully unload the 2500' reel. It took
me 3 days to collect and discard all of the tape, since nobody else
wanted to. Still have the reel--and yes, the hub is smaller than the
computer variety reel.
--Chuck
Hub size looks
small on the 1/2" for later style tapes. 2" tape? I wonder if that was linear?
Had to have impressive motors.
Early on the hub specs tended to vary. For example, the EL-X1 10-track 1/2 inch tape
uses 1/2 inch instrumentation type reels (same as professional audio reels) which have a
bigger hub than the later standard 1/2 inch tapes, with 3 notches. 
9 Mar
9 Mar
11:40 p.m.
That reel of 3 onch tape is heavy... Ihave a reel and the 30 something track tape
head....gee I could rig a rrader.... ed#
Sent from AOL on Android
On Thu, Mar 9, 2023 at 11:16 PM, Chuck Guzis via cctalk<cctalk(a)classiccmp.org>
wrote:
I believe that this photo shows a Datamatic 1000 tape next to a standard1/2" drive.
https://i.pinimg.com/564x/00/3e/7d/003e7d4e3a2478db0b9a7c94f2033252.jpg
--Chuck
6:06 a.m.
On Mar 8, 2023, at 10:23 PM, Chris Elmquist via cctalk
<cctalk(a)classiccmp.org> wrote:
I saw an article reporting on that recently. An effort of the CHM, I think, and yes, it
definitely worked. Al, can you tell us more?
paull
On Mar 8, 2023, at 4:18 PM, Chuck Guzis via
cctalk <cctalk(a)classiccmp.org> wrote:
On 3/8/23 13:53, Sellam Abraham via cctalk wrote:
Heavy bugger,no?
Nickel-plated Vicalloy (a type of phosphor-bronze).
Yes, heavy. I have one too, from UNIVAC 1
Who can read them now? ;-)
cje On Wed,
Mar 8, 2023 at 1:39 PM Chuck Guzis via cctalk <cctalk(a)classiccmp.org>
wrote:
On the subject of 1/2" open-reel tape, I note that the tapes initially
used with the IBM 726 drive (1952) used a cellulose acetate base. In
1956, a switch was made to Mylar. That's unfortunate, since early
existing 726 tapes have almost certainly rotted away due to vinegar
syndrome.
I have what appears to be a stainless steel UNIVAC tape. It isn't
crumbling away into dust anytime soon.
8 Mar
8 Mar
3:34 p.m.
On 3/8/23 13:03, Dennis Boone via cctalk wrote:
OK, well, 1973 would have been built from MST instead of
SLT, that gives a huge density improvement.
Thanks for the update,
Jon
Wow! I'd
love to see the 1971 vintage GCR tape controller, it must
have been the size of a 360 CPU! We had a GCR controller from
Storage Tech. in 1982 or so that was the same size as a PDP 11/44
large cabinet. CDC Keystone drives (92185) had it integrated into
the 680x controller micro, which I thought was pretty amazing.
The IBM history pages seem to say that the initial 3420 offerings were
1600, in 1971, and that later models added GCR in 1973. The control
unit, 3803, was similarly sized to the 3420 drive, iirc a bit shorter,
but very roughly the same occupied square footage.
2:27 p.m.
On Mar 8, 2023, at 8:31 AM, Jon Elson via cctalk
<cctalk(a)classiccmp.org> wrote:
On 3/7/23 22:34, Zane Healy via cctalk wrote:
https://www.ibm.com/ibm/history/exhibits/storage/storage_3420.html
It turns out that it was the 3420 models 2, 4, and 6 that were announced in March 1973
that supported 6250.
Zane
I’ll be the first to admit my question is a bit strange. Basically I’m trying to use the
date that various media types were first introduced to show the oldest possible date for a
bunch of media I’m trying to date. The 9-Track tapes have been inventoried as “700 6250
BPI”, and I know they’re the smaller reels. Doing some digging, it looks like 6250BPI
tapes date back at least as far as 1971 with the IBM 3400 series drives, I’d thought that
6250 came about in the 80’s.
Wow! I'd love to see the 1971 vintage GCR tape controller, it must have been the
size of a 360 CPU! We had a GCR controller from Storage Tech. in 1982 or so that was the
same size as a PDP 11/44 large cabinet. CDC Keystone drives (92185) had it integrated
into the 680x controller micro, which I thought was pretty amazing.
Jon
7 Mar
7 Mar
5:35 p.m.
On 2023-03-07 20:23, Chuck Guzis via cctalk wrote:
On 3/7/23 17:04, Zane Healy via cctalk wrote:
I was a CE on a site with multiple Uniservo VI C units at Bell Canada in
1971-1975. They were 200, 556, and 800 bpi NRZI, and were instilled at
that site in 1968. We used a chemical called 'Visimag' to coat the tape
and see the physical bits and check that they were in line! You cannot
do that with later GCR densities!
cheers,
Nigel
--
Nigel Johnson, MSc., MIEEE, MCSE VE3ID/G4AJQ/VA3MCU
Amateur Radio, the origin of the open-source concept!
Skype: TILBURY2591
I’m working on a project, and I need to know the
age of various tape formats. For example when were 6250bpi 700’ 9-Track tapes or DC600A
cartridges introduced? Is there any good resource online that documents this? Wikipedia
is of some help, but the older you go, the spottier it is
Strictly speaking out of an orifice, I'd suggest that 9 track tapes in
NRZI and PE first came around with the IBM 2400 series tapes, GCR with
the 3400.
Prior to the S/360, tape drives were largely 7 track and used NRZI in
200, 556 and 800 bpi densities (IBM 700 series drives). Of course,
there are many outliers.
As far as QIC-24 (DC600A), the applicable standard dates from 1983.
https://www.qic.org/html/qicstan.html
FWIW,
--Chuck
5:30 p.m.
I’m working on a project, and I need to know the age
of various tape
formats. For example when were 6250bpi 700’ 9-Track tapes or DC600A
cartridges introduced? Is there any good resource online that
documents this? Wikipedia is of some help, but the older you go, the
spottier it is.
For QIC, qic.org has a some info. For DLT and LTO, the wikipedia pages
are fairly useful.
De
8 Mar
8 Mar
4:25 a.m.
On 3/7/2023 8:30 PM, Dennis Boone via cctalk wrote:
What about the data cassettes used on things like Plato? Not at all
like the
audio cassettes later used on home computers.
bill
I’m working on
a project, and I need to know the age of various tape
formats. For example when were 6250bpi 700’ 9-Track tapes or DC600A
cartridges introduced? Is there any good resource online that
documents this? Wikipedia is of some help, but the older you go, the
spottier it is.
For QIC, qic.org has a some info. For DLT and LTO, the wikipedia pages
are fairly useful. 
4:35 a.m.
Some information about the origin of CUTS here :
https://retrocomputing.stackexchange.com/questions/8099/whats-the-differenc…
I recall a Logabax computer (a french office / accounting system that seems
to e completely forgotten) in about 1975 that had a built-in mechanism that
used audio cassettes. The tapes, if played on an audio system, were a
series of tones not unlike CUTS - I guess the idea of recording as audio
something intended to be sent over the telephone system was fairly obvious.
On Wed, Mar 8, 2023 at 12:25 PM Bill Gunshannon via cctalk <
cctalk(a)classiccmp.org> wrote:
On 3/7/2023 8:30 PM, Dennis Boone via cctalk wrote:
What about the data cassettes used on things like Plato? Not at all
like the
audio cassettes later used on home computers.
bill
I’m
working on a project, and I need to know the age of various tape
formats. For example when were 6250bpi 700’ 9-Track tapes or DC600A
cartridges introduced? Is there any good resource online that
documents this? Wikipedia is of some help, but the older you go, the
spottier it is.
For QIC, qic.org has a some info. For DLT and LTO, the wikipedia pages
are fairly useful.
6:11 a.m.
On Mar 8, 2023, at 7:25 AM, Bill Gunshannon via cctalk
<cctalk(a)classiccmp.org> wrote:
On 3/7/2023 8:30 PM, Dennis Boone via cctalk wrote:
What about the data cassettes used on things like Plato? Not at all like the
audio cassettes later used on home computers.
I'm not familiar with PLATO cassettes. Are those attached to terminals? The oldest
data cassettes I know of are on the TI Silent 733 terminals -- which were thought of as
paper tape emulation done on audio cassettes, at 300 bps. But I've never heard of
anything like that on PLATO. The closest similar thing I can think of is floppy disks,
which were used as peripherals to store "micro TUTOR" programs for some later
terminals. The current PLATO emulation at cyber1.org supports this.
Do you have any documents describing the cassettes you mentioned?
paul
I’m
working on a project, and I need to know the age of various tape
formats. For example when were 6250bpi 700’ 9-Track tapes or DC600A
cartridges introduced? Is there any good resource online that
documents this? Wikipedia is of some help, but the older you go, the
spottier it is.
For QIC, qic.org has a some info. For DLT and LTO, the wikipedia pages
are fairly useful.
7:07 a.m.
On 3/8/2023 9:11 AM, Paul Koning wrote:
Nope. No data. Somewhere here in the house I still have a cassette. They
were just like audio cassettes but much sturdier. And had slides on the
back
where you breakout the write-protect tabs on audio cassettes. I haven't
seen
a Plato terminal since very early 80's which is when I acquired the one
tape I
have. I seem to remember that if you put it in an audio cassette player
all you
got was noise. No recognizable patterns. But I could be wrong as that
was a long
time ago.
I was hoping someone here had more info on it as I have always been curious.
bill
On Mar 8, 2023, at 7:25 AM, Bill Gunshannon via
cctalk <cctalk(a)classiccmp.org> wrote:
On 3/7/2023 8:30 PM, Dennis Boone via cctalk wrote:
What about the data cassettes used on things like Plato? Not
at all like the
audio cassettes later used on home computers.
I'm not familiar with PLATO
cassettes. Are those attached to terminals? The oldest data cassettes I know of are on
the TI Silent 733 terminals -- which were thought of as paper tape emulation done on audio
cassettes, at 300 bps. But I've never heard of anything like that on PLATO. The
closest similar thing I can think of is floppy disks, which were used as peripherals to
store "micro TUTOR" programs for some later terminals. The current PLATO
emulation at cyber1.org supports this.
Do you have any documents describing the cassettes you mentioned?
I’m
working on a project, and I need to know the age of various tape
formats. For example when were 6250bpi 700’ 9-Track tapes or DC600A
cartridges introduced? Is there any good resource online that
documents this? Wikipedia is of some help, but the older you go, the
spottier it is.
For QIC, qic.org has a some info. For DLT and LTO, the wikipedia pages
are fairly useful.
7:25 a.m.
On Mar 8, 2023, at 10:07 AM, Bill Gunshannon
<bill.gunshannon(a)hotmail.com> wrote:
On 3/8/2023 9:11 AM, Paul Koning wrote:
Nope. No data. Somewhere here in the house I still have a cassette. They
were just like audio cassettes but much sturdier. And had slides on the back
where you breakout the write-protect tabs on audio cassettes. I haven't seen
a Plato terminal since very early 80's which is when I acquired the one tape I
have. I seem to remember that if you put it in an audio cassette player all you
got was noise. No recognizable patterns. But I could be wrong as that was a long
time ago.
I was hoping someone here had more info on it as I have always been curious.
bill
I posted a question in the "public notes" file on Cyber1, we'll see if
anyone has any memories of this.
On the "sturdier" and write protect slides, that rings a vague bell -- I think
the cassettes supplied with the Silent 733 terminals looked like that.
paul
On Mar 8, 2023, at 7:25 AM, Bill Gunshannon via
cctalk <cctalk(a)classiccmp.org> wrote:
On 3/7/2023 8:30 PM, Dennis Boone via cctalk wrote:
I'm not familiar with PLATO
cassettes. Are those attached to terminals? The oldest data cassettes I know of are on
the TI Silent 733 terminals -- which were thought of as paper tape emulation done on audio
cassettes, at 300 bps. But I've never heard of anything like that on PLATO. The
closest similar thing I can think of is floppy disks, which were used as peripherals to
store "micro TUTOR" programs for some later terminals. The current PLATO
emulation at cyber1.org supports this.
Do you have any documents describing the cassettes you mentioned?
> I’m working on a project, and I need to
know the age of various tape
> formats. For example when were 6250bpi 700’ 9-Track tapes or DC600A
> cartridges introduced? Is there any good resource online that
> documents this? Wikipedia is of some help, but the older you go, the
> spottier it is.
For QIC, qic.org has a some info. For DLT and LTO, the wikipedia pages
are fairly useful.
What about the data cassettes used on things like Plato? Not
at all like the
audio cassettes later used on home computers.
10:35 a.m.
On Wed, Mar 8, 2023 at 6:12 AM Paul Koning via cctalk <cctalk(a)classiccmp.org>
wrote:
I'm not familiar with PLATO cassettes. Are those attached to terminals?
The oldest data cassettes I know of are on the TI Silent 733 terminals --
which were thought of as paper tape emulation done on audio cassettes, at
300 bps. But I've never heard of anything like that on PLATO. The closest
similar thing I can think of is floppy disks, which were used as
peripherals to store "micro TUTOR" programs for some later terminals. The
current PLATO emulation at cyber1.org supports this.
The Silent 700 uses digital cassette tapes. I'm not sure what the actual
difference is between them and audio cassettes except for the notch on the
top side.
Sellam
13 Mar
13 Mar
1:51 p.m.
On Mar 8, 2023, at 7:25 AM, Bill Gunshannon via cctalk
<cctalk(a)classiccmp.org> wrote:
On 3/7/2023 8:30 PM, Dennis Boone via cctalk wrote:
What about the data cassettes used on things like Plato? Not at all like the
audio cassettes later used on home computers.
bill
I asked on Cyber1 and got a single reply, but it wasn't all that definitive:
---
Was there any PLATO/NovaNet arrangements with Atari like
there was for Texas Instruments computers? The TI system
used a cartridge if I remember. Atari had ROM cartridges
as well as a cassette attachment to store programs written
in ATARI BASIC. The cassette device looked like a standard
cassette recorder that was attached to the ATARI 800 using
a proprietary serial port. Could this be what they were
referring to?
---
paul
I’m
working on a project, and I need to know the age of various tape
formats. For example when were 6250bpi 700’ 9-Track tapes or DC600A
cartridges introduced? Is there any good resource online that
documents this? Wikipedia is of some help, but the older you go, the
spottier it is.
For QIC, qic.org has a some info. For DLT and LTO, the wikipedia pages
are fairly useful. 
2 p.m.
New subject: Atari PLATO was Re: Re: Age of Tape Formats?
Was there any PLATO/NovaNet arrangements with Atari
like
there was for Texas Instruments computers?
Yes, though not exactly. The TI implementation was a true, full Micro-TUTOR
runtime that ran Off-Line System lessons directly. Atari had a PLATO cartridge
that could connect to a server via modem ("PLATO Homelink") and was arguably
more functional than the contemporary PC Homelink, but the Micro-PLATO (*not*
Micro-TUTOR) lessons on floppy disk for Apple II and Atari were ported to the
6502 and had no runtime or interpreter per se.
--
------------------------------------ personal: http://www.cameronkaiser.com/ --
Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser(a)floodgap.com
-- You are not ready! ---------------------------------------------------------
2:23 p.m.
New subject: Atari PLATO was Re: Re: Age of Tape Formats?
On 3/13/23 14:00, Cameron Kaiser via cctalk wrote:
I've got a Plato disk for an IBM PC, but it's kind of useless nowadays.
--Chuck
Was there any
PLATO/NovaNet arrangements with Atari like
there was for Texas Instruments computers?
Yes, though not exactly. The TI implementation was a true, full Micro-TUTOR
runtime that ran Off-Line System lessons directly. Atari had a PLATO cartridge
that could connect to a server via modem ("PLATO Homelink") and was arguably
more functional than the contemporary PC Homelink, but the Micro-PLATO (*not*
Micro-TUTOR) lessons on floppy disk for Apple II and Atari were ported to the
6502 and had no runtime or interpreter per se. 
8 Mar
8 Mar
11:36 a.m.
If you want authoritative sources I highly recommend:
* IBM J. RES. DEVELOP. • VOL. 25 • NO. 5 • SEPTEMBER 1981, has an article
“Innovations in the Design of Magnetic Tape Subsystems”
* IBM Journal of Research and Development Vol. 47, No. 4, July 2003 has an article
“Fifty years of IBM innovation with information storage on magnetic tape”
* Magnetic Recording, the First 100 Years, Daniel et al, Chapter 17, Data Storage
On Tape
* Magnetic Recording, Vol II: Computer Data Storage, Mee et al, Chapter 4 Data
Storage
* The Complete Handbook of Magnetic Recording, Jorgensen, Parts 4 and 5 which deal
with tape materials and transports
The first ref above gives the date of IBM’s shipment of 6250 bpi as 1973, AFAIK that
became the industry standard for ½ r-t-r tape
I have all of the above in my library and might be able to help u off line if you have
specific questions.
I’ve worked on tape articles in Wikipedia and they are for the most part pretty good. If
u find any errors or omissions I hope u will update
If you are willing and able to share I’d like to see yr results
Good luck
Tom
-----Original Message-----
From: Zane Healy [mailto:healyzh@avanthar.com]
Sent: Tuesday, March 07, 2023 5:05 PM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: [cctalk] Age of Tape Formats?
I�m working on a project, and I need to know the age of various tape formats. For example
when were 6250bpi 700� 9-Track tapes or DC600A cartridges introduced? Is there any good
resource online that documents this? Wikipedia is of some help, but the older you go, the
spottier it is.
Zane
noon
Tom,
What an excellent bibliography for the topic.
Thank you.
Sellam
On Wed, Mar 8, 2023 at 11:45 AM Tom Gardner via cctalk <
cctalk(a)classiccmp.org> wrote:
If you want authoritative sources I highly
recommend:
* IBM J. RES. DEVELOP. • VOL. 25 • NO. 5 • SEPTEMBER 1981, has an
article “Innovations in the Design of Magnetic Tape Subsystems”
* IBM Journal of Research and Development Vol. 47, No. 4, July 2003
has an article “Fifty years of IBM innovation with information storage on
magnetic tape”
* Magnetic Recording, the First 100 Years, Daniel et al, Chapter
17, Data Storage On Tape
* Magnetic Recording, Vol II: Computer Data Storage, Mee et al,
Chapter 4 Data Storage
* The Complete Handbook of Magnetic Recording, Jorgensen, Parts 4
and 5 which deal with tape materials and transports
The first ref above gives the date of IBM’s shipment of 6250 bpi as 1973,
AFAIK that became the industry standard for ½ r-t-r tape
I have all of the above in my library and might be able to help u off line
if you have specific questions.
I’ve worked on tape articles in Wikipedia and they are for the most part
pretty good. If u find any errors or omissions I hope u will update
If you are willing and able to share I’d like to see yr results
Good luck
Tom
-----Original Message-----
From: Zane Healy [mailto:healyzh@avanthar.com]
Sent: Tuesday, March 07, 2023 5:05 PM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: [cctalk] Age of Tape Formats?
I�m working on a project, and I need to know the age of various tape
formats. For example when were 6250bpi 700� 9-Track tapes or DC600A
cartridges introduced? Is there any good resource online that documents
this? Wikipedia is of some help, but the older you go, the spottier it is.
Zane
10 Mar
10 Mar
8:06 a.m.
On Mar 8, 2023, at 11:36 AM, Tom Gardner via cctalk
<cctalk(a)classiccmp.org> wrote:
I’ve worked on tape articles in Wikipedia and they are for the most part pretty good. If
u find any errors or omissions I hope u will update
If you are willing and able to share I’d like to see yr results
Good luck
Tom
I can’t actually share the project I’m working on. Overall Wikipedia has been an
excellent resource for this, even for a couple 8mm formats I was unaware of.
One thing that strikes me as odd is that DLT III XT media is apparently from 1995, while
DLT IV media is from 1994?!? I’m not sure about that, and I was sure DLT IV wasn’t that
old, but it might be. It’s also possible that there are some problems with the DLT page
on Wikipedia, since the age of the drives is given, not the media.
The one that’s really hurt my brain is DC 600A, DC 1000, and DC 2000. Using
https://www.qic.org/html/qicstan.html and other info at https://www.qic.org/ I’m fairly
confused.
As best as I can tell:
DC 600A = 1983
DC 1000 = 1994
DC 2000 = 1991
The problem I have is that with what I’m working on, I have indications of DC 1000 being
used in 1985.
Zane
8:44 a.m.
On Fri, Mar 10, 2023 at 8:06 AM Zane Healy via cctalk <cctalk(a)classiccmp.org>
wrote:
A good resource for data on issues like this is the scans of old computer
magazines or catalogs in either Google Books or the Internet Archive.
Sellam
On Mar 8,
2023, at 11:36 AM, Tom Gardner via cctalk <
cctalk(a)classiccmp.org> wrote:
I’ve worked on tape articles in Wikipedia and they are for the most part
pretty good. If u find any errors or omissions I hope u will update
If you are willing and able to share I’d like to see yr results
Good luck
Tom
I can’t actually share the project I’m working on. Overall Wikipedia has
been an excellent resource for this, even for a couple 8mm formats I was
unaware of.
One thing that strikes me as odd is that DLT III XT media is apparently
from 1995, while DLT IV media is from 1994?!? I’m not sure about that, and
I was sure DLT IV wasn’t that old, but it might be. It’s also possible
that there are some problems with the DLT page on Wikipedia, since the age
of the drives is given, not the media.
The one that’s really hurt my brain is DC 600A, DC 1000, and DC 2000.
Using https://www.qic.org/html/qicstan.html and other info at
https://www.qic.org/ I’m fairly confused.
As best as I can tell:
DC 600A = 1983
DC 1000 = 1994
DC 2000 = 1991
The problem I have is that with what I’m working on, I have indications of
DC 1000 being used in 1985.
Zane
8:54 a.m.
On Mar 10, 2023, at 8:44 AM, Sellam Abraham via cctalk
<cctalk(a)classiccmp.org> wrote:
A good resource for data on issues like this is the scans of old computer
magazines or catalogs in either Google Books or the Internet Archive.
Sellam
Good idea, just need to get my google-fu working right. :-)
I’ve also had to use a Law Magazine, and City Council transcripts in this project, to put
the timeline together.
Zane
650
days inactive
655
days old
45 comments
17 participants
participants (17)
-
Adrian Godwin -
Bill Gunshannon -
Cameron Kaiser -
Chris Elmquist -
Chris Zach -
Chuck Guzis -
dave.g4ugm＠gmail.com -
Dennis Boone -
ED SHARPE -
jim stephens -
Jon Elson -
Nigel Johnson Ham -
Paul Koning -
Sellam Abraham -
Tom Gardner -
Tony Duell -
Zane Healy