[cctalk] Re: Age of Tape Formats?
> On Mar 8, 2023, at 7:25 AM, Bill Gunshannon via cctalk > wrote: > > > On 3/7/2023 8:30 PM, Dennis Boone 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. >> >> 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. > > 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
[cctalk] Re: Age of Tape Formats?
On 3/10/23 06:14, Paul Koning via cctalk wrote: >> 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. 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
[cctalk] Re: Age of Tape Formats?
> On Mar 10, 2023, at 8:44 AM, Sellam Abraham via cctalk > 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
[cctalk] Re: Age of Tape Formats?
On Fri, Mar 10, 2023 at 8:06 AM Zane Healy via cctalk wrote: > > On Mar 8, 2023, at 11:36 AM, Tom Gardner via cctalk < > cctalk@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 > 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
[cctalk] Re: Age of Tape Formats?
> On Mar 8, 2023, at 11:36 AM, Tom Gardner via cctalk > 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
[cctalk] Re: Age of Tape Formats?
> On Mar 10, 2023, at 2:30 AM, jim stephens via cctalk > wrote: > > > > 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. 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
[cctalk] Re: Age of Tape Formats?
On 3/9/23 23:30, jim stephens via cctalk wrote: > > > 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. Noted! Possibly a H400 drive that uses 3/4" tape (10 channel).? Very early in any case. --Chuck
[cctalk] Re: Age of Tape Formats?
That reel of 3 onch tape is heavy... Ihave a reel and the 30 something track tape headgee I could rig a rrader ed# Sent from AOL on Android On Thu, Mar 9, 2023 at 11:16 PM, Chuck Guzis via cctalk 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
[cctalk] Re: Age of Tape Formats?
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
[cctalk] Re: Age of Tape Formats?
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
[cctalk] Re: Age of Tape Formats?
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
[cctalk] Re: Age of Tape Formats?
> On Mar 8, 2023, at 10:23 PM, Chris Elmquist via cctalk > wrote: > > > >> On Mar 8, 2023, at 4:18 PM, Chuck Guzis via cctalk >> wrote: >> >> On 3/8/23 13:53, Sellam Abraham via cctalk wrote: On Wed, Mar 8, 2023 at 1:39 PM Chuck Guzis via cctalk 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. >>> >> 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 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
[cctalk] Re: Age of Tape Formats?
On 3/8/2023 1:19 PM, Dave Wade G4UGM via cctalk wrote: -Original Message- From: Chuck Guzis via cctalk Sent: Wednesday, March 8, 2023 6:08 PM To: cctalk@classiccmp.org Cc: Chuck Guzis Subject: [cctalk] Re: Age of Tape Formats? I think it remarkable in retrospect that the original Star Trek (ca. 1966) used countless mentions of "computer tapes" in the 23rd century. Yes, but Space 1999 still had slide rules.. It's 2023 and so do I. Have started teaching my grandson what it is and how it works. bill
[cctalk] Re: Age of Tape Formats?
On 3/8/23 22:23, Chuck Guzis via cctalk wrote: 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 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/page_01.htm
[cctalk] Re: Age of Tape Formats?
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
[cctalk] Re: Age of Tape Formats?
> On Mar 8, 2023, at 4:18 PM, Chuck Guzis via cctalk > wrote: > > On 3/8/23 13:53, Sellam Abraham via cctalk wrote: >>> On Wed, Mar 8, 2023 at 1:39 PM Chuck Guzis via cctalk >>> >>> 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. >> > 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
[cctalk] Re: Age of Tape Formats?
On Wed, Mar 8, 2023 at 2:16 PM Chuck Guzis via cctalk wrote: > 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@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. > > > Heavy bugger,no? > Nickel-plated Vicalloy (a type of phosphor-bronze). > 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
[cctalk] Re: Age of Tape Formats?
On 3/8/23 13:03, Dennis Boone via cctalk wrote: > 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. OK, well, 1973 would have been built from MST instead of SLT, that gives a huge density improvement. Thanks for the update, Jon
[cctalk] Re: Age of Tape Formats?
On Mar 8, 2023, at 10:07 AM, Chuck Guzis via cctalk wrote: > > I think it remarkable in retrospect that the original Star Trek (ca. > 1966) used countless mentions of "computer tapes" in the 23rd century. > > A lack of foresight on the part of the script writers? > > What can we predict for the year 2250? > > --Chuck > Tape is dead, Long live tape! Every time someone proclaims that tape is dead, I laugh. How many here realize that there is now Tape-based Object Storage? Zane
[cctalk] Re: Age of Tape Formats?
> On Mar 8, 2023, at 8:31 AM, Jon Elson via cctalk > wrote: > > 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 > 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
[cctalk] Re: Age of Tape Formats?
On 3/8/23 13:53, Sellam Abraham via cctalk wrote: > On Wed, Mar 8, 2023 at 1:39 PM Chuck Guzis via cctalk > 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. > Heavy bugger,no? Nickel-plated Vicalloy (a type of phosphor-bronze). --Chuck
[cctalk] Re: Age of Tape Formats?
On Wed, Mar 8, 2023 at 1:39 PM Chuck Guzis via cctalk 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
[cctalk] Re: Age of Tape Formats?
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
[cctalk] Re: Age of Tape Formats?
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@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:heal...@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 > > > > > > > >
[cctalk] Re: Age of Tape Formats?
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:heal...@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
[cctalk] Re: Age of Tape Formats?
> 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
[cctalk] Re: Age of Tape Formats?
On 2023-03-08 11:07 a.m., Chuck Guzis via cctalk wrote: I think it remarkable in retrospect that the original Star Trek (ca. 1966) used countless mentions of "computer tapes" in the 23rd century. A lack of foresight on the part of the script writers? What can we predict for the year 2250? --Chuck The use of the old tape drives as 'computers' still found in the movies. Ben.
[cctalk] Re: Age of Tape Formats?
I hate to throw a spanner in the works but no one has mentioned U-Matic tapes. Normally used for video recording the early CD audio and CD-Rom industry encoded the digital image on to U-Matic tapes which were then used to drive the laser for writing to the CD Master. On 3/8/2023 11:42 AM, Paul Koning via cctalk wrote: On Mar 8, 2023, at 12:20 PM, Chuck Guzis via cctalk wrote: On 3/8/23 06:19, Paul Koning wrote: I wouldn't exclude those, certainly not if they are relevant to the evolution of the technology. Are X1 tapes (and Eliott tapes if they are the same format, which I don't know) in some way anticipating LINCtape and DECtape? Are they an independent invention of roughly the same concept? For that matter, would you exclude DECtape on the grounds that it's single vendor? I hope not. For that matter, I suspect the Uniservo I format is specific to Univac, yet you can't very well exclude that from a history of magnetic tape data recording. I view "captive formats" such as DECtape to be evolutionary dead ends. Consider, for example, the Datamatic 1000 tapes--I doubt that more than a handful of people here have ever heard of the system. A captive format. Or the early Uniservo metal tapes? I would disagree with that blanket assertion, for two reasons. One is that something isn't an "evolutionary dead end" only if nothing later was inspired by it and constructed, to some extent, along similar lines. In that sense the Uniservo tapes are not at all a dead end; instead, they are the ancestor of all later tapes. Properties like metal vs. plastic media and 6 tracks vs. 7 or 9 or more are details. Second, I would consider a format to be significant if it had a major market presence and major place in the technology space. In that sense, DECtape I clearly belongs -- being either the primary or a significant secondary storage device for a decade or two of some of the world's most successful computer lines. Similarly, is DLT a "dead end"? It was captive to some extent until it spread out, but then LTO replaced it. On the other hand, isn't LTO clearly an evolutionary variant of DLT? I'd agree that there are a number of other formats that were neither significant players nor a significant influence on later work. The CDC 14-track tapes would fit that description, and the Eliot or X1 10-track tapes most likely as well. But I would argue that "if it wasn't an industry or ISO standard it doesn't count" is too restrictive a view, especially if you aim to produce a history of the technology space. paul
[cctalk] Re: Age of Tape Formats?
On Wed, Mar 8, 2023 at 6:12 AM Paul Koning 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. > 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
[cctalk] Re: Age of Tape Formats?
On 3/8/23 10:19, Dave Wade G4UGM via cctalk wrote: > > Yes, but Space 1999 still had slide rules.. I thought this discussion by one of the JPL people working on the tape mechanism for Voyager (1980) might be interesting to some: https://space.stackexchange.com/questions/2053/how-was-magnetic-tape-decay-prevented-in-voyager-1 --Chuck
[cctalk] Re: Age of Tape Formats?
> -Original Message- > From: Chuck Guzis via cctalk > Sent: Wednesday, March 8, 2023 6:08 PM > To: cctalk@classiccmp.org > Cc: Chuck Guzis > Subject: [cctalk] Re: Age of Tape Formats? > > I think it remarkable in retrospect that the original Star Trek (ca. > 1966) used countless mentions of "computer tapes" in the 23rd century. Yes, but Space 1999 still had slide rules.. > > A lack of foresight on the part of the script writers? > > What can we predict for the year 2250? > > --Chuck Dave
[cctalk] Re: Age of Tape Formats?
I think it remarkable in retrospect that the original Star Trek (ca. 1966) used countless mentions of "computer tapes" in the 23rd century. A lack of foresight on the part of the script writers? What can we predict for the year 2250? --Chuck
[cctalk] Re: Age of Tape Formats?
On 3/8/23 09:42, Paul Koning wrote: > Second, I would consider a format to be significant if it had a major market > presence and major place in the technology space. In that sense, DECtape I > clearly belongs -- being either the primary or a significant secondary > storage device for a decade or two of some of the world's most successful > computer lines. And all of them DEC. No IBM, CDC, UNIVAC, etc. As to what it inspired, I can't say. > Similarly, is DLT a "dead end"? It was captive to some extent until it > spread out, but then LTO replaced it. On the other hand, isn't LTO clearly > an evolutionary variant of DLT? But DLT was used in systems made by various manufacturers. Yes, it originated at DEC, purchased by Quantum and used on various systems. In fact, Quantum probably made the bulk of the drives, not DEC. Being a cross-vendor interchange medium, I'd include it. The same for DDS and 8mm (Exabyte) media. Exabyte didn't make computer systems, so it necessarily had to be cross-vendor. DDS is, of course, DAT re-imagined. How about the 2mm Pereos tapes? Never really took hold and used Sony audio mechanisms. I'd call that a dead-end, not being aware of anything that it inspired. --Chuck
[cctalk] Re: Age of Tape Formats?
> On Mar 8, 2023, at 12:20 PM, Chuck Guzis via cctalk > wrote: > > On 3/8/23 06:19, Paul Koning wrote: > > >> I wouldn't exclude those, certainly not if they are relevant to the >> evolution of the technology. Are X1 tapes (and Eliott tapes if they are the >> same format, which I don't know) in some way anticipating LINCtape and >> DECtape? Are they an independent invention of roughly the same concept? >> For that matter, would you exclude DECtape on the grounds that it's single >> vendor? I hope not. For that matter, I suspect the Uniservo I format is >> specific to Univac, yet you can't very well exclude that from a history of >> magnetic tape data recording. > > I view "captive formats" such as DECtape to be evolutionary dead ends. > > Consider, for example, the Datamatic 1000 tapes--I doubt that more than > a handful of people here have ever heard of the system. A captive format. > > Or the early Uniservo metal tapes? I would disagree with that blanket assertion, for two reasons. One is that something isn't an "evolutionary dead end" only if nothing later was inspired by it and constructed, to some extent, along similar lines. In that sense the Uniservo tapes are not at all a dead end; instead, they are the ancestor of all later tapes. Properties like metal vs. plastic media and 6 tracks vs. 7 or 9 or more are details. Second, I would consider a format to be significant if it had a major market presence and major place in the technology space. In that sense, DECtape I clearly belongs -- being either the primary or a significant secondary storage device for a decade or two of some of the world's most successful computer lines. Similarly, is DLT a "dead end"? It was captive to some extent until it spread out, but then LTO replaced it. On the other hand, isn't LTO clearly an evolutionary variant of DLT? I'd agree that there are a number of other formats that were neither significant players nor a significant influence on later work. The CDC 14-track tapes would fit that description, and the Eliot or X1 10-track tapes most likely as well. But I would argue that "if it wasn't an industry or ISO standard it doesn't count" is too restrictive a view, especially if you aim to produce a history of the technology space. paul
[cctalk] Re: Age of Tape Formats?
On 3/8/23 06:19, Paul Koning wrote: > I wouldn't exclude those, certainly not if they are relevant to the evolution > of the technology. Are X1 tapes (and Eliott tapes if they are the same > format, which I don't know) in some way anticipating LINCtape and DECtape? > Are they an independent invention of roughly the same concept? For that > matter, would you exclude DECtape on the grounds that it's single vendor? I > hope not. For that matter, I suspect the Uniservo I format is specific to > Univac, yet you can't very well exclude that from a history of magnetic tape > data recording. I view "captive formats" such as DECtape to be evolutionary dead ends. Consider, for example, the Datamatic 1000 tapes--I doubt that more than a handful of people here have ever heard of the system. A captive format. Or the early Uniservo metal tapes? Or the tapes used in the IBM 2321 Data Cell or 3850 MSS? Captive formats and evolutionary dead-ends. How about the stuff that never made it out of the lab? Such as the CDC SCROLL? I suspect that I may be one of few who even have heard of the beast--yet it was included in our forward-looking boilerplate in STAR proposals. How about the 9 track 1/2" 3200 fci tapes? Not mentioned yet. Quarter-inch cartridge tapes were quite varied. Although looking the same at first glance, there were significant differences. Consider the Alphamat...Zetamat 3M series of quarter inch tapes. (e.g. DC600HC). No optical sensing of BOT/EOT/media type holes--all done with preformatting. Those were popular with ADIC crowd--I have a couple of those drives in the eventual case that someone digs a tape up from the trash heap of history. How about the adapters that allowed use of VHS cassette equipment for backup? All dead-ends. Before disks were affordable, or even available, half-inch tape was used as primary storage. Consider the 7090 IBSYS shops--all tape operations. --Chuck
[cctalk] Re: Age of Tape Formats?
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_200_2000.pdf 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
[cctalk] Re: Age of Tape Formats?
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
[cctalk] Re: Age of Tape Formats?
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
[cctalk] Re: Age of Tape Formats?
> On Mar 8, 2023, at 10:07 AM, Bill Gunshannon > wrote: > > > On 3/8/2023 9:11 AM, Paul Koning wrote: >> >>> On Mar 8, 2023, at 7:25 AM, Bill Gunshannon via cctalk >>> wrote: >>> >>> >>> On 3/7/2023 8:30 PM, Dennis Boone 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. 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. >> 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? >> >> > > > 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
[cctalk] Re: Age of Tape Formats?
On 3/8/2023 9:11 AM, Paul Koning wrote: On Mar 8, 2023, at 7:25 AM, Bill Gunshannon via cctalk wrote: On 3/7/2023 8:30 PM, Dennis Boone 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. 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. 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? 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
[cctalk] Re: Age of Tape Formats?
> On Mar 8, 2023, at 7:25 AM, Bill Gunshannon via cctalk > wrote: > > > On 3/7/2023 8:30 PM, Dennis Boone 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. >> >> 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. 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
[cctalk] Re: Age of Tape Formats?
Some information about the origin of CUTS here : https://retrocomputing.stackexchange.com/questions/8099/whats-the-difference-between-kansas-city-tape-standard-and-cuts 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@classiccmp.org> wrote: > > On 3/7/2023 8:30 PM, Dennis Boone 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. > > > > 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. > > > bill > > >
[cctalk] Re: Age of Tape Formats?
On 3/7/2023 8:30 PM, Dennis Boone 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. 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. bill
[cctalk] Re: Age of Tape Formats?
> -Original Message- > From: Zane Healy via cctalk > Sent: Wednesday, March 8, 2023 4:35 AM > To: General Discussion: On-Topic and Off-Topic Posts > Cc: Zane Healy > Subject: [cctalk] Re: Age of Tape Formats? > > On Mar 7, 2023, at 5:32 PM, Paul Koning via cctalk > 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 > Our Honeywell H3200 had 1200BPI NRZI 7-track drives. http://www.bitsavers.org/pdf/honeywell/datapro/70C-480-01_7404_Honeywell_200_2000.pdf page 13 onwards... Needed chrome tape Dave
[cctalk] Re: Age of Tape Formats?
On 3/7/23 20:34, Zane Healy via cctalk wrote: > On Mar 7, 2023, at 5:32 PM, Paul Koning via cctalk > 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. 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
[cctalk] Re: Age of Tape Formats?
On Mar 7, 2023, at 5:32 PM, Paul Koning via cctalk 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
[cctalk] Re: Age of Tape Formats?
On 3/7/23 17:32, Paul Koning wrote: > > >> On Mar 7, 2023, at 8:23 PM, Chuck Guzis via cctalk >> wrote: >> >> 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. > > Was IBM the first for each of these? 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. > 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
[cctalk] Re: Age of Tape Formats?
On 2023-03-07 20:23, Chuck Guzis via cctalk wrote: 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 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
[cctalk] Re: Age of Tape Formats?
> On Mar 7, 2023, at 8:23 PM, Chuck Guzis via cctalk > wrote: > > 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. 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. > 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
[cctalk] Re: 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. For QIC, qic.org has a some info. For DLT and LTO, the wikipedia pages are fairly useful. De
[cctalk] Re: Age of Tape Formats?
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
