Primarily worry about tapes (old and new) for the 729 drives
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Allen,
This is good info! Would you ask for me if the tape he recommends is that called "IBM Multisystem Tape", sold in the 70's? Also, some 1970's tapes had binder problems and would develop stiction and squeal, did this tape ever have that problem? Please let me know if you find a good source for this tape. If thats a problem, I have stacks of 3420-vintage scratch tape that might serve, but I don't know the brand or formulation. You probably have, too. On the heads, I would not worry about them if you don't plan to run the system in "production". I never had any trouble with the heads on my drives when my 1401 was running, and its my understanding these heads have deep gaps so even if they are pretty worn they will work OK especially at the lower densities. In my opinion, the only reconditioning you might consider would be lapping to eliminate grooves where the edges of the tape runs, only if the grooves are deep enough to cause trouble. Paul Pierce |
Richard Bradshaw to Garner/Palmer
Tape source June 29, 2004
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thanks for forwarding the note...yes the remarks about the binder
degradation problems is real and that is why I suggested that this team
not try to use any of the earlier formulations..they are all dead at this
stage..and the tape I was suggesting to use is indeed MST
formulation...although that is now over thirty years old as well. I
believe only Imation and possibly Graham magneitcs are still making new
gamma iron oxide "MST" like tapes. I would strongly urge the team to use
these tapes and I would assume that you don't need many so you might be
able to get some donated for this cause from Imation. Let me know if you
want me to pursue this as I have contacts there.
Cheers, Ric
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Eric Smith to Team
Tape source July 1, 2004
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?from R. Bradshaw?
> I believe only Imation and possibly Graham magneitcs are still making new > gamma iron oxide "MST" like tapes. I would strongly urge the team to use > these tapes and I would assume that you don't need many so you might be > able to get some donated for this cause from Imation. If true, this is great news. It was widely reported in the press a few years ago that the last company in the 1/2" magtape reel market had ceased production. But one can't always believe what one reads. In fact, Google turns up a recent article stating that Graham ceasing production in 2001: Eric |
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Even if Imation has ceased production, it is possible that they and Graham
have some unsold stock that they'd like to unload -- perhaps as a charitable
donation. I've already contacted Graham to find out. They haven't yet
responded -- well, it would be unreasonable to expect them to respond in
thirty seconds!
Van Snyder I just received a response from Graham Magnetics concerning gamma iron oxide MST-like tapes. The response was "how many do you need. Not having a clue, I sent the following to "Brendan Sullivan" Brendan: I'm not directly working on the restoration project, but now that I (believe) I know you have some, I'll ask the folks at CHM to contact you. I assume that's OK with you? Thanks for getting back to me so quickly. Best regards, > How many do you need? > |
| Yes, the binder does degrade. However, the problems are similar
(probably easier) to those we have had with Umatic and earlier video
(helical scan heads really beat up the tape) tapes. We have
successfully used a tape cleaning service to "restore" old video tapes
and some of them were in good shape anyway. A standard computer tape
cleaning machine would probably do the job pretty well if we paid
attention to it. Does anybody know if we have one or where we might
find one? Mike Walton has the experience with the restoration service
in San Francisco.
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I don't know if or why computer tape is different than video tape, but
a tape cleaner is definitely NOT adequate. I don't know the full
details, but the tape substrate and/or binder undergoes a chemical
change and becomes very sticky. Cleaning does not help this problem
at all, and if you attempt to read such a tape, it sticks to the heads,
and the oxide gets stripped off. Thus if you try to read a sticky
tape, you will ruin it, and NEVER be able to recover the data.
Whether tapes get sticky with age seems to vary a lot with the brand, and to a lesser extent, the lot. Memorex and BASF tapes are very prone to this problem; 3M Blackwatch is not. (Somehow this is not surprising because Memorex and BASF were the el-cheapo brands and 3M was the expensive stuff.) The solution to the problem is to bake the tape. Once you bake it properly, you have a short time to read the tape (it doesn't permanently cure it).
Details are available online, but I don't know where. Contact
Al Kossow
Because of this problem, at some point it will no longer be possible
to use old tapes even as scratch tapes for demo purposes. It is
unclear how long the last tapes made in 2002 will be usable.
Eric
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Here is my experience -
Many tapes last years, even in poor conditions. I have had little trouble reading tapes from the 1960's. I know some were not stored well. This includes tapes so old they have brown (instead of almost black) oxide. As far as I know, I've only encountered Mylar backing, not acetate. I have had no trouble with oxide coming off on any tape. On the other hand, I have a batch of tapes from the 1970's that sticks and so far does not bake out. They do not stick so badly that the oxide comes off, thus I am able to experiment. But I have not been able to bake them out yet at the Ampex recommended time and temperature. (50C, 72 hr.) Perhaps I need to check my humidity. I have a tape cleaner. It is good for taking dust off so there are fewer dropouts (my current setup handles dropouts so well this is almost not necessary.) It does nothing for sticky tape. Well made, recent tape should work well indefinitely, especially if it is stored properly. Paul |
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Paul Pierce wrote:
> Well made, recent tape should work well indefinitely, > especially if it is stored properly. I'm not sure that there is any easy way to tell that tape is well made, other than by checking whether it can be read many years later. I've dealt with tapes from the 1960s that read fine, and tapes from the 1990s that have failed. Eric |
| In the early 80s I wanted to read our system accounting tapes going back to the late 60s. We brought them back from the vault where they were kept and kept them in the computer room for a few days before we tried to read them. We then cleaned the tapes and I tried to process them. Out of over 100 tapes I had one that I could not read. These tapes were 9 track tapes recorded at either 800 or 1600 bpi. I hope that you have close to the same luck. Ted |
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Ric et al,
In the SanJose history collection I find: There is no indication that there is any special data on them - I think they are mostly scratch tapes from Product Test. Are these gamma iron oxide? Are they suitable for the 729's? If so, I think there is a good possibility that they could be made availale. If not these, how would suitable tape reels be marked? Perhaps there are some that could be found... Thanks! |
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Dave,
the MST is good media from a formulation view point and was the best of breed in its day..it is however probably at least 15 years old and probably more like 30! If I can't find some more recent stuff then that is probably the next best thing. I have some MST here also...from the 1980's..made in Boulder CO by IBM. It is all gamma iron oxide..the only changes form the 50's until the 80's was the improvement in the particle size and coercivity distribution as well as the move to better Mylar substrates and improved formulations and lubricants. There is certainly no reason for anyone to run this restored system on the original tapes which in their hey day were marginal and caused capstan glazing and mandatory drive cleaning with solvents every six to eight hours. The tapes that you have Dave can be bulk erased even if their is data on it and that will improve the signal output for this system....but any of hte older tapes will generate more debris than a new tape and if they are over 15 years old (which almost all will be) then they also tend to produce adherent debris which will gum up the head and require frequent cleaning. These tape drives and tapes continued to be optimized over the course of the 2401-2415, 3410 and 3420 devleopment. The 3420 was the most reliable but still required way more maintenance than any drives produced since. I am still trying to locate a current source for "new" media. Graham Magnetics I believe has ceased production of this media....but I am checking.
Cheers, Ric
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Ric Bradshaw > the MST is good media from a formulation view point and was the best of > breed in its day..it is however probably at least 15 years old and probably > more like 30! If I can't find some more recent stuff then that is > probably the next best thing.
Keep in mind that "Brendan Sullivan"
> How much do you need?
This suggests that Graham still has some of the stuff, and may be willing
to donate it. Not having a clue how much the project will want, I didn't
respond, but rather passed the buck to the members of the team who are
able to participate in person. Has anybody who actually has an idea
how much the project could use followed up with Sullivan?
--
Van Snyder
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Ric,
Is your souce of "new vintage gamma iron oxide tapes" in addition to the source that Van Synder found at Graham Magnetics (email from Brenda Sullivan)? I suspect we'll eventually need many tape reels: I would guess 50 - 100, afterall they need to last well into the future(!), and we may have head problems, etc.. We'll work out a number, specs (density?) and Allen Palmer will communicate and intial quantity. - Robert p.s. Would you like me to add you to the 1401 team alias? |