5. From Atsushi Akera's 2006 Oral History Interview with Bernie Galler

posted Dec 22, 2011, 11:38 AM by Jeff Ogden   [ updated May 15, 2019, 4:07 AM ]
Pages 61-66 from http://dl.acm.org/ft_gateway.cfm?id=1141883&type=pdf :

AKERA: . . . But returning again back to time-sharing, and particularly virtual memory, which is what we were just beginning to speak about, can you tell us a little bit more about the development of virtual memory? Both separate from and integrated with the time-sharing effort.

GALLER: Some of the early ideas came from the Atlas computer in England. They actually switched among users, but they didn’t have a two-level scheme, and it was not very efficient. But they had the idea of swapping and so on. Burroughs, also on the B5000, had a kind of a segmentation thing. Again, it was only, sort of, half the problem.

AKERA: I imagine most of these are simply software solutions, so that in terms of efficiency, the dynamic relocation hardware was not available in any of these systems until the earliest…

GALLER: I think that’s right, although the Atlas had a very sophisticated user-switching mechanism in hardware, saving the state of this user and bringing back the state of the machine.

AKERA: This is all meant to make those transitions as efficient as possible, as quick as possible?

GALLER: Right, but that was not really virtual storage, in a sense. So people had ideas and pieces of it. There were the MIT people who sort of envisioned the whole thing--

AKERA: Or at least wrote about it first.

GALLER: Or talked to us about it. As much as they were willing to talk, and then there was a whole controversy of whether we took their ideas and didn’t give them credit and so on. We thought we gave credit to Jack Dennis in that article because we felt that what we took from them was what he had told us.

AKERA: This is also an aside, but as a historian of technology, we tend very much to downplay priority disputes because most ideas happen because of the circumstances surrounding them. Similar ideas are floating around and things come together at different places. You know, simultaneous invention is something we talk about, and it’s a very frequent phenomenon. Nonetheless, there are intellectual lineages, and of course, to the participants, these are very important issues because this is about their academic reputations, and contributions.

GALLER: That’s right. So we worked with IBM, and as I said, with Gerrit Blaauw in particular. They proposed some things that we shot down, and then we proposed some things they shot down. It really was a good collaboration. We had some very good people on this—not only Westervelt, but Mike Alexander, who is still with us and so on.

AKERA: He first worked on LTS (Lincoln Terminal System),[19] putting LTS on Michigan’s computer, and then transforming it into MTS eventually (Michigan Terminal System). [when talking about LTS here, Akera and Galler are actually talking about the Lincoln Laboratory Multi-Programming Supervisor (LLMPS); LLMPS was the supervisor upon which what eventually became the University of Michigan Multi-Programming Supervisor  (UMMPS) was based; LTS stood for "LLMPS Terminal System" and was the initial name that was used briefly for what became the Michigan Terminal System (MTS); LTS / MTS was developed entirely at the University of Michigan; MIT's Lincoln Laboratory did develop something called Lincoln Terminal System (LTS), but that was a computer aided instructional system and had nothing to do with LLMPS, UMMPS, or LTS / MTS at Michigan. -Mike Alexander and Jeff Ogden, May 2019.]

GALLER: That’s right. Yes. LTS [LLMPS] was a very nice, multitasking thing.

AKERA: The Lincoln Terminal System developed by Lincoln Laboratories.

GALLER: Not terminal system, but Lincoln Multiprocessing System, Multi-programming System—LMS, something like that. [LLMPS, Lincoln Laboratory Multi-Programming Supervisor.]

AKERA: Hmm… but in any event, it was MIT’s Lincoln Laboratories, which was separate from Project MAC.

GALLER: That’s right. In fact, when IBM finally formed this group of the inner six important customers, Lincoln Labs was one of them. And GM and Princeton.

AKERA: In fact, I should probably ask you to spell out that history a little bit. But before going there, I think it is worth noting for the historical record (and you may not be familiar with this), but IBM did have very extensive conversations with MIT about the design of computer time-sharing systems, of which virtual memory and dynamic relocation hardware were very much part of the conversations. So one of the possibilities is that some of the knowledge that became embedded in the Michigan system, in the IBM hardware, may have come not through your group at Michigan, but through the history of conversations between MIT and IBM.

GALLER: Yes. We know that they had a falling out at some point, which is why they [MIT] went to GE. I guess we were never really aware of that other avenue of communication. We certainly didn’t take credit for everything. We just worked with IBM, and they came with ideas and we came with ideas.

AKERA: As much as the initial group at IBM evaluated the suggestions that Robert Fano, at MIT, advanced to them, IBM had quite a bit of internal discussion about what MIT was asking for. As a consequence, I think they did understand what the technical changes were that MIT asked for. That information was very broadly disseminated within the organization. I don’t know the specific history and all of the connections, but I believe Gerrit Blaauw may have been one of the participants in that conversation.

GALLER: He probably was. But as I recall, he was a hardware architect type person; we were software people. As I recall, when we began to talk to them, we realized that they had not thought through the software implications of all of this. That’s why we published our article, saying, “If you’re going to do this kind of thing, there are some interesting software issues.”

AKERA: Indeed, there was a lot of confusion within IBM, and they [probably] did not see the software side. [In speaking with MIT, there were definitely those within IBM who] couldn’t understand initially why you needed the dynamic allocation hardware because they didn’t know enough about operating system software to spell out [the implications]-- I think that’s absolutely correct.

GALLER: Right.

AKERA: Perhaps more for the historical record, could you fill us in on the history, starting with the falling out at Project MAC with IBM, and then how Michigan came into the picture? How did that sequence of events happen?

GALLER: I’m not sure who contacted whom, now that I think of it. Well, we had been talking to various vendors, and--

AKERA: Even before Project MAC’s falling out. Is that right?

GALLER: I think so. We wanted to get involved.

AKERA: MIT received funding from ARPA IPTO under J. C. R. Licklider, and they held a series of meetings, particularly a summer study, in which IBM, General Electric, and other manufacturers were invited. At that point, Robert Fano proposed certain hardware changes, and General Electric turned out to be more responsive than IBM. IBM thought that their solution was adequate, and then was, in a sense, surprised [by MIT’s decision. Actually,] by the time the decision was made they knew how the decision was going to go, but they were very frustrated that MIT chose to work with General Electric rather than IBM, with whom they had a long-term relationship. Now, Michigan also had an established relationship with IBM going back to the very deep educational discount that IBM provided on Michigan’s leased 704 and 709 and 7090 computers. So there was already a precedent for working between Michigan and IBM, not so much at a detailed technical level, but at least in terms of the education discounts on the machines.

GALLER: Well, more than that though, because I was already doing operating system [development] on the 701 and 704 through GM, and interacting with IBM people at SHARE.[20] For example, I pointed you to what we published as an anecdote just in the last year in the annals about relocation bits. If you look at that, what I’m discussing there is an IBM proposal for a whole new structure of relocation bits. So I was interacting with IBM people all the time, really. When they had a falling out with MIT, they probably came to us and said, “Would you like to work with us?” They wanted our contract. Whatever we were going to do, they wanted it on an IBM machine.

AKERA: My sense from the actual historical, IBM documents of this period…

GALLER: …Which I have not seen. I hope to see it someday.

AKERA: Exactly. Well, actually you saw some of them originally… You wrote some of them! Well, not the ones on the IBM side. But these are actually some of your own papers. I found some of these documents in the records of the University of Michigan Computing Center.[21] But in any case, my understanding is that Michigan itself carried out a major long-range computing needs study, sort of modeled after [the one carried out at MIT], in which it became obvious that computer time-sharing was also the way for Michigan to go.

GALLER: Yes, there was a specific study.

AKERA: In fact, it was carried, I believe, by Donald Katz, who we mentioned yesterday in the context of the Ford Foundation Project.

GALLER: Right. That [study] was deliberately made bigger than the computing center. We wanted, and of course our friends wanted the campus to be aware and educated that this was a good way to go.

AKERA: I think it was in that context that you had independently decided to approach IBM, partly knowing that IBM had had this falling out with MIT. So there was a window of opportunity to really do unique computer time-sharing research. Of course, this [was apparently] when you were also in conversation with, and had been invited to join the MIT group, or collaborate with them.

GALLER: When we decided not to, then we said, “Okay, let’s work with IBM.”

AKERA: I don’t have definite knowledge of this, but I think that was the first contact, the letter that you and Bruce Arden sent to IBM…

GALLER: Right. But I think at that time it was when we were talking to all the other vendors and finding they didn’t have any idea.

AKERA: Yes, and please elaborate. I’m sort of just setting up the question…

GALLER: As I said, we talked to MIT, but I know we invited other people in. It must have been right about that time.

AKERA: I think that’s right. In other words, you promised to the campus community that you’d go into time-sharing research, and then you were actually beginning to do the early phases of that research. I believe it was actually funded by the General Funds of the University.

GALLER: I think so.

AKERA: As a consequence, you did some technical work, but in the process you had to approach various manufacturers to see if anybody was willing to do the hardware changes that were required. IBM was one of the obvious people to approach. I think you might have had some extra hope that that would [work with you]…

GALLER: Right, especially knowing that they had broken up with MIT. They were ripe for someone-- Of course, we were able to offer our expertise in operating systems. We’ll take advantage of whatever we can get you to do. Let’s put some of this in the hardware to make the software easier to do.

AKERA: That’s good. Now, can you tell us how that history unfolded then? You had mentioned a core group of six, and but you [were the ones that] originally approached IBM. What happened next?

GALLER: Yes, that was a little later. We talked about the inner six business first, but that came later. That was only after Michigan-- we had already ordered a machine with virtual storage capability. So the question of the development of that, we worked with Blaauw and his team to define the hardware. Meanwhile, we were writing to the software requirements to know how to take advantage of the hardware. That was useful because they had mentioned a “W” register. I remember we were able to shoot that down because it didn’t help our--

AKERA: …had negative consequences?

GALLER: Yes, negative consequences and whatever. So we did finally agree on the hardware.

AKERA: Do you remember the actual dates during which this work took place?

GALLER: I was on sabbatical in ‘65–’66. I think it was before I left. Of course, we didn’t know about the 360 until they announced it.

AKERA: They sort of pre-announced it to a certain select group of people. They didn’t let you know too much before the official announcement was made…

GALLER: Yes, but I’m not sure we were in that group. I don’t really recall exactly when.

AKERA: Actually, Michigan was among those that were told about the system 360 before its official announcement, but they couldn’t release that knowledge until fairly close to the…

GALLER: Right.

AKERA: So it’s possible that the initial conversations took place a little more in the abstract as opposed to in the context of the 360 series. But eventually you knew that it would be, in fact, the 360 model, 66M.

GALLER: Yes, that’s right. We never really knew whether “M” was “Modified” or “Michigan.” [chuckles] We did work on the software at the time, and as I said, we can get a better idea of the date from the ACM Journal article. I can look that up. Then they said they would do the 67, and I we said, “Okay, and we’ll do the operating system.”

AKERA: And IBM was comfortable with that decision at that point. They felt that you had the software operating system expertise.

GALLER: That’s right. And it was a machine for Michigan, so if the software didn’t work, it was our problem. But once they began to tell people about it, there were two developments. One is a lot of universities suddenly said, “We want that.” Then some industrial firms said—GM in particular, and I, again, was telling GM what we were going to get—and they said, “We want it, except we want the operating system to do this or that.” They weren’t asking for different hardware, but they wanted the operating system. So IBM finally said, “Well, we’d better do an operating system TSS, which will have things that other people want.” GM, Lincoln Labs--

AKERA: …that was different from what Michigan was doing?

GALLER: Right. So that began to grow, and we said, “Fine, we’ll use TSS if and when it’s good. Meanwhile we’ll do MTS, because one: we think we can do it faster, and two: it’ll be more tailored to our work.”

AKERA: I imagine there were local pressures to get a time-sharing system up and running fairly quickly.

GALLER: Not that much. It was more our own interest.

AKERA: Oh okay, you just wanted to get it running quickly as part of your research.

19 This was from the Lincoln Laboratories. I believe Lincoln Laboratories was one of the sites that adopted MAD, at least for experimental purposes, and hence they remained in touch with Michigan, even after Galler and Arden chose to go their own way and worked independently of MIT’s Robert Fano, Fernando Corbato, and Project MAC.
20 In fact, IBM helped broker the arrangement with GM, giving GM a discount for Michigan’s use of the machine to develop its systems programs.
21 There were also other papers referred to in documents at the IBM Archives, made available to the interviewer courtesy of IBM.

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