Seibel Peter. Coders at Work

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Fran Allen

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Allen: Yes, I think it does. They were often viewed as not going to put up a

fight—that they were more isolated and don’t have the advocates who will

deal with a famous thief. He was a famous thief, known but nobody dared

touch it. And there are plenty of others way back from the Stretch days.

There was a woman who essentially was the inventor of multiprogramming

and credit was taken by somebody who eventually became a Turing Award

winner.

Seibel: Would you have rather won the Turing Award, but not had to have

been the first woman? There were a lot of newspaper stories: “Woman

Wins the Turing Award,” which I imagine might be a little annoying. If

another woman had won it ten years ago, and been the first, and you could

have just won it when you did, do you think you would’ve preferred that?

Allen: Well, I can’t say preferred or not preferred. I feel I won it for a very

good set of reasons. And it took a long time because it was not always clear

what I was doing in some sense. I always worked with a group. Worked

with some great, famous people often. And the work could easily be

attributed to somebody else—to John Cocke, who distributed ideas

everywhere. Lots of people have received accolades and awards because

they picked up on something from him, as we all did.

But I was very glad to get it and partly because it was late for a woman to

get it. I felt it was an embarrassment for the community that there were 50

men in 40 years, or whatever it was. So I felt it was certainly overdue for

some woman to achieve it, and I was perfectly happy to be the first. But I

steered a little bit clear of making a big deal out of that aspect of it. I tried

to focus a lot more on the length of my career and the whole history of it.

Seibel: How does it feel to have spent your whole career at IBM?

Allen: Working for IBM Research was one of the most fortunate things

that ever happened to me because IBM Research sits between industry and

academia. I have a picture of a stone wall that I’m standing on and can look

either way and find interesting problems and opportunities in both ways.

Seibel: From your vantage point on this stone wall, do you feel there is

enough going back and forth between the academy and industry?

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Allen: Well, NSF published a wonderful report with a one-page graph a few

years ago which showed where several billion-dollar industries come from,

like graphics, the Internet, high-performance computing, transistors. These

billion-dollar industries were down the y-axis and on the x-axis was a

timeline showing when it started, what was the role of industry, by lab, and

what was the role of academia.

Some started in industry; some started in academia. Together, these two

entities had contributed pretty much equally into building these multiple

billion-dollar industries. I think the real important thing is to protect the

interplay so that there’s a lot of cross-channeling of ideas, and of

technologies, and methods, and investments to see it continuing.

Right now, with the focus that the U.S. has on maintaining innovation, and

the importance of it, I think we’re doing pretty well in terms of interaction,

working together, and solving problems together. And solving the problems

that keep us from solving problems—intellectual property being one of

them.

Seibel: IBM is not exactly blameless there.

Allen: Not at all.

Seibel: You must have your name on patents.

Allen: No, none. Part of it is that software wasn’t patentable. The other

thing was that I was often working at the leading edge of things and the best

way to get it into IBM was to publish it and some other company would pick

it up. I was much more interested in getting it into products than to getting

a patent on things.

Seibel: So that was easier than convincing someone within IBM to build a

product based on your research?

Allen: We have a much better way of doing things now. But there was a

long way, sometimes, between a good idea in research and a product.

Seibel: Since receiving the Turing Award has caused you to reflect a bit on

your whole career, is there anything that you’ve realized ties it all together?

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Allen: I think my career and the way I do things—the one word that kind

of sums it up is “exploring.” I love exploring the edges—of ideas, of

projects, and the physical earth, whatever it is—people too—and that I find

very exciting.

But there’s a flip side in that I’m a starter, not a finisher. I get attracted to

new things. The field of compilers was just a marvelous field because the

computers continued to present challenges. And the problems being solved

continued to be increasingly challenging.

C H A P T E R

Bernie Cosell

In 1969 when the first two nodes of the ARPANET—the network that would

become the core of the Internet—came on line, every packet that flowed over 50

kilobit/second leased lines was routed through two specialized computers called

Interface Message Processors, or IMPs. The IMPs were designed and built by Bolt

Beranek and Newman (BBN), and the software that ran the IMPs had been

written by a team of three programmers, one of whom was Bernie Cosell, who had

left MIT three years before, at the beginning of his junior year, to join BBN.

Originally hired as an application programmer on a project building one of the

earliest timesharing systems, Cosell quickly moved to the systems programming

side of things and was soon “czar of the PDP-1 timesharing system” responsible

for finishing the operating-system code and keeping the system running.

Over a 26-year career at BBN, Cosell would work on a little bit of everything,

earning a reputation within BBN as a master debugger and “fixer” who could be

thrown onto a struggling project to make the software work. And he hacked just

for fun: to hone his Lisp skills he wrote DOCTOR, a version of Joseph

Weizenbaum’s ELIZA, based on Weizenbaum’s description in a journal article.

Written in BBN-LISP, which spread around the ARPANET along with the TENEX

operating system, Cosell’s version of DOCTOR also had a wide distribution—wider

than Weizenbaum’s original—inspiring new implementations and related

programs.

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In 1991 Cosell left BBN and bought a sheep farm in Virginia, where he now lives

with his wife Lynn, three dogs, innumerable cats, and lots of sheep. He does some

programming for a local ISP, hacks a bit on his own projects, and teaches a few

courses in programming and computer security but is glad he no longer works as a

full-time programmer. Ironically, as a result of his move to the country, Cosell—

one of the fathers of the Internet—now has only dial-up access from his home.

In this interview we talked about how he won his reputation as a master debugger,

the importance of writing clear code, and how he convinced the other

programmers on the IMP project to stop patching the binary.

Seibel: When did you first get involved with programming?

Cosell: In high school. I don’t know if it was true or not but the rumor was

that our high school was the first high school in the country to actually have

its own computer. IBM donated a 1620 to our high school. I think it arrived

either the year before I arrived, or the year I arrived at high school in ’59.

Seibel: And what high school was it?

Cosell: Bronx High School of Science in New York. I believe the previous

generation of students were using Columbia University’s 650. But the head

of the math department was very pleased that he had his own computer. In

fact, he was writing a book on programming and this was back when there

weren’t many books on programming. I ended up debugging all of his

examples. Almost the only thing I remember about high school is learning to

program.

Seibel: What were you programming then? Assembly on punch cards?

Cosell: Yeah. Well, it was punch cards but the 1620 also had a console. It

had an IBM Selectric typewriter that was the input/output console, and you

could input programs from that. To show you the era it was, they chose not

to put arithmetic hardware in it. It had table-lookup arithmetic: there was

an area of memory and when you wanted to do an addition, one digit gave

you the row, one digit gave you the column, and the value was there. And

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part of every program was loading that part of memory with the addition

and multiplication tables.

So you could actually type from the typewriter but mostly we punched

cards and loaded them in. There was a Fortran for it but I never did very

much Fortran. Mostly, I programmed in 1620 assembler.

The other thing I learned in high school is how to wire plug boards.

Someplace along the route, we had something like an old 403 calculating

printers and I learned how to wire a plug board. It was such a primitive art,

even at the time, but it turned out to be useful. At BBN, like ten years after

I was in high school, we actually needed somebody to wire a plug board and

I just said, “Oh, give me the manual on that thing.” And I read the manual

and made an old standalone accounting-machine printer do a primitive

protocol to serve as a line printer on our PDP-1.

Seibel: And in between high school and BBN you went to MIT?

Cosell: I graduated from high school and entered MIT in ’63. I was a solid

math major at MIT, taking an odd computer course. Computers were still

an occasional class taught out of the electrical engineering department; you

couldn’t major in computer science. Folks were just starting to build the

first time-sharing systems on the 709 or 7094, whatever they had at the

computer center, but I was pretty busy doing math.

I took some EE courses and logic courses and I took the odd computer

course and seemed to be OK at it. I didn’t understand what the really good

programmers did because I was just a little kid. But I seemed to be able to

program.

I did fall in with a group called the Tech Model Railroad Club. I really

thought that was great. Relay logic was right up my alley. They had a

railroad layout completely done with relay logic and stepping switches.

Through that, I got slightly in touch with the people at RLE—Research Lab

of Electronics. This was still in the era where we spent all of our time in the

basement of Building 26 typing up punch cards on the keypunch, which we

would then hand to the shaman, who would give us listings back the next

day. Then I started hanging out at Project MAC. Basically, when I was

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supposed to have been doing lots of math lessons, I discovered I was

spending more and more time hanging out in the computer places.

And after RLE, you went over to Tech Square. I met people like Richard

Greenblatt and Bill Gosper. But I was just drifting through that world; I

don’t think I was doing much programming. Like I remember how I got

involved with Project MAC: I was really taken by Spacewar! on the PDP-1.

But I didn’t approach it as a hacker or a programmer—“Let me see the

source code. How did you do that?” I just thought the game was the neatest

thing. I was just a gamer at that point, as opposed to a programmer, and I

had heard that the guys over at Project MAC had done a super version of

Spacewar!, that they had fancy consoles, and they had a spare PDP, so I

wandered up there. So I got to meet Peter Samson in his great failed

attempt to solve the New York City subway system, to ride the whole

system on one ticket as fast as possible.

I was probably a sophomore, deeply entrenched in the usual sophomore

things, watching all of these guys who were clearly adept and clearly knew

what they were doing. I was writing little programs to solve a maze. The

frog had to hop from lily pad to lily pad and get out of the middle of the

pond. I remember writing that program and helping other students from my

dorm get theirs working. But that’s where I was at. I had no clue what

happened after I handed my deck in.

As I look back, I would say that at that point, I was learning the craft of

programming. I could sort of make computers do what I wanted. But the

light hadn’t gone off. I hadn’t internalized it; I didn’t really understand what

was happening. It was all a little bit magical and strange. And that was how I

was drifting through college. The thing that really made me a programmer

was going to work at BBN.

One of the guys I had met at college, who had graduated and worked at

BBN said, “Come out here.” He took me out one night in the middle of the

night because BBN was a 24-hour-a-day, 7-day-a-week weird place. It was

sort of an extension of the MIT labs. People could come and go at all hours.

And he was part of the night crew. So we went out one evening. It was all

too mysterious and marvelous to understand; I just had no clue what he was

showing me. Not long after that, he suggested that they hire me. And so

they had me out, interviewed me, and hired me.

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Seibel: This was when you were three years into MIT?

Cosell: Correct. In September of my junior year they hired me part-time. I

believe I made it until October before I dropped out and went to work full-

time at BBN.

In retrospect, I wasn’t very good. I had seen a PDP-1 but I had no idea how

to program one. I didn’t know anything about time-sharing. That, of course,

was not surprising, since there were probably maybe 50 people on the

planet who knew what time-sharing was.

But BBN was working on a project with Massachusetts General Hospital to

experiment with automating hospitals and I got brought onto that project. I

started out as an application programmer because that was all I was good

for. I think I spent about three weeks as an application programmer. I

quickly became a systems programmer, working on the libraries that they

were using. And not long after that, the two systems gurus, the guys that

had written much of that PDP-1 time-sharing system, took me under their

wing and designated me their heir apparent. That winter they both left BBN

to go back to grad school. By January I was the czar of the PDP-1 time-

sharing system—I was responsible for the whole mess.

But in that little interval, a whole series of lightbulbs lit up. All of a sudden, I

understood time-sharing. I understood real-time systems. Once I

understood it, I absorbed the time-sharing system. And everything’s been

downhill for me after that.

The project was quite ambitious for its time. The idea was that there would

be a Model 33 Teletype—noisy and clunky and uppercase only—on each

ward. There would be a Model 33 Teletype in each doctor’s office. There

would be a Model 33 Teletype in the pharmacy. And there would be, I

guess, a Model 33 Teletype in the admissions office. And our little time-

sharing system was going to coordinate all of that.

When a patient got in, they would be assigned a bed. The doctor would

schedule lab tests. At which point, the nurse’s Teletype would say, “Take

these samples. Put this number on it.” The lab would get a message saying,

“Run these tests.” If the doctor prescribed something, the pharmacy would

be told and the cart would be ready.

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It was amazing to have those little noisy, silly things on the wards. Having

that level of professional dealing with these clunky things was really pretty

offensive, so there was a lot of resistance. But I was sort of immune to all of

that, because I had gravitated off to the systems part of the world.

And I had decided it was really important that the system not stop. I don’t

know if they told me that or not, but I decided that we had to prove—I had

to prove—that time-sharing could work. That it was a good enough and

solid enough thing that you would consider running a hospital with it. I

thought about what happened if a patient needed medication and the system

crashed? Or worse, the system lost the prescription and the patient never

got dosed? Or the system juggled prescriptions and the nurses had actually

started trusting the system? So I started thinking the system should not

crash. This system should be good as Unix 30 years later.

But there was no real-time debugging. When the system crashed, basically

the run light went out and that was it. You had control-panel switches

where you could read and write memory The only way to debug the system

was to say, “What was the system doing when it crashed?” You don’t get to

run a program; you get to look at the table that kept track of what it was

doing. So I got to look at memory, keeping track on pieces of graph paper

what it was doing. And I got better at that.

In retrospect, I got scarily better at that. So they had me have a pager. This

was back in the era when pagers were sort of cool and only doctors had

them. It was a big, clunky thing and all it would do is beep. No two-way. No

messages. And it only worked in the Boston area, because its transmitter

was on top of the Prudential Center. But if I was within 50 miles of Boston,

it worked.

And basically, I was a trained little robot: when my pager went beep, beep,

beep, I called in to find out what the problem was. What was bizarre was

that with no paper, in a parking lot, on a pay phone I could have them

examining octal locations, changing octal locations and then I would say,

“OK, put this address in and hit run,” and the system would come back up. I

don’t know how the hell I managed to do that. But I could do those kinds of

things. I took care of the time-sharing system for probably a good two or

three years.