Seibel: So you were very comfortable at MIT but you ended up going to Harvard and working at MIT. What happened?

Steele: By the time I was applying to colleges I applied to MIT, Harvard, and Princeton and really wanted to go to MIT. I got accepted at all three. The headmaster of Boston Latin School was Wilfred L. O’Leary, an oldschool classicist, a wonderful gentleman. He called up my parents and said, “Do you realize that your son is actually considering going to Tech when he has an acceptance at Harvard?!” So he twisted their arms and they twisted my arm and I decided to go to Harvard after all.

Then my parents were on my case to get a summer job and not just sit around the house—you know, the classic syndrome. I knew I was interested in computing and didn’t want to flip burgers. So I interviewed for keypunching jobs, figuring that was something I’d be reasonably qualified to do. But nobody wanted to hire me, in part because I wasn’t 18 yet. I didn’t figure that out until later. They just listened to my story and said, “Don’t call us, we’ll call you.”

Then around the beginning of July I heard that Bill Martin at MIT was looking for Lisp programmers. I thought, “Aha, I know Lisp.” I’d hung around MIT so much and had obtained copies of Lisp documentation from the Artificial Intelligence Lab and I would sneak into the labs and play with the computers. The doors were open in those days—the Vietnam protests had not yet happened, which is what caused them to put locks on the doors. And I had spent my senior year implementing my own Lisp for the IBM 1130.

So I showed up at Bill Martin’s office, this skinny kid out of nowhere, and poked my head in and said, “I hear you’re looking for Lisp programmers.” And he didn’t laugh at me. He just looked at me and said, “Well, you have to take my Lisp quiz.” “OK. How about now?” So I sat down and spent two hours working on a list of questions and puzzles. When I was done I gave him the papers and he spent ten minutes looking them over and said, “You’re hired.”

Seibel: Was Lisp one of the things you had actually studied in this High School Studies Program?

Steele: A little bit, though it was more Fortran and some other things.

Seibel: Did you have any important mentors when you were starting out?

Steele: At Latin School I’d primarily have to credit the math teachers with encouraging me just the right amount. In the ninth grade Ralph Wellings, who lent me those books over the Thanksgiving weekend, struck a deal with me. He said, “I notice you’ve been getting 100 percent on all your math quizzes.” He said, “I’ll let you spend four math classes a week in the computer room if on the fifth day you take the quiz and get 100 percent. If you ever get less than 100 percent then the deal is over.” So that was incentive. I proceeded to ace quizzes for the rest of the year—I studied math especially hard and that gave me access to the computer. Even better, the next year my math teacher would not offer the same deal, which was appropriate because I did not know the math for that year. So they judged it about right. So I had good teachers that gave me what I needed to learn all kinds of things.

Seibel: And then, as you got more involved in computers, were there particular folks who helped you along the way?

Steele: Well, certainly Bill Martin, who hired me. And Joel Moses, who was in charge of the Macsyma project into which I was hired at MIT.

Seibel: And you ended up working on that project throughout college?

Steele: Yes, I was an employee of MIT all the time I was at Harvard. It was a full-time job in the summers and it became a afternoon job during the school year. I’d do my best to arrange my classes to be in the mornings at Harvard, then I could take the T down to MIT and get in two or three hours of programming before heading home.

Seibel: And that was all working on Macsyma in Lisp?

Steele: Yeah. My specific job was to be the maintainer of the Maclisp interpreter. JonL White had been in charge of both the interpreter and the compiler and he became pretty much the compiler guru, and I took care of the interpreter, and it was a pretty good split. So JonL White was a mentor of mine. All the people on the Macsyma project kind of took me under their wing. I also got to know some of the people in the AI Lab. So by the time I applied to MIT for graduate school it was pretty easy to get accepted because they already knew me and what I was doing.

Seibel: Did you get your undergrad degree in computer science?

Steele: Yeah. I set out to be a pure math major and arranged my courses appropriately and then discovered that I had no intuition whatsoever for infinite dimensional Banach spaces. That’s what did me in. Fortunately, just out of interest, I had taken enough computer courses on the side that I was well-positioned to make the switch in major. To be precise, what I switched to was an applied math major. Computer science was part of applied math, and applied math was part of the engineering department at Harvard.

Seibel: At Harvard what kinds of machines were you dealing with?

Steele: DEC PDP-10s. There was a PDP-10 on campus, but I think that was mostly used for the graduate work. Undergraduates had access to teletype terminals to a commercial system that Harvard was renting or leasing or something.

Seibel: Is there anything you would do differently about how you went about learning to program? Is there anything you wish you had done earlier?

Steele: It’s not as if I set out with a particular goal in mind. I have no regrets about the particular path I took. Looking back I think I was the fortunate beneficiary of a number of interesting coincidences or blessings.

This experience of being, in effect, both at MIT and Harvard at the same time I now realize was a very unusual experience. I could run back and forth and say, “The professor at the other end of the river says this.” And this one will say, “Oh, he’s full of it; here’s the way you should think about it.” That gave me a very broad education, very quickly.

Having access to MIT as a high schooler was another relatively unusual thing. And to be allowed to play with million-dollar computers when I was 15, back when a million dollars was real money. So no, I certainly don’t have any complaints or regrets or wishes that I had done anything differently. I also tend to be a laid-back kind of guy and to take things as they come.

Seibel: What has changed the most in the way you think about programming now, vs. then? Other than learning that bubble sort is not the greatest sorting technique.

Steele: I guess to me the biggest change is that nowadays you can’t possibly know everything that’s going on in the computer. There are things that are absolutely out of your control because it’s impossible to know everything about all the software. Back in the ’70s a computer had only 4,000 words of memory. It was possible to do a core dump and inspect every word to see if it was what you expected. It was reasonable to read the source listings of the operating system and see how that worked. And I did that—I studied the disk routines and the card-reader routines and wrote variants of my own. I felt as if I understood how the entire IBM 1130 worked. Or at least as much as I cared to know. You just can’t do that anymore.

Seibel: Were there books that were important to you when you were learning to program?

Steele: In the ’70s, absolutely: Knuth, The Art of Computer Programming.

Seibel: Did you read those cover-to-cover?

Steele: Pretty close to cover-to-cover, yes. I worked as many exercises as I felt I was capable of tackling. Some called for higher math or other things I didn’t understand, and I’d sort of gloss or skip over those. But the first two volumes and much of the third I read pretty carefully. The Aho, Hopcroft, and Ullman algorithms book—that’s where I learned how to do sorting for real, I think. I’d have to step across to my library to try to remember other ones. I’m a pack rat—I’ve saved all these books. But those are the ones that I would cite off the top of my head. And books about Lisp. The Triple-I Lisp book edited by Berkeley and Bobrow: kind of a scatter-shot collection of papers, but I learned a lot of interesting stuff from that. And then I started reading SIGPLAN Notices and Communications of the ACM. Back in those days CACM had real technical content and was well worth reading.