Robert P. Colwell oral history Oral history of Robert P. Colwell (1954- ) Interviewed by Paul N. Edwards, Assoc. Prof., University of Michigan School of Information, at Colwell’s home near Portland, Oregon, on August 24-25, 2009 Robert P. Colwell is an electrical engineer. His PhD work at CMU (1980-1985) demonstrated the theoretical superiority of CISC architectures over RISC. From 1985-1990 he worked at Multiflow, an innovative developer of “minisupercomputers” using a VLIW (very long instruction word) architecture. In 1990 he joined Intel as a microchip designer, serving as the chief architect of Intel’s IA32 line from 1992-2000. He left Intel in 2001. Colwell recounted his experiences at Intel in his book The Pentium Chronicles: The People, Passion, and Politics Behind Intel's Landmark Chips (WIley-IEEE, 2005). Since retirement, he has been a prolific columnist and a consultant on legal and patent issues. This oral history generally follows the chronology of Colwell’s life and career (see table of contents), with occasional digressions. The interviewer chose to avoid the areas discussed in Colwell’s book, which is semi-autobiographical. Some of Robert P. Colwell’s major achievements: • Senior CPU Architect, Intel Corporation, Hillsboro OR, 1990-1992 • Chief IA-32 Architect, Intel Corporation, Hillsboro OR, 1992-2001 o Lead IA32 architect, responsible for all of Intel's Pentium CPU architecture efforts o Initiated and led Intel's Pentium 4 CPU development o One of three senior architects responsible for conceiving Intel's P6 microarchitecture, the core of the company's Pentium II, Pentium III, Celeron, Xeon, and Centrino families • Intel Fellow - 1997 • 2005 Eckert-Mauchly Award from ACM: for “outstanding achievements in the design and implementation of industry-changing microarchitectures, and for significant contributions to the RISC/CISC architecture debate” • 2006 IEEE Fellow and the National Academy of Engineering for “contributions to turning novel computer architecture concepts into viable, cutting-edge commercial processors” 1 of 164 Robert P. Colwell oral history Interview contents Part 1 (1954-1980): Overview, Early Life, Higher Education, Bell Labs............. 2 Overview............................................................................................................................................................................................. 2 Early life ............................................................................................................................................................................................... 4 Higher education...........................................................................................................................................................................17 Bell Labs ............................................................................................................................................................................................30 Part 2 (1980-1990): Bell Labs continued, CMU (PhD), RISC, Multiflow ......... 43 Bell Labs (continued) ...................................................................................................................................................................43 CMU PhD program — thesis on RISC vs. CISC ..............................................................................................................45 Multiflow...........................................................................................................................................................................................69 Part 3 (1990-2001): Intel ................................................................................... 80 Leading the IA32 design team..................................................................................................................................................84 Part 4 (1990-2001): Intel continued................................................................ 122 Interaction of work and family life in the Intel years .................................................................................................128 Women at Intel............................................................................................................................................................................133 Customer visits and marketing .............................................................................................................................................135 Final year at Intel; Consumer Products Division; parting ways.............................................................................139 Part 5 (2001-2009): Recent activities: writing, consulting, legal work .......... 146 Hobbies: analog synthesizer restoration, woodworking, others...........................................................................146 Legal work: expert witness appearances, patent system..........................................................................................150 Writing: IEEE Computer columns, The Pentium Chronicles, other projects....................................................157 Part 1 (1954-1980): Overview, Early Life, Higher Education, Bell Labs Overview 0:00:01 Paul Edwards: This is Paul Edwards interviewing Bob Colwell... Robert P. Colwell at this home in Oregon on August 24, 2009. And Bob, just to say a few words about your past: among many other honors and achievements, you were an Intel fellow in 1997. In 2005, you received the Eckert-Mauchly award from ACM for outstanding achievements in the design and implementation of industry changing microarchitectures, and for significant contributions to the RISC/CISC architecture debate. And in 2006, you were IEEE fellow, and also a fellow of the National Academy of Engineering for a contributions for turning novel computer architecture concepts into viable cutting edge commercial processors. You were the chief architect of the IA32 processor line at Intel from 1992-2001 and also worked at Intel from 1990-1992. Say a little bit for yourself of what you think of as your major achievements. 2 of 164 Robert P. Colwell oral history 0:01:38 Bob Colwell: Technical achievements because I think there's other things. I would say, I would think, if I had to point one single thing, it'd probably be the P6 microarchitecture that we did at Intel. Because we did that with an eye towards a long term contribution to the company as opposed to “let's do a chip and after that let's do another chip”. You might think there wasn't much like that at Intel because they had this long history of X86 chips, like the 8086 and the 80186, 286, 386, 486 and then, they did the Pentium and you might think, "Oh, that's evidence of a nice long term view of where they're going." That's probably more misleading than correct. It was very much one chip at a time, expecting that each new chip might be the end. It's kind of how those guys viewed it. You mentioned the RISC/CISC debate a few minutes ago. That's related to this because Intel was the canonical CISC place, and they weren't doing heck a lot of research, they were just turning out commercially successful microprocessors. But they were aware of what's happening in the field at Intel back then and they were seeing that one heck of a lot of publications were saying RISC is great and CISC is going to die. And if your product line is heavily CISC based, you have to pay attention to talk like that. So there was a fair amount of consternation in the late 80s bordering on almost panic at times wondering, what's Intel going to do. I joined Intel in '90 and I just kind of walk right into that and listened to these people and sort of frightening themselves to death about what X86 is going to go. How can we not die? The RISC guys are going to kill us and so on. So when we did the original P6, we did that with an eye towards finding a microarchitecture that can serve as a basis for a long time, not just a single chip in 1995 and then we start over. And in doing that, we had to do things for example, like boosting floating point. The computers back then were measured basically on how good are they at integer performance and how good are they at floating point? And X86 was recently good at integer, but it was lousy at floating point, and it was partly because of a legacy decision made in the early 80s. It was pretty twisted up. It made it very hard to do fast floating point in X86, but we purposely chose to boost that, expecting that if we were successful at the microarchitecture then, that balance would come in handy. And if we failed to do that, we would end up with a chip that couldn't go anywhere because it wasn't good enough to sort of hit all the bases that needed to hit. They're still designing chips with big pieces of P6 lore embedded in them, so I think that's pretty cool. 0:04:55 PE: I was struck by this, reading through your papers and your book that the RISC/CISC did they, it carried right through your entire career as one of your first published papers, was about the RISC/CISC debate. I'm wondering if you think that it could be said that you basically settled that issue. 0:05:15 BC: Well, every time I would start to think that, I would run across somebody from the other side who is by no means a convert to my side. So no, there's still plenty of room to, sort of, have different opinions in that general area. A lot of significant work got done, and so anytime, you take an extreme position like the CISC one and RISC lost, it just devalues a