Jim Keller and his pioneering work on chip design and architecture

Who is Jim Keller? AMD’s former CTO Fred Weber famously called him the Forrest Gump of the chip industry, according to the Fortune story “Why Intel is betting its chips on microprocessor mastermind Jim Keller.” From x86 to PowerPC and MIPS to Arm, Keller has got his hands clean at almost every chip architecture and is genuinely a chip design superstar.

Keller is in the news for being appointed CTO of Tenstorrent, a fabless AI chip design and software company. While that’s making waves in the trade media for Keller’s rich track record in chip design for heavyweights like AMD, Apple, and Intel, it’s worth looking at his pioneering work in chip architectures spanning across three decades.

Design simplification is at the heart of the chip architectures created by veteran CPU developer Jim Keller. Source: Intel

Keller’s storied career as a CPU design guru began in 1984 when he joined Digital Equipment Corp. (DEC), the mini-computer pioneer and a tech titan of its era. He was part of the engineering team that designed DEC’s ultra-fast Alpha chip targeted at workstations that were one step higher to PCs in the IT food chain. Alpha—released in 1992—ran at 500 MHz with a memory cache that hit 1 GHz, a speed unheard at that time.

However, DEC was building the fastest computers and going out of business at the same time. Its mini-computers were becoming obsolete while PCs and servers got faster and more powerful at a much lower cost. So, in 1998, when the Alpha architecture was sold to PC maker Compaq along with most parts of DEC, Keller joined AMD, the x86 chipmaker establishing itself as a second source to Intel.

Keller had seen how Alpha chips faced extinction from Intel’s Pentium Pro processors, which unlike their predecessors that ran highly complex instruction sets, quickly translated instruction sets to simpler chunks. Keller’s other observation regarding x86 chips: bottlenecks between a processor and other computing parts like memory. That became the hallmark of his subsequent work at AMD.

The birth of system-on-chip

The system-on-chip (SoC) design movement has many pioneers, and Keller is one of them. He came to AMD with the idea of integrating the processor with separate units such as memory and data transfer. AMD put to use such ideas to the K8 chips that eventually disrupted the market leadership of Intel’s 64-bit Itanium chips and provided AMD with a foothold in the highly profitable server market.

Here, it’s worth mentioning that AMD’s flamboyant chief Jerry Sanders was against entering the server market due to a lack of resources to support the server design ecosystem. However, Keller’s simplified approach to chip design overcame much of these hurdles, and subsequently, AMD launched the K8 chips with the official name of Opteron in 2003. Keller also co-authored the HyperTransport specification for the interconnection of server processors.

Keller, however, had left AMD in 1999 when K8 chips were still in the earlier phase of development, this time to join a chip startup co-founded by his comrade from the Alpha chip design, Dan Dobberpuhl. SiByte was developing MIPS-based network processors, and Keller joined this little-known upstart founded by former DEC engineers as chief architect.

Advent of dual-core designs

At SiByte, Keller pioneered the idea of dual-core designs, which placed two processors side by side on the same piece of silicon. A year later, in 2000, Broadcom acquired SiByte for $2 billion in stock and began shipping the dual-core chips in routers to move around huge amounts of data. Eventually, later in the decade, dual-core processors would find their way into PCs.

Then, in 2004, Keller leaped to another Dobberpuhl startup, P.A. Semi, which focused on PowerPC-based chips for high-end PCs and servers. However, he moved to Apple to work on Arm-based chips that Samsung designed for iPhones two years before Apple acquired P.A. Semi to design its own chips for iPhones and iPads.

Apple’s purchase of P.A. Semi in 2008 saved the company billions of dollars while Keller sharpened the iPhone chips for smoother graphics and faster speech and image processing. He once called his work at Apple akin to intense engineering and liked working with Apple’s feisty chief Steve Jobs.

Next, in 2012, Keller was ready to put his new insights to work at his old employer AMD as chief cores architect. AMD was lagging far behind Intel at that time while its advancements in PC processor design were slowing down. He laid the groundwork for AMD’s turnaround with the design of Zen micro-architecture.

Again, by the time Ryzen chips—drawn from Keller’s design work—were launched in 2017 and started gaining share from Intel, he had already moved on, this time to electric vehicle maker Tesla.

Chip for self-driving cars

The next twist in Keller’s remarkable career as a chip architect came in 2015 after a meeting with Tesla’s Elon Musk. Tesla had been using chips from Mobileye, now part of Intel, and Nvidia for its driver-assistance system called Autopilot, and the carmaker wasn’t happy.

Keller was able to convince Musk that Tesla should design its own chip, and in return, Musk reportedly persuaded Keller that he was the right man to spearhead this ambitious task. Keller simplified the chip design as per Tesla’s software, and within two years, the in-house chip was ready to be incorporated into Tesla’s Series 3 and other models to be launched in 2019.

Meanwhile, Keller was ready for his next challenge at Intel, now desperately looking for engineering help after multiple strategic missteps like missing the mobile and table sockets at Apple. In April 2018, the rock star chip designer joined Intel as VP of the Silicon Engineering Group, but then abruptly left the Santa Clara-based chip behemoth in June 2020.

Now the chip design legend has joined a fabless AI chipmaker that is part of the score of AI upstarts focused on training and inference applications. Will he be able to make a difference this time around? His profile in pioneering work and celebrated track record is definitely good news for Tenstorrent.

Majeed Ahmad, Editor-in-Chief of EDN, has covered the electronics design industry for more than two decades.

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