Despite the x86 (CISC) architecture's long reign in PCs, the proliferation of ARM-based (RISC) chips in mobile and other devices means RISC architectures now account for 99% of all processors, effectively winning the historic debate.
To compete with the speed of RISC architectures, Intel's CISC-based x86 processors adopted a hybrid approach. They internally translate complex x86 instructions into simpler, RISC-like instructions for execution, gaining performance benefits while maintaining crucial backward compatibility.
While Moore's Law continued adding transistors, the failure of Dennard scaling around 2005 meant they no longer became more power-efficient. This created a "power wall," making single cores too hot and forcing the industry to use multiple, simpler cores to continue performance gains.
The viability of RISC architecture hinged on compilers becoming sophisticated enough to efficiently manage low-level instructions and register allocation. This software co-evolution was critical to bridging the gap between high-level programming languages and the simpler hardware.
The first TPU's breakthrough performance came from radical design choices. It eliminated hardware caches, which are less useful for predictable AI memory access, and introduced bfloat16, a floating-point format prioritizing range (exponent) over precision (fraction), perfectly suited for neural networks.
The difficulty of competing with NVIDIA isn't just the CUDA language. A larger barrier is their massive investment in specialized software libraries. NVIDIA's army of engineers constantly optimizes these for new hardware and applications, creating a performance moat that startups struggle to cross.
As performance gains from general-purpose CPUs stalled, the industry shifted to domain-specific architectures (DSAs). By designing hardware like GPUs and TPUs for narrow tasks like AI, architects can achieve dramatic performance improvements that are no longer possible with traditional CPUs.
To build a meaningful career, concentrate your efforts on finishing a few important projects rather than starting many. As Stanford President John Hennessy noted, you will ultimately be remembered for only five or six key accomplishments. This intense focus is essential for achieving significant impact.
David Patterson advises making life decisions that optimize for happiness, not wealth, noting they are two distinct goals. He observes that in a field like technology, a happy and fulfilling career often leads to financial success, whereas chasing wealth alone does not guarantee happiness.