A Brief History of Intel CPUs, Part 2: Pentium II Through Comet Lake
In Part 1 of this guide, we discussed the various Intel CPUs from the beginning of the company through to the Pentium Pro. Before we dive into the other CPUs in Intel’s overall history, in celebrating the 40th anniversary of the 8086, let’s take a moment to further discuss the Pentium Pro. In a very real sense, the PPro is the core that revolutionized the x86 architecture and Intel’s microprocessor design and can be thought of as the “father” from which modern CPUs are descended (the original 8086 itself, in this context, is more of a grandfather).
The Pentium Pro was, in many ways, a true watershed of CPU design. Up until its debut, CPUs executed programs in the order in which program instructions were received. This meant that performance optimizations heavily relied on the expertise of the programmer in question. Instruction caches and the use of pipelines improved performance in-hardware, but neither of these technologies changed the order in which instructions were executed. Not only did the Pentium Pro implement out-of-order execution to improve performance by allowing the CPU to re-order instructions for optimal execution, it also began the now-standard process of decoding x86 instructions into RISC-like micro-ops for more efficient execution. While Intel didn’t invent either capability out of whole cloth, it took a substantial risk when it built the Pentium Pro around them. Needless to say, that risk paid off.
The Pentium Pro’s P6 microarchitecture would be used for the Pentium II and III (all forms) before being replaced by the Pentium 4 “Netburst” — at least for a little while. It resurfaced with the Pentium M (Intel’s mobile CPU family) and Core 2 Duo family. Modern Intel CPUs are still considered to have descended from the Pentium Pro, despite the numerous architectural revisions between then and now. The original Pentium Pro, however, didn’t perform particularly well with 16-bit legacy code and was therefore mostly restricted to Intel’s workstation and server product families. The Pentium II was intended to change that — so let’s pick up our history from there.
To trace the history of Intel CPU cores is to trace the history of various epochs in the evolution of CPU performance. In the 1980s and 1990s, clock speed improvements and architectural enhancements went hand in hand. From 2005 forward, it was the era of multi-core chips and higher efficiency parts. Since 2011, Intel has focused on improving the performance of its low power CPUs more than other capabilities. This focus has paid real dividends — laptops today have far better battery life and overall performance than they did a decade ago.
Compare the Core i7-10810U with the Core i7-2677M to see what we mean. The Sandy Bridge-era CPU had a maximum clock of 2.9GHz, supported just 8GB of RAM (not shown), and offered one-third the cores and L3 cache of the modern Coffee Lake SKU. Overall mobile performance per watt has improved dramatically. At the same time, Intel faces real challenges, both from AMD and ARM. We’ve compared against the Core i7-10810U rather than the Ice Lake-based Core i7-1065G7, because the 10nm ICL CPUs are balanced differently between CPU and GPU, and they make the straight-line CPU improvements harder to see.
But regardless of what the future holds, Intel CPUs have driven consistent performance improvements over the past four decades, revolutionizing the personal computer in the process. We hope you’ve enjoyed the trip down memory lane.
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