Not long ago, dual-core processors were considered cutting-edge and were found mainly in servers and high-end workstations. Today, dual-core CPUs are the new minimum for most midrange PCs and laptops, quad-core chips are standard in many new Apple MacBooks, and Apple's desktops can be had with as many as 12 processor cores.
Heck, virtually all new smartphones now come with two cores, and some even have four. What's more, Google and Microsoft in their forthcoming tablets set the bar at four application cores plus as many as 12 more for graphics processing. By comparison, Apple's latest iPad 3 had "just" two application cores and another four for graphics. More on what's inside Google's Nexus 7 and Microsoft's Surface for Windows RT later.
Multicore processors and multiprocessor systems are now as commonplace as smartphones themselves. But how did this happen? Why did processor makers depart from the ever-increasing clock speeds through the 1990s and move toward multicore designs instead? The answers may surprise you.
As chip designers scurried to stay ahead of Moore's Law, which prescribes that computer-processor transistor count doubles every two years, the complexities of doing so became apparent. In the days of the Pentium, Intel and its competitors continued to improve processor performance by adding transistors and logic to their CPUs and increasing clock frequencies.
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For a while, the strategy worked, and the International Technology Roadmap for Semiconductors (ITRS) and other organizations that track the semiconductor industry predicted that clock rates would reach 12GHz by 2013.
But by around 2002, according to "The Manycore Revolution: Will HPC Lead or Follow?" a research report conducted by the SciDAC Review, the performance curve began to flatten -- and chip makers were hitting a power wall. Indeed, in 2004 when Intel canceled Tejas, the high-speed processor that was to be the successor to Pentium 4, President and then-COO Paul Otelinni cited power concerns. "You just can't ship desktop processors at 150 W," he said at the time. Soon after, Intel, AMD and others all had multicore processor strategies.
NEXT: Striving For Parallelism