Multi-core processors

Have you ever been in the middle of a tedious chore and thought it might be easier if there were two of you to share the work? Believe it or not, this kind of thinking has led to continued improvements in computer performance!

A commercial Quad-Core AMD Opteron processor. Note the four identical processing units situated adjacently on a single chip. Image Credit: Advanced Micro Devices, Inc. (AMD).

A computer’s central processing unit (CPU) is very much like its brain. The CPU performs the fundamental steps required to run a computer program, such as basic mathematics and logic operations, through very tiny electronics components called transistors. Electronics specialists keep finding ways to build smaller, higher-frequency transistors, so that every new model of CPU can hold even more "brain" power!

In fact, since the mid-1960’s, the number of transistors that can fit on a chip has doubled approximately every two years, a trend referred to as "Moore’s law." Unfortunately, while in theory more, higher-frequency transistors mean faster calculations, too many can cause the CPU to generate a great deal of heat, which counteracts at least some of the improvements.

Instead of using more transistors to create more complicated CPUs that operate at high frequencies and produce a lot of heat, why not combine several simpler processing units to perform the task in less time? This is quite like getting some friends to help you with a chore instead of rushing to get it done alone. Computer designers first tried this by connecting multiple processors to each other. However, it can take a longer time for signals to travel between separated CPUs than it does to travel within a single, small unit, which can limit the improvements. It wasn’t until the mid-nineties when one research group put several processing units on the same tiny piece of silicon, and the multi-core processor was born. Over the next decade or so, the idea caught on! Today, multi-core processors are used to make computers, from smartphones to servers, more responsive and powerful with decreased heat generation.