Dual cores mystery no longer

Two heads are better than one. That’s what people say. In the geek world, however, two cores are better than one.

New computers these days have processors with multiple cores. That means that the processor chip contains two or more brains available to do work independently of each other.

In 2004, Intel introduced the Pentium D processor, the first multi-core processor for the consumer. That replaced the single-core Pentium 4. The Pentium D introduced two cores (or two processors) in a one-chip package.

Since then, Intel has added the Core brand lineup of processors. It started with the Core Duo, only to give way to a second-generation chip called the Core 2 duo. If you buy a computer today, in 2007, chances are that it will have a Core 2 Duo processor onboard. Like the Pentium D, it has two brains onboard, but it runs more efficiently and uses less power. (Geek trivia: It was actually based on the mobile processor called the Pentium M found on laptops.)

The next generation of multi-core processor is the Core 2 Quad. Quad means four. So it has four cores.

What’s handy about multiple core processors is that each brain can take on a separate task. A traditional single-core processor like the Pentium 4 can juggle multiple tasks but it uses something called “time slicing” to achieve more than one task. If you “time sliced” soup preparation, you’d cut some carrots, then stop. Then cut some onions, then stop. Then put them in a pot. Then stop.

On a multi-core processor each core handles separate tasks. So while one is cutting the carrots, the other is cutting the onions. There are two knives and two dedicated cooks working together to make the broth.

Since these two cores run independently of one another, there’s no lag. So you can watch a movie with one core and check your e-mail with another core and they don’t interrupt each other. In a quad-core environment you have four cores to do the work.

Now there is one more wrinkle to all of this. You maybe have seen the moniker “Extreme” in a Core 2 Duo logo. Extreme is Intel’s way of saying the chip has some extra oomph.

Each core in an Extreme processor runs as two virtual cores. What does it mean? It means that when a processor works at a task, not all of it is in use. So a core can be optimized to harness the unused portion of the chip as a second processor. One core works as two virtual cores (or two virtual brains). In a Core 2 Duo Extreme processor, there are two cores, each one working as two virtual cores. You get the effect of four brains. This isn’t as efficient as four actual cores, but it can certainly add more computing power to your system.

In our soup preparation analogy, there are two cooks, each working with two hands. It’s not as efficient as four separate cooks, but it sure gets the soup made faster.

Modern operating systems are able to harness multiple core processors and in the case of Windows XP Professional or Windows Vista, you can assign specific programs to use a specific processor or core.

So now that you understand multiple cores, here’s how to tweak them:

• Open the program so it is running.
• Right-click an empty spot on the taskbar (the bar across the bottom of your Windows screen) or press CTRL+ATL+DEL.
• Choose Task Manager.
• Click the Processes tab.
• In the left column, find the process you want to assign (for example, WinWord.exe for the Word program).
• Right-click it and choose Set Affinity.
• By default, both cores will be checked. Check only the core (CPU) you want the process to run on (CPU0 or CPU1).
• Click Ok. This can be useful if you want to keep one processor free for use by a particular program, or if you’re running older applications that don’t work as well with multiple processors.

A handy application of this tip would be to dedicate one core to play a DVD without stutter while the other core was assigned to a memory-intensive application such as photo editing or video rendering.