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Win9X, SMP unfriendly

The way a multi CPU system works cannot be so easily cracked down. The work of controlling all the CPU's functions is done in hardware, but it has to be administered by the operating system. As I said, you can indeed load and run Win9X on a dual processor system, but since Win9X is not made to run both CPUs, the O/S will only use the primary processor. Win9X is a user operating system. It was never designed for, nor meant to be a high Power Dual CPU operating system. That's what Windows NT is all about!

Even though the operating system handles the SMP activity, you will see the most benefits of having a multiprocessor system by using applications such as Photoshop or Quake III that are designed for SMP. If you use an SMP capable O/S, the load usually isn't evenly balanced between the two processors. In other words, it's not really as simple as one CPU works on Quake III while the other does Photoshop.

You can think of the two processors in a dual system sort of the way a master and slave hard drive relationship works. The master drive is the one that contains your operating system software, and is where (usually, unless you changed it) the swap file goes. So the master drive is going to be doing a majority of the work while you are using your system. The second drive is going to mainly sit there and wait until you ask it to do something.

Dual CPU's work more or less the same way. The primary CPU will be handling most of the work, and when there is more than it can handle, the operating system should automatically take threads and send them to the second CPU to help out with. Even if this only were to happen to a minor extent, your second CPU would be working on processes that would otherwise still be waiting in line for attention from the first CPU. In that respect, it would make a notable performance improvement.

When using an SMP capable O/S, the multi-CPU threads are handled by the operating system using some ancient cryptic science called the HAL (Hardware Abstraction Layer) that automatically assigns tasks to the processors accordingly. Don't be surprised when the primary CPU is much more active than the secondary -that is normal. As for gaming, QIII is the only game I am so far aware of that will support Dualies, but again, if the O/S you are running can't do it, then neither can your application. (If you want more information on SMP, just go to Intel's site and search for it, but be warned: what you find there is NOT for the faint of heart ;)