Dual core processors have been the subject of so much hype that perceptions about the technology seem to have trumped some of the realities.

Both AMD and Intel have posted Web pages in which they extol the virtues of their respective dual-core devices. That makes timely sense, since most industry watchers agree that 2006 is the year dual-core will become ascendant.

However, hidden in the such venues, and among numerous news stories on the subject, are some surprising and uncommon facts. Accordingly, we bring you five things you probably didn't know about dual core.

Intel and AMD weren't the first to ship dual-core processors.

The widespread assumption is that the dual-core duel has been fought solely on the PC front, with AMD and Intel vying for the title of first to market. That's incorrect. In fact, IBM beat both companies to the multicore punch, albeit with a non-X86, server processor. That occurred when Big Blue rolled out its dual-core Power 4 chip in 2001, for use in IBM's RISC servers, in 2001.

AMD and Intel announced their respective dual core plans in 2004 and began their first dual-core shipments in 2005. (Here for AMD, and here for Intel.)

However, there's such a dizzying array of dual-core parts -- including dual-core Opteron server and Athlon 64 desktop chips from AMD and dual-core Pentiums and Xeons from Intel -- that it's hard to keep up with the ongoing blizzard of announcements from both companies.

On the mobile front, IBM is also technically winner of the race to market, with low-power versions of its PowerPC 970FX, unveiled in 2005. However, this is pretty much an OEM product that's not available to the average buyer. Nor is it an x86 part.

In the x86 world, Intel won the mobile dual-core race, with its Centrino Duo, announced in January. The mobile device powers the popular new iMac, notwithstanding the fact that the iMac is a desktop. (Internally, it's designed something like a large notebook computer stuffed into the back of a flat-panel display, as this internal teardown shows.) The new iMac is also the first Apple computer to use an Intel processor.