The current form factor of the Athlon 64 processor is very conducive to a dual core design. The fact that the memory controller and hypertransport links are built right into the die of the chip means that supporting a second full processor core is no huge logistical feat either for making the die of the chip or the motherboards it will operate in. This is not the biggest advantage that the Athlon 64 architecture has for dual operation though.

Due to the Northbridge-like provisions that AMD had to add to the Athlon 64 die in order to support the onboard memory controller and hypertransport link, it is possible for the dual cores to communicate with each other inside the processor itself.

While this might seem like an obvious thing, Intel dual-core processors cannot do this at all (currently). Intel's solution must relay all information over the external 'frontside bus' link that connects the processor to the rest of the system.

AMD dual-core Athlon64 X2 processorss more than double the transistor count of previous Athlon 64 processors. The Athlon 64 X2 4800+ chip sports 233million transistors as opposed to the 106 million or so of the Athlon 64 FX-55.

Since the new dual-core chips use the 90nm fabrication method though, overall chip size has just barely increased. Operating voltage will be 1.35 to 1.4V and heat output will be just slightly increased over the high-end Athlon FX processors at 110W.

Each processor core has its own L1 and L2 cache memory, 128KB for L1, and between 512KB and 1MB of L2, depending on the specific model.

On paper, it really appears that AMD has done its homework. More than that, its engineers appear to have done it months ago when the company first introduced the 64-bit Opteron processor.

The "crossbar switch" that accumulates and distributes address and data transfers from each core to the other core and the rest of the system already had an available connection for a second core.

Where AMD scores major points for paying attention to its user base is with the fact that the first run of dual-core Athlon 64 X2 chips will be compatible with any current Socket 939/940 motherboard, provided the manufacturer updates the BIOS to support the new feature.

Given the havoc that the company wreaked on its users and its bottom line by shifting to Socket 939 so early in the life of the Athlon 64, essentially orphaning Socket 754, this is the kind of good PR that AMD really needs. Here's hoping this is a return to the glory days of Socket A and the huge range of processors that that platform ended up supporting. Selling a dual-core desktop processor as a direct upgrade will be a lot easier than trying to persuade home users to update their motherboards... yet again.