Originally Posted by publius

Yes, dual core is two processors, that's what it means, two CPU cores on one chip that plugs in one socket. Those two cores do share some minor things.

What I was talking about was a *hyperthreading* CPU, something Intel did a while back. Here a single CPU core splits itself into two logical processors. It is conceptually the same thing as time-slicing and regular threading, where the OS just time slices pieces of code in a queue, except here the hardware does it itself by processing two instruction streams at once (AMD always poo-pooed this, IIRC)

There is a big difference between those two, and that's what I was commenting about. Dual core is two physical pieces of instruction stream processing hardware.

My other comment was about the *licensing*. NT Workstation/Win2K/XP/Vista was limited to "two processors". The SMP kernel can theoretically go to 32, but for licensing reasons, they put limits. Now, with hyperthreading and dual core, that seemed unfair.

So they relented and said that, for purposes of licensing, one processor is one socket. The licensing refers to the number of sockets that will be supported. How many cores and hyperthreaders per socket will not matter.

So XP, running on a board with two sockets, each of which contains a Quad-core Intel chip with each core hyperthreading, will see that as 16 logical CPUs total. That is 8 physical cores, each splitting into two logical CPUs, for a total of 16.

-Richard