I see on many vendor sites the tern 64EM technology and the terms you use like "supports 64-bit". Given Intel's record on marketing _schemes_, frankly it worries me. Remember the 386sx? It was "32-bit capable". More digging on the subject revealed that it was 32-bit addressing in 16-bit data chunks.

So let's get to my main question. Looking at the Core 2 Duo, the Pentium D, and the Celeron D, are they 64-bit addressing *and* 64-bit data? If so, why not just *say* that?

Once I find out for sure I'm rushing to my favorite vendor to purchase one. But my first PC was a 386sx... so fool me once, shame on me, fool me twice -- and it's AMD. ;)

Yes, reading thru these posts has not answered the question whether Intel Core 2 Duo is a 64 bit processor. I went to Best Buy and Circuit City and all the reps there told me that Intel's Core 2 Duo is a 32 bit processor. They said Intel is coming out w/ a 64 bit processor in scheduled in December. They also said that AMD 64 is a 64 bit processor. Yes, Core 2 Duo will support 64 bit apps but it is NOT a 64 bit processor. I don't know why Intel's reps can't answer a simple question.

Alright I'm getting tired of people getting mad about this when all of the answers are right there above. Let's recap. Both the Athlon x64 and the Core x64 technologies are, by and large, the same. The calls themselves are a bit different, but in reality the bus structure, the support abilities, and the main architecture are close enough that they support the same apps and OS's. Neither is an "x64 bit processor" in the truest sense. The Itanium is an x64 bit processor. It is only an x64 bit processor. It's also outlandishly expensive for the average consumer, because it's not made for the average consumer. In order to have an "x64 bit processor" it would be required that the OS, the apps, the drivers, 100% of the computer, be 64 bit. If that's what you want, you can run XP Pro 64, and I think there is an open office x64 distro as well. But if you want to use any software that isn't x64, about 95% of the software out there, then you're just SOL. So if that's what you want, tell Intel and I'm sure they would be happy to put one out for you. However, if you actually want to use your computer, you'll need x86 support as well, which is 32 bit. Therefor, you have a non-x64 bit proc. To clear up the rest, Pentium D, Celeron D, and Pentium D EE all have EM64T. Core Duo, ie the x4000 series chips, are x86 based, no x64 bit. The Core 2 Duo, x6000 series, ARE 64 bit. The Merom x5000 series is the same as the x4000 desktops, and are 32 bit. While the x2000 series does not support 64 bit, the x5000 and x7000 do. Just to stress it one more time, for all of you who have had the wool pulled over your eyes by AMD, they don't have a "true" x64 processor either. And the reason that Intel can't answer a "simple" question, is that if they did, they would have all kinds of legal issues to deal with. And you have the idiots who like to sue for every little thing to thank for that. Also, in case I missed something here, and you're not sure if a processor supports 64 bit, just go to newegg and look it up. It says right at the top "64 bit support: yes or no."

I'm an architect working on Intel® 64 architecture so let's see if I can clear up a few things.

Markchm, the external data bus has been 64-bits wide since at least the mid 90's, but the external data bus width is not what is meant by a "64-bit processor" or by Intel® 64 architecture. A 64-bit processor is defined as one whose basic, internal arithmetic/logic unit (ALU) is 64-bits wide so it can process 64-bit wide data as a fundamental arithmetic size. Intel® 64 architecture does this and the Merom processor family architecture supports this native instruction width as did earlier Intel® Xeon® and Pentium® processor generations (with Intel® 64 architecture) on the desktop, workstation and server.

I believe another point of confusion here is virtual addressing vs. physical addressing. Virtual addresses are what applications use to refer to memory locations. The OS manages the translation of these virtual addresses into physical addresses (which correspond to the physical memory in the system) and this provides great flexibility in application management. While the Intel® 64 processors can support significantly greater than 4G of RAM, not all platforms will support greater than 4G of RAM.

"Here's what you need to use Windows XP Professional x64 Edition

Important: Windows XP Professional x64 Edition cannot be successfully installed on x86 (32-bit) systems or 64-bit Intel Itanium"“based systems. 32-bit device drivers are not supported on Windows XP Professional x64 Edition.

"¢ Computer with a supported processor: AMD Athlon 64, AMD Opteron, Intel Xeon with Intel EM64T support, Intel Pentium 4 with Intel EM64T support"

from Microsoft Website - why doesn't the only "true" 64bit processor support Win XP 64?

Thank you, Bret from Intel, for putting everything is precise terms. I will now go w/ the Intel Core 2 Duo instead of the AMD x2. I didn't have a preference but just wanted to find the answer. From reviews that I've seen, the C2D seems to do what I need.

Wow this is certainly an interesting debate. As the "demogod" from Softimage (thanks Steve) who has done considerable testing of x64 running on a variety of processors I think I can add a little bit information for you all.

First, the formerly named EM64T processors are, as far as im concerned 64 bit. I dont care if the CPU is a "real" 64 bit part or not, what I care about is that I can install XP 64, drop 8 or 16 gigs of RAM in the machine and actually use it with one app. While at first Intel didnt make a lot of noise about which procs did or did not include EM64T I was pleasantly surprised when I found my P4 (Prescott rev E core) was 64 bit- months after I bought it. So as any good nerd would do I dual booted to Win64 and went "Ok that works, now what" I only had 2 gigs of RAM in the machine so my experiment quickly turned back to using the x32 partition... that is until...

So about a year and a half ago I was invited to go to WinHEC in Seattle and show off Softimage XSI's brand new 64bit native version...and Intel was kind enough to send me a bad-ass 840EE with 8 gigs in it. x64 was installed, XSI 64 bit was installed and holy cow if i didnt suddenly have a 3D scene with 500,000,000 triangles in it occupying over 6 gigs of total RAM footprint. 64 bit had arrived.

Since then every non-mobile Intel CPU has been 64 bit enabled to best of my knowledge. I think the confusion here is really in the notebook line up. But you have to ask yourself, if your notebook can only support 2 or 4 gigs of RAM maximum (chipset and physical limitations) why would you ever need a 64 bit OS? Its highly doubtful that any "killer-app" in the foreseeable future is going to be 64 bit only unless it uses huge amounts of RAM, in which case your notebook wouldnt cut the mustard anyway. I just think running x64 on a notebook isnt practical today for 99.9% of the users out there.

On the workstation side though it is entirely a different story, especially in 3D content creation space (film and games). We routinely hit the RAM barrier both creating the scenes; high poly count, large textures and also during render time when millions of "rays" are firing around the scene ray-tracing. So for our industry 64 bit has been remarkable, and I think Intel has done a great job in educating our market of the advantages. At all the industry events I have been to recently they have done a great job explaining which parts are 64 bit and which are not and why you need or don't need 64 bit. Again, I think all the confusion lies with notebooks.

Microsoft and Intel produced this video with me showing off the differences between Softimage's 64 and 32 bit versions. If you want to see a crazy 3D scene check it out... http://www.microsoft.com/windowsxp/64bit/videos/default.mspx click on the second link for "revolutionizing 3D Animation." You can also check out http://www.softimage.com for more information of the software and its native 64 bit version.

cheers!

I am completely baffled as I cannot figure out if the newest IBM/Lenovo Thinkpad notebooks X60 and T60 using the Core 2 Duo (Merom) will be able to run Vista-64 or not? Will there be some restriction because of the Napa platform/chipset or is there some sort of Napa-64 platform/chipset that enables the Core 2 Duo (Merom) to run in 64-bit so that it can run Vista-64.

There is this business week article which implies that the answer might be no, but perhaps they are not talking about the Napa-64 platform/chipset but using the Napa-32 platform/chipset?

http://www.businessweek.com/technology/content/oct2006/tc20061011_416502.htm?chan=top+news_top+news+index_technology

Because 64-bit has many more registers and especially for double precision float point as used in programs such as Matlab there are some benchmarks that run much faster in 64-bit mode versus 32-bit mode regardless as to the amount of RAM.

There are a lot of questions about this in the Thinkpad forum (http://forum.thinkpads.com)

Incidentally, Novell SLED Linux works on Thinkpads and the reason why I read is because Intel asked IBM/Lenovo to put a Linux on the Thinkpads so for chip designers who use chip design software that runs under Linux.

I was bothered by the Business Week article in a previous post to this forum and wrote the author. This is what he wrote back:

You and Intel are both right. There was an editing error in that item that I missed; it should have said that the 945 chipset prevents Merom from taking full advantage of its 64-bit nature. Specifically, Merom can handle 64-bit instructions and has a 64-bit data path. The 945 chipset, however, can only handle 32-bit addressing, meaning that the Core 2 Duo/945 pairing is still limited to 4 GB of RAM. This will be fixed in Santa Rosa.

Not long ago, I though the 4 GB ceiling didn't mean much on anything but servers but I underestimated the memory appetite of apps, especially for image and sound processing. Apple is currently selling 3 GB Macbook Pros and will surely go above 4 GB max when Santa Rosa is available.

Steve Wildstrom Technology & You columnist
BusinessWeek
1200 G St NW
Suite 1100
Washington, DC 20005
http://www.businessweek.com/technology/wildstrom.htm

I'm recompiling a xen kernel right now and did a bunch of hardware probing on a D820 Latitude with a Cuor 2 Duo T72000. It reported a 36 bit address register with 48 bits of virtual address. The "system" consume over half a gig when you go to 4 gigs of ram. My guess is it is using the Ram for the EMT64 addressing space (Yes 36+ 48 = 84 not 64 but they probably have error checking bits in there. They can run 64 bit OS's but they are Virtual 64 bit processors.