#256009 - 11/05/2005 18:46
Dual core
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carpal tunnel
Registered: 08/03/2000
Posts: 12338
Loc: Sterling, VA
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Could someone explain dual core what it means for processors today? I'm sure the concept is pretty simple (it's like...two cores...instead of one...), but I want to state what I understand about it, and see how far off I am. (also, where do you guys usually go to read about PC hardware technology?)
Basically, from the little I've heard, later this year AMD will release four dual core processors (the Athlon X2 line). They will be around the speed of their current single core counterparts, or a little slower, but with two cores does that mean that basically they're twice as fast? Or is that not technically true? That's where I wonder what the technology means.
As for the computer that I hope to build within a few months, here's what I'm thinking it means for me. In the past, it wasn't really feasible to get in on a new CPU technology at the very low end, then upgrade to the high end a couple years later. The performance increase wouldn't make it financially smart. But now, the X2 line will work in socket 939 motherboards (w/BIOS upgrade). That means there will probably be a huge difference in the 3000+ and, say, the 4800+, a difference that would make a future upgrade when the price comes down.
So, please correct my horrible misconceptions 
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Matt
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#256010 - 11/05/2005 19:01
Re: Dual core
[Re: Dignan]
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pooh-bah
Registered: 13/09/1999
Posts: 2401
Loc: Croatia
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As far as I understand, dual core means two more or less complete processors (perhaps sharing some levels of cache) on the same piece of silicon. Each of them can possibly have multiple hardare threads ('hyperthreading') capability, that is, capability to simultaneously process more than one independent instruction stream. So, your machine will benefit from a dual-core processor the same way it would from two single-core ones (except that cache-coherency processing might be a tad faster when the procesors share the die). A particular CPU-intensive single-threaded task will not run any faster, but anything more parallel than that (e.g. the whole managerie of 'system' tasks) will. Now perhaps someone actually having a clue about this could take over 
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Dragi "Bonzi" Raos
Q#5196
MkII #080000376, 18GB green
MkIIa #040103247, 60GB blue
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#256011 - 11/05/2005 19:14
Re: Dual core
[Re: Dignan]
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carpal tunnel
Registered: 25/12/2000
Posts: 16706
Loc: Raleigh, NC US
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As always, I suggest falling back to Wikipedia's entry on it.
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Bitt Faulk
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#256013 - 11/05/2005 19:31
Re: Dual core
[Re: Attack]
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carpal tunnel
Registered: 08/03/2000
Posts: 12338
Loc: Sterling, VA
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Thanks for the links. I prefer the Lian-Li V1000 to the V1100. I've never liked doors on cases.
Good idea, Bitt. I should have thought of that, as Wikipedia is becoming a great source of info these days.
Thanks as well, Bonzi. That echoes what I've been gleaming from the information I've read, so I don't think you're far off.
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Matt
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#256014 - 12/05/2005 13:17
Re: Dual core
[Re: Attack]
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carpal tunnel
Registered: 08/03/2000
Posts: 12338
Loc: Sterling, VA
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Again, thanks for the links. I think this review (that I found following one of those links) is an excellent review of the AMD CPU. Looks like it came out on top in their tests I'm drooling already. Given that it's going to come out at $1000, I think I might try that plan I mentioned. It might just be worth it now to get a 3000+ for the fairly low price of about $130, then upgrade significantly to the 4800+ when the price comes down a little. Hell, I'd probably still be able to get about $50 for a used 3000+ at that point. Anyway, I'll have a bit to think about while I wait for the funds to build up
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Matt
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#256015 - 12/05/2005 18:17
Re: Dual core
[Re: Dignan]
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carpal tunnel
Registered: 08/06/1999
Posts: 7868
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Looks like things have been mostly answered thus far. Dual core is very similar to hhaving dual processors.
The big advantage companies are seeing though is they can nearly double the processing power per inch in their racks. For example, the Proliant DL585 server takes 4 AMD processors. Putting dual core chips into it results in pretty much an 8 processor box, but with the price being slightly higher then the non dual core version, instead of much higher going to 8 real processors.
Consumers aren't going to see a ton of advantage until more programs switch to multithreading. It's very much a chicken and egg situation, but with the hardware coming out now, the programmers will finally see reasons to do it. For now, clock speed has hit a brick wall for the most part, so dual core makes a lot of sense.
I'm just waiting/hoping for a dual core Powerbook. OS X is very capable of taking advantage of dual processors, so it would give a noticible speed boost to a laptop line that hasn't seen equal growth to the x86 world in the past two years.
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#256016 - 12/05/2005 18:36
Re: Dual core
[Re: drakino]
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carpal tunnel
Registered: 08/03/2000
Posts: 12338
Loc: Sterling, VA
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Well, hardware has been ahead of software lately. 64 bit has been out for a while now, and the software hasn' t caught up to that yet. I've been reading that general multi-tasking of single-threaded programs is also improved on dual core processors. Basically, it's faster. Heck, it's the fastest. It's the best. It must be mine! (heh, like I've got a grand to drop on a tiny piece of silicon)
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Matt
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#256017 - 12/05/2005 18:38
Re: Dual core
[Re: Dignan]
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carpal tunnel
Registered: 24/12/2001
Posts: 5528
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The average home user out there doesn't actually need 64 bit processors yet which is why it's not really majorly taking off at the moment. In the server market however, stuff has been 64 bit for years now.
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#256018 - 12/05/2005 19:15
Re: Dual core
[Re: tman]
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carpal tunnel
Registered: 08/03/2000
Posts: 12338
Loc: Sterling, VA
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Yeah, that's what I said. The hardware is ahead of the software. It's most likely going to all be 64 bit in the future, right? So if that's the trend, then you might as well start in that direction.
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Matt
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#256019 - 12/05/2005 19:20
Re: Dual core
[Re: Attack]
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carpal tunnel
Registered: 08/03/2000
Posts: 12338
Loc: Sterling, VA
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Quote:
If I wasn't on a budget I would get this and this power supply
Okay, I was definitely going for the Lian-Li V1000, but it has casters on it and this computer is for my father. He's going to have his machine on a rolling computer tray that matches his desk, so having a rolling computer on top of a rolling tray would not be good.
Can someone recommend an attractive case? I've been looking around all day, and have been astonished by the complete lack of design sense that most manufacturers seem to have. Apparently all the kids these days are covering their PC cases with melted down Voltrons. So I'd like an attractive mid-tower with noise levels close to a standard Dell. Not silent, but quiet. It's only going to have one hard disk.
Thanks folks. My father thanks you too.
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Matt
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#256020 - 12/05/2005 19:44
Re: Dual core
[Re: Dignan]
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addict
Registered: 01/03/2002
Posts: 599
Loc: Florida
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I have this at work and home (about 10 of them in all). As for the sound you will need to buy 4 these and these to replace the fans that come with the case. As for the CPU a Zalman in Silent Mode is great.
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#256021 - 12/05/2005 21:00
Re: Dual core
[Re: Dignan]
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carpal tunnel
Registered: 24/12/2001
Posts: 5528
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Quote:
Yeah, that's what I said.
Yup.
Unless you've got a real need for it or you just want a flashy new chip then it's better value for money to just stay 32 bit at the moment. Whatever you buy now won't be upgradable to the next version anyway. Anybody remember back when all PCs were advertised as future proof with some special daughterboard which never actually gets produced?
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#256022 - 12/05/2005 22:43
Re: Dual core
[Re: tman]
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carpal tunnel
Registered: 08/03/2000
Posts: 12338
Loc: Sterling, VA
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Quote:
Whatever you buy now won't be upgradable to the next version anyway.
And what I was saying is that if, when the 939 chips first came out, you had bought a 3000+, for probably the first time you would be able to upgrade in about a year to the 4800+ (without replacing the motherboard) and see a significant advantage. I think that's cool.
Have you looked at the prices recently? The Barton 3000+ is on Newegg for $120. Or you could buy the 64 bit processor which will have other advantages, for another $25. You also get the advantage of more recent motherboards.
If you were building a new system now, you would really go 32 bit?
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Matt
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#256023 - 12/05/2005 23:15
Re: Dual core
[Re: Dignan]
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carpal tunnel
Registered: 08/07/1999
Posts: 5546
Loc: Ajijic, Mexico
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If you were building a new system now, you would really go 32 bit?
Yes, if for no other reason than none of the current games (or few of them, anyway) will run on a 64 bit processor.
tanstaafl.
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"There Ain't No Such Thing As A Free Lunch"
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#256024 - 12/05/2005 23:34
Re: Dual core
[Re: tanstaafl.]
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carpal tunnel
Registered: 08/03/2000
Posts: 12338
Loc: Sterling, VA
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Quote:
If you were building a new system now, you would really go 32 bit?
Yes, if for no other reason than none of the current games (or few of them, anyway) will run on a 64 bit processor.
Odd, I hadn't run into that yet. I wonder why that hasn't been coming up.
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Matt
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#256025 - 13/05/2005 00:48
Re: Dual core
[Re: tanstaafl.]
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addict
Registered: 01/03/2002
Posts: 599
Loc: Florida
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Quote:
If you were building a new system now, you would really go 32 bit?
Yes, if for no other reason than none of the current games (or few of them, anyway) will run on a 64 bit processor.
tanstaafl.
The Athlon 64's still run 32bit games and programs FAST AS F***. Just look at how fast WinRar is on all the Athlon 64's. I WinRar about 100 GBs of data every week and then burn to DVD (I get everything compressed to about 20 - 24 GBs).
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#256026 - 13/05/2005 02:13
Re: Dual core
[Re: Attack]
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pooh-bah
Registered: 19/09/2002
Posts: 2494
Loc: East Coast, USA
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Quote:
The Athlon 64's still run 32bit games and programs FAST AS
Thank you! I'm glad someone mentioned trusty Athlon 64. No need to "go 32 bit" when Athlon 64 gives you both 32 bit and 64 bit, at a good price, too. When home user software finally catches up to 64bit, you'll be ready. Which leads me to:
Quote:
Well, hardware has been ahead of software lately
Hasn't hardware always been ahead of software? Sure, Microsoft wants you to think your computer isn't fast enough for XP 2003 ServicePack 9. I'm willing to bet the highly advanced optimization hardware in my processor is gathering dust from underuse thanks to overstructured code. Hm, when will they release Seti@Home 64? (Super Mario 64?)
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Can someone recommend an attractive case?
Ah, attractive cases are for kids who bring them to LAN parties. What your dad (and you, and everyone else) needs is a trusty SuperPower Polaris II, Landmark, Concord, Triumph, or like my PC case, Zephyr. These are the best constructed cases in a decent price range that I've ever seen; and I've seen many. So sturdy, so simple, so hard to cut yourself on them, so easy to quickly work inside them, etc. Unfortunately, they are impossible to find for sale anywhere. My last sighting of them was at Axion Technology. (wait, $20 for the mid tower?? nice.) Just be sure to swap out their crappy power supply, or simply replace the 80mm power supply fan, immediately. I've never seen such a high failure rate in PSU fans as the ones bundled with my many (10?) SuperPower cases.
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#256027 - 13/05/2005 12:27
Re: Dual core
[Re: tman]
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carpal tunnel
Registered: 25/12/2000
Posts: 16706
Loc: Raleigh, NC US
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Okay, here's another question. Here in Solaris world, all 64-bit really gets you is a larger memory addressing space. We've been 64-bit at the OS for a long time, but the OS can run 32-bit and 64-bit applications. All the 64-bit applications buy you is a larger memory addressing space, at the expense of slightly slower runtime. (After all, now it constantly has to deal with 64-bit numbers instead of 32-bit.) As such, virtually all applications are still 32-bit, except for the ones that really need to address more than 4GB of memory. In many cases, they provide both.
Anyway, what does 64-bit buy you on the Windows side? There have been Wintel computers for quite some time that have been able to address more than 4GB of system memory (I assume there's some sort of paging algorithm being used), so I'm not sure what 64-bit gets you.
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Bitt Faulk
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#256028 - 13/05/2005 13:14
Re: Dual core
[Re: wfaulk]
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carpal tunnel
Registered: 18/01/2000
Posts: 5683
Loc: London, UK
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Quote:
Anyway, what does 64-bit buy you on the Windows side?
It gets you increased address space.
Quote:
(I assume there's some sort of paging algorithm being used)
There is -- Windows has two different things going on in this area: one is PAE, which allows the OS to use more than 4Gb of RAM. When switching between apps, it'll map the 36-bits (on Intel, 37-bits on AMD) worth of RAM into the 32-bit address space.
An individual application can use AWE, which allows it to page areas of 36-bit-space into 32-bit-space.
However, it ain't transparent, and smacks a bit of the bad old days of Expanded Memory (EMM) on DOS.
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-- roger
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#256029 - 13/05/2005 15:13
Re: Dual core
[Re: Roger]
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carpal tunnel
Registered: 25/12/2000
Posts: 16706
Loc: Raleigh, NC US
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I was reading something else that pointed out that it helps in memory-mapping files, especially large ones, too.
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Bitt Faulk
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#256030 - 13/05/2005 15:33
Re: Dual core
[Re: tanstaafl.]
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carpal tunnel
Registered: 08/06/1999
Posts: 7868
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With a 64 bit x86 chip, you can run two versions of Windows:
Windows 32 bit versions, the normal XP/2000 and such that we have now. This runs 32 bit and 16 bit code fine, just as it does on a non 64 bit chip.
Windows x64 bit (the x64 is how Microsoft is keeping the terms seperate from their Itanium versions) will run on AMD Athlon 64 or Intel Pentium 4 with EM64T instructions. This runs 32 and 64 bit programs, but support for 16 bit programs is dropped.
So gaming wise, you could still play everything you do today on a 64 bit chip with the normal install of Windows. With the x64 one, games from 1998 and before might be showing signs of having 16 bit code and may not run. Though to avoid this, you could employ a dual boot between 2 versions of Windows.
The hard part about switching to Windows x64 today is driver support. All drivers it uses must be 64 bit.
With things moving towards 64 bit, my next wintendo will likely have a 64 bit capable chip in it. I'll just have to decide if I want a 64 bit OS now as well and deal with that possible hassle, or just keep the existing XP I use today.
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#256031 - 13/05/2005 23:29
Re: Dual core
[Re: Dignan]
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carpal tunnel
Registered: 24/12/2001
Posts: 5528
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Quote:
Have you looked at the prices recently? The Barton 3000+ is on Newegg for $120. Or you could buy the 64 bit processor which will have other advantages, for another $25. You also get the advantage of more recent motherboards.
Nope. Didn't know it was that low. Last time I checked it there was a significant price premium for decent 64 bit stuff. If it really is only $25 for one of equivalent or greater performance and the motherboards aren't much more then yes, no point not getting 64 bit unless you have hardware or software which won't work on it.
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#256032 - 14/05/2005 12:42
Re: Dual core
[Re: wfaulk]
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carpal tunnel
Registered: 13/07/2000
Posts: 4180
Loc: Cambridge, England
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Quote:
Anyway, what does 64-bit buy you on the Windows side?
From the Debian amd64 page: While architectures like sparc64 or powerpc64 [...] default to executing 32bit applications, amd64 defaults to 64bit binaries because of the performance benefits it offers in 64bit mode.
The "extra performance" is probably because you get more general-purpose registers in amd64 than you do in ia32, so you don't cane the memory system so badly.
Peter
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#256033 - 14/05/2005 14:06
Re: Dual core
[Re: peter]
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carpal tunnel
Registered: 25/12/2000
Posts: 16706
Loc: Raleigh, NC US
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Couldn't they just as easily define a new architecture that's ia32 plus more registers and gotten improved performance out of that?
Hmm. I suppose that you might as well go to 64-bit anyway since you're already defining an incompatible architecture.
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Bitt Faulk
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#256034 - 15/05/2005 16:50
Re: Dual core
[Re: wfaulk]
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carpal tunnel
Registered: 30/04/2000
Posts: 3810
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Quote:
Couldn't they just as easily define a new architecture that's ia32 plus more registers and gotten improved performance out of that?
Hmm. I suppose that you might as well go to 64-bit anyway since you're already defining an incompatible architecture.
That's, more or less, what the x86-64 (as appearing in AMD's Opteron, Intel's Xeon EMT, etc.) architecture is all about. It's backward compatible with x86 in all the ways you'd expect but they added a 64-bit mode, which gets you more and wider registers, and other assorted goodies. This is almost exactly the same process that Sun and MIPS went through in moving their architectures from 32 to 64-bits. The general rule of thumb, for an architect managing a transition like this, is to make sure that old code keeps getting faster, but that new code can really rock the house when it takes advantage of the new features.
Probably the coolest feature of getting a 64-bit address space is that you can now memory map the whole damn filesystem if you want and do everything through demand paging. That's a big win for scientific computing, databases, and even web server applications. Of course, with wider registers, you can move that much more data back and forth at a time. This can be a particualrly big win for "media" applications (e.g., MPEG decoding, Photoshop filters, etc.) that use the parallel half-word instructions (e.g., SSE).
Incidentally, part of why we're seeing dual core CPUs now is that increasing clock speeds are bumping into some nasty heat issues that will, eventually, get worked out. Meanwhile, they can always stamp out two cores on the same die with any of a variety of different cache architectures (either sharing or not sharing the biggest cache). That's easy to do, from the chip designer's perspective, and it puts all the software people on notice that they need to get on the ball and write multithreaded apps when performance matters. Of course, the OS can always run multiple processes on multiple processors.
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