X86 vs X86-64

[planecrazy.eu]

Hey, very simple post. I came about X86 and X86-64. To me the 64 would mean 64Bit?

But under X86-64 it had things like P4 extreme and Pentium D's. Pentium D's are dual cores i think (i dont keep upto date with computers these days), so is a dual core intel classed as X86-64?

I have a Intel Centrino Core Duo, i am guessing this is just X86, but core duo is part of the D range i think, dual core, so is it X86-64?

Please unconfuse me...

[Gertrude the Wombat]

32 bit is 32 bit, 64 bit is 64 bit.

Whether it's single core or dual core or hyperthreading or whatever is orthogonal to that.

To understand what a particular chip does, look it up on the manufacturer's web site.

[IO540]

I think all these chips do run the basic 8086 code though.

That's where AMD stole the market share from Intel: maintaining backward compatibility with 80x86 opcodes. Intel tried to go in a different direction, but as soon as you can't run good ole Windoze (especially the bootleg copies that most of the world is running) you consign yourself to a very niche market (commercial servers, basically).

[Saab Dastard]

planecrazy.eu

Good question - what you ask is not easily answered! Even Intel is (possibly deliberately) vague about what the answer is.

Does Intel do 64-bit? (http://or1cedar.cps.intel.com/isn/community/en-us/blogs/mult-core_com/archive/2006/09/20/30224178.aspx)

32 bit is 32 bit, 64 bit is 64 bit.

Not always so - some processors can be either 32 OR 64-bit depending on what OS is running on it! If you boot up a 32-bit OS, the processor will operate in 32-bit mode only and will NOT run any 64-bit code. You can boot the SAME processor with a 64-bit version of the OS and it will run BOTH 32 AND 64 bit code.

IO540, it wasn't the backwards compatability that allowed AMD to leapfrog intel - it was that AMD could sell a 64-bit processor that also ran 32-bit code as fast as (or faster than) a 32-bit processor.

At the time, intel's 64-bit offerings (think Itanium cores) ran 32-bit code like treacle.

There was never any question of intel 64-bit CPUs not running mainstream COTS OS and applications, just that they weren't particularly good at running 32-bit code - and there was little native 64-bit code around for them to show how good they were at that!

Intel has more than caught up with AMD - it has passed it by with its dual-core CPUs running faster and (crucially) significantly cooler, hence lower running and cooling costs.

SD