I'm quite confused....

daneoni

macrumors G4
Original poster
Mar 24, 2006
10,807
79
At the WWDC conference in 2005 steve said Mac OS X had been living a double life and that Mac OS X has been compiled for both PowerPC and Intel. My questions is this....if they compiled for Intel (x86) surely they would have compiled for the AMD platform as well right? i mean its a major chip company and if i was CEO i'd add that to my just in case scenario. So is it possible there is a AMD version of Mac OS X in cupertino?
 

strider42

macrumors 65816
Feb 1, 2002
1,460
6
daneoni said:
At the WWDC conference in 2005 steve said Mac OS X had been living a double life and that Mac OS X has been compiled for both PowerPC and Intel. My questions is this....if they compiled for Intel (x86) surely they would have compiled for the AMD platform as well right? i mean its a major chip company and if i was CEO i'd add that to my just in case scenario. So is it possible there is a AMD version of Mac OS X in cupertino?
I may be missing some details here, but as far as I know, AMD is the same instruction set as intel. Its the same platform. If apple decided to use AMD chips, it would require absolutely no work whatsoever in terms of compiling programs. So there's no such things as an AMD version of anything. Just an x86 version. You don't see an intel and amd versions of windows do you, but they work just fine.

At most they might have to support a few different things on the logic board design, but that would be pretty trivial.

Similarly, intel is going to be using AMD's 64 bit instruction set, so when apple does 64 bit under x86, it would work on AMD or intel.

When apple says "compiled for intel" they just mean compiled for x86. They use intel to describe it since that is the company they are using right now.
 

danny_w

macrumors 601
Mar 8, 2005
4,380
124
Austin, TX
strider42 said:
I may be missing some details here, but as far as I know, AMD is the same instruction set as intel. Its the same platform. If apple decided to use AMD chips, it would require absolutely no work whatsoever in terms of compiling programs. So there's no such things as an AMD version of anything. Just an x86 version. You don't see an intel and amd versions of windows do you, but they work just fine.

At most they might have to support a few different things on the logic board design, but that would be pretty trivial.

Similarly, intel is going to be using AMD's 64 bit instruction set, so when apple does 64 bit under x86, it would work on AMD or intel.

When apple says "compiled for intel" they just mean compiled for x86. They use intel to describe it since that is the company they are using right now.
There are probably some AMD-unique instructions that could be used to optimize the os for AMD, but are not necessary. I know the older AMD chips had some unizue instructions that Windows used in some instances.
 

balamw

Moderator
Staff member
Aug 16, 2005
19,368
974
New England
danny_w said:
There are probably some AMD-unique instructions that could be used to optimize the os for AMD, but are not necessary. I know the older AMD chips had some unizue instructions that Windows used in some instances.
Yeah, but Intel has co-opted the most interesting AMD 64 bit instructions, so there really is much less difference. http://en.wikipedia.org/wiki/AMD64.

Note also that the same versions of Windows are intended to run on CPUs from both vendors.

B
 

danny_w

macrumors 601
Mar 8, 2005
4,380
124
Austin, TX
balamw said:
Yeah, but Intel has co-opted the most interesting AMD 64 bit instructions, so there really is much less difference. http://en.wikipedia.org/wiki/AMD64.

Note also that the same versions of Windows are intended to run on CPUs from both vendors.

B
Just because they both run the same version of Windows doesn't mean that Windows doesn't have some cpu-specific code that gets run only on that cpu. This used to be common when chips that were "x86-compatible" had some more major differences.
 

balamw

Moderator
Staff member
Aug 16, 2005
19,368
974
New England
danny_w said:
Just because they both run the same version of Windows doesn't mean that Windows doesn't have some cpu-specific code that gets run only on that cpu. This used to be common when chips that were "x86-compatible" had some more major differences.
True also for PPC, where you could have some code compiled specifically for G5, G4 or G3.

All I was meaning to say is that the bulk of any code will be common for AMD or Intel, be it 32 bit or 64 bit. There may be small optimizations possible for very specific code.

I think this is most clearly in evidence where there have been reports of people actually running OSX Intel on AMD machines currently. Not that that's legal or anything.

B