PPC vs Intel versions of OSX

mhar4

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Original poster
May 7, 2003
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This may seem like a dumb question, but when at home, I am in the habit of running my 12" PowerBook from an external 250GB HD, as a Boot drive, with Tiger installed on it. Am I right in thinking that if I upgraded to something with an Intel processor, say an Intel Mini, it couldn't boot from the external HD? I'd need to install an Intel version of OSX?
 

Chundles

macrumors G4
Jul 4, 2005
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mhar4 said:
This may seem like a dumb question, but when at home, I am in the habit of running my 12" PowerBook from an external 250GB HD, as a Boot drive, with Tiger installed on it. Am I right in thinking that if I upgraded to something with an Intel processor, say an Intel Mini, it couldn't boot from the external HD? I'd need to install an Intel version of OSX?
Yeah, pretty sure that's correct. But then I don't think it will run on the PPC computer.
 

mhar4

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Original poster
May 7, 2003
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Hmm... so OSX is actually not a universal binary itself. It's an either/or. Nuisance.

Great avatar, btw.
 

robbieduncan

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Jul 24, 2002
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Not only would you need an Intel version of OSX but I seem to remember that the disk partition scheme is different on Intel Macs so you'd need to repartition the disk.
 

Chundles

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Jul 4, 2005
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mhar4 said:
Hmm... so OSX is actually not a universal binary itself. It's an either/or. Nuisance.

Great avatar, btw.
10.5 will be but then it still won't work cause you'd still have an Intel version of the OS on the disc - it just came from a Universal binary.
 

sintaxi

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Dec 15, 2005
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mhar4 said:
Hmm... so OSX is actually not a universal binary itself. It's an either/or. Nuisance.

Great avatar, btw.
Actually, I think all Universal Binary is Either/Or. a Universal app identifies your architecture upon intalation an installs either the PPC or X86 version depending on what you have. That is my uneducated guess.
 

robbieduncan

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Jul 24, 2002
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sintaxi said:
Actually, I think all Universal Binary is Either/Or. a Universal app identifies your architecture upon intalation an installs either the PPC or X86 version depending on what you have. That is my uneducated guess.
Your guess is wrong. Current Universal Binaries contains code for both architectures. You can confirm this for yourself. For example to see what architectures your current copy of iTunes is built for type this in the terminal:

lipo -info /Applications/iTunes.app/Contents/MacOS/iTunes

Results in (for me):
Architectures in the fat file: /Applications/iTunes.app/Contents/MacOS/iTunes are: ppc i386

The code to run is determined at runtime. Otherwise the "Run in Rosetta" checkbox would be pretty much useless.
 

mhar4

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Original poster
May 7, 2003
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robbieduncan said:
Your guess is wrong. Current Universal Binaries contains code for both architectures.
But this doesn't apply to the actual OS you install on your hard drive. So there aren't actually two versions in a single installation which a PPC or Intel Mac could choose from to boot from an external drive?
 

OnceUGoMac

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Mar 3, 2004
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Didn't Steve Jobs say that OS X has always been both PPC and x86 native at MWSF in January?
 

emaja

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May 3, 2005
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OnceUGoMac said:
Didn't Steve Jobs say that OS X has always been both PPC and x86 native at MWSF in January?
Yes he did, but they are not shipping as one OS with coding for both PPC and x86.

The current shipping versions of Tiger is 10.4.3, but it is a PPC version. You cannot buy an x86 version of OS X yet.
 

Platform

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Dec 30, 2004
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OnceUGoMac said:
Didn't Steve Jobs say that OS X has always been both PPC and x86 native at MWSF in January?
Yes, but he didn't say that the same version ran on both, just that OS X ran on both platforms, not crossover, and right now Apple has no reason to release a UB of OS X, because everyone who needs OS X for x86 they need to buy a Mac.....When Leopard comes there is a different issue since people using Intel machines want to upgrade too ;)
 

slb

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Apr 15, 2005
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The apps included with OS X are universal binaries, but the underlying operating system is compiled for its specific architecture.
 

4JNA

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Feb 8, 2006
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i can confirm that an 'internal' image moved from a intel machine to a ppc machine did not work. had to wipe the disk clean and start from scratch with the ppc version to get back to working. :cool:
 

Eidorian

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Mar 23, 2005
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emaja said:
Yes he did, but they are not shipping as one OS with coding for both PPC and x86.

The current shipping versions of Tiger is 10.4.3, but it is a PPC version. You cannot buy an x86 version of OS X yet.
It's 10.4.6 now. It's still PowerPC only though.
 

pianoman181

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Jan 6, 2004
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If you install OSX with an intel dvd (ie an install dvd from an intel mac) you can boot a ppc mac off of it if you bless the disk.
 

mhar4

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Original poster
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So you can run either an Intel or PPC Mac from the same external HD? As long as it's the Intel version of the OS.
 

Chris Grande

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Jun 17, 2003
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The entire OS on the intel machines is universal, the problem comes in with the specific boot loaders. People on the MacEnterprise mailing list have done it using Radmind to merge the 2 to make a dual boot image. Currently the intel and ppc versions of OS X are separate (hence the different build numbers) and the intel version has been worked on much more (hence the higher build numbers) I'm guessing with 10.5 there will be one universal version.

So while its currently possible its not easy. People on MacEnterprise were creating Universal NetBoot images for maintenance and troubleshooting.
 

matthew24

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May 30, 2002
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I don't believe a true universal OS exists or is even possible: This would mean that the installed OS would have all X86 and PPC code on board (why?), this is highly inefficient/complicated and serves no coarse.

What Apple could do is make one DVD with both codecs on board, the loader will determine which codec gets installed.
 

netdog

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Feb 6, 2006
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mhar4 said:
This may seem like a dumb question, but when at home, I am in the habit of running my 12" PowerBook from an external 250GB HD, as a Boot drive, with Tiger installed on it. Am I right in thinking that if I upgraded to something with an Intel processor, say an Intel Mini, it couldn't boot from the external HD? I'd need to install an Intel version of OSX?
You are correct that you would need a new boot system (the CD for which would come with your Mini). You can boot off a firewire drive, but it must be setup with an OS X to run the Intel machine. The current OS X comes as a Universal. Not sure about the ones that come with new Intel machines, though my guess is that they just contain the Intel code.
 

pianoman181

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Jan 6, 2004
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matthew24 said:
I don't believe a true universal OS exists or is even possible: This would mean that the installed OS would have all X86 and PPC code on board (why?), this is highly inefficient/complicated and serves no coarse.

What Apple could do is make one DVD with both codecs on board, the loader will determine which codec gets installed.
codecs? Please don't talk about things you do not understand. Universal apps are not much larger than thinned apps (~5-20% larger depending on app). All the universal part does is basically remaps procedure calls, the vast majority of apps (especially user-based apps, as opposed to system services) remain by and large the same, with no duplication. It is far more efficient to create one dvd with universal binaries and leave those universal binaries as universal. Thinning them at install time is absolutely pointless.
 

gnasher729

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Nov 25, 2005
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sintaxi said:
Actually, I think all Universal Binary is Either/Or. a Universal app identifies your architecture upon intalation an installs either the PPC or X86 version depending on what you have. That is my uneducated guess.
Apple advises all software developers very, very, __very__ strongly to ship universal products that include both PowerPC and Intel versions, and not even give the customer the option to install only half of the application.
 

mhar4

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Original poster
May 7, 2003
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London
Now I'm just confused.

How about this: if I bought a Macintel Mini (say) and used its installation disk to install OSX onto the Firewire drive, could this version run both the Mini and the PowerBook? i.e. is the version of Tiger which comes with Intel Macs a "Universal" version or is there, in fact, no such thing. i.e. there are "Universal" applications, but still two versions of OSX for the two processor classes, rather than one new Universal version which contains both PPC and Intel code.