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10.5: Create a single Intel+PowerPC diagnostic drive System 10.5
There are many purposes for a single partition to boot multiple architectures. Running diagnostics and repair utilities is just one of them. You can use this tip for many other purposes as well.

Background: Tiger only allowed you to boot either an Intel or a PPC Mac, but never was there a choice for a heterogeneous boot partition (without some drastic measures; here's one hint) because the binaries are different. Leopard gets one step closer because they are the same binaries. One might think that you could easily build a diagnostic drive out of an old FireWire drive that will boot either Intel or PowerPC machines. And you can, but there's a catch. Intel Macs can "only" boot to a drive that is partitioned using the GUID partition table scheme, while PowerPC Macs can "only" boot to a drive that has an Apple Partition Map scheme.

The exception is for the Install DVD. You can boot either kind of Mac using the same DVD. I believe that this is because of the special partition map that DVD's use. In any case, you can use this to your advantage if you need to make a single drive that can boot either type of machine. This is especially helpful for people who support multiple CPU types in their Mac OS life.

Disclaimer: Please be sure that you have the appropriate legal rights to follow these steps before proceeding (i.e. be sure to own enough copies of Leopard for the number of machines you intend to support with this disk.)

What you'll need:
  1. A Leopard Install DVD or a disk image of it (i.e. from Apple Developer Connection).
  2. A Leopard diagnostic partition. You can just do a base install for now and add your diagnostic utilities later, or you can configure this partition as you would like your diagnostic drive. Consider doing a custom install and installing only what you will be using in your diagnostic environment (i.e. no printer drivers or bundled applications).
  3. Another "primary" partition running OS 10.4 or later, with Carbon Copy Cloner, version 3 (CCC3). It *can* be the Leopard diagnostic partition, but that isn't ideal for a number of reasons. You're better off if you have another partition to use.
  4. A FireWire drive that is big enough to accommodate the files you'll need on the Leopard diagnostic partition, plus 1GB to 2GB of additional space. Note that it does not have to be as big as the Leopard diagnostic partition, just the total size of the files, plus an extra 1GB or 2GB for a swap file and other temp files.
The steps:
  1. Boot to your primary partition.
  2. Insert your Install DVD or mount the disk image of it. Use CCC3 to clone your Installer DVD (source) to your FireWire drive (target). Under Cloning options, select Copy Everything from the source to the target, then check Erase the target volume and Require block-level clone.

    When this step is done, you will have a FireWire disk that will install Leopard faster than the DVD, but that isn't the point of this tip. (Take it as a bonus tip if you ever find the need to install Leopard on a number of machines.)
  3. Next use CCC3 to copy all of the files from your diagnostic partition (source) to the FireWire disk (target). This time, use Copy selected items under Cloning options. Also check Delete items that don't exist on the source. This step will take a long time.
When you've finished the clone, it should be bootable by either an Intel or PowerPC Mac. I don't recommend using this as a primary drive. It will likely be slower due to the limitations of the DVD partition scheme, but it should do the trick if you're looking to have just one drive to boot multiple architectures.

Note: if some of your applications end up looking like folders instead of applications, just rename them with an ".app" at the end. Also, be sure to consider a donation to the author of Carbon Copy Cloner if this works out for you; he makes this and many other Mac OS X hints possible.
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10.5: Create a single Intel+PowerPC diagnostic drive | 15 comments | Create New Account
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may be a bit of overkill
Authored by: EricMc on Oct 31, '07 12:51:16PM

I installed on an external fw drive to test leopard on several macs before installing. I used an APM partitioned drive and did a fresh install to it from a PPC mac. This drive boots PPC and Intel without any issues.

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may be a bit of overkill
Authored by: mflender on Oct 31, '07 12:56:04PM

My understanding is that Intel macs will boot from APM and GUID, PPC only boots from APM. However, the installer disk will not install to APM drives from an Intel Mac.

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may be a bit of overkill
Authored by: woodgie on Nov 01, '07 12:09:50AM

My testing bears this out. And DAMN useful it is!

The other major benefit is that if you're having problems with the DVD mounting as I and MANY other people seem to be having then it's the quickest and easiest way around the problem (of course, it assumes you can mount the DVD on at least one of your machines).

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10.5: Create a single Intel+PowerPC diagnostic drive
Authored by: macavenger on Oct 31, '07 12:53:27PM

Actually, all you have to do is make sure your drive uses the Apple Partition Map scheme, and install 10.5 from a PPC mac. Intel machines will boot from a drive with this partition format quite happily, the only restriction is that you can't install the OS onto a drive with the APM from an intel machine.

Aluminum iMac 20" 2.4 GHz/3GB/300GB HD

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10.5: Create a single Intel+PowerPC diagnostic drive
Authored by: thornezilla on Oct 31, '07 01:14:08PM

To address the issue of what kind of partition can boot what kind of Mac, here's what I discovered.

The difference isn't "Intel vs PPC" for partitioned hard drives, but "Older Intel & PPC vs Intel 2.4GHz".

I had 4 different external FW Hard Drives, all partitioned with the older Apple Partition Map via Disk Utility. They all booted all my PPC and Intel Macs until the 2.4 GHz "Santa Rosa" chipset MacBookPro's shipped.

At that time I was forced to reformat two of the drives with GUID formatting, so that I could load/copy/restore a bootable OS for the new 2.4 GHz systems. These two drives can boot any of the new 2.4 GHz systems, but I don't use them to boot or repair the older Intel Macs or PPC systems.

The other two FW drives are used as before, to boot and repair the PPC and older Intel Macs. So even though Apple's documentation said that GUID formatting was required for Intel systems, it wasn't **required** until the Santa Rosa chipset shipped.

Can't address the main issue of a drive that will boot both, but will try it ASAP. Thanks again, MacOSX Hints!

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10.5: Create a single Intel+PowerPC diagnostic drive
Authored by: brett_x on Nov 01, '07 10:35:49AM

Please let us know if this works on your SantaRosa machine. I'll be surprised if it doesn't work.... unless it requires a different Installer DVD.... which it absolutely shouldn't this early in the Leopard game.

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10.5: Create a single Intel+PowerPC diagnostic drive
Authored by: bulge on Oct 31, '07 02:29:59PM

Yeah sorry bra,

Not quite right, 3x votes against this.

APM partitions will boot both intel and PPC macs, GUID is bootable on intel only. The installer in 10.4 and 10.5 have a constraint applied to stop intel macs from installing on APM drives. I am sure Intel machines on APM is unsupported, but that doesn't necessarily mean it doesn't work.

The only thing you need to do in order to make a universal booting external drive is get your 10.5 install onto an APM external drive. Do this by installing from a PPC machine (hence no Installer constraint) or CCCing from a GUID drive to an APM external on an intel.

I have built a 10.4.8 universal system with radmind, put it on a partition on an APM external firewire and intel / PPC machines boot happily from it.

I do agree that cloning your install DVD on to an external HD is good way to go if you are loading a bunch of machines... super fast!

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10.5: Create a single Intel+PowerPC diagnostic drive
Authored by: bulge on Oct 31, '07 02:32:55PM

*except of course for the 'new' intels, as above :)

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10.5: Create a single Intel+PowerPC diagnostic drive
Authored by: poenn on Nov 04, '07 11:58:03AM

Hi everyone,

I just tried it myself. I partitioned an external FW HD using APM with 2 partitions. I then cloned the 10.5 Install DVD onto the first partition and the 10.5 Server Install DVD onto the second. My MBP 2.4 GHz can boot from both partitions without problems and presents the Installer screen and my old PPC Mac too.

Does the "2.4GHz forced GUID" only apply to installed systems? It seems to me that I STILL can create one APM drive for both architectures?!


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10.5: Create a single Intel+PowerPC diagnostic drive
Authored by: curtinsmith on Nov 05, '07 04:32:33AM
Mac OS X 10.5: Creating and maintaining a bootable "universal" external disk

Simple 3 step process from

Creating the external bootable disk

Note: To initially set up the external disk, use a PowerPC-based Mac. These instructions are intended for an external disk that will be used with both PowerPC- and Intel-based Macs. If you're not sure what processor types your Macs have, see this article.

1: On a Mac OS X 10.5-compatible PowerPC-based Mac, make sure the external hard disk has a Partition Map Scheme of "Apple Partition Map (APM)".

This can be verified in Disk Utility. APM is the default Partition Map Scheme of PowerPC-based Macs. In Disk Utility, select the external Hard Disk on the left side of the window and click Info.

If the Partition Map Scheme is not APM, you will need to reformat the disk with Disk Utility with a Partition Map Scheme of "Apple Partition Map (APM)". Important: Partitioning the disk will erase all data on it; back up important files that are on the external disk first.

2: With the external hard disk connected to your Mac OS X 10.5-compatible PowerPC Mac, insert your Mac OS X 10.5 installation DVD and double-click Install Mac OS X.

3: Go through the Mac OS X 10.5 Installer but select the external hard disk as the destination with whatever installation options that you want.
Once installation is complete, you will have an external hard disk that can start up ("boot") both PowerPC-based Macs (that are Mac OS X 10.5-compatible) and Intel-based Macs that were available when Mac OS X Leopard 10.5 was released.

Keeping Mac OS X 10.5 up-to-date for Intel-based Macs

Keep Mac OS X 10.5 on the external hard disk up-to-date so that it can start up future Intel-based Macs which may be released after your Mac OS X 10.5 Installer DVD was produced.

Simply connect the external disk to a compatible Intel-based Mac, select the disk in Startup Disk preferences, and restart. Once booted from the disk, choose Software Update from the Apple menu. Download and install any available updates.

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10.5: Create a single Intel+PowerPC diagnostic drive
Authored by: jamescoy on Dec 04, '07 07:18:31PM

I followed these instructions, creating three partitions on a PowerPC, then getting the image of the Leopard Installer on the first partition. I then installed Leopard onto the second partition, again, using a PowerPC, and now I cannot boot an Intel Mac with it. In spite of selecting the second partition, the drive reverts to the installer partition! What gives here? Bad install or..?

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10.5: Create a single Intel+PowerPC diagnostic drive
Authored by: jiclark on Feb 03, '08 11:44:37AM

In the hopes that people are still watching the comments for this hint...

So James, did you ever discover why the technique wasn't working for you? I can't imagine what might be the problem... Anyone else have similar experiences, or ideas about why his drive isn't working as it should?

I'm about to try this myself, so I'll keep you posted if I run into any issues.

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10.5: Create a single Intel+PowerPC diagnostic drive
Authored by: lexah on Apr 01, '08 12:06:43AM

I just tried this today and had no problems... so am pretty happy!

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10.5: Create a single Intel+PowerPC diagnostic drive
Authored by: lexah on Apr 01, '08 12:08:54AM

Sorry I replied to the wrong bit - I meant I tried what was suggested above as per Apple's site and it worked fine.

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10.5: not needed... boot w/D key@startup
Authored by: appleman_design on Aug 25, '08 10:40:02AM


With newer Mac models, the Leopard DVD is no longer needed to run the Apple Hardware Test for diagnosing hardware problems. Users can simply boot the computers startup while holding the "D" key down to boot into diagnostic mode -- the utilities are stored somewhere on the hard drive.

One Apple Discussion board user experimented with his setup, and found the system does not boot into diagnostic mode if the hard drive is disconnected. Additionally, it seems this feature is only available on original factory-installed operating systems (or reinstalls from the Apple-provided restore DVDs), so users who have upgraded from Tiger or who have reinstalled their operating systems from retail boxes may not have this feature. Speculation holds that Apple enabled this feature to facilitate diagnostics with the driveless MacBook Air.

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