Creating bootable installer for old OS X version with M2 laptop?

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Creating bootable installer for old OS X version with M2 laptop?

I'm running an M2 Air with Sonoma and would like to install any version of OS X, preferably Yosemite or El Capitan, on an iMac 7,1 via bootable installer (hard drive or flash drive doesn't matter). The iMac currently has an empty hard drive installed (no OS). When I download the .dmg files for any of the OS X versions from Apple, my laptop won't open the .pkg files and so I cannot get to the .app version I need in my applications folder to create a bootable installer via the usual terminal commands (see article below).

I've also tried Mavericks from another site but it was trash so I guess I know why Apple doesn't offer it anymore.

For Mountain Lion and Lion I tried restoring a hard drive with the .dmg files and that also didn't work.

So my question is: Is this even possible with my Air? And if yes, how to I get from the .dmg file to .app installer from which to run the infamous createinstallmedia script?

Thanks in advance :).

Create a bootable installer for macOS - Apple Support

MacBook Air

Posted on Oct 24, 2023 9:42 AM

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Answer 1

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D.I. Johnson

Level 7

22,373 points

Oct 24, 2023 10:08 AM in response to fcala

Creating a bootable installer requires using a Mac that qualifies to run the version of macOS that you are creating the installer for. To create a bootable installer for Yosemite or El Capitan, you will need to use a Mac that can actually run under either of those macOS versions, i.e. a Mac of the 2010-ish era.

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Answer 2

Oct 24, 2023 10:24 AM in response to fcala

I believe that's possible, but the original .dmg will have to be of a flash drive properly created with a qualified Mac. By this I mean if you have a working bootable installer on a flash drive, you can use your MB Air to create a .dmg of that flash drive and copy/restore it to another.

The .dmg files that you will find in Apple's downloadable macOS installers and apps are not suitable for direct restore to a flash drive and will not result in a bootable device. They must be properly processed by the Terminal app and applied to a flash drive.

If I'm wrong on this, someone, please correct me. 🙏🏽

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Answer 3

fcala Author

Level 1

4 points

Oct 24, 2023 10:30 AM in response to D.I. Johnson

Alright, thanks. So I'm just better off getting a bootable usb drive from eBay? Alternatively I can try using some old Snow Leopard disk I maybe have laying around and then trying to upgrade from there... Thanks again!

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Answer 4

Oct 24, 2023 10:42 AM in response to fcala

You're welcome.

Yes, iMac7,1 can run 10.4.10 Tiger to 10.11.6 El Capitan.

Be wary when buying on eBay... I'm sure you're aware of the potential issues there. But bootable flash drives are cheap so not much real exposure.

Regarding the Snow Leopard discs... you'll be looking for the white-label cat-face disc, v. 10.6.3, I believe.

You can also look for the original grey-label Mac OS X Install DVDs that iMac shipped with. These are very machine specific, so similar discs will not work between models.

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Answer 5

fcala Author

Level 1

4 points

Oct 24, 2023 10:10 AM in response to D.I. Johnson

Thanks! And what about restoring a flash drive with the .dmg file (still using my M2 Air)?

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Creating bootable installer for old OS X version with M2 laptop?

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