In case you didn't know, some Intel Macs now have the Hardware Test built in so that you don't need to scurry for your original install discs. Just reboot and hold down the "D" key.

I thought that Apple simply added a partition on the original HD for Intels that came with 10.5.4 or above, but it works on new MacBook Pros even with a replacement HD in there.

I've been hunting through Apple's support pages, but can't find any acknowledgment that the feature even exists.

Has anyone got a link to Apple's documentation of the feature?

...

Edit: Yes, I know that all of the MBAs have the Hardware Test built-in. That much is well-documented. But I'd like to know how it's implemented and specifically which other Macs have it.



Edited 2 time(s). Last edit at 08/12/2009 12:15AM by Doc.

I've seen it in the MacBook Early 2008, and it seems to be implemented through a combination of the boot firmware and a special partition on the hard drive.

I tried moving the hard drive from that MacBook to an earlier MacBook and it didn't work on the older MacBook.

I had also sent that Early 2008 model in for repair and Apple replaced the hard drive and the contents of the new drive (with 10.5.6 pre-installed on it) broke that feature, it would try to load the HW test, but then put up a message saying that it was an incompatible version.

I then restored from the full drive backup (including partition maps) that I had made using Disk Utility, and the feature worked again.

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GGD
I've seen it in the MacBook Early 2008, and it seems to be implemented through a combination of the boot firmware and a special partition on the hard drive.

I've been told that it's a disk image on a partition, but it's definitely not on the HD on a new Unibody. So far as I can tell, the HD that I took out of that Mac did not have a Hardware Test partition and the MBP still boots into the AHT with a brand new HD.

I guess there's a disk image in firmware. They may not have implemented it that way initially.

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Doc

Quote
GGD
I've seen it in the MacBook Early 2008, and it seems to be implemented through a combination of the boot firmware and a special partition on the hard drive.

I've been told that it's a disk image on a partition, but it's definitely not on the HD on a new Unibody. So far as I can tell, the HD that I took out of that Mac did not have a Hardware Test partition and the MBP still boots into the AHT with a brand new HD.

I guess there's a disk image in firmware. They may not have implemented it that way initially.

Not sure exactly how it was done, Disk Utility didn't show an extra partition/volume in it's list, but when I did the full drive backup, the progress display showed that it was copying a small partition before it got to the large MacOS partition.

How to test if it's data on a disk or in firmware? Remove the drives and see if it still works.
My guess is it's a small amount of data in the EFI partition.
g=

Link to Apple support:

[support.apple.com]

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b-bender
Link to Apple support:

[support.apple.com]

Thanks, but that's not what I'm looking for.

it does not mention that there's a Hardware Test in firmware and does not list the models that have the Hardware Test in firmware.

Just tested it on my 2009 Mini; Just "d" with no disk in the optical drive and it booted into AHT.

This is also a replacement internal drive I installed. If it's on the drive, it must be part of the OS install. My guess is firmware.

Might open the little guy up again and disconnect the drive, but that requires work!

MJD