View attachment 83105
Looks like the only file that's named differently is Apple HD SC Setup. On this disk, it's called Internal HD Format.
Someone I know just bought a boxed 550. It has working HDD. I am asking him to confirm what disk he has. Let me know if there is anything I can find out.
*edit* Yeah, just looked at the back of the disk. This is actually 7.1.2P1. Oops. So, that explains the difference.Thanks for taking a photo! Ah yes, I've heard of Internal HD Format. My understanding is that it only works with Macs that have IDE drives: https://machut.net/files/manuals/macintosh_performa/0306379PerformaHDupdt.PDF
I'm thinking maybe that disk actually came with a Performa 630 series machine?
Oh wow, a boxed 550 has to be very rare at this point! Assuming it still has the original 160 MB internal hard drive, it would be very interesting to see if it also has this partition. The two pieces of info I'm still missing are: did the older caddy-loading models also have this partition, and is Apple Backup what's really responsible for making it.
One good piece of info to know is, if the hard drive is dead, it may very well be possible to revive it.
This is the picture he sent me. He is far and not that tech savvy so I am trying to find a way to get copy of this HDD.
Yeah, just looked at the back of the disk. This is actually 7.1.2P1. Oops. So, that explains the difference.

Macintosh Model:
(ID = 80)
Physical Ram Size:
36 Mb (36864 Kb)
Logical Ram Size:
72 Mb (73728 Kb)
ROM Version:
$67C
ROM SubVersion:
$25F1-14.12
NuBus Slot Information:
No card found in NuBus slot: $E
@dougg3 I'm guessing the drive came from the commanderscott seller? I did see one that he was selling as parts/repair.


There is software available to recover stuff from previeously formatted drives. Think of something like the "Disk Drill.app" for more recent Macs. If a reformatted drive that came originally from a P550 has not seen much write load after reformatting, could't there be enought leftover from the original recovery partition to restore it to a functional state?
Now featured on OS News:
Upon reflection, shouldn't that recovery partition include the version of Apple Backup on it that created it in the first place? If it doesn't, then that kind of suggests Apple pre-populated the image at the factory, and never got around to getting Apple Backup to back up to it or restore from it.
It's too bad (although from a use-case, probably good) that the 550 came with 7.1P6. I wish we had similar recovery partitions for 7.0.1P through 7.1P5....
The 550 holds that unique space in time where the earlier Apple Backup that backed up to floppy disks required too many disks, but CD-Rs weren't standard yet.