Install Mac OS X from a USB drive on a PowerPC-based Mac

When nothing else worked when trying to install Mac OS X Leopard onto my PowerBook G4 1.67GHz without the original installation DVD, here's what eventually did.

What you'll need

• PowerPC-based Mac you want to install OS X on by using a USB drive
• ...USB drive (16GB or more in capacity; 8GB might work, but come on, it's 2020)
• Second old Mac that already boots Mac OS X Leopard (other versions may work, but are untested. All I know is that my macOS Catalina hackintosh did NOT work)

Part 1: Preparing the disk image for restore

1. Boot up your second old Mac running Mac OS X Leopard
   
2. Download #31 (Leopard_10_5_4.dmg_.zip) from here and extract the DMG
3. Scan the DMG for restore using Disk Utility ("Images" -> "Scan Image For Restore...")
4. Lock the DMG (right-click -> "Get Info" -> check "Locked")

Part 2: Restoring the disk image to the USB

1. Format your USB as "Mac OS Extended (Journaled)" using the "Apple Partition Map" using Disk Utility
   
2. Restore the DMG to your USB using Disk Utility, making sure you check "Erase destination" (open the Restore tab, drag and drop the DMG to the "Source" field, drop and drop the partition you formatted in Part2Step1 to the "Destination" field)
3. Eject your USB drive and plug it into the PowerPC-based Mac you want to install OS X on
   

Part 3: Installing Mac OS X (okay kids, this is where it gets complicated - mostly copy/pasted from here; follow that if this doesn't work for some reason)

1.  Boot your PowerPC-based Mac into OpenFirmware (power it down and hold Command + Option + O + F while powering it back up)
2. Run dev / ls and look for the entry with "/disk@1" at the end of it (in my case "usb@1b,1")
3. Run devalias and look for the entry with the text you found in Part3Step2 at the end of it (in my case "usb0")
4. Run dir text_from_Part3Step3/disk@1:3,\System\Library\CoreServices (a.k.a. dir usb0/disk@1:3...) and make sure the entry that contains "BootX" also contains "tbxi" (if it doesn't, panic!)
   
5. Run boot text_from_Part3Step3/disk@1:3,\System\Library\CoreServices\BootX (a.k.a. boot usb0/disk@1:3...)
   
6. You should see a little spinner, then some white-on-grey text, and finally the Apple logo. Congratulations, you've successfully booted your accursed PowerPC Mac from a USB drive! The installation process is the same from here on out as if you were booting from an official Mac OS X Install DVD.
   

Legend of the PowerMac G5

A few days ago I bought a PowerMac G5 for $13 because hey, why not. The seller listed it as not working, and they had removed the hard drive for privacy reasons. From experience, I could extrapolate that it probably worked just fine. This would mostly be the case (making this a pretty boring blog post).

I set up the computer on my desk, plugged into a display and whatnot. It booted up with no issue to the flashing question mark folder; it couldn't find a filesystem because the HDD was empty. However, it did not make the "BONG" noise when booting up — I would later discover that this meant some of the RAM was bad.

So I burned the Mac OS X 10.5.6 installer to a USB drive and– uh oh, guess what's not detected by the OPTION menu. After a fiasco with trying and failing to get the Mac to boot from the USB, I thought, "Fuck it." I ran out to Office Depot, bought some DVD+R DLs, and burned the 10.5.6 installer to one of those. I put it in the machine and, once again, failed to get it to work.

It was at this point I reached out to Reddit™. "Try booting it off another Mac via FireWire," one helpful soul suggested. The only other Mac I had with a PowerPC 970 processor was an iMac G5 — with no OS installed, might I add. While digging that out of storage, I found a "Not for Resale" 10.5.6 retail installation DVD, which I then used to reinstall Leopard on the iMac.

Once that was done (it took about an hour), I decided to put the retail DVD in the PowerMac, because I figured it was worth a try. Lo and behold, it booted off the DVD and I had Mac OS X installed in no time. Absolutely maddening. But at least Mac OS X was working now.

Afterwards, I dug some old RAM out of storage (2GB total) and pulled out the broken RAM (4GB total), leaving my Mac with 4GB of RAM. Hey, that's pretty good. Don't forget to join me next week for "Twist Hopefully Sticks to the Trend of Not Saying 'fuck' That Much."