Unsupported System Software on the PowerBook 500 Series

Normally, the MacOS 8.6, 8.5, and 9.0 installers refuses to run on the PowerBook 500 series, even with a PPC upgrade card. Luckily, you can use a small gestalt trick to get the installer to run. Here, I'm only going to cover the PowerBook 500 series, since that's what I have.

Try and get as much RAM as possible when running these newer versions of the MacOS. Modules for the 500 series are still sold at places such as Ramjet, or you can try looking for parts on eBay.

Proceed at your own risk. Always back up anything important before trying this or any other system altering procedure.

Other Sites of Interest

Installing MacOS 8.5, 8.6 and 9.0

It isn't too difficult to get these unsupported versions running on a PowerBook 500 series. Before you start, you'll need the software listed below.

Useful Software

Save the software to your PowerBook's hard drive. Use of the NUpowr System Update is optional, but recommended.

Phase One: Run the Installer

The first hint you get that the installer doesn't like a PPC upgraded PowerBook 500 is clear: the installer refuses to start, and presents you with a nice error message referring you to read the documentation. To get arount this, download and install a copy of "Wish I were...". Set it to "PowerBook 5xx/PPC" and restart.

After restarting, run the installer or updater and go through the normal installation procedure. A full install can take some time, usually around 40 minutes. Make sure the PowerBook is plugged in, does not dim the display, sleep the hard drive, or go to sleep. If it tries, the installer might crash and you'll have to start all over with a clean install of a supported system.

Phase Two: The Reboot

Restart the machine when the installation is complete. Upon restarting, you will probably see the error message "This startup disk will not work on this Macintosh model. Use the latest Installer to update this disk for this model." Here's where we need to use the boot disk (or a boot CD, if you have an external CD drive handy) and ResEdit gestalt trick.

Boot your PowerBook from a boot disk and open ResEdit.

Phase Three: ResEdit the System File

Now that that you have access to the PowerBook's hard drive, use Res Edit to open the "System" file in your System Folder. Before chancing anything, read the steps below! Here's what you want to do:

1) Scroll down and find the resource named "gusd" and open it.
2) Open resource ID 1.
3) Look for a line that says "007C 0024"
4) Change that line to read "007E 0024"
5) Save the changes to the System file and quit ResEdit.

Now, reboot the PowerBook without the boot disk.

Phase Four: Success!

If all went well your PowerBook should be booting an unsupported system. After it finishes starting up, shut it down and reboot once more just to give it a clean cycle through a startup and shutdown.

Congratulations, you're now running new system software! If it didn't work you may want to try this procedure on a clean install. Other users who have tried this have reported success on a clean install when it didn't work the first time through.

Also, remember to disable any of the PowerBook's power saving features while installing, and use the power adapter, not battery power.

Updating to MacOS 9.0.4

The 9.0.4 updater won't work, and may crash. You will need to re-enable "Wish I were..." to get the updater to function properly. After you install the update, you'll note that your system still says it's still running 9.0.

The problem lies in the "PowerPC Enabler 9.0.4" system file not loading at startup time because it doesn't recognize your PowerPC upgraded PowerBook as a valid machine to run on. Unfortunately, the same trick to get the system to boot described above does not seem to work with the enabler file. The "System Resources" file was also not updated to 9.0.4.

Unfortunately, I have been unable to get 9.0.4 to work. It will install all of its related files, but still report itself as 9.0. It appears this is the end of the line for these old PowerBooks.

For other computers...

If you're not using a PowerBook 500 series, use this gestalt table instead of steps 3 and 4 above:

1) Look for a line that says "001F 001C"
2) Replace that line with "00xx 001C" where xx is the hex value of your machine in the table below.

Unlike the 8.5 hack to get it to run on unsupported machines, 8.6 does not appear to work on all of these same machines. See the "MacOS 8.6? On Unsupported 68K to PPC Upgrades" page for further information.

Gestalt Table

Hex ValueUpgraded Machine Name
68PowerMac LC 475/Performa 47x
69PowerMac LC 575/Performa 57x
6APowerMac LC-Quadra 630/Performa 63x
6BPowerMac LC 580
74PowerMac Quadra 700
75PowerMac Quadra 900
76PowerMac Quadra 950
77PowerMac Centris 610
78PowerMac Centris 650
79PowerMac Quadra 610
7APowerMac Quadra 650
7BPowerMac Quadra 800
7EPPC PowerBook 520-540
CEPowerMac IIci
CFPowerMac IIsi
D0PowerMac IIvi
D1PowerMac IIvx
D2PowerMac IIvm
D3PowerMac IIfx