MacOS X on Unsupported (Legacy) Macs

I have some old PowerPC Macs; the kind that predates the first G3 from Apple. In fact, these old Macs come from a company that was bought out and shut down by Apple. Give up? They're Power Computing clones. I have a PowerCenter Pro 240, PowerCenter 120, and PowerCurve 601|120.

Sadly, these poor Mac clones won't run anything past MacOS 9.1, and I think the last "supported" version is 8.6. But today, thanks to a nifty little utility called XPostFacto, they can run MacOS X.

Thus far I've only tried the PowerCenter 120. The PowerCenter Pro doesn't seem But the PowerCenter (not pro) seems to work great. (Disclaimer: Your mileage may vary. Not everything works properly on these machines. There are a series of caveats you may need to be aware of depending on what you're going to do with it. Some are noted in detail on the XPostFacto website, while my personal experiences are noted here.)

The PowerCenter 120

Some handy items you'll need to install MacOS X:

  • MacOS 9 CD
  • MacOS X CDs (For me it was 10.0 installer and 10.1 upgrade)
  • Latest version of XPostFacto
  • L2CacheConfig Utility (if you have a G3/G4 upgrade card)

You may want to burn XPostFacto and the L2CR utility to a CD and keep them handy.

Phase One - Install MacOS X 10.0

PowerCenter 120

  • PowerLogix G3 Upgrade Card (CPU: 400, Bus: 50, Cache: 200)
  • 224 MB RAM
  • 4.2 GB SCSI hard drive
  • Seagate TR-4 SCSI Tape Drive
  • Aiwa TR-4 SCSI Tape Drive
  • Exabyte TR-4 SCSI Tape Drive
  • AsanteFAST 590 PCI Ethernet Card
  • ATI XClaim VR Video Card (After the fact addition, see below.)

I bet you might have been wondering how useable the 120MHz version of the PowerCenter would have been. Well, I can't tell you, because this one has a G3 upgrade card in it. But I'd have to say it would probably be slower. Need one? I get a lot of stuff from eBay, but know what you're looking for and be careful. I think you can still buy one new if you wanted to.

This computer didn't have a CD drive, but I did have an old AppleCD 300e Plus on hand. It's slow (2x), hails from March of 1994, but it still works and reads CD-R discs. Using XPostFacto and my handy 10.0 installer CD, I fired it up... and nothing happened.

To make a long story short, it turns out that for some reason, Open Firmware in my clone can't drive the onboard video properly, resulting in a blank screen. Since MacOS X relies on OF more than OS 9 does, the video never came up. The solution? I used an old ATI XClaim VR card that works better. (I say "better" because the OF command prompt still won't show, but the video does come up once MacOS X starts booting. Go figure.)

The bottom line: aside from the onboard video problem, the MacOS X 10.0 install CD was able to load and install without any problems. The includes the use of the USB card and the ATI card, which are listed as possible problems on the XPostFacto page. OS X behaves as if it were installed on a supported machine. It feels reasonably responsive and usable, plus the L2CacheConfig utility helps in this department. Once running, software update installed the 10.0.4 update, also without any trouble.

Phase Two - Upgrading to 10.1

No problem with the 10.1 upgrade. Since this was the "upgrade" CD, the whole process of installing 10.0 has to be done first. After installing the 10.1.5 upgrade, and everything else that needed to be installed from Software Update, the Asante 590 OS X driver was installed. The system was having ramdon booting problems, which I traced to a tape drive on the SCSI bus (see below.)

Phase Three - Using The System

It appears to work well, aside from the minor problems described below. Time will tell how stable it is over the long run. However, this setup doesn't seem to want to cooperate with Retrospect. It's probably a SCSI timing issue, as when it tries to access the tape drive, the bus loops in attention until you power down. But it will work otherwise.

Phase Four - MacOS X 10.2

Running MacOS X 10.2.2 was highly successful. The problem with the tape drive (as described below) has disappeared and it has been running stable for over 24 hours. I added an AppleCD 300i to the internal SCSI bus (I picked one up for $5 from Small Dog), and I have yet to install the Asante driver or run L2CacheConfig. All updates from Software Update were installed, including the 10.2.2 update.

Things That Didn't Work

  • Exabyte Eagle NS8 SCSI Tape Drive
    • Description: This tape drive seemed to cause booting problems, in addition to not being recognized on the SCSI bus if the computer was booted into MacOS X. This tape drive (Along with an Aiwa NS8 and Seagate NS8) was used with Retrospect, which would also only see the other two tape drives. Upon rebooting into OS 9, the tape drive was not recognized on the bus until the drive was power cycled. My best guess is that MacOS X initialized something during the boot process that caused it to be unusable until cleared by a cold boot. A cold boot (before the drive was put into its non-functional state) into MacOS X would sporadically fail until the Exabyte drive was removed from the SCSI bus, or it got locked into its not-recognized-on-the-SCSI-bus state.
      Bottom line: The Exabyte Eagle NS8 does not appear to be compatible with MacOS X.
      Workaround: Problem does not present itself under 10.2.2
  • Onboard "platinum" Video
    • Description: XPostFacto appeared to boot the system. The hard drive was running and the CD drive was loading something, but the video never came up. The Command-Option-O-F key combo failed to bring up an Open Firmware (OF) prompt. Since it sounded like it was working, but of little use without video, a spare ATI XClaim VR video card was installed into the system. While still unable to produce the OF propmt, video through the ATI card comes up a few seconds after the boot process starts. This problem seems to be present on a PowerCenter Pro; no onboard video when trying to enter Open Firmware. As far as I recall, I had never been able to get into OF on these machines even before MacOS X was around. This is probably a ROM defect or something.
      Bottom line: Onboard video on these Catalyst-based clones doesn't seem to work with Open Firmware or MacOS X.
      Workaround: Get a video card. ATI cards seem to work well.
  • Onboard Sound
    • Description: Onboard sound doesn't work under 10.2 on this configuration.
      Bottom line: Well... no sound. =)
      Workaround: Perhaps a USB based sound output device like the SoundSticks would work. (I haven't tried this.)

The Final Word

It works, with some minor issues. Your mileage may vary, but if you've got some time and are willing to play with it, give it a try and see how it works for you. I plan to keep using MacOS X on my unsupported Mac, and it makes an excellent server.

I have noticed that Retrospect and the SCSI bus will start to act up after running for extended periods of time; a cold boot clears things up.

Have a question? Email me at and I'll try to get back to you in addition to posting the answer online.