OS X on Pre-G3 PCI Power Macs

In about 1997, Apple promised that all Macs made then would be able to run Mac OS X. However, when X was released many people were somewhat disappointed to see that it requires a G3 processor to install.

In reality, Mac OS X doesn't require a G3 processor; it can work on older PCI Power Macs. But is yours compatible? Currently, OS X can be installed on a 7300, 7500 (with an upgraded processor; it's not compatible with the 601 processor), 7600, 8500, 8600, 9500, 9600, and several clones.

How do you do this? Other World Computing hosts the free XPostFacto program, which lets you install OS X from an unmodified install CD.

Before you run out to OWC and download the application, you might want to think of a few things. First of all, do you use your pre-G3 Mac for any important work? If so, you probably don't want to install X on it. Second, do you have a lot of legacy peripherals? No USB or FireWire card? Forget printing out a document - the serial port doesn't work with older non-laser printers.

Planned to play a CD in your Mac? Oops, it seems that some CD-ROM drives won't play audio CDs in OS X. However, there does appear to be a patch that may fix the problem. Still, if you need to play an audio CD on your Mac, you may be better off sticking to OS 9.

What about performance? We already know that OS 9.1 on a 200 MHz 604e runs at a reasonable speed. On a 132 MHz 604, it runs slightly slower, but it is still tolerable. We also know that OS 9.1 runs amazingly well on a 300 MHz G3. It has been found that OS X decreases that performance dramatically.

You think you could tolerate your 200 MHz 7600 feeling about 100 MHz slower?

It's not only the processor that will slow things down. It's the bus speed as well. Remember that these Macs run with bus speeds of around 50 MHz. Compare that to the 100-133 MHz bus speeds we have today.

This brings us to G3 upgrades. Even though, as I said, it's not just the processor that's slowing performance down, a faster processor will help compensate for the slow bus speed. A 400 MHz G3 card will not feel as fast as a 400 MHz G3 computer from Apple, but it will make OS X feel faster.

I'd like to hear from anyone who has successfully run OS X on a pre-G3 Mac, especially with the stock processor. I'd be curious to know how the speed compares to that of an actual G3 or G4 (especially in application launching times and startup time). Perhaps I will include some sort of graph in a future article if I get enough responses to do that with.