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I know that there was a period of time after Mac OS X came out that new Macs still shipped with Mac OS 9 for a number of reasons (OS X was buggy, better compatibility with Classic apps, etc). This is more of a curiosity than anything, but I'm wondering what the most powerful Mac capable of running Mac OS 9 is, and what the maximum specs are.

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According to Wikipedia, the Power Mac G4 (Mirrored Drive Doors 2003) is the newest and most powerful computer that can run Mac OS 9.

1.25 GHz PowerPC G4 (7455/7455B); can hold up to 2 GB memory (although OS 9 might not recognize all 2 GB).

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I wonder about that 2GB - there are a few models that Wikipedia says have a limit of 2GB but only 1.5GB under Mac OS 9, but the MDD model isn't one of them. Hopefully someone with a MDD can clear it up. – Kyle Cronin Nov 14 '11 at 5:34
Is it the 1.25 GHz processor in the referenced MDD that was the determining factor? That is - is any Mac (laptop, mini, iMac etc. with less than a single 1.25 GHz G4 processor able to run OS9 natively? What about dual processor models of less than 1.25 GHz each? – user16947 Jan 13 '12 at 0:34

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