Mac Forum / General / Portable Macs / March 2008

I gather you actually mean you want to install a bootable copy of Mac OS
9 on a 12" PowerBook G4.

Installing "Classic" would mean setting up the Classic environment on
Mac OS X. You can certainly do that, with the software supplied with the
computer.

A friend of mine has managed to get Mac OS 9 booting on a few Mac models
which are officially unsupported (FW800 PowerMac G4, and first PowerMac
G5, I think). I gather he did it mainly by patching various parts of the
system to recognise the new computer model. Some features were not
available, e.g. you can't use Firewire 800 or USB 2.0 high speed in Mac
OS 9 because there are no drivers to support them.

If the computer has substantially different hardware from earlier
models, this approach isn't likely to work. In particular, if you can't
get Mac OS 9 drivers for the video hardware or main logic board chipset,
then it isn't likely to be feasible.

The 12" PBG4 has a new video chipset (NVIDIA GeForce4 420 Go) which was
never used in an earlier model. This could be a show stopper as there
aren't likely to be Mac OS 9 drivers for it. If it is similar enough to
NVIDIA GeForce 4MX cards then there might be a solution.

The memory technology switched to DDR (compared to an iBook G3 or 15"
Titanium PBG4) so this probably means a new chipset and that won't have
any Mac OS 9 drivers.

Airport Extreme and Bluetooth aren't supported by Mac OS 9 either.

Overall I'd say the odds are slim. If someone did manage to get it
booting, some features of the computer wouldn't work.