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Booting Mac OS 8.6 on 1st Gen Clamshell iBooks (Model # M2453)


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I got an early version of the first generation iBook (the one that came in either Tangerine of Blueberry) last year, and it boots OS 8.6. Newer ones which came from the factory with 9.0 (such as my first one, bought new) apparently cannot boot 8.6. The main difference appears to be the boot ROM version.

According to EveryMac:

Early models can run Mac OS 8.6 whereas models shipped after Mac OS 9 was released cannot run earlier versions of the Mac OS. Specifically, if the iBook has ROM version $77D.45F3, it will run Mac OS 8.6, but if it has a later ROM version, it cannot.

What I'm wondering is, is it possible to somehow copy the firmware form an early model (which I have), transplant it into a firmware updater, and use that to downgrade a newer model's ROM to $77D.45F3?





Well-known member
I can't speak to what it would take to replace an existing ROM, but flashrom does support copying PowerPC firmware to a file, even though it's hard for me to determine what's supported given that the listings under supported hardware refer to firmware chips, and I don't know exactly which ones Apple used.

This was the original announcement thread regarding flashrom working on PPC Macs to explain how it works. You might have to find an older version of Ubuntu that runs on PowerPC to pull this off "easily", but there should be something lurking around that you can boot from a CD-R with a recent flashrom on it. If you can't just download it from the package manager "apt-get".

I believe flashrom also has the capability to overwrite as well as dump the existing ROM. Chances of bricking your Mac are high since I haven't seen anyone do this yet. However, this is the tool that people that like to take risks use to unofficially upgrade Mac Pro firmware in a Mac OS X GUI wrapper, such as upgrading a 4,1 to resemble a 5,1.

YMMV, especially considering Open Firmware is certainly not exactly the same as EFI and UEFI.

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