Tiger OSX - OS9 not recognized as startup volume

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Hi folks,

I have a Mac Mini G4 that dual-boots OSX Tiger ("Shuriken") and Mac OS 9.2.2, each on their own partition.

The OSX Startup Volume control panel doesn't recognize the OS9 installation as bootable, giving me only the OSX partition as an option. It *does* recognize the OS9 partition in general though (e.g. mounts it on the Desktop, shows in Disk Utility, etc.)

OS 9.2 works perfectly fine on the Mac, no troubles when booting via holding the option key on startup. Does anyone know why OSX refuses to recognize the OS9 partition as bootable in the startup volume panel and how to fix that?

Not much of a OSX guy here ... appreciate any help!
 

scj312

Tinkerer
Oct 29, 2021
83
93
18
Mac OS X hides OS 9 from Startup Disk if the machine's "compatible" property in Open Firmware is set to "MacRISC3" (which it is set to on all machines that are "X only.") Presumably this is to prevent confusion after installing a system folder for Classic.

You can change the "compatible" property in Open Firmware to "MacRISC2" and that will cause Startup Disk to show OS 9 again. Here's a bootscript that does just this on my "X only" iMac G4, allowing me to select OS 9 from Startup Disk (it also lets me boot "unsupported" versions of OS X, such as 10.0 and 10.1.)

Code:
\ comment
cr

dev /
" PowerMac4,2" encode-string " MacRISC" encode-string encode+ " MacRISC2" encode-string encode+ " Power Macintosh" encode-string encode+ " compatible" property

boot hd:12,\\:tbxi

(note, this takes effect for only one "boot". You will also need to change the partition ID on the last line for the partition to boot.)