Although the standard was withdrawn in 2000, it continued to be used by PowerPC Macs until Apple moved to x86 and EFI/UEFI.
Open Firmware is now actually open source as OpenBIOS (and OpenBoot is also available under a BSD license.) Apparently it can be used as a qemu boot rom for Linux, BSD, Solaris, and PowerPC versions of Mac OS 9 and OS X.[2]
Although the standard was withdrawn in 2000, it continued to be used by PowerPC Macs until Apple moved to x86 and EFI/UEFI.
Open Firmware is now actually open source as OpenBIOS (and OpenBoot is also available under a BSD license.) Apparently it can be used as a qemu boot rom for Linux, BSD, Solaris, and PowerPC versions of Mac OS 9 and OS X.[2]
[1] https://en.wikipedia.org/wiki/Open_Firmware
[2] https://www.openfirmware.info/OpenBIOS