Editing Macintosh Old World ROM (section)

== Alternative Operating Systems ==

=== Boot Method Limitations ===
The ROM-centric boot process creates challenges for alternative operating systems:

'''68k and NuBus Power Macs:'''
* Must boot Mac OS first
* No direct boot from alternative OS
* Requires Mac OS-based boot loader
* Examples: BootX for Linux, Basilisk II for Mac OS on Mac OS

'''PCI Power Macs:'''
* Can modify Open Firmware settings
* Possible to boot directly with proper OF configuration
* Requires compatible boot loader (quik, yaboot)
* Still defaults to Toolbox boot without intervention

=== BootX Boot Loader ===
The most common solution for running Linux on Old World ROM systems:
* '''Mac OS application''': Runs from within System 7/8/9
* '''Kernel loading''': Loads Linux kernel and initrd into memory
* '''Hardware takeover''': Disables Mac OS and transfers control to Linux
* '''System extension option''': Can intercept boot process automatically

=== A/UX Compatibility ===
Apple's Unix implementation required special consideration:
* '''Mac OS dependency''': A/UX required Mac OS ROM Toolbox
* '''Modified boot sequence''': Special boot blocks load A/UX kernel
* '''Toolbox emulation''': A/UX provided Mac OS compatibility layer
* '''Hardware requirements''': Only specific 68030/040 models supported