The process is pretty straight forward and has to be implemented Manually at the moment...
1) Own an MDD FW400 System (Only one really tested so far)
2) Replace "ROM" file with ELN/NanoPico Limit breaking ROM and reboot
3) cross your fingers and test your apps
Although not tested extensively, the ROM has been booted with no issue on the following machines and worked.
PowerMac G4 AGP with GigaDesign CPU upgrade and 2 GB RAM.
PowerBook G3 (Bronze Keyboard)
PowerMac QS
Again remember not a lot of testing, but simple testing. Almost no extensions used for testing.
Also, from my postings above, Sawtooth/1.75GB RAM/Sonnet Dual 1.8GHz, MDD FW800/2GB RAM/Sonnet Dual 1.8GHz, Xserve Rev.1/2GB RAM/Dual 1.0GHz. (Known hardware limitations unrelated to RAM on FW800 and Xserve still apply at this time, plus Xserve requires two Open Firmware commands prior to boot in order to disable the Promise ATA controllers - CD ATA channel or Firewire boot fine then.) My normal full set of extensions was used to boot each system. All of these machines have so far exhibited no abnormal behavior for me, but I still need to perform a suitable 'stress test' that actually accesses the additional 128MB of RAM. I guess I need to follow MacTron's lead...
I also did a basic boot test of the ROM on a Quicksilver with Giga Designs Dual 1.8GHz CPU just to see if it would work at all before moving on to the other machines. QS can only have 1.5GB of RAM installed due to the timing limitations in the official industry specification of the required PC133 DIMMs, hence why this machine has only three RAM slots. G4 Digital Audio has the same limitation. Sawtooth and Gigabit Ethernet models support 2GB because they have four slots running at the slower PC100 timing.
In summary, with the replacement Mac OS ROM file and without any alterations to extensions, you should be able to boot the following machines with more than 1.5GB of physical RAM installed:
- G4 AGP "Sawtooth"
- G4 Gigabit Ethernet
- G4 Quicksilver (both revisions)
- G4 MDD FW400 and FW800
Keep in mind, as I experienced with my Sawtooth, that these Macs are notorious for often being extremely picky about what brands of RAM and timings they will accept. Once you get a config that the memory controller accepts you should be home-free. It's just getting that far that could be challenging right off the top. The same goes for whether or not you wish to run with a third-party CPU upgrade. It should have no bearing on your functionality if you've already got it working properly and booting normally before you test the replacement Mac OS ROM file. Basically what I'm saying is, get your computer booting Mac OS 9.2.2 properly with all the hardware you want, ensuring the extra RAM is recognized by the computer and the OS
BEFORE you try the new ROM file. The only difference you should see at that point is that the Mac OS will include the extra 128MB of RAM in it's available RAM figure. You should still see any additional physical RAM reported as present without the new ROM, just not available to the OS to use.
BTW, the dual 1.8GHz Giga Designs upgrade isn't necessarily the best choice available for OS 9 since the CPU patch for OS 9 booting is volatile because it is held only in PRAM. If it is lost you have to boot into OS X to re-run the OS 9 patch from there. (The OS X patch is separately applied in firmware, therefore not volatile.) Sonnet's firmware patch on the other hand is not volatile and supports booting both OS's. I personally have chosen to avoid unnecessary aggravation by sticking with Sonnet upgrades for my OS 9-booting G4s and relegating my Giga-upgraded Quicksilver to OS X duties.
If anyone experiences anything different to what I have said in terms of difficulties, please be sure to post details in this forum thread. Alright members - get to testing!