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Most of the Apple G4 models dropped support for natively booting Mac OS 9 and only support Mac OS X. Through a lot of hard work the folks at MacOS9Lives.com have been able to get Mac OS 9 booting on most of these systems. Below is a compiled list of tutorials from my own experiences, and the others from MacOS9Lives.

Unsupported Mac OS 9 Install Disc Image

There are a number of disc images available for multiple models at MacOS9Lives.com. I recommend burning these CDs with an application such as Toast Titanium.

Models known to work

  • Mac Mini - All G4 models
  • PowerBook G4
    Best Models: [5,1], [5,2], [5,3], [5,4]
  • eMac G4 (1.25Ghz)
  • Power Macintosh G4 Mirror Drive Doors (1.25Ghz FW800)
  • iMac G4

Hardware Support

Most of these machines have newer hardware that was never available for Mac OS 9, therefore there are missing drivers and system components - not all devices will work. The most common issues are with unsupported sound cards, video cards, Bluetooth, and Airport cards. The most success has been achieved with machines that have an ATI Graphics card/chip-set. Graphics acceleration is unavailable unless you have a graphics chip-set that is officially supported under Mac OS 9.

Preparation

Before you install Mac OS 9 on your machine, your Hard Drive must have the Mac OS9 disk drivers installed. You can do this with either of the following methods:

  • Boot from an OSX install CD, open ‘Disk Utility’ and partition/erase your HD with the ‘Mac OS Extended’ format. Ensure the option ‘Install Mac OS 9 Drivers is ticked!
  • Connect the Hard Drive into a computer already running Mac OS 9 and re-partition/format it with the application ‘Drive Setup’

Booting into Mac OS 9

This is achieved by performing some modifications in Open Firmware, and tricking your machine into thinking it has a different CPU version (This does not effect performance in OSX).

  1. Boot into Open Firmware by holding Command + Option + O + F when turning on or restarting your machine.
  2. Once Open Firmware has loaded you will need to open the NVRAM editor by typing nvedit, and then press Enter.
    dasdasd
  3. Open the CPU device by typing the following:
    dev /cpus/PowerPC,G4@0 then press Enter
  4. Make the following modification to the cpu-version property:
    80010201 encode-int " cpu-version" property
  5. Enter device-end to close the CPU device.
  6. Press Control + C to close the NVRAM editor.

Note: If there is text present after you open the NVRAM editor, these are settings that are already stored. You can either clear this by holding the delete key, or press the down arrow key for a new line, then you can start typing. When you open the editor you can think of it like you're viewing a document, but you're only seeing one line at a time. You can scroll through lines with the arrow keys. Once you're on a blank line you can enter any settings you'd like to add.

Performing the above only allows you to boot into Mac OS 9 temporarily. These commands need to be stored in the NVRAM so they persist between boots. Running the commands below will store this information in the NVRAM and restart the machine.

nvstore
setenv use-nvramrc? true
reset all

Your machine will restart and you should now be able to boot from the Mac OS 9 For Unsupported G4’s CD from MacOS9Lives.com.

Any data stored in the NVRAM will be erased if the machine loses power (e.g. the main power cable is disconnected from a wall outlet/power adapter, or has a flat battery. Since this is a lot to type each time you lose power, a better way of performing the above is to write everything into a script, and tell Open Firmware to run it at boot. Now if you lose power you only need to remember one line to enter into Open Firmware.

Writing an Open Firmware Script

Open Firmware Scripts can be created with the application ‘SimpleText’, or any other text editor that will allow you to save .txt files without any rich text content. Open SimpleText and add the following to your new document.

\ comment
cr
dev /cpus/PowerPC,G4@0
80010201 encode-int " cpu-version" property
device-end
boot hd:,\\:tbxi

The beginning of the script must contain an Open Firmware \ comment, followed by a carriage return cr.

The last line sets the boot device to the default HD so the machine continues to boot after running the script.

Save the file to the root/base directory of your hard drive and call it ‘bootscript’.

Some machines have incompatible soundcards and will crash or refuse to boot OS9 after the above steps have been taken. If this happens try adding the following to the NVRAM, or your script.

dev /pci@F2000000/mac-io/i2s/i2s-a " screamer" encode-string " compatible" property device-end

An example of this would look like the below:

\ comment
cr
dev /cpus/PowerPC,G4@0
80010201 encode-int " cpu-version" property
device-end
dev /pci@F2000000/mac-io/i2s/i2s-a
" screamer" encode-string " compatible" property
device-end
boot hd:,\\:tbxi

Mac OS 9 does not have good thermal management for unsupported systems. If you're worried about elevated hardware temperatures under Mac OS 9, see the article Controlling System Fans with Open Firmware. You can combine both scripts to make things easier.

Installing from a CD

After booting successfully into Mac OS 9 you will need to install the system onto your hard drive. It’s a good idea to erase your HD with ‘Drive Setup’ if you don’t have anything important on it already.

If you install from one of the MacOS 9 Lives CD images start the restore process and follow the instructions. Once the restore process has completed DO NOT restart your machine. Open the ‘System Folder’, then ‘Extensions’ and remove the ‘Multi Processing’ folder. Move this to your desktop or delete it. This extension causes some incompatibilities and will freeze the system during boot.

If you install from any other CD/image the same step is recommended.

Once the system is installed and you have removed the ‘Multi Processing’ folder, restart the machine.

Video/Monitor Settings

When you've booted into the newly installed system you may be stuck with a small screen resolution.

If your machine has an ATI Graphics chip-set it is highly recommended that you add this driver modified by darthnVader (alternative link) from Mac OS 9 Lives. This adds better compatibility with more resolutions and color depths. Expand the file with Stuffit Expander and move the extension to your ‘Extensions’ folder, which is located in the System Folder, then restart the computer.

If you've still got a small screen resolution, or limited colour set open the ‘Monitors’ control panel and adjust the monitor arrangement. First drag the menu-bar from the smaller screen to the bigger screen. This sets the default desktop. Next, change the screen arrangement by moving #2 to the left before #1.

 

Woohoo!

You should now hopefully have a working Mac OS 9 system!

Comments

abdalwahab orabi

speakers working great but screamer fix can not open the link because it is broken is there any other link or way of explanation by the way "you may be stuck with a small screen resolution. If this happens open the ‘Monitors’ control panel and adjust the monitor arrangement. Try swapping the right-hand screen over to the left etc. To change the default desktop, drag the menu bar across to the desired screen." i did not understand what you mean

Greystash - Admin

If the speakers are working fine then it's likely you won't need the screamer fix. If they aren't functioning correctly you don't need to download anything, just add the screamer fix code detailed above to your Open Firmware script.

abdalwahab orabi

i flow you instructions on my ibook 12 early 2004 and i works great except screen resolution stuck at 640*480 ant the link you provided is broken and i can not fix the screen resolution

Greystash - Admin

Hi there, I've edited the page to explain the monitor/resolution problems in more detail. I've also added an alternative link for the video driver, so see above for these edits.

RetroDelirium

I followed your guide and now have a working MacOS9-capable eMac 1.25GHz! The sound only comes out from one speaker though, i don't know if a fix exists.

Greystash - Admin

Hi there! That's great news, congrats! Do both speakers work correctly under OSX?
If they do it might be a driver compatibility issue under OS9.

If you haven't tried the "screamer" fix mentioned above you could try that, otherwise if it's already present in your script/NVRAM you could try removing it.

Also, this probably isn't the issue but check the speaker balance in the Sound control panel.

Irene

Wow :) !

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