Installing 10.4/10.5 on a Mac with a broken/or incompatible optical drive

Leopard (10.5) is only available on DVD. Tiger (10.4) is available on DVD and there was a limited time "media exchange program" available on CD as well. If you can't get the "media exchange program" CDs you will need a DVD drive to install Tiger. By default you need a DVD drive to install Leopard.

In addition, Leopard requires a Mac with an 867 Mhz or greater processor and officially 512 MB of RAM but it works better with 1 GB of RAM. Tiger requires a Mac with Firewire built-in (not PCI/PCMCIA cards) and 256 MB of RAM but works better with 512 MB of RAM. There are space limitations depending on the hard drive installed, which you can ask about in the forums. Also Macs normally can't have an operating system installed that is older than what they shipped with, as this article explains:

Mac OS: Versions, builds included with PowerPC Macs (since 1998) - Apple Support


Target Mode, which becomes important later in this page, is described here:

How to use and troubleshoot FireWire target disk mode - Apple Support

Leopard is available as an installer that works on both Intel and PowerPC Macs.
For Tiger you must use the installer that shipped with your Intel Mac if your Intel Mac shipped with Tiger.

These installs will work subject to license agreement which is on your disc and the above compatibility limitations:

1. Connect an external firewire drive to any machine.
2. Boot off Leopard or Tiger DVD or CD (Tiger only) and install on external firewire hard drive drive.
3. Clone back to same machine or move said hard drive internally into the same
machine if it has the same interface inside the Firewire enclosure as inside the machine (i.e. if the external Firewire hard drive has a Parallel ATA interface internally and your Mac you are moving to has a Parallel ATA port).

1. Setup an iMac G4 1.25 Ghz in Target mode with a broken or incompatible optical drive.
2. Boot off Leopard or Tiger on a second iMac G4 1.25 Ghz and connect the machine in step one to the machine in step 2.
3. Install Leopard or Tiger.

1. Boot off Firewire DVD drive the Leopard or Tiger installer.
2. Install Leopard on the same machine the drive is connected to.

1. Put a machine with a working optical drive in target mode.
2. Insert the installer in the machine with the working optical drive.
3. Connect the machine with the working optical drive to one without via Firewire.
4. Install to the one without a working optical drive.


1. Put a PowerPC compatible installation DVD in an Intel Mac.  Do not attempt to boot the Intel Mac, just shut down.

2. Set the Intel Mac in Target mode.

3. Attach the Intel Mac to the PowerPC using Firewire.  If needed use adapters that exist such as Thunderbolt-2 to Firewire, or Firewire 800 to Firewire 400.

4. Run the installer of the PowerPC Mac on the PowerPC Mac.

Note: when I say PowerPC compatible Mac, be sure the disc is a newer retail disc, or the disc that came prebundled with the Mac.  Snow Leopard is not compatible with PowerPC.


*These types of install will NOT work*:

1. Setup an iBook G4 1.25 Ghz in target mode with a broken optical drive.
2. Boot off an iBook G4 1 Ghz and connect the machine step one to the machine in step 2.
3. Install Leopard or Tiger

1. Install on an external firewire hard drive from an iBook G4 1 Ghz Leopard or Tiger.
2. Connect an iBook G4 1.25 Ghz to the hard drive in step 1.
3. Clone back from the hard drive Leopard or Tiger (whichever is installed) or if the firewire hard drive case was a 2.5" hard drive Parallel ATA move the hard drive into the iBook.

The reason is that each vintage Mac, and each Mac model has distinct drivers.
In Target mode, the target machine (the machine you held the T key down) is assumed by the installer to be nothing more than an external drive, to be a machine with the same configuration of the host machine because that's the only machine's firmware it can detect.

And by "work" I mean, the installation may appear it succeeds but circumstances such as kernel panics, and unsuccessful upgrades later will make the whole effort in vain.

Either replace the internal optical drive or attach an external Firewire DVD drive to install on a machine whose optical drive is broke, or get an identical Mac model to install using Target Disk Mode. If you don't have an identical machine, don't waste your effort on what can become an even worse install than had you left everything alone.

Compatible Firewire and internal DVD drives require specific firmware and/or third party software. Ask here or visit for compatible drive database.


1. Setting an Intel Mac to be a Target to a PowerPC Mac, or vice versa using Target Disk Mode will not allow you to install to said Mac.

2. Installing an operating system on the Target machine which is older than the target or host machine will not work.

3. Installing an operating system on the Target machine which is newer than the specs allowed by the Target or Host machine will not work.

4. Installing an operating system from system specific discs will only work if the Target and Host machines are identical in vintage and model, and you have the license to install on both, or the Host machine has a newer retail operating system as the sole installation.

A more modern version of this tip is found here:

Using Target Disk Mode to install an operating system