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Trying to upgrade G5 iMac to 10.5 from DMG

I have an old iMac G5 with 10.4.11 on it. It has a bad CD drive, and doesn't seem to even power an Apple CD/DVD superdrive when connected by USB. So I have a .DMG file of my 10.5 install disk. First I tried to copy it onto a Firewire hard drive, but the iMac won't even see the drive (FW tab in About this Mac sees nothing), even though two other (Intel) Macs can see it fine. I've also put it on a USB flashdrive, but when I run update to 10.5, it says "reboot to begin" and then just reboots into its normal 10.4 on the internal disk. What am I missing - how do I make this DMG to update my 10.4 iMac? I also see that the iMac can boot off the network; is there a way I can get one of my other Macs to serve the 10.5 update via network so it can boot off of that? Or, can I make the USB drive (32 GB) an actual boot drive and boot the iMac off that??

Posted on Jan 24, 2016 4:32 AM

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11 replies

Jan 24, 2016 5:27 AM in response to Michael Levin

Most PowerPC Macs can only start up from FireWire external drives (not USB). Older USB ports (even if 2.0) may not supply enough power for a USB optical drive, if it's the type that gets power from the USB port (not its own power supply). And it would not work for this purpose, because it's USB, not FireWire. That's why the USB flash drive did not work either, to start up the iMac.


So, it will have to be that FireWire external drive. What kind of FireWIre external drive is it? Is it a 2.5-inch drive that is powered by the FireWire port, or a larger 3.5-inch drive that has its own power supply? The type with its own power supply is preferable, to not rely on the port for power. Is it connected directly to the iMac's FireWire port? If you have more than one FireWire cable, have you tried more than one (to rule out a faulty cable)? FireWire 400 (older type) or FireWire 800 (newer type)? Either should work, as long as you have the right cable. Which type of FireWire port does the iMac have?


If you can get it recognized by the Mac, you can use Disk Utility to "restore" the .dmg file to the FireWire drive. The FireWire drive needs to be erased to have partition scheme of Apple Partition Map and format of Mac OS Extended (Journaled), to be bootable with a PowerPC Mac.

Jan 24, 2016 11:28 AM in response to Michael Levin

So, it sounds like you have ruled out the external drive (and the cable) being faulty, because it can connect to your two other Macs. You tried more than one FireWire port on iMac, if it has more than one?


Can you get any other FireWire device (if you have another FireWire device) to connect to the iMac?


You can try doing an SMU (power management) reset. Depending on iMac G5 model, this may be shutting down and disconnecting it from power for a few minutes, and then reconnecting it. Or there may be a more involved procedure. This article has more details


http://www.ehow.com/how_2091889_reset-smu-imac-g5.html


In case it matters, how is that external drive formatted? Connect it to one of your other Macs, and run Disk Utility. Select the drive (not the volume indented below) in the sidebar. What does it say for Partition Map? I'll assume Format is Mac OS Extended (Journaled), and not something odd...

Jan 24, 2016 6:05 PM in response to Kenichi Watanabe

so I found out that the iMac can be seen as a FW disk if I put it into Target Disk mode and attach it to another machine, but it does not see any other disk (e.g., another laptop in Target Disk mode) any more than that drive... What about booting/installing into 10.5 over the network? I see that there's an option when you choose a Boot Disk in System Preferences to boot over the net, how do I serve 10.5 from one of my other machines - where is it expecting the networked OS to be? And I think I saw somewhere a native Apple utility for updating a Mac over the network (install an OS X) but I can't remember the name.

Jan 25, 2016 4:19 PM in response to Michael Levin

I think the NetBoot option is for an environment, like at a school, where there is a server running with an existing disk image of a system. I don't think you'll be able to do it that way, with only a disk image of the install disc.


What is your other Mac? Is it old enough to boot the Leopard installation disc, from its working optical drive? If so, you may be able to put the iMac G5 into target disk mode, and connect it to the other Mac's FireWire port. Then, use the other Mac to run the Leopard installation, targeting the iMac G5's hard drive.

Jan 26, 2016 2:02 AM in response to Kenichi Watanabe

From what I've read, you don't want a different Mac to be doing the install via Target disk mode because the wrong drivers etc. will get installed - you're supposed to put another mac into Target disk mode and install onto the iMac using the other mac's DVD drive. And that's not working because my iMac is not seeing any drives via its FW port (although it itself can be seen as a target disk via FW). I could have sworn I saw some utility that allows installing an OS X over the network.

Jan 27, 2016 2:13 AM in response to Michael Levin

Preferably, you want the Mac using the system to do the install. However, with Mac OS X (unlike Mac OS 9), the system is complete. I wanted to try Leopard on my old PowerBook G4 (not officially supported so cannot install directly). I used my PowerMac G5, with the PowerBook in Target Disk Mode, to run the installation, and it worked. And Leopard is Universal, so the other Mac can even be an Intel Mac (as long as it can run Leopard). I had a small external FireWire drive that I used as a maintenance startup disk, and it could boot my PowerPC Mac and Intel Mac. I would have advised doing it the reverse way (with other Mac in Target Disk Mode), except you already told me the iMac G5 was not seeing anything connected to the FireWire port.


You didn't tell me what your other Mac is, so it may not work at all, if it's too new to boot the Leopard install disc from its optical drive.


Here's another idea that might work (although I've never tried it this way). In Leopard, you can add a partition to an existing drive with data, without erasing the data. Use Disk Utility to add a small partition to the iMac G5's internal drive. 10GB should be enough. Then, use Disk Utility to Restore the Leopard installation disc's disk image to that small partition. When that's complete, eject the disk image and set System Preferences Startup Disk pane to start up from the small partition (which is now a duplicate of the installation disc). If you can get the iMac to start up from that partition, run the installation targeting the other (primary) partition that currently has Tiger.


NOTE: You should not do this if the iMac's current internal drive volume has low free space remaining (50GB or more should be good to add a 10GB partition). Adding a partition involves moving existing data on the drive, to clear out a contiguous area on the drive media (at the "end" of the drive) that is at least (in this case) 10GB. The more free space you have, the better, for this operation. If you don't have a recent backup of the iMac's internal drive, you should do one before adding a partition. You should already have a backup, since you are trying to do a major system upgrade, which is also somewhat risky.

Jan 27, 2016 3:39 AM in response to Michael Levin

I didn't think that through completely... Disk Utility in Tiger (and earlier) is not able to add a partition (without erasing the drive's data). Disk Utility in Leopard (and later) can do it...


You can use the method (in Tiger) using Terminal that recharges linked to (I'm no command line expert). Or (assuming that "other" Mac runs Leopard or later) you can put the iMac G5 into Target Disk Mode again, and connect it to the other Mac; use Disk Utility on the other Mac to add the small partition to the iMac's internal drive. Now that I think about it more, you can use the same Target Disk Mode connection to Restore the Leopard installation disc onto that new partition, again done by Disk Utility on the other Mac. Then, disconnect and restart the iMac G5 while holding down the Option key to get Startup Manager, where you can select to start up from its new partition.


And definitely have a recent backup of the Tiger's internal drive data. One way to do it (if the other Mac has enough free space) is to use the same Target Disk Mode connection (before doing the add partition) to make a disk image of the iMac's internal drive volume. If the add partition causes a serious problem, or if the upgrade to Leopard causes a serious problem, you can Restore that disk image to the iMac's internal drive.

Trying to upgrade G5 iMac to 10.5 from DMG

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