I've searched for this topic for an hour so hopefully I'm not covering old ground.
I have an Intel iMac with 4 GB Ram and a 2 TB hard drive. I need to run some software that works only in pre-lion OS. How can I do this on just this one Mac?
djohn7000


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Moved from "Other OSes on the Mac" to "Mac OS X 10.6 & 10.7" as the more appropriate venue by joemikeb

you can repartition your hard drive (or plug in an external hard drive) and install another OS on the other drive/partition. Unless you muck with the user folders you will be in two different user accounts booted off the different drives. So as long as that's not a problem, and you don't mind rebooting to switch, there's your solution.

Assuming, of course, that the Intel iMac in question didn't ship with Lion.

That caveat is generally true, but it appears that (some of) the early Lion Macs could boot into Snow Leopard. Still, not knowing the specs of this particular Mac makes V1's solution a bit iffy.

Right- my Intel Mac was running Leopard when I bought it.

I'm not sure what you mean by "was long as you don't muck with the user folders" What is the danger I don't see?

Another solution a friend suggested: using "Parallels" thereby avoiding having to reboot to switch. Does anybody have any experience here?

I don't think Parallels is applicable for your purpose; it allows you to run OS X side-by-side with Linux or Windows, but I don't think it allows you to run two different versions of OS X.

This TechSurvivors thread is an interesting read.

I think I read somewhere, that the newer machines do not have the SL (required) kexts installed. What it would take to custom install them, I haven't a clue, though I suspect significant system instability would be the likely result.

Perhaps others, who truly understand kexts and really know where of they speak, will add the proper insight to the matter.

kexts are mainly hardware drivers. The big thing is they are loaded on-demand during boot usually (tho can sometimes be loaded or unloaded on the fly) but if the hardware claims the computer REQUIRES support for a piece of hardware, and no kext will claim it, you'll get a panic with "no supported drivers found for platform xxx".

If the driver isn't found but not essential, something won't work. Could be fan management (fans ramp up) or camera or mic don't work, etc. SOMETIMES you can copy kexts from one computer to another, but they are often OS version specific.

You'll run into both problems when trying to use say, a 10.6.3 retail install disc on a somewhat newer mac that shipped with say, 10.6.6. The restore disc may not be able to boot, and you have to boot the mac in FWTDM and cable it to an older machine that CAN boot the 10.6.3 disc, install it over firewire, then get the 10.6.8 combo run on it before it will boot on its own. The combo updaters tend to have the catch-up kexts and will clear up problems.

Another example, some of the early macbooks would boot off the 10.5.6 restore disc but the fans and wifi wouldn't work right after booting, until the combo updater was run.

Sometimes the combo updater won't do it. One line of imacs wouldn't have a functional camera even after the combo updater was run, you had to copy over the kext. But I've tried doing things like that recently and have gotten error messages telling me there was a kext with improper security settings or that wasn't installed properly etc, and it refused to use it. Not sure what's up with that.

Thanks, everyone. I think you have removed all my doubts and I will proceed with partitioning the hard drive and installing Snow Leopard.
Dale