How to tame a Leopard

HOPE SPRINGS ETERNAL. Apple's Mac OS X 10.5 - not-very-secretly-at-all codenamed "Leopard" - isn't even out yet, but hacks for it are starting to appear.

As we revealed a couple of days ago, Apple has raised the bar still further for Mac-o-philes who fancy upgrading to the latest OS X - whenever it finally appears. The last we've heard, you're going to need a G4 running at a minimum of 867MHz. That rules out a lot of fairly recent machines: lots of early G4 desktops, the first three generations of flat-screen "anglepoise lamp " G4 iMacs, the first two generations of eMac, the first generation of 12-inch Ibook G4 and most of the Titanium PowerBooks</a>. Of the eight revisions of the Tit, only the last two are fast enough; if you've got a 400, 500, 550, 667 or 800MHz machine, well, it's tough tit for you, really.

But that's only the official line.

What the OS X installer does isn't check how fast your processor is running; it looks at the model number of your Mac and compares it to a list of "bad" machines that are officially rated as too slow. So if you've got an upgraded CPU and your box is actually fast enough, well, it won't work.

This problem has come up lots of times before. With every release of OS X, Apple has lopped off some of the older machines and rendered them "unsupported" .

There are several ways around this, though.

If you've got a faster, supported machine, there's an easy way to try. You could just start the old one in Firewire Disk mode, plug it into the newer, faster Mac and install in the normal way onto what is now just an external drive. If that's too easy, you could remove the slower Mac's hard disk, plug it into the newer machine and install onto it, then transfer it back.

Of course, this is no help if you don't have a faster Mac and can't borrow one. In which case, you can make your own install DVD and tweak the file that lists the supported machines. Here's how to do it for Tiger, OS X 10.4. For 10.5, the procedure is much the same, but now, the "OSInstall.dist" file is inside a xar archive, so you need something that can open and create those.

It looks like Leopard is compiled without support for G3 processors, so it probably will never run on G3 machines unless they've got a G4 upgrade installed, but this opens it up to an awful lot more Macs. If you're interested in such things, there's even a mailing list for discussing it, exchanging tricks and tips and getting help.

If all this sounds a bit too much like rocket science, there's a great little tool called XPostFacto by Ryan Rempel that will let you install an unmodified OS X CD or DVD on an unsupported machine. It works a treat - we've used it to install 10.4 onto a couple of elderly Blue & White G3s, and before that, to put 10.3 on a Beige and both 10.2 and 10.1 on a truly ancient 7300/166, albeit with a G3 card in it. It works, it's easy and there's no mucking about with editing config files. A couple of clicks and it's done.

The only snag is that XPostFacto hasn't been updated in a while and nobody has heard from its guru creator Mr Rempel for a year or so. So for now, there's no Leopard version - but then, it is an as-yet unreleased OS. Maybe if a horde of Inq readers stampede over to the site and register their copies of XPF, the sound of cash collecting in his online account might lure him back? µ