how do I install rosetta 1 on osx 10.6?

Just spun up the 10.6.3 DVD on my old White MacBook running Snow Leopard and yes, Rosetta is a checkbox in the Optional Installs package. I see no standalone download for Rosetta 1 on the Apple Support downloads site, so it would have to be obtained from the 10.6.3 DVD and the optional package. I don't know if subsequent Snow Leopard combo updaters automatically installed Rosetta 1 if it was found to be missing from that DVD installation.

Rosetta should automatically run when you attempt to run it within Mac OS X.

If for some reason it isn't, check that there isn't an option to do so in Finder's File menu -> Get Info of the application.

Please note, Classic is no longer available in 10.6. If this application does not have an option to run in Rosetta and it has a do not enter circle in gray over the icon, then it probably is a Classic application.

Open the System Profiler in Applications -> Utilities to see the kind of application your application is. That will verify if it is Classic or PowerPC. PowerPC is Rosetta based. Some Rosetta applications won't launch because they need PowerPC drivers. I've also see the internet needs to be accessed to initially download the software for Rosetta if it wasn't during installation.

It would depend on how that USB stick was created. Otherwise, I know that the official Apple 10.6.3 DVD has that optional package installer on it.

I think it was an optional install on the Disc.

I believe that the original Rosetta on Snow Leopard (10.6.8) was part of the operating system installation and not a user-installed option. It was only intended for compatible PowerPC applications (e.g. AppleWorks) with all of their components present.

A stick? Apple only ever released Snow Leopard on a DVD. There's no way for you to know what else may be tucked into that installer that shouldn't be there. I'd toss it in the trash.

Get a genuine disk. $30 with free shipping is pretty typical.

Leopard is 10.5.x for Powerbook. 10.6 or later will not work with Powerbooks.

10.6 and 10.6.3 were both released as retail release, and now only available on places like eBay for Macs from January 7, 2006 through March 15, 2010.

MacBook, MacBook Pro, iMac Intel, and Mac Mini and MacBook Air models from before March 15, 2010 all supported the retail install.

These never said OEM, upgrade, or Dropin or system specific

System specific discs were prebundled with August 28, 2009 to July 22, 2011 Macs and only could be used with the Mac of that vintage and model.

If the firmware update was applied on March 15, 2010 to July 22, 2011 Macs, internet restore was possible with command-option-shift-R. Otherwise system specific installs, and bootable installs compatible with those Macs were the only ways to get an OS on them using cloning software.

10.6 Server was available and could run under Parallels virtualization on newer Macs to get Rosetta 1.

Rosetta/PowerPC Applications and Lion and… - Apple Community

All these discs are hard to find presently.

The MacBook Airs of the time did come with a USB stick system specific install.

Generally system specific installs could not be used with other models or different vintages of models. I'm not familiar if there were restrictions with those, but I had only briefly encountered them in 2010.

Thanks, a brody. That's interesting. I had never heard of any Apple OS released on a USB stick other than the reluctantly produced version for Lion.

Heck, I can't even find a reference to any official version of Snow Leopard on a USB stick. Only how to create one of your own from the DVD.

The original gray disks that would have come with a 15" PowerBook was Leopard, 10.15.x.

Apple ran out of Snow Leopard and Snow Leopard Server disks to sell. But there's plenty of the retail 10.6.0 and 10.6.3 disks for sale on eBay (per my link) and elsewhere.

Yup, I just typed in the wrong name. I was looking right at the OP's description, MBP, for MacBook Pro, and still wrote Powerbook.

The Mac in question here has an Intel Duo 2 CPU. So Snow Leopard will of course run just fine on it. I picked up the notation of 10.15.x Leopard from everymac.com. That's what they list for this model.

As you know, there was never a retail disk of Leopard for Intel Macs, but the gray disks that came with the very first Intel based Macs were for Intel CPUs. That was the only way to get Leopard disks for Intel Macs.

All of this gets tossed out the door if the firmware update you mentioned was applied. Then that Mac will only boot to Lion as the oldest OS it will recognize as an installer. As you also already noted, the only way to get Snow Leopard on such a Mac is the restore a full backup you made before applying the firmware update.

I think you are right.