Since I repaved my MacBook with Snow Leopard this morning, I was about to reinstall one of the applications I use, Adobe Flex Builder 3. When I opened FB3's installer, the following was displayed:
(Dialog says: "To open FB3_Mac_Installer, you need to install Rosetta. Would you like to install it now?")
Questions:
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What exactly is Rosetta? (I have an idea, but your expert answer is probably better than my understanding.)
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Why don't I already have Rosetta included with my fresh from-scratch Snow Leopard install? It looks like Rosetta comes from Apple. Why would Apple decide to not include it? Would this have been an optional install from my Snow Leopard DVD, or is it only available online from Apple?
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Why would a relatively recent installer such as Adobe Flex Builder 3 require Rosetta? I've installed many other packages already and hadn't seen this message, until now. Is Adobe doing something silly?
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Is there any performance or other impact or concern with having Rosetta installed?
Best Answer
Rosetta is a piece of software through which PowerPC code can be run on an Intel Mac.
Snow Leopard is Intel-only. Apple essentially wants the few remaining developers who still have PowerPC-only software to recompile it for Intel. Rosetta is an optional install which is available on the Snow Leopard DVD.
Adobe's Mac range is possibly the worst-made set of applications that anybody actually uses. See Adobe UI Gripes for more Adobe hating.
Only when you're running PowerPC code. Simply having it installed will not decrease performance. There is little reason for you not to install it; it's a small package that allows some software to be run slowly that otherwise couldn't run at all.
I've made this CW so please edit this if you have something to add.