As promised last week we will be covering the topic of emulation as we move closer to the big switch, last week we covered how Apple could play the naming game, this week we will be looking into Rosetta, Apple’s name for the PowerPC emulator.
It's True
Rosetta will ship with every Intel version of Mac OS X, quite simply it translates PowerPC binaries into Intel binaries on the fly providing a layer of emulation for PowerPC applications to run on the new Intel machines.

Now lets delve deep into how exactly Rosetta will work and what it will do. Rosetta is based on Transitive Corp’s QuickTransit technology and can translate the following instruction sets:

  • G3
  • G4
  • AltiVec
  • OpenGL

As you’ve probably worked out the G5 instruction set is missing from this list and that simply because Rosetta is not designed to emulate G5 code, this quite simply means that development of such applications will require re-compiling to Universal Binaries (more on this later).

Rosetta does not run the following:

  • Mac OS 9 applications
  • System preference code
  • Kernel Extensions
  • Java applications with JNI libraries

It is currently hard to know how well Rosetta will translate code on the fly as systems are rare and those using them wouldn’t risk losing them by releasing benchmarks but surprise, surprise some people have and the figure sits somewhere between 60-80% native software speed, which lets me honest isn’t bad. This figure was released before Apple officially announced OpenGL and AltiVec support so it is quite possible that this figure has increased further.

For those developers who have G5 code only applications or wish to have their applications work natively on Intel systems they must recompile their applications using a thing called a Universal Binary.

A Universal Binary is an application that can run natively on both Intel and PowerPC systems, Universal Binaries are often referred too as Fat Binaries as they contain more code, as we mentioned last week a similar technology was used in the switch from 68k to PowerPC. To aid developers in creating Fat binaries Apple updated Xcode to version 2.,1 which allows the creation of Fat Binaries.

Here at World of Apple we believe Apple has gone the right way about the switch, offering two very concise methods of getting applications to run and giving developers enough time to develop for one of those methods, the question is how well will it all run?

Next Week - We move onto our countdown to MacWorld San Francisco