[MacinSas]

Hey all. Question for you since I haven't heard or read anything about the subject:
Will OSX 10.5 be available for BOTH Intel and PowerPC based macs? Or is OSX development dead for the RISC processor?

[jmincey]

The word from Apple is that OS X 10.5 will be available for both hardware platforms. At this point, the installed base of Macintosh still consists far more of PPC than of Intel. It would be foolish of Apple to freeze out this majority. I wouldn't be surprised if 10.6 might even be released for both architectures. But 10.7 is a different question.

[icu400]

As long as it is technologically possible, i'm sure apple will release its OS's for both architectures. Lets not forget, that jobs pointed out, that EVERY version of OS X has been compiled for intel as well. Obviously they've gotten the hang of writing the OS for both platforms. There may come a day where we will see OS 11, and that may not be compatible with PPC (like OS 7 isn't compatible with g3 and beyond, and OS 9 isn't compatible with intel) but likely that will be several years down the road.
Fairly good bet is all new versions of OS X will be bootable on powerpc.

[d00d]

Both.
If they went Intel only, that's like locking out 80%+ (I'm favoring Intel adoption rates) of the installed base. If they don't support PowerPC, then software developers will see little reason to adopt new technology in the new version of the OS, effectively killing it from the start.
Besides, Steve Jobs said something along the lines of PowerPCs being supported for years. Going back on that statement will generate animosity in any sane Mac user.

[mdawson]

Everyone else has pretty much covered the bases. Apple tends to be rather good with supporting older versions of their OS for quite some time. Mac OS 9 was declared dead in 2002, but Apple continued to make the Classic environment a part of the standard OS X install until Tiger was released in 2005. Despite no longer being a part of the standard installation Classic can still be installed by the user after the fact from the second installation CD. As a recent migrant to OS X, I still need Classic, but once I can afford to get an OS X version of Vectorworks and FileMaker then complete the re-cataloging of my music collection from MusiCatalog (OS 9-only) to Music Collector, my need for Classic will be no more.
Apple dropped Classic support for Intel-based Macs due to the overhead that would be required to port the environment. Simply put, four years after declaring Mac OS 9 dead, there was no reason for Apple to pour time and resources into developing a Universal Classic environment that would perform as if it were on a 400 MHz G3. Prior to OS X, the Mac OS was not designed to run on Intel-based processors, plus on the Intel platform Classic would not perform at the close to native speeds that is does on PowerPC Macs; Classic would operate much as Window does in VirtualPC.
The key point that some people seem to be missing about Intel-native Mac software is that it is not Intel-exclusive software but instead universal software. The key word here is universal, meaning that developers can compile their code for both platforms instead of having to develop for Intel and PowerPC separately. Therefore, until the demand for PowerPC apps drops off substantially Mac developers will find that it is in their best interest to continue to compile PowerPC versions of their software. The user base for the PowerPC is probably still well over 90 percent and many of the Intel Mac users are switchers that do not have an investment in legacy Mac software to begin with.
The entire point behind universal binaries, as Apple described it, is that software purchases will be a non-issue for the consumer. It is the developers responsibility to compile both PowerPC and Intel installs on their installation discs; from the user point-of-view, we just continue to buy Mac software. When you install the software the installer will determine the proper installation and install the proper version on your hard drive. Unless we start getting reports about software developers releasing Intel exclusive versions of their software you have nothing to worry about.
Unless Apple decides to enrage a great many Mac users, we can expect that OS X 10.6 will run on PowerPC Macs let alone 10.5. It is fairly safe to assume that 10.6 will fall into the four to five year expected lifespan of Power Macs that are as of now still PowerPC systems. Also, given the state of professional Mac software, Apple may need to continue to release PowerPC Macs alongside their Intel equivalents in the pro line for at least the first generation.