Is Snow Leopard/Lion simply an interface?

Question

I happened to purchase a 64bit iMac just before Lion came out. But Xcode 4 was in my installation discs.
So is the assembler for 64bit instructions on the machine, on the Xcode discs, or on the Snow Leopard/Lion interface (if those are really just interfaces)?

Answer 1

You all probably know this already, but part of this might be interesting to some:
http://developer.apple.com/library/mac/#documentation/developertools/reference/a ssembler/010-Using_the_Assembler/using_asm.html#//apple_ref/doc/uid/TP30000820-T PXREF101
So there is an assembler that runs from the terminal. It comes from the GNU/GCC 'free' project, which is actually strictly controlled. I was concerned that Apple's standard of assembly code to binary was all coming from 'shareware' but the GNU/GCC is a strictly controlled project (with freedom-loving standards for participation).
So, basically, the answer is that the assembler is available through the terminal shell commands, but it is coming from the GNU/GCC project. So there is really no difference between inserting assembly language into an xCode project interface and putting the assembly code together on a more 'basic' or 'fundamental' level. The xCode interface is as fundamental as it gets, except that it's pleasant to look at and easier to use.
But it makes perfect sense for any programmer to learn the architecture of the IA-64, and learn to add assembly language in the 3-directive bundles, I think. It just provides a better understanding of the capability of the IA-64. At least that's the direction I'm going, before heading back to study the standard libraries.
I can't believe I'm at least a decade behind on this, and I'm still at least a decade ahead!