Question: I am on a Mac with Snow Leopard (10.6.3). I hear that the assembly language I work with has to be valid with the chipset that you use. I am completely new to this I have a basic background in C and Objective-C programming and an almost strong background in PHP. I have always wanted to see what assembly is all about. 

The tutorial I'll be looking at is by VTC [[link]](http://www.vtc.com/products/Assembly-Language-Programming-Tutorials.htm).

What I want to know is: are the tutorials that I'm about to do compatible with the assembly version on the Mac that I have?

I am completely new to this language although I do recall studying some of it way, way back in the day. I do have Xcode and what I'm wondering is what kind of document would I open in Xcode to work with assembly and does the Mac have a built in hex editor (when it comes time to needing it)?

Answer: 
The assembly language you use is not dependent on your OS but rather your CPU's instruction set. Judging by your Mac version, I'd say you are using an Intel processor - so you would want to learn x86 or amd64 assembly.
The linked tutorials look like they use NASM, which is included with Macs. However, system calls are usually different on different platforms (they're very different between Mac and Linux), and without seeing the tutorials, it's hard to know whether they'll target different platforms (I'd guess not, though). A better bet might be to install [SPIM](http://pages.cs.wisc.edu/~larus/spim.html) and to learn MIPS assembly, which is more straightforward than x86 anyways.