A long time ago in a processor architecture far, far away, mikeb commented, "the help file for the Debugging Tools for Windows package has (or maybe "had") really, really good Itanium information in the Debugging Techniques/Processor Architecture section."
I'll take that as a compliment, because I'm the author of that part of the documentation.
The story begins with a "Bluffer's Guide to the Alpha AXP Processor" document that I wrote as a way to capture the information I learned from reading the processor manual. That document led to a little side gig doing brownbags for teams interested in bringing their developers up to speed on this Alpha AXP processor thing. The recently-completed Alpha AXP series was an expansion of that original document.
When the Itanium project started up, Richard Bond taught me the rudimentary elements of Itanium assembly language. As I recall, it happened only by chance: The two of us happened to be in the same meeting room at the same time, and there was some time to spare.
Armed with a very basic understanding of the Itanium, I dove into the official documentation from Intel and emerged with a corresponding "Bluffer's Guide to the Itanium Processor" document. That document served as the basis for the Itanium section in the Debugging Tools for Windows package, and the Itanium series from 2015 was an expansion upon that document.
With two new processor architectures under my belt, I developed a reputation for being "the guy who knows all about these exotic processors." (Where "exotic" has the rather parochial definition of "anything that isn't x86 or x86-64".) When Windows 8 was ported to ARM, people just assumed that I knew ARM assembly language too.
I didn't, but I found the documentation and taught myself. Once you know a few processors, adding another one to your repertoire isn't that hard, assuming it's similar to one you already know.¹
So at this point, I may as well try to live up to my reputation. I have written up series for the other two defunct processors that were at one point officially supported by Windows NT: The MIPS and the PowerPC. They'll show up someday.
¹ This is also why I stick to Germanic languages: Once you know English, German, and Swedish, adding Norwegian to the collection isn't so hard.