I was just looking over the enhancements and refinements of Snow Leopard, and noticed the one about a “Redesigned Services menu.” That made me realize just how long it’s been since I even looked at my Services menu.
This thing is out of control. I’m glad Apple’s doing something about it. But as I looked down the list, one caught my eye:

ISA Reference > Lookup ARM Instruction?

No way! I’ve got the entire ARM reference manual on my laptop, with a customized instruction lookup field! This would have been great to know about last quarter, when I was taking Computer Architecture. Still, I’m excited: The Mac OS X developer tools (Shark, it seems) comes with instruction set manual browsing applications for x86, ARM, and PowerPC. They’re not the best for actually reading the manuals; for that, it’s probably better to just peek inside the packages and open the PDF in Preview. But to quickly look up an instruction, it’s fantastic.

And for those who don’t know, these instruction set manuals detail how particular processors (like the x86 on your Intel Mac, or the ARM inside your iPod touch) encode their assembly language instructions. When a student like myself is learning about processor architecture, figuring out how computer processors go about executing instructions, it helps to see how existing instruction sets have been defined. It helps even more to have a quick reference from an assembly language instruction to its digital layout.
Note: It looks like Wolf Rentzch blogged about these a while back, before they were standalone applications. They now live in /Library/Application Support/Shark/Helpers/.