Of course I'll never in my life even get to see one of those expensive monstrosities... maybe I'll get to emulate it, but my questions will still remain unanswered.

So... I know that on most systems, there's a PC of some sort running OS2/warp which boots up and controls the mainframe or loads images on it.

But... What about everything else? What kind of CPU architecture does System Z use? How many CPUs/memory? What kind? How powerful is it? What kind of OS can it use (other than Z/OS)? What the hell is Z/OS? How does one access a mainframe? What are its applications and what purpose do they serve? How does one develop for this platform? How is it different from System i/ASXXX? There's Linux for System/Z, but how does one use it?

I'm asking this question here because if you do any search for IBM mainframe systems, all you get are powerpoint presentations and youtube videos with flowcharts, or some dude in a suit, sporting a conservative mustache talking about a new era of computing.

Hello, appreciate your interest in our Mainframe and Z/OS. We do have an official course here: https://www.ibm.com/training/course/ES05G

Self-paced or instructor led available.

It does cost money of course.

There is a cheaper version from Pluralsight: https://www.pluralsight.com/courses/z-os-mainframe-introduction

These should answer all of the questions you have.