These deserve their own space. I’ll share what I know here, links to where you can learn more, and open up the world of Big Iron.
I got my start in a mainframe shop, the IT department’s Help Centre at CP Rail. Mainframe is like speaking a different language: CICS, abends, Roscoe, TSO, JSL, IMS. Let me clear up a couple of key misconceptions. One, most people think these are obsolete. But no. They are what run our banks and finances, governments. Anything really important is on a mainframe. Second, by virtue of being a mainframe, they are kept sequestered, unsullied by external contact, and therefore impervious to harm. No. Even though they are incredibly reliable, with incredible uptime and processing speed, they can be infected and are increasingly connected.
I know two guys … Yes, I do. Chad Rikansrud and Phil Young are security experts on mainframes, because they dared to challenge the policies in place on mainframe security. It’s a good thing they did. What they’ve been learning means we have serious work to do, because you can bet the attackers are already there. This is their talk that started it all for me:
Mainframe Security by Bigendian Smalls (https://www.bigendiansmalls.com/)
Soldier of Fortran on Tumblr (http://mainframed767.tumblr.com/)
Fantastic Resources and Where to Find them (Sorry JK – I couldn’t resist!) as curated by Bigendian Smalls
Great place to start is this one.
In no particular order places to start:
ABCs of System Programming Volume 1 (All the ABCs books are good)
The hardcore manuals (Think Intel’s Architecture Software Developer Manual)
Other mainframe or similar links