Is there anything particularly different about mainframes compared to working on a server besides it probably being a different operating system? I assume it has a command line and you ssh into it somehow (or something similar)? Or are they still running punch cards or something?

It's a very different (and foreign) environment. Job control language, how data is stored... if you come from a typical modern server environment you'd be pretty lost in the mainframe world.

In 1996 I took a TCP class in Chicago for which it turned out I was overqualified; it was mainly how to use tools like telnet and FTP.

But what I remember most: the two other students were mainframe programmers, and they were just as baffled by my world as I was by theirs. It really was an entirely different computing paradigm, although 30 years later I probably have enough experience to make more connections than I could then.

You can find videos on Youtube, it's like an IDE where you would do everything in a user interface with menus, but the interface is a 25x80-char screen only :-) Everything is "almost" similar to a Unix system, but with different names, files are called "datasets", there are very few tools, but every one of them has a language to do very complex tasks...

I know two people that spend some of their time writing COBOL for a major bank. They do find that part of the job pretty boring, it is basically just writing down SQL queries in a COBOL file and then trying to get passed their 50 year old development workflow (merge to master, then do testing in a testing environment, then get code review..).

I would love to do that for a living assuming it has job security, no crazy obsession with "velocity" and sane working hours.

The goal of SuperBOL (https://superbol.eu) is to allow companies to migrate from mainframes to Linux workstations, to get a "modern" experience of development and deployment.

Indeed, mainframes are hard to get access to, and require a training by themselves, I have worked on Linux and Windows for years, and development on a Mainframe has nothing in common :-)

I think the problem of COBOL is not only the lack of COBOL developers, it is the lack of expertise in COBOL environments, because they have become obsolete (both on mainframe and proprietary tooling for Linux/Windows). By providing a modern environment on Linux for COBOL, our goal is to solve the hardest part of the problem, as learning COBOL itself is not so hard for existing open-source developers...

I imagine 99% of the work is to be done on "obsolete" mainframes as you call them. I doubt there is much new development in COBOL in 2024.