For whatsoever little it's worth, I have fond memories of my mainframe days. One of the wonderful things about them is that they never change. You can sit down

For whatsoever little it's worth, I have fond memories of my mainframe days. One of the wonderful things about them is that they never change. You can sit down and, in a period of weeks or months, read all the black binders containing all of the (usually excellent) documentation, and then you'd know everything about it, forever. Close enough to everything, anyway. Some people might find this horribly boring, but it meant I could easily partition my time between "the familiar thing that always works the way I expect", and "the experimental stuff on the side". Today, those lines are super blurred; I rarely get the opportunity to become a proper expert on anything at all in the web world, so 100% of my time is "omg something's broken and quick, find the quirky part in the experimental thing that's running in production." And, speaking of documentation, we just don't have anything like mainframe documentation in modern software. O'Reilly books often come sort of close, or used to, but Unisys for instance had something like a 30-volume set of binders, about 500 or so pages each, containing extremely deep, carefully edited documentation on every single system call. Imagine if your favorite web framework had an entire wikipedia, with a big team dedicated just to testing and reviewing every page for accuracy. And finally, with modern queues, databases, file systems, and -- much as I'm loathe to admit it -- systemd, we're finally just now catching up to the disaster recovery procedures that were standard for mainframes in 1995. You could literally walk into the data center and yank the power cord for the mainframe while it was in the middle of running payroll, plug it back in, and it would pick up where it left off without skipping or double-counting a single record. They had gigantic limitations too. TCO was astronomical by modern standards, so the hardware never got upgraded, so you'd never be able to do any of today's big data stuff on a mainframe. Software development, such as it was, was done in COBOL or JCL or WFL or, maybe, Algol or FORTRAN, and git isn't a thing and a lot of that software has decades of history behind every single line of code. But it wasn't all bad.