And even if the character subset is quite small (26 lower case, 26 upper case, 10 digits), it's still good enough if it's completely random and never leaked once. Just max out the password length (start at 32 char) and back track from there.
[0] https://www.paypal.com/us/smarthelp/article/Tips-for-creatin...
I'd say most if not all of this code is probably running on some IBM mainframe from the 1980s or 90s - possibly later - and likely in some kind of emulation or backwards compatibility mode (so something from the 80s/90s would likely allow for running S/360 stuff, and so forth).
The actual hardware, though, has either been scrapped or is in a museum somewhere. There are very, very few instances of organizations still running "ancient" hardware (though the few that are tend to be known by the mainframe collecting community from what I understand).