I find old Linux executables, and Python programs, are two particular cases where it's very hard to run old versions. I keep a set of old Debian VMs around, to

I find old Linux executables, and Python programs, are two particular cases where it's very hard to run old versions. I keep a set of old Debian VMs around, to find a machine from the time a program was created, so I can run older stuff. (If you wonder why I'm running so much old, unsupported stuff, that's academic research software for you)