It would be interesting to know if anything older than Fortran 77 is still in active use. I know that there is a lot of F77 still around, but the Fortran code I've seen at NASA is at least up to F90/F95. Someone who learned F95 or later and never wrote fixed format Fortran would be pretty lost if they had to work on F77 or, Backus forbid, F66. C, on the other hand, has changed much less, beyond the ANSI function declarations. I first used the C version that was in 6th Edition AT&T UNIX and that had some features that would look strange to modern users, such as initializers not using = signs:
int i 4;
and the assignment operators being the other way round:
a =+ 2;
The point is, when discussing the age of a language, how important is the degree of change over time? At what point is it a new language? The same is true of human languages. I can understand Shakespeare with little trouble, but I miss some points unless there are footnotes. I can get a bit of Chaucer, but far from full comprehension. Beowulf? Not a prayer. But it's all "English"...
People still run production COBOL programs, today, that were written in the 60s and 70s. They may compile it with a version of COBOL that has support for features like object oriented programming. But the programs were written decades ago, and do not use those features.
I know one person who, 10 years ago, went back to work for the same company that she had worked at 30 years prior. Among other things she found a PL/I program that not only was around, but the last commit on was hers. She asked them, "I'm the last person to touch that, and I don't even know that language any more! Why are you still running it?" The answer was, "It never broke." (Sadly that company went bankrupt in the financial crisis, so her code is probably now dead.)
A few years back, we bought a commercial address processing/validation library to use with .NET. I noticed it had a dependency on the .NET Fujitsu COBOL runtime. So even newer development might pull in COBOL code without even knowing it.
> It would be interesting to know if anything older than Fortran 77 is still in active use.
In active use, that's actually easy, especially in the industrial space (that's why I mentioned distributed as well as active, which gives another metric entirely)
Just about a year ago I was tasked with recovering software from a HP1000/RTE machine (driving an industrial oven in a forge), written in a Fortran dating back from before it was properly standardized.
We recovered the code through the machine's serial port, with the built in print functionality, which conveniently prepended a header along with the file's content. Together with pyserial at the other end, a few hours of hacking had a laptop listen via a PL2302 serial/USB adapter, parsed the printed header to get filename and a few metadata, and wrote content to the proper location.
The harder part was manually moving through directories, and printing the files at 1200 baud, through a terribly laggy and completely burned out 80x23 passive monitor.
Headers in the code mentioned it was actually older than me.
With a few massaging, the code actually compiled on a recent gfortran (F95!), but hte linking part was entirely different, and many proprietary symbols were missing. We went through the 30 years old documentation and found what we needed to stub them and plan how to act forward. The thing was actually quite close already to Unix and what we find on Linux these days, only much much more primitive. The code contained critical functions whose role was to compute thermal data for automation, according to various (thermodynamic and other) complex and undocumented rules, so I built a detailed plan about possible actions to take, including linking to C wrappers binding the stuff into Python, complete with a prototypal HTML5 visual status feedback of the automation system. That's when I left the project (and the job).
Ya, I have no clue either. Pascal was the first language I was originally taught (though I had been messing with QuickBasic for a few years before that). Pascal seemed to have died out in the late 90's.
Pascal is 42, C is 40. Lots of fun info on that page.