Program files from the 1980s. Operating system files from the 1970s.

Their timestamps don't show those ages, unfortunately, as they have been transferred from machine to machine and medium to medium over the decades.

Here's one of my own COBOL files:

     0130*  INSTALLATION.   Giacomo Software, P.O. Box 584, Hamilton, 3300
     0140
     0150 DATE-WRITTEN.    29 MARCH 1984.

Would you believe that was from an 8080 disassembler written in COBOL? I suppose we did silly things like that because we could. And we used whatever it was that we happened to have on hand.