Cleve Moler is 78 (https://en.wikipedia.org/wiki/Cleve_Moler), he is popularly known as the co-founder of MathWorks, and co-author of numerical computing libraries such as LINPACK and EISPACK. He maintains a blog (https://blogs.mathworks.com/cleve/) and still programs in MATLAB from what I can tell. He talked about a bit of MATLAB history last year in Argonne Training Program on Extreme-Scale Computing (ATPESC) -- https://extremecomputingtraining.anl.gov/sessions/dinner-tal...).