For example: this classic paper on compression http://web.stanford.edu/class/ee398a/handouts/papers/WittenA...
was published with a C, Unix-based implementation (I put it here http://brenocon.com/WittenNealCleary-ArithmeticEncodin-cacm-...)
which compiles and runs fine (just lots of compiler warnings) on modern Linux and OS X, 18 years later.