The code is a the bottom of the page (text_viz.f90.gz). I have not tested it and don’t know if you can make an animation (but probably).
This is the header of the module:
! small module to do text mode graphics using ANSI terminal escape sequences
! Copyright (c) 2013 Axel Kohlmeyer akohlmey@gmail.com
! v0.1 2013-06-22, initial public version
! v0.2 2013-06-24, better autoscale and overflow protection
The calculations were done on a CDC 6400, but there is no mention of the programming language (the paper does say the computer program is available from the author).
It was most probably Fortran 66 (Fortran IV with some extensions). The CDC 6000 series were excellent computers for obtaining numerical solutions of physical problems. Some of the CDC installations had, in addition, the student oriented MNF computer, which was faster to compile, and gave better diagnostic messages. Users typically developed and debugged their programs using MNF first, and then switched to the CDC Fortran compilers (RUN, FUN and FTN) for faster execution.
The assembly language was COMPASS. (Note the peculiar dedication note in page 3 of the manual. Address registers A6 and A7 were used for writing the contents of registers into central memory. Setting an address into A6 caused the contents of register X6 to be stored into that address.)
Some of the CDC 6000 series computers had Wirth’s Pascal compiler. Some even had an Algol compiler. Unfortunately, Algol programs ran extremely slowly compared to the corresponding Fortran programs.