program for authoring ASCII animations?

Back in the early 80's we created such animations by writing Fortran codes that had hardcoded strings to set up the static parts and used DO loops to emit the escape characters to do the animation on the terminals of the time (first VT52 then VT100). As necessary for regulating the speed of playback, NUL's and other "do nothings" would get inserted along the way in the DO loops. In my circle it was, by definition, being done on a DEC machine (either a -11 or a VAX, sometimes taking advantage of easy portability of the Fortrans). Some guys did this on PDP-10's but the Hollerith strings were not so portable between -10's and the -11/VAX platforms. There wasn't really much abstraction going on in those programs. Fortran was great for do loops etc. but a little bit ugly when it came to emitting character strings. It was often a kludgey combination of Hollerith strings stored in integer variables or arrays, format statements, and (where we had F77 later on) CHARACTER datatypes. We had absolutely no inhibition at using a 4-byte integer to store an escape sequence and then through the ugliness of equivalence statements making one of those bytes be the index of a do loop, and emitting it as a Hollerith string. Usually we did whatever was easiest so it was very common to see multiple approaches mixed together often inside the same format statement :). After making a file containing the escape sequences for an animation it was "released" by putting it in a public directory and/or copying it from site to site via DECNET. VMS Mail could (for a while) be used to send ASCII animations in the body of the message but most sysadmins eventually disabled control characters in message bodies (details of this... oooh I used to know but it escapes me now.) After my time (e.g. by the late 80's and early 90's) the animations were done by younger guys who knew C and some of them even used termcap libraries.