Tech Tinkering

If you want to internalise the vi cursor movement keys, play the old unix game "hunt" with your colleagues or classmates.

See http://techtinkering.com/2009/08/11/my-top-10-classic-text-mode-bsd-games/ (it's at no. 2)

"This is a multi-player games that can be played over a network, or via multiple terminals on one machine. It consists of a top-down view of a maze where you run around trying to find your opponents to kill. There are a number of weapons and you can also play in teams. It is surprisingly fun, a sort of top-down text mode doom.

Originally written by Conrad Huang and Greg Couch in 1979/80."

It's easy to compress a sorted dictionary by turning something like

a ab abc to

a 1b 2c where the prefix is the number of characters shared with the last word (and might be coded as a byte as opposed to a digit like you're thinking there. This would be a simple form of compression to code up in BASIC unlike Huffman or most LZW variants which involve bit twiddling and maintaining tree data structures... Though I do remember writing SQ and USQ [1] in BASIC)

[1] https://techtinkering.com/articles/compression-and-archiving-on-cpm/

It's a war story from my father, so I have to admit that the details could be corrupted. He worked with a variety of machines in the 60s, so it was believable that one had a permissive enough FORTRAN to allow that. It's also possible that your explanation of it being reference-argument corruption.

I'm almost curious enough to fire up a PDP-8 emulator and see what 4K FORTRAN does. Almost.
http://techtinkering.com/2009/07/14/running-4k-fortran-on-a-dec-pdp8