This reminds me of how expensive RAM was back then. I remember spending $180 to add 512KB to my Amiga 500 in 1988 or so. $180 was a lot of money back then.
IIRC, one of the 8-bit Atari magazines had an article describing a similar setup back in the mid/later 80s. Basically, put a photoresistor in a shroud (I used the cap from a Bic pen and some electrical tape), attach it to the dot matrix print head and wire it to the Atari joystick port's analog/paddle input. Place a bright light over the printer. Then the software told the printer to move the print head back and forth while it read the port value. The image quality was terrible but it was a fun project.
Chess? Wow. I did some 6502 programming in hex on my Atari 800XL, but just for simple things like display list interupts. I had a list of all the 6502 opcodes and hex encodings from a magazine or book and figured it out from there.
I loved programming in Action! The editor was great and both compilation and runtime were really fast. I used it for several years from high school into college until I got an Amiga. I wrote a paint program, 3D modeler and 3D renderer with Action! No floating point. Fixed-point math with lookup tables for sin/cos/etc.