Same here. Tweaking FILES= and BUFFERS= etc. in CONFIG.SYS and discovering DEVICE=ANSI.SYS enabled me to create custom DOS prompts with positioning and colours was a game changer and really what started me on the road to programming decades ago!

I loved tweaking AUTOEXEC.BAT so much that I created a front end menu shell which could be end user customised that at one stage became the de-facto program launcher for an entire state government here in Australia for a couple of years in the '80s.