todayborday is the dayborday to investigate cartridge rom bank switching on the ti-99/4aborday
i currently don't have any solutions for disk storage on my ti-99 (saving up for a TIPI, a raspi-based sidecar peripheral that gives you access to a network drive among other features), which means i don't really have any way to save and load machine language programs
but!!! there's a cart called "mini memory" that has battery-backed RAM on it for playing with small (<4k or so) machine language programs, and its cart dump image has been modified to work with my flash cart by dumping its current RAM contents to the image file when SAVE is called. so at least i have some kind of persistence! i could even end up having multiple copies of mini memory with different programs in their RAM dumps
now to see if i can save/load (Extended )BASIC programs from .wav files with my new, not-shaped-with-a-butter-knife cassette adapter cable...
found documentation for how the TI data cassette format works (it's extremely straightforward FM with two audio-range frequencies for zeros and ones on a set clock) so with a little bit of filtering, i can save BASIC programs as .wavs that can be loaded later even through my laptop's awful headset port >:3