Here it is, in all its glory!
First, the audio is converted to PWM.
Then both PWM edges are converted to falling-edge pulses.
This, then, could be fed directly into a floppy drive's "write data" input, storing the PWM on-disk.
When read-back from the disk, the floppy drive will give these same falling-edge pulses to indicate each edge of the recorded PWM.
That, then, gets fed into my single-comparator T-Flip-Flop, to convert those falling-edges back into PWM, then directly drives a speaker.
Ahh, right... So, this video was recorded months ago... long before I ran the 500KHz simulations. I can't recall the frequency this is running at, but it's surely slower than 500KHz, otherwise, as my conclusions, after running the sims... concluded... This system probably won't run at 500KHz, with the LM311's I used.
I do have faster (2ns!) comparators in the ol' storage-unit... but haven't really decided to go that route, much easier to use a 7474... and, realistically, I only need 500KHz for the *image* portion of #Floppy-bird, which wouldn't benefit from a T-FF at all, being that it'd still have to go into the uC for processing...