No, it was under control of a stepper motor driver circuit located directly on a Floppy drive pcb. This driver in turn received instructions from a dedicated Floppy drive controller (WD1771 and compatibles).
> For an 80 track disk, the movement required to step between tracks was a certain known amount.
"certain known amount" being one step per track
>If you formatted the disk with the tracks spaced closer together, by altering the stepper movement during that process, you would 'magically' get more space.
Above is incorrect.
Its impossible to move HEAD stepper motor between tracks. Floppy drive has a STEP (/STEP) and DIRECTION (/DIR) pins. All you are able to do is pick direction and step one track at a time. Step distance is Fixed. The whole point of using a stepper motor is you dont have to worry about head tracking/alignment.
The only personal computer Floppy drives with flexible head positioning all used voice coil head actuator - Floptical, LS-120/240, Zip drives etc.
You could format extra tracks, if you felt lucky. Usually you could get away with couple extra. I never did this with any files I valued.
I recall the default format was 9 sectors, 80 tracks, 2 sides with 512 bytes per sector = 720KB, and you could push up to sometimes 82/83 tracks and maybe 10 or 11 sectors to get more out of a diskette.
Actually, I think my ST originally came with a single-sided floppy drive and had to be upgraded.
Sad thing was, due to the early single sided models, many games would limit to 720k so as to not limit there market. That saw games that would happily fit upon a single double sided disc, cast upon two floppies forcing switching. So that small batch of single sided initial release systems, really did have a legacy impact that lasted for years and did it no favours.
In the ST era, the control of that motor was directly under the control of the operating system. For an 80 track disk, the movement required to step between tracks was a certain known amount.
If you formatted the disk with the tracks spaced closer together, by altering the stepper movement during that process, you would 'magically' get more space.