An exception are the Vortex F1-S, F1-D, M1-S and M1-D drives. (How are they different?)
The floppy disc rotates at a nominal speed of 300rpm, with some tolerance.This tolerance of the FDC has been measured by Roudoudou to be ±12% (it worked from 220bits/s to 283bits/s for a reference of 250bits/s). [https://64nops.wordpress.com/2021/09/02/a-la-decouverte-du-fdc-episode-4/ Source]
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