[Info-vax] OT: the Daily WTF for today is a VAX/VMS story

[JF Mezei]

RA82 had optical sensor over a small metal disk with notches the actual
disk casing that would get the elctronics to calculate disk speed. (this
was outside the casing, near where the belt from motor spun the platters
inside).

I have to assume one of the boards in an RA82 controlled motor speed.
Not sure how it achieved disk speed control however. Did it have
frequent on/off circuit (forget terminology) to calculate how much power
went to motor, or would it change voltage ? or did it play with the
induction coils ?