An historical nit about FDDs

[Jon Elson]

On 07/12/2018 01:40 PM, Paul Berger via cctalk wrote:
> IBM created the 8" diskette as an inexpensive and reliable 
> means of loading microcode and shipped the first read only 
> drives in 1971.
I am quite certain the original FDD on the 370/168 used a 
pair of solenoid coils to ratchet the head in and out.  I 
think the mechanism was a leadscrew and toothed wheel.  I 
heard a 370/168 loading a microcode overlay and it sounded 
like a machine gun, even in a pretty loud machine room.

I think the same scheme was used in the 370/145.

Jon