Floppy drive pin 2 question?

[Randy McLaughlin]

From: "Jules Richardson" <julesrichardsonuk at yahoo.co.uk>
Sent: Thursday, March 10, 2005 2:33 PM
> Just futzing around with this Manta board (SCSI floppy controller).
>
> The docs I have say that pin 2 of the floppy connector is normally an
> input to the controller from the drive, but that some drives expect pin
> 2 to be an output to the drive from the controller (e.g. for changing
> rotation speed on a drive capable of 300 and 360rpm)
>
> That sounds wrong to me; surely most drives either don't use pin 2 for
> anything, or they expect it to be an output from the controller (to cope
> with things like speed changes)
>
> What drives use it as a signal driven by the drive, and what for?
>
> I'm tempted to ignore the docs I have and configure it as an output from
> the controller - I'd just rather not blow up a drive or controller
> board :-)
>
> cheers
>
> Jules

I have a webpage describing disks and disk drives.

Pin 2 on a 34 pin floppy connector is a little used pin.  It was used to 
change the RPM on some 5.25" 1.2mb drives.

It changed the RPM from 360 RPM (pin 2 high) to 300 RPM (pin 2 low).  This 
was supposed to make it easier to read/write DD disks in a HD drive.

Only early AT controllers needed it, later controllers kept this pin high 
and used an odd transfer rate.


Randy
www.s100-manuals.com