50Hz vs 60Hz fixed drive speed ?

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Thu Feb 19 16:23:35 2004

>
> A friend and I were discussing 8" floppy drives recently, in particular
> that they often have two pulley sizes so that the rotational speed is
> 360rpm regardless of 50Hz or 60Hz operation, assuming that they are
> setup properly.
>
> The question then turned to whether or not a fixed hard drive would

Demouintable hard disks (like the DEC RK05) were certainly like 8" floppy
drives in this respect -- you had to change the spindle motor pulley (and
sometimes the belt) to change from 50Hz to 60Hz operation.

> typically be designed in a similar fashion, such that the spindle
> would rotate at the same number of RPM when configured for 50Hz or
> 60Hz operation, or if they did not worry about the speed differences
> as the media was not removable?

I think this was the case with early Winchesters too. IIRC you have to
change the pulley on a Shugart SA4000 if you change the mains frequency,
for example

After all, you want the same data rate and track length (in bits, and
therefore in time, given the same data rate) no matter which side of the
Pond you use the drive.

-tony
Received on Thu Feb 19 2004 - 16:23:35 GMT