From: Chuck Simmons
Organization: You jest.
X-Mailer: Mozilla 4.61 [en] (X11; U; Linux 2.0.33 i586)
Subject: Re: Q. why 5400 and 7200 rpm disk drives?
Date: Fri, 11 Oct 2002 00:15:01 GMT
NNTP-Posting-Date: Thu, 10 Oct 2002 17:15:01 PDT
John Eaton wrote:
> Winfield Hill wrote:
> : Hmm, why did disk drive manufacturers settle on rotation speeds
> : like 5400 and 7200 rpm? These correspond to 90 and 120 rps, or
> : 1.5 and 2.0 rotations per ac cycle for 60Hz ac power. Early disk
> : drives ran at 3600rpm = 60Hz, and perhaps some ran from ac motors,
> : and such numbers would make sense for a synchronous ac motor.
> : But modern disk drives run from dc power, and therefore should
> : not be beholden to any ac-power parameters. While it's true that
> : the bleeding-edge of new disk-drive performance is in 10000 and
> : 15000 rpm drives, etc., we still see impressive new 5400 and 7200
> : rpm drives. So, hey, what's the deal? How come no spec. creep?
> : E.g., no 6000 rpm versions to out-compete the 5400 rpm models?
> : Is there in fact some engineering magic in 5400 and 7200 rpm?
> Just be thankfull that they settled on a fixed speed. Didn't Apple's LISA
> have a floppy that changed rpm for every track?
> John Eaton
That was the Twiggy drive. I interviewed at Apple in 1982 and saw it in
development. It was not such a bad idea. After all, most CD drives and
DVD drives do it today.
... The times have been,
That, when the brains were out,
the man would die. ... Macbeth
Chuck Simmons email@example.com