From: John Woodgate
Subject: Q. why 5400 and 7200 rpm disk drives?
Date: Thu, 10 Oct 2002 08:39:23 +0100
Organization: JMWA Electronics Consultancy
Reply-To: John Woodgate
NNTP-Posting-Date: Thu, 10 Oct 2002 09:32:15 +0000 (UTC)
X-Newsreader: Turnpike (32) Version 4.01 <5Z8C9wtxbnpWyFnyfFzqmVF739>
I read in sci.electronics.design that Winfield Hill
wrote (in ) about 'Q. why 5400 and 7200
rpm disk drives?', on Wed, 9 Oct 2002:
> 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?
For reasons that I am not allowed to disclose, the digits have to add up
to 9. 3+6+0+0 = 9, and so on.
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
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