Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!samsung!usc!wuarchive!decwrl!ucbvax!hplabs!hp-sdd!ncr-sd!serene!rfarris
From: rfarris@serene.UUCP (Rick Farris)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Transfer rates
Message-ID: <1207@serene.UUCP>
Date: 17 Dec 89 05:21:11 GMT
References: <44807@bu-cs.BU.EDU>
Reply-To: rfarris@serene.UU.NET (Rick Farris)
Organization: Serenity BBS, Del Mar, California
Lines: 22

In article <44807@bu-cs.BU.EDU> ngeow@cs.bu.edu (Yee Ngeow) writes:

> Winchester drives spin at a rate of 3000 revolution per second

So close, Kwong, yet so far away :-).

5 1/4 inch winchesters spin at 3600 rotations per *minute*, not per
second.  That's 60 rps.

That would make your calculation:

	60 * 26 * 512 = 798,720 bytes/sec

But consider what would happen if each head on a disk were feeding
it's own buffer, so that one revolution could read an entire
*cylinder*!  A 12 head drive could approach 10 MB/s (80 Mbits/sec
YOW!).  It goes without saying that the controller would need to
optimize cylinder writes....


Rick Farris   RF Engineering  POB M  Del Mar, CA  92014   voice (619) 259-6793
rfarris@serene.uu.net      ...!uunet!serene!rfarris       serene.UUCP 259-7757