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From: bill@bilver.uucp (Bill Vermillion)
Subject: Re: More annoyance on the DMA problem
Organization: W. J. Vermillion - Orlando / Winter Park, FL
Date: Mon, 16 Aug 1993 14:33:05 GMT
Message-ID: <1993Aug16.143305.16861@bilver.uucp>
References: <jmonroyCBoq14.Kz0@netcom.com> <jmonroyCBp5Ks.CM3@netcom.com> <junaid.745467838@nella30.cc.monash.edu.au>
Lines: 21

In article <junaid.745467838@nella30.cc.monash.edu.au> junaid@nella30.cc.monash.edu.au (Mr A. Walker) writes:

>	I always thought that 3.5 drives rotate at 250rpm= 5 rev/s.
>There are 18 sectors/track. ie 90 sectors/sec .  therefore the transfer
>rate is 512*90 = 50KBytes/s (aprox.). ...

Rev rate is 300rpm - same as MOST 5.25 drives.   HD 5's can go 360, but
usually this is 'emulated' by upping the xfer rate from 250kbit/sec to
300kbit/secs.  (That went back to the old 8" SD rate of 250kbit/sec at
360rpm for 1.2 megs).
 
The 3.5" data rate is 500kbit/sec for HD.  Remember that there are a
lot of bytes used up by track and sector numbering and a few bytes for
pad at the end of the track to make up for differing rotational speeds.

No need to try to work backward.  These are standard hardware specs.



-- 
Bill Vermillion - bill@bilver.uucp  OR  bill@bilver.oau.org