Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!uakari.primate.wisc.edu!gem.mps.ohio-state.edu!tut.cis.ohio-state.edu!ucbvax!pro-europa.cts.com!jeffn
From: jeffn@pro-europa.cts.com (Jeff Noxon)
Newsgroups: comp.sys.apple
Subject: Reading 720k disks with the Apple 3.5 Drive
Message-ID: <8910200601.AA21133@trout.nosc.mil>
Date: 19 Oct 89 23:57:33 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 30

Brian Willoughby asked if I had read/written 720k disks from experience,
and my answer to this question is no.

I now realize that it is in fact qute possible for the Apple 3.5 Drive
to read/write an IBM format 720k disk.  The PC Transporter does it.

You CANNOT read or write a 720k IBM disk through the SmartPort, however.
The reason for this is the smartport does not support the same modulation
scheme the IBM disks use.  Actually, I believe the SmartPort does support
it but the IWM chip does not -- that is why the PC Transporter requires
your 3.5" drives to be connected to it instead of the SmartPort:  It can
use it's own disk controller.

Perhaps someone will one day create a peripheral card that does support
the IBM modulation scheme so that we may transfer data without buying a
PC Transporter.  Or maybe someday Apple will let lowly GS users upgrade
to a SWIM chip so all this can be done without a card.

Also, someone mentioned something about Apple 3.5 drives speed control
that didn't sound quite right.  I can't find that post now.  Anyway,
the 3.5 operates at a variable recording speed depending on the track.
The drive automatically adjusts this speed so it can fit the same amount
of data on every track.

Jeff


|uucp: [ucsd, nosc] ..!crash!pro-houston!jeffn  | "If I wanted your opinion, |
|inet: jeffn@pro-houston.cts.com                |    I would have given it   |
|arpa: crash!pro-houston!jeffn@nosc.mil         |           to you!"         |