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From: hoffman%pitt@CSNET-RELAY.ARPA (Bob Hoffman)
Newsgroups: mod.computers.vax
Subject: Re: uVAX-II diskettes
Message-ID: <8608202001.AA05174@ucbvax.Berkeley.EDU>
Date: Tue, 19-Aug-86 10:34:22 EDT
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Posted: Tue Aug 19 10:34:22 1986
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>From: jsweet@ICS.UCI.EDU
>
>My limited experience with MicroVAX-II diskettes has been: "Digital"
>brand floppies work in the drives, but others do not.  Is there
>anything really special about Digital's floppies, e.g. pre-formatting
>or some other marketing conspiracy?  Has anyone had a successful
>experience with non-Digital floppies?  I've never heard of a (commonly
>available) >96tpi diskette, but is that what's required?  What's the
>story?
>
>-jns

Digital RX50 diskettes are indeed pre-formatted, and there appears to
be no way to format blank (i.e. degaussed) diskettes in DEC drives,
except for those on the Rainbow.  This is right in keeping with DEC's
"tradition", as neither the RX01 nor the RX02 could format a blank
diskette.  Third-party RX50-compatible drives are usually able to do
this formatting.  Maxell, Verbatim, and others market pre-formatted
RX50 diskettes.  If you are interested, the RX50 format is as follows:

	- Single Sided
	- 80 track (96 tpi)
	- 10 sectors/track
	- 512 bytes/sector

I believe one of the third-party controllers (Andromeda? Emulex?)
allows use of double-sided drives in an upward-compatible fashion.
Why didn't DEC go with double sided drives?  The technology had certainly
been proven by the time the RX50 was introduced.

-- 
Bob Hoffman, N3CVL       {allegra, bellcore, cadre, idis, psuvax1}!pitt!hoffman
Pitt Computer Science    hoffman%pitt@csnet-relay