Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!mephisto!mcnc!thorin!clocs!davis
From: davis@clocs.cs.unc.edu (Mark Davis)
Newsgroups: comp.sys.ibm.pc
Subject: ESDI Compatibility (was Re: ESDI controller/disk recommendations wanted)
Summary: Are ESDI Controllers Really Different?
Keywords: ESDI disk controllers standards formatting
Message-ID: <10869@thorin.cs.unc.edu>
Date: 1 Dec 89 16:42:25 GMT
References: <259@cica.cica.indiana.edu> <52@qmsseq.imagen.com>
Sender: news@thorin.cs.unc.edu
Reply-To: davis@cs.unc.edu (Mark Davis)
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Organization: University Of North Carolina, Chapel Hill
Lines: 25

In article <52@qmsseq.imagen.com> pipkins@qmsseq.UUCP (Jeff Pipkins) writes:
> ...
>
>The only thing on the con side is for existing users: it appears
>that anytime you change ESDI controllers, you have to low-level
>format again.  No problem if the machine is new, and worth the 
>trouble if you're switching.
>
> ...

Pardon my skeptism, but is this really true?  In the case of ST 506/412
interface drives, the analog interface allows different type (read
manufactures') controllers to be incompatible and require repeating the
low level format.  However, the ESDI interface is (1) all digital, and
(2) relatively addressed.  Since the ESDI controller cannot control
either the level or the timing, I don't see how any controller would work
with the drive, but still require the drive to be reformatted.

Unfortunately, I have never tried to move disks between different
brands of ESDI controllers, so I have no real world experience.

Anyone have any examples?  Perhaps some ESDI/Controller guru can
comment.

Thanks - Mark (davis@cs.unc.edu or uunet!mcnc!davis)