Large ESDI Disks

From: Richard Erlacher <edick_at_idcomm.com>
Date: Sun Feb 3 10:09:32 2002

According to what I. Dal Allen told an audience some 15+ years back, ESDI was
an outgrowth of SMD, having been designed to fit the smaller form factor of
the the-current 5-1/4" drive technology. Like other schemes that migrated
controller functions onto the drive, albeit less than most, it put functions
such as formatting on the drive, so that all one had to do was send the drive
the command to format a track, along with some parameters such as sector size,
sometimes jumpered on the drive, and sector interleave, etc, and the drive did
the dirty work, including recovery of data, thereby eliminating the costly PLL
normally found on the controller. Unfortunately, the relative intelligence
interms of such functions as command queueing, seek overlaps, error
management, etc, were still left to the controller, hence, though it
transferred data at a pretty high rate, the actual performance was no better
than an average SCSI.

If ESDI lives on, I don't know why. The old Miniscribe drives I still have,
I've kept because they have logic boards that allow them to be switched to
SCSI, though that doesn't preserve the resident data. It's not a particularly
good reason to keep 'em, but it serves as an excuse.

Dick

----- Original Message -----
From: <jpero_at_sympatico.ca>
To: <classiccmp_at_classiccmp.org>
Sent: Friday, February 01, 2002 2:24 PM
Subject: Re: Large ESDI Disks


> > From: "Richard Erlacher" <edick_at_idcomm.com>
> > To: <classiccmp_at_classiccmp.org>
> > Subject: Re: Large ESDI Disks
> > Date: Fri, 1 Feb 2002 19:06:26 -0700
> > Reply-to: classiccmp_at_classiccmp.org
>
> > Gee! I've never seen one that SMALL in the flesh, though I guess I read
that
> > there had been such things. The smallest I ever owned was 150, and that
was
> > just because it was half-height, meaning it would fit in the bay above the
> > floppies ...
> >
>
> The smallest ESDI HD I had was 50MB by microscience. yup!
>
> The biggest ESDI HD I have currently; 1.3GB and second biggest is
> 800MB (working w/ ultrastor U24F. Problem is with that Micropolis
> 1.3GB ESDI I couldn't get it LLF'ed w/ Ultrastor U24F, I think
> something is not set right despite that card supports 2048 cyls.
> Help?
>
> About the current production of ESDI biggies what on earth it is used
> for? Also can't be on 5.25", they're costly. I think they are
> making ESDI 3.5" HH or even 3.5" x 1" ESDI, which would be a big wow
> from me.
>
> I thought ESDI interface is long since dead except for
> formatting design and basic electronics of ESDI design still lives
> on in most of HDs.
>
> Cheers,
>
> Wizard
>
>
Received on Sun Feb 03 2002 - 10:09:32 GMT