Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!rutgers!gatech!mcnc!thorin!clocs!davis
From: davis@clocs.cs.unc.edu (Mark Davis)
Newsgroups: comp.periphs
Subject: ST296 - How does Seagate Do it?
Keywords: hard disk capacity encoding techniques
Message-ID: <5754@thorin.cs.unc.edu>
Date: 7 Dec 88 16:48:56 GMT
Sender: news@thorin.cs.unc.edu
Lines: 22

The Seagate advertisement on page 36 of the December 5 Info world
claims that the ST296 is part of the ST251 hard disk drive family (6
heads, 820 cylinders, 1/2 height 5.25", stepper motor head
positioning).  Of course, the 296 has a SCSI interface, but some
encoding has to be used used between the on board SCSI and the disk
itself.

From other Seagate SCSI drives, it appeared that their SCSI drives
were just the MFM drive with the SCSI adapter.  However, for the 296,
they would have to be using some exotic encoding technique (like ARLL)
to get the almost 200% capacity increase.

So, how do they do it:

	(1) Really not a 251 family member; more heads/ more cylinders/
	    different positioning method.
	(2) ARLL or similar encoding techniques.
	(3) some other method.

Any facts or ideas?

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