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Date:      Wed, 3 Jan 1996 10:59:04 -0700 (MST)
From:      Terry Lambert <terry@lambert.org>
To:        ptroot@uswest.com
Cc:        joerg_wunsch@uriah.heep.sax.de, freebsd-questions@freebsd.org
Subject:   Re: Three problems with FreeBSD 2.1
Message-ID:  <199601031759.KAA14999@phaeton.artisoft.com>
In-Reply-To: <9601031423.AA01369@kermit.acs.uswest.com> from "ptroot@uswest.com" at Jan 3, 96 08:23:26 am

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> > > 		Could it be that the partition goes past 1024 cylinders?
> > 
> > No idea for this.  The 1024 cylinders are not a problem for FreeBSD
> > (except for the boot process, where the BIOS is involved).
> 
> Can you expand on this?

INT 13 BIOS calls for absolute read and write use C/H/S values, which
are 24 bits in size:

	C:10
	H:6
	S:8

Thus the largest Cylinder addressable by DOS is 1024.

Thus the Abomination Before God of geometry translation, since the
old IBM engineers thought that you'd be upping your platters and
sector density before you could reliably get more cylinders on a
disk (guess they never heard of optical interferometry).

Thus OnTrack and EZ-Boot and other TSR INT 21-to-LBA redirectors.

Thus the coining of the term "LBA" to refer to what has always been
"Absolute Sector Addressing" in the SCSI world to make it look like
it was some "new" soloution to the "problem" (which is really that
the INT 21 interface and C/H/S addressing are a dumb idea that no one
is willing to give up even though they would only live two years after
they were killed).

Thus engineers love SCSI.


					Terry Lambert
					terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.



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