Path: utzoo!mnetor!uunet!husc6!bloom-beacon!mit-eddie!uw-beaver!cornell!rochester!ur-tut!ur-valhalla!jal
From: jal@valhalla.ee.rochester.edu
Newsgroups: comp.sys.ibm.pc
Subject: Compaq DOS
Message-ID: <1241@valhalla.ee.rochester.edu>
Date: 12 Apr 88 14:47:47 GMT
Sender: usenet@valhalla.ee.rochester.edu
Reply-To: jal@galaxy.ee.rochester.edu (John Lefor)
Organization: URochester Department of Electrical Engineering
Lines: 34

I just got back from vacation and in skimming the articles I 
noticed a comment that Compaq Dos supports > 32 Mbyte disks
by using sectors>512 bytes.

I have spent some time studying Compaq DOS 3.31 support of
"extended partitions" and want to be sure everyone know that
this support for disks > 32 Mbytes does not involve a larger
sector size.  Rather there is a new interface to INT 25H/26H
which allows specifying sector numbers as a double-word for 
the "extended partitions".  Note that this will break any program
which tries to use INT 25H/26H in an "extended partition"
but things are fine for smaller partitions.

This is not meant as a flame to the poster about Compaq DOS
but rather an attempt to be sure there is understanding about the
nature of Compaq DOS 3.31 support of "large disks".

BTW - The interface for an "extended partition" is
documented in the "interrupt list" and full details are
still available direct from me with a SASE to:

	John Lefor
	Department of Electrical Engineering
	Computer Studies Building
	Rochester, NY 14627
(it's about 10 pages long and so >$0.25 postage is required).


- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

I program ... therefore I am.

John Lefor    	University of Rochester		Dept of E. Engineering
716-275-8265	jal@ee.rochester.edu		...!rochester!ur-valhalla!jal