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From: gold@aecom.UUCP
Newsgroups: net.micro.pc
Subject: DOS 2.1 slow speed fix
Message-ID: <624@aecom.UUCP>
Date: Fri, 11-May-84 11:00:22 EDT
Article-I.D.: aecom.624
Posted: Fri May 11 11:00:22 1984
Date-Received: Sun, 13-May-84 10:09:06 EDT
Organization: Albert Einstein Coll. of Med., NY
Lines: 16


DOS 2.1 slowed down the disk head settle time to make it compatable with the
pc jr. The easiest way to fix this is to replace the settle time (now 25 I
think) in RAM , a harder way would be to replace this on the disk. The vector
for the location of the disk table is interupt 30, so the location of the
table is 30*4 bytes per interupt or 120 decimal ( segment 0 ) . the first
two bytes hold the offset and the second two hold the segment. you must
write a program to read the memory locationthe vector holds and check that
address + 10 bytes for the offset of the head settle time. replace that value
with 0.  It should not be too hard to do.  This information was taken from
Peter Norton's book Inside The IBM PC.  His description is a lot clearer than
mine and you may want to look at it for more details.


					yosef gold
				  (  philabs/aecom/gold )