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From: markz@microsoft.UUCP (Mark Zbikowski)
Newsgroups: net.micro.pc
Subject: 2.1 vs 2.0
Message-ID: <8680@microsoft.UUCP>
Date: Tue, 17-Jan-84 11:14:20 EST
Article-I.D.: microsof.8680
Posted: Tue Jan 17 11:14:20 1984
Date-Received: Sat, 21-Jan-84 23:10:25 EST
Organization: Microsoft Corporation
Lines: 24


    What is the difference between DOS 2.0 and DOS 2.1?.


The differences are as follows:

	Support for PCJr's half-height diskettes.  These require a greater
	head settle time than did the previous full size-floppies.
	Unfortunately, there is no way to tell the half-highs from the full
	sized ones so every IBM diskette now has the slower head settle.
	This slower head settle is only applied to seek/write combinations and
	seek/verify combinations.  It is still slow.

	Support for the PCJr's ROM.  This consists of looking up a command
	in the ROM tables and then setting up an EXEC for it.

	Bug fix 1: IOCTL control read/write used to perform a media-check
	sequence before issuing the command to block devices.  The function
	no longer issues the media-check sequence.

	Bug fix 2: Due to the strangeness of having one system call (exec)
	being loaded as part of COMMAND, there was a segment register foulup
	that resulted in locations 2Eh through 31h being trashed in the data
	segment at the time of the exec system call.  This problem was fixed.