xms20.doc

Information about this file, S12023.EXE (formerly XMS20.ARC)

1989 March 21

Copyright (c) 1988, 1989, Microsoft Corporation, Lotus Development
Corporation, Intel Corporation, and AST Research, Inc. Refer to the 
document "eXtended Memory Specification (XMS), ver 2.0" for HIMEM.SYS
copyright and warranty information.

This file contains the contents of the XMS distribution disk.
However it is not the OFFICIAL XMS distribution disk. It does contain
all of the files that the current XMS release disk does. The only
item which this archive does not contain is the printed version of the
file SPEC\XMS.TXT. In the domestic United States, to obtain the
latest official XMS release disk, call Microsoft customer service at 
(800)426-9400 and ask for a copy of the "XMS Specification and it's
supplemental diskette." 

This file, S12023.EXE, contains the following files:

    README.TXT   general information: read this file first
    HIMEM.SYS    the latest xms driver (v2.06)
    \CLIB.ARC    c/masm library code
    \OEMSRC.ARC  code for the latest himem.sys driver (v2.06)
    \SPEC.ARC    xms and himem documentation
    \TESTS.ARC   c and masm xms test code


    \README.TXT
    \HIMEM.SYS
    \CLIB\XMM.LIB
    \CLIB\XMM.ASM
    \CLIB\XMM.H
    \CLIB\CMACROS.INC
    \CLIB\XMMLIB.DOC
    \OEMSRC\XM386.ASM
    \OEMSRC\XM286.ASM
    \OEMSRC\HIMEM
    \OEMSRC\HIMEM.ASM
    \SPEC\XMS.TXT
    \SPEC\HIMEM.TXT
    \TESTS\XMSTIME.EXE
    \TESTS\TEST
    \TESTS\TEST.EXE
    \TESTS\HITEST
    \TESTS\HITEST.COM
    \TESTS\HITEST.ASM
    \TESTS\TEST.C

See the file README.TXT for general information, SPEC\XMS.TXT for XMS
programmer information, and SPEC\HIMEM.TXT for HIMEM.SYS user
information.

This file also includes the latest release of HIMEM.SYS, version
2.06, released February 7, 1989. The following problems were found in
the previous release of HIMEM.SYS and have been corrected in this
release:

1) When a program would call the XMM HIMEM.SYS to query the amount of
free extended memory, HIMEM would incorrectly report back a value
that is 64KB too large. HIMEM was not properly taking the 64KB High
Memory Area (HMA) into its calculations of the size of free extended
memory, which could cause a program to allocate an EMB on top of the
HMA, causing data to be overwritten. This problem has been fixed in
HIMEM.SYS Version 2.06.

2) When using the command line option NUMHANDLES with the value of 0,
the driver would hang. This problem has been fixed in HIMEM.SYS 
Version 2.06.

3) The minor version returned by HIMEM.SYS (the version of the XMM,
as opposed to the version of the XMS the driver is based on), was
incorrectly returning 2.03. It now returns 2.06. This problem has
been fixed in HIMEM.SYS Version 2.06.

4) On a 80286 system, EMBs were not being properly accessed due to
the 80286 move procedure not being properly initialized. This 
problem has been fixed in HIMEM.SYS Version 2.06.

5) The HIMEM.SYS source code located in the OEMSRC subdirectory on
the XMS Distribution Diskette will now produce a binary-identical
copy of HIMEM.SYS, which was built using using Microsoft Macro
Assembler (MASM) 5.10. Previous versions of the source code did not
build an exact copy of the distributed copy of HIMEM.SYS. This
problem has been fixed in HIMEM.SYS Version 2.06.

Note that the HIMEM user documentation (HIMEM.TXT) as well as the XMS
programmer documentation (XMS.TXT, included with the XMS distribution
disk) both state that VDISK.SYS is not compatible with HIMEM.SYS.
This is no longer completely true. The VDISK.SYS that is shipped with
IBM PC-DOS 4.00 is compatible with HIMEM.SYS, since it uses a
compatible method of allocating extended memory. This is a
documentation errata, not a change in HIMEM.SYS 2.06.

Some users may not need all of this programmer-oriented information,
and may instead want to obtain the just the latest HIMEM.SYS driver,
in the file S12137.EXE. (formerly HIMEM206.ARC)  This file contains
the latest version of HIMEM.SYS 2.06, and the user documentation for
this device driver. However, this is also included in this file.