Changes in EMM386.EXE Version 4.45 (MS-DOS 6.0) (93375)
The information in this article applies to:
• Microsoft MS-DOS operating system 6.0
This article was previously published under Q93375
Version 4.45 of the Microsoft expanded memory manager (EMM386.EXE),
provided with MS-DOS version 6.0, has the following new features:
• Advanced Upper Memory Scanning
• Expanded and Extended Memory Sharing
• Ability to Provide Upper Memory Regions for Microsoft Windows
• Ability to Load with NOEMS When No Page Frame Is Available
• NOVCPI Switch for Smaller Load Size
• Automatic IBM Token Ring Adapter Detection
• Quiet Loading
• Ability to Provide ROM Shadowing
This article describes these features in detail.
Advanced Upper Memory Scanning
EMM386.EXE can now scan the F000h-F7FFh region when the system
read-only memory (ROM) is duplicated between F000h-F7FFh and
F800h-FFFFh. Also, EMM386.EXE includes the ROM BASIC area on IBM PS/2
By default, EMM386.EXE version 4.45 scans the C000-EFFF memory range.
EMM386.EXE version 4.44 (which shipped with Windows 3.1) scanned the
C600-DFFF memory range, and EMM386.EXE version 4.33 (MS-DOS 5.0)
scanned the C800-DFFF memory range.
To enable advanced upper memory scanning, add the HIGHSCAN switch to
the DEVICE line for EMM386.EXE in the CONFIG.SYS file.
Expanded and Extended Memory Sharing
Previous versions of EMM386.EXE allocated as much extended memory as
possible during the initialization phase. This tied up memory that
could otherwise have been used by programs that use expanded memory.
EMM386.EXE version 4.45 includes support for dynamic allocation of
memory. This means EMM386.EXE can create and make available different
types of memory as your system requirements change.
Ability to Provide Upper Memory Regions for Windows
EMM386.EXE version 4.45 includes a new WIN= switch that defines upper
memory regions available for use by Windows. These regions are similar
to X= regions; memory is not mapped to those areas. But unlike X=
regions, Windows (in 386 enhanced mode) can map its own memory into
these upper memory regions and make more conventional memory available
to MS-DOS-based applications running with Windows.
Ability to Load with No Page Frame
Previous versions of EMM386.EXE do not load if expanded memory support
is enabled and there is not enough contiguous available address space
for an expanded memory page frame. To support MEMMAKER.EXE, EMM386.EXE
4.45 displays a warning message and continues to load when this
NOVCPI Switch for Smaller Load Size
Previous versions of EMM386.EXE disable both expanded memory and
virtual control program interface (VCPI) support when the NOEMS switch
is used. EMM386.EXE 4.45 leaves VCPI support enabled by default when
the NOEMS option is used, relying on the expanded and extended memory
sharing enhancement to supply VCPI memory.
VCPI support can be disabled with the new NOVCPI switch. Using NOEMS
and NOVCPI together results in a reduction in the amount of extended
memory used by EMM386.EXE.
Token Ring Adapter Detection
EMM386.EXE automatically detects the memory location of IBM Token Ring
adapter cards and prevents the mapping of expanded or upper memory
over the adapter. The new Token Ring adapter detection can be disabled
by using the new NOTR command line switch.
By default, EMM386.EXE version 4.45 displays messages only if it
encounters an error condition. Adding the /VERBOSE (or /V) switch to
the EMM386 line in the CONFIG.SYS file forces EMM386.EXE to display
status and error messages while loading.
To display status messages without adding the /V switch, press and
hold down the ALT key while EMM386.EXE starts and loads.
For more information on the EMM386.EXE switches, type help emm386 at the MS-DOS command prompt.
Ability to Provide ROM Shadowing
EMM386.EXE version 4.45 includes a new ROM= switch that defines
regions of read-only memory (ROM) for EMM386.EXE to "shadow."
EMM386.EXE copies the contents of the ROM to extended memory (RAM) and
maps the ROM addresses to this memory. Specifying this switch can
speed up your system if it does not already use shadow RAM.
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