Windows 3.1 Resource Kit SYSTEM.INI [386ENH] Section M-Z

• Microsoft Windows operating system versions 3.1, 3.11

SUMMARY

This article contains information from the SYSINI.WRI file that ships in the Microsoft Windows Resource Kit for the Microsoft Windows operating system version 3.1. You can view SYSINI.WRI within Microsoft Windows Write.

The [386ENH] section of the SYSTEM.INI file contains information specific to running Windows in 386 enhanced mode, including information used for virtual-memory page swapping.

MORE INFORMATION

The [386Enh] section can contain the following settings:

____________________________________________________________ MapPhysAddress=<range> Default: None Purpose: Specifies the address range (in megabytes) in

          which the memory manager preallocates physical
          page-table entries and linear address space. Use
          this setting if you are using a DOS device driver
          (such as an older version of RAMDrive that uses
          extended memory) that needs contiguous memory.

          method for transferring control to 386 Enhanced
          Windows) that can be used by the Virtual Memory
          Manager. You may need to increase this value if
          you are using a third-party virtual device driver
          that requires more break points than the default
          value.

          supported in enhanced mode. Change this value if
          you have more than 4 COM ports installed in your
          computer.

          computers)

          can be used for Direct Memory Access (DMA). This
          setting works only with hard drives that support
          DMA.

          temporary swap file.

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          physical page number detected by the Memory
          Manager during initialization.

          the Memory Manager can manage as a useable page.
          This setting allows pages to be added at a
          physical address beyond what the Memory Manager
          recognized during initialization. If the value
          specified is less than what the Memory Manager
          determines, the Memory Manager will ignore several
          physical pages that it would normally use,
          preventing the use of memory. This is useful if
          you are using a hardware device that cannot
          recognize all of the physical memory in your
          computer (for example, ISA DMA Network cards
          cannot access physical memory above 16 megabytes.)

          computers

          extensions to direct- memory access (DMA). This
          setting only applies to MCA computers. Disable
          this setting if you are using an MCA computer, but
          the DMA extensions are not implemented.

          such as the screen that appears when you press
          Ctrl+Alt+Del.

          message screens, such as the screen that appears
          when you press Ctrl+Alt+Del.

          milliseconds) a virtual machine is allowed to run
          before other virtual machines can take over. A
          smaller value (such as 10 milliseconds) will make
          multitasking appear smoother, but will decrease
          overall system performance.

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          unlocked and available for use when resuming a
          virtual machine if more than one virtual machine
          is running.

            should never need to change this setting.

          leave free when creating a temporary swap file.
          Use this setting if your system's paging drive has
          less available space than Windows can use for
          paging. This setting does not apply if a permanent
          swap file exists.

          your system configuration.)

          mouse hardware in 386 enhanced mode.

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          function 0 hard initialization calls to function
          33 soft initialization calls, which do not reset
          the mouse hardware. If enabled, you can use a
          mouse with a non-Windows application that you
          start in a window. Disable this setting if the
          cursor and screen information appear garbled or
          distorted when using the mouse with an
          application. If you disable this setting, you may
          not be able to use the mouse when running a non-
          Windows application in a window.

          NetBIOS request. When an application issues an
          asynchronous NetBIOS request, Windows will attempt
          to allocate space in its global network buffer to
          receive the data. If there is insufficient space
          in the global buffer, Windows will normally fail
          the NetBIOS request. If this setting is enabled,
          Windows will attempt to save such a request by
          allocating a buffer in local memory and preventing
          any other virtual machines from running until the
          data is received or the timeout period (specified
          by the NetAsynchTimeout setting) expires.

          Windows needs to enter a critical section in order
          to service an asynchronous NetBIOS request. It is
          used only when NetAsynchFallback is enabled. This
          value can include a decimal (such as 0.5).

          compatible); 0 on non-Micro Channel machines (IBM
          PC/AT compatible).

          NetBIOS transport software if a network has been
          installed. In this case, the buffer size is the
          larger value between this value and the value of
          DMABufferSize.

          transfer buffers in conventional memory that
          Windows allocates for transferring data over a
          network when running in 386 enhanced mode. All
          values are rounded up to the nearest 4K.

          your system configuration.)

          Windows in 386 enhanced mode.

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          nonmaskable interrupt is received.

          from installing its expanded memory driver. This
          differs from setting EMMSize to zero, which does
          not prevent the EMM driver from being loaded.

          NetBIOS commands to asynchronous commands. When
          this setting is enabled, synchronous NetBIOS
          commands are converted. This can improve overall
          system performance when running several
          applications.

          and write requests to  a disk before the first
          request has been completed. If disabled, virtual
          machines cannot issue a request to read or write
          to a disk until any previous read and write
          requests have been completed.

            should never need to change this setting.

          store asynchronous read and write pages. This
          setting is used only if you are using 32-Bit Disk
          Access and a permanent swap file. You can specify
          a value between 0 and 32. Increasing this value
          can improve Windows' performance.

          amount of linear address space the Memory Manager
          will create for the system. The amount of linear
          address space that the Memory Manager will create
          is computed by rounding up the amount of available
          physical memory to the nearest 4 megabytes and
          then by multiplying that value to the value
          specified for this setting. You can specify a
          value between 1 and 20. Increasing this value
          increases the amount of available linear address
          space, causing the size of data structures to
          increase. This also increases paging activity
          proportionately and can slow down the system.

          and permanent and temporary swap files. Disable
          this setting only if you need the disk space
          normally used for a temporary swap file.

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          enhanced mode will create a temporary swap file.
          This setting is ignored if you have a permanent
          swap file. If you don't have a permanent swap file
          and no drive is specified or the specified drive
          does not exist, Windows will attempt to put your
          temporary swap file on the drive containing your
          SYSTEM.INI file. If the specified drive is full,
          paging will be disabled.

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          swap file that is created when you start Windows
          in 386 enhanced mode. This file is deleted when
          you quit Windows. This setting overrides the
          PagingDrive setting.

          needs to fill in memory  based on how DOS is
          occupying memory.)

          of memory to a computer that has less than 640K of
          base conventional memory. Enabling or disabling
          this setting overrides the automatic checking done
          by Windows.

            should never need to change this setting,
            because Windows can automatically detect whether
            or not to perform a backfill.

          enhanced mode will create a permanent swap file.
          This setting is ignored if you are using a
          temporary swap file.

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          permanent swap file.

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          Windows should allocate to each virtual machine.
          Increase this value if an application does not
          have enough file handles to run. The total number
          of file handles, including the global handles
          specified in the FILES= statement in CONFIG.SYS,
          cannot exceed 255. If it exceeds 255, this value
          will be rounded down. Set this value to 0 to
          prevent the allocation of any private file
          handles. If SHARE is installed, then this setting
          is ignored in the SYSTEM.INI file.

          byte increments, that Windows should reserve in
          each successive virtual machine when the
          UniqueDOSPSP setting is enabled. The setting that
          works best for your  machine might vary depending
          on your memory configuration and the applications
          you are running. Valid values are 2 through 64.
          See UniqueDosPSP for more information.

          reflect DOS INT 2A signals. The default means
          Windows will consume these signals and therefore
          run more efficiently. Enable this setting if you
          are running memory-resident software that relies
          on detecting INT2A messages.

          scan to find unused address space. This has the
          side effect of turning off the RAM and ROM  search
          code for the range. The range (two paragraph
          values separated by a hyphen) must be between A000
          and EFFF. This scanning can interfere with some
          adapters that use the same memory area. The
          starting value is rounded down and the ending
          value is rounded up to a multiple of 4K. For
          example, you could set ReservedHighArea=E100-E3FF
          to prevent Windows from scanning the first 12K of
          memory starting at E100. You can specify more than
          one range by including more than one
          ReservedHighArea line.

          to EMS page frame space or conventional memory
          when it has to use one of the two to allocate MS-
          DOS transfer buffers. This choice is necessary
          when Windows cannot find space (other than EMS
          page frame space) between 640K and 1MB. If
          enabled, this setting will preserve EMS page frame
          space at the expense of conventional memory. If
          your non-Windows applications do not require
          expanded memory, disable this setting to make more
          conventional memory available to non-Windows
          applications.

          exists in pages C6 and C7. If the text font
          appears scrambled when starting non-Windows
          applications, enable this setting.

            should not need to change this setting, because
            the default setting causes Windows to detect
            video ROM correctly.)

          memory area in the adapter region (usually between
          C000-EFFF) that has no ROM header or incorrect
          header information is read-only memory (ROM). The
          number for this setting specifies how many
          different values must occur within the memory area
          to determine whether or not it is ROM. If the
          number of transitions is greater than the value
          for this setting, Windows recognizes the memory
          as ROM. If the number of transitions is less than
          the value, Windows recognizes the memory as usable
          memory. A value of 0 disables this setting,
          causing Windows to recognize this memory area as
          usable.

            should never need to change this setting.)

          non-Windows application that is running in a
          Window before its display is updated.

            should never need to change this setting.)

          port to the Windows screen rather than to the
          current virtual machine.

          time with the computer's CMOS clock. If this
          setting is disabled, Windows usually maintains the
          correct time, unless TrapTimerPorts is disabled
          and you are running applications that can cause
          the system time to run faster or slower than the
          actual time. This setting is related to the
          TrapTimerPorts setting.

          80386/486 CPU. False if Windows is started in
          virtual mode of the 80386/486 CPU. Most 386 memory
          managers, such as QEMM and 386MAX, require this
          value to be set to false. If a 386 memory manager
          is running Windows is started in virtual mode.
          Otherwise, Windows is started in real mode.

          space between F000:0000 and 1MB for a break point.
          Windows in 386 enhanced mode normally searches
          this space to find a special instruction that is
          used as a system break point. If this address
          space contains something other than permanently
          available ROM, you should disable this setting.

          Windows is permitted to use. Setting this value to
          0 prevents Windows from gaining access to any
          expanded memory. Setting it to -1 gives Windows \
          all the available expanded memory that it
          requests.

          used by Windows applications to the hard disk.
          Locking expanded memory (enabling this setting)
          can improve the performance of a Windows
          application that uses it, but can slow down the
          rest of the system.

            should never need to change this setting.)

          must be free in order to start Windows. Leave this
          setting at zero if no Windows applications require
          expanded memory.

          the system virtual machine to remain locked in
          memory instead of swaping it out to disk.

            (Because Windows controls this process, there is
            no need to change this setting.)

          kilobytes) the extended  memory driver allocates
          to DOS device drivers and memory-resident software
          in the system virtual machine. Set the value to -1
          to give an application all the available extended

          memory that it requests.

          must be reserved by the XMS driver in order to
          start Windows. Leave this setting at zero if there
          are no XMS users in the system virtual machine.

          around all timer interrupt code, and specifies a
          timeout period (in milliseconds). Specifying a
          positive value causes only one virtual machine at
          a time to receive timer interrupts. Some networks
          and other global memory-resident software may fail
          unless this setting is used. However, it slows
          down performance and can make the system seem to
          stop for short periods of time.

          network adapter on machines with IBM PC/AT (R)
          architecture. Disable this setting if you are not
          using a token ring card and the search interferes
          with another device.

          scan codes to make them compatible with standard
          IBM scan codes. Use this setting only if you  have
          a keyboard that generates non-standard scan codes.
          This setting is used only for the Switcher Screen
          and fullscreen message boxes.

          write operations to the system timer ports that
          are performed by applications. If disabled,
          Windows will not trap these operations, allowing
          applications that fequently read or write to the
          timer to run faster. However, this may interfere
          with Windows' ability to keep accurate system
          time. If disabled, Windows can usually detect when
          an application has changed the timer interrupt
          interval and then make any adjustments to the
          time. If your system's time appears to be running
          fast or slow, enable this setting. If you do not
          want to enable this setting, enable the SyncTime
          setting. This causes Windows to check the time
          periodically and then make any necessary
          adjustments.

          Microsoft Network or LAN Manager. See the
          NETWORKS.WRI online document to find out whether
          the network you are running is one of these);
          False for all other networks.

          unique address (PSP). Each time Windows creates a
          new virtual machine to start a new application,
          Windows reserves a unique amount of memory (i
          bytes) below the application. For example, if the
          first application is loaded at address M, the
          second application is loaded at address M+i, the
          third at M+2i, and so on.The amount of memory (i)
          is determined by the PSPIncrement setting. These
          settings ensure that applications in different
          virtual machines all start at different addresses.
          Some networks use applications' load addresses to
          identify the different processes using the
          network. Disabling this setting on such networks,
          might cause one application to fail when you exit
          another because the network interprets them as the
          same application. If you enable this setting,
          slightly less memory is available for non-Windows
          applications.

          treat as unused address space regardless of what
          may be there. UseableHighArea takes precedence
          over ReservedHighArea if you specify ranges that
          overlap. The range (two values separated by a
          hyphen) must be between A000 and EFFF. The
          starting value is rounded down and the ending
          value is rounded up to a multiple of 4K. For
          example, you could set UseableHighArea=E100-E3FF
          to ensure that Windows can use the first 12K of
          memory starting at E100. You may specify more
          than one range by including more than one
          UseableHighArea line.

          INSTANCE.386 file for information it can use to
          determine whether data structures within MS-DOS
          need to be local. There are two other methods for
          giving Windows this information: internal tables
          within the device, and an INT 2Fh call documented
          in the OEM Adaptation Kit. Both methods are
          preferable to using this setting; it is provided
          only for compatibility with Windows/386 version
          2.x.

          the video read-only memory (ROM) for displaying
          messages that appear when non-Windows applications
          are running in a full screen, and for displaying
          the text that appears when switching away from a
          non-Windows application. Disable this setting if
          the font used to display messages is different
          than the font used in the application, or if
          random dots and shapes appear on your screen.

          address space in VGA displays, usually used for
          monochrome adapters. When this setting is
          disabled, Windows can use the B000h through B7FF
          range for upper memory space, provided that no
          hardware device is using these addresses and your
          applications do not use the monochrome display
          mode of your VGA adapter.

To change: Use Notepad to edit the SYSTEM.INI file. ____________________________________________________________ VideoBackgroundMsg=<Boolean> Default: True Purpose: If enabled, Windows displays a message when a

          background application is suspended, or if its
          display cannot be updated properly because video
          memory is low. Disabling this setting turns off
          the warning message. This setting affects all non-
          Windows applications that are currently running.

          running in the background if their display become
          corrupted. If this setting is enabled, the
          application continues running. If disabled,
          applications become suspended and a warning
          message appears, if the VideoBackgroundMsg setting
          is enabled.

To change: Use Notepad to edit the SYSTEM.INI file. ____________________________________________________________ VirtualHDIrq=<Boolean> Default: On for AT-compatible computers; Off for all other

          computers.

          terminate interrupts from the hard disk
          controller, bypassing the ROM routine that handles
          these interrupts. Some hard drives might require
          this setting to be disabled in order for
          interrupts to be processed correctly. If this
          setting is disabled, the ROM routine handles the
          interrupts, which slows down system performance.

          kilobytes) must be free in order to start Windows.

          can use for itself. The default value (-1)
          indicates that Windows can use as much
          conventional memory as it needs. If there is not
          enough memory to run Windows in 386 enhanced mode,
          try entering a positive value less than 640.

          Windows takes before it updates the display oXf
          non-Windows applications running in a window.

          is allocated to Windows whenever a Windows
          application is in the foreground. If this setting
          is enabled and a Windows application is in the
          foreground, no non-Windows application will run.

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          number specifies the relative amount of processing
          time (based on the MinTimeSlice setting) given to
          all Windows applications running in the
          foreground, relative to the time allocated to all
          non-Windows applications running in the
          background. The second number specifies the
          relative amount of processing time given to all
          Windows applications running in the background
          when a non-Windows application is running in the
          foreground. The range of valid numbers is 1
          through 10000. The important value is the ratio of
          these settings to the corresponding settings in
          the PIF's of the active non-Windows applications.

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          memory when running non-Windows applications.
          These fonts are also available to your Windows
          applications as long as a non-Windows application
          is running.

            This setting changes when you change the
            Codepage or Display setting in Setup.

          to map MS-DOS calls from protected mode to virtual
          386 enhanced mode. Increasing this value can
          improve the performance of protected mode Windows
          applications that read or write information in a
          large number of bytes (for example, some database
          applications). However, this may decrease the
          amount of memory available for running non-Windows
          applications and may cause problems on networks
          that use named pipes. These networks may require a
          value of 4. The value you specify is rounded to
          the next 4-kilobyte increment. For example, if you
          set this value to 5, Windows rounds it up to 8.

          extended memory manager you are using.

          extended memory driver's upper memory block (UMB)
          management routines.

            should never need to change this setting.)

Reference(s):

"Microsoft Windows Resource Kit," version 3.1, SYSTEM.INI