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Q73324: Devices/TSRs Do Not Load High with RAM Switch

Article: Q73324
Product(s): Microsoft Disk Operating System
Version(s): MS-DOS:5.0,5.0a
Operating System(s): 
Keyword(s): 
Last Modified: 19-NOV-1999

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The information in this article applies to:

- Microsoft MS-DOS operating system versions 5.0, 5.0a 
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SYMPTOMS
========

Even if you install HIMEM.SYS and EMM386.EXE and are using DEVICEHIGH for device
drivers and LOADHIGH for terminate-and-stay-resident (TSR) programs, your device
drivers and TSR programs do not load high.

CAUSE
=====

This problem can occur if you are loading EMM386.EXE with the RAM switch.

MORE INFORMATION
================

The RAM switch establishes a 64-kilobyte (K) page frame and sets up the upper
memory blocks (UMBs) for loading device drivers and TSR programs high. The
search algorithm allocates the first contiguous 64K of unused upper memory area
(UMA) addresses for the page frame and UMBs are created from any leftover
addresses.

If EMM386.EXE finds only 64K of the UMA for a page frame and UMBs, it creates a
page frame and does not have any addresses remaining from which to create UMBs.
Or, if only 74K is available for EMM386.EXE, only 10K would be used for a UMB,
which is too small for most drivers.

To work around this problem, force EMM386.EXE to use more addresses in the UMA by
using the I= switch; or, if expanded memory is not necessary, use EMM386.EXE
with the NOEMS parameter to make available all addresses used for UMBs.

For example, the range E000-EFFF is frequently unused. If the usable portion of
the UMA starts at C800h and you know there is a 64K free block of memory
starting at E000h, you can modify the EMM386.EXE line in your CONFIG.SYS file as
follows:

  DEVICE=EMM386.EXE I=E000-EFFF RAM

By using the I= switch, the search algorithm includes the specified range when
attempting to create a page frame and UMBs.

EMM386.EXE can also be forced to include address ranges for a page frame when a
page frame is specified using the FRAME=, /P, or M switch that includes
addresses which EMM386.EXE would not have otherwise used. As in the above
example, you can modify the CONFIG.SYS file as follows:

  DEVICE=EMM386.EXE FRAME=E000 RAM

This line forces the page frame to start at E000h and leaves the range from C800h
to DFFFh free for loading programs high.

To view the location of programs loaded high and in conventional memory, use the
MEM command with the /DEBUG switch. For more information on the MEM command and
using the UMA, see the version 5.0 "Microsoft MS-DOS User's Guide and
Reference."

For more information optimizing your upper memory blocks, query on the following
words in the Microsoft Knowledge Base:

  "optimizing" (without the quotation marks) and "blocks" (without the
  quotation marks) and "5.00" (without the quotation marks)

Additional query words: 5.00 5.00a

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Keywords          :  
Technology        : kbMSDOSSearch kbMSDOS500 kbMSDOS500a
Version           : MS-DOS:5.0,5.0a

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