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Q76199: Using Quarterdeck’s BUFFERS.COM With MS-DOS 4.0 and Later

Article: Q76199
Product(s): Microsoft Disk Operating System
Version(s): MS-DOS:4.0,4.01,4.01a,5.0,5.0a
Operating System(s): 
Keyword(s): 
Last Modified: 23-NOV-1999

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The information in this article applies to:

- Microsoft MS-DOS operating system versions 4.0, 4.01, 4.01a, 5.0, 5.0a 
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SUMMARY
=======

Using the BUFFERS.COM utility from any version Quarterdeck expanded memory
manager 386 (QEMM386) before 6.0 with MS-DOS version 4.0 or later will trigger
the following error message:

  BUFFERS requires DOS version 2 or 3 to run

Support for MS-DOS version 5.0 was added in the 6.0 release of QEMM386.
BUFFERS.COM continues to be incompatible with MS-DOS versions 4.00, 4.01 and
4.01a.

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

Look-ahead buffers, introduced in MS-DOS 4.0, allow multiple sector processing
when sequential data is read from or written to a disk. Quarterdeck BUFFERS.COM
does not support this format.

BUFFERS.COM, prior to QEMM version 6.0, is designed to allow users with QEMM and
MS-DOS versions earlier than 4.0 to load system buffers out of conventional
memory with the following line in the AUTOEXEC.BAT file:

     loadhi buffers=##

This loads the disk buffers into High RAM, also known as Upper Memory Blocks.
Buffers created with BUFFERS.COM are in addition to buffers allocated via the
BUFFERS= statement in CONFIG.SYS.

With the 6.0 release of QEMM, support for MS-DOS 5.0 was added to BUFFERS.COM and
buffers can be loaded high through the AUTOEXEC.BAT in the manner listed above.
However, there is less need to use BUFFERS.COM with MS-DOS 5.0 as up to 48 disk
buffers can be loaded into the high memory area (HMA) when MS-DOS is loaded
high. For example, the following lines in the CONFIG.SYS file will allocate 20
buffers which load with MS-DOS into the HMA:

     device=c:\qemm\qemm386.sys
     dos=high
     buffers=20

If more than 48 buffers are in specified using BUFFERS=, all of the buffers
allocated by BUFFERS= will be loaded into conventional memory.

Although all versions of BUFFERS.COM continue to be incompatible with MS-DOS
versions 4.0, 4.01, and 4.01a, buffers can be loaded into expanded memory (when
present) by adding /X to the end of the buffers line in the CONFIG.SYS file. For
example, the line below loads 20 disk buffers into expanded memory:

     buffers=20 /x

The product included here is manufactured by vendors independent of Microsoft; we
make no warranty, implied or otherwise, regarding this product's performance or
reliability.

Reference(s):

"Quarterdeck expanded memory manager 386," version 5.0 pages 43-44. "Quarterdeck
expanded memory manager 386," version 6.0 page 67.

Additional query words: 4.00 4.01 4.01a 5.00 5.00a

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Keywords          :  
Technology        : kbMSDOSSearch kbMSDOS400 kbMSDOS500 kbMSDOS401 kbMSDOS500a
Version           : MS-DOS:4.0,4.01,4.01a,5.0,5.0a

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