KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q78573: The Second Parameter of the BUFFERS Command

Article: Q78573
Product(s): Microsoft Disk Operating System
Version(s): MS-DOS:4.x,5.x,6.0,6.2,6.21,6.22
Operating System(s): 
Keyword(s): 
Last Modified: 17-DEC-2000

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft MS-DOS operating system versions 4.0, 4.01, 5.0, 5.0a, 6.0, 6.2, 6.21, 6.22 
-------------------------------------------------------------------------------

SUMMARY
=======

The second parameter on the BUFFERS line represents the secondary cache. It
basically performs a pre-read of sectors, and therefore provides better disk
performance. This functionality was introduced in MS-DOS 4.0, and it works the
same way in later versions of MS-DOS.

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

When an application starts reading from disk, it is likely that the application
will continue reading more sectors from the same area. If MS-DOS pre-reads
beyond the read issued into the buffers, when the user asks for them, they are
already in the buffers. This improves disk performance considerably, especially
during file loads.

The syntax for the BUFFERS command is:

  buffers=n[,m]

The "m" can have a value between 1 and 8.

If a second value ("m") is specified, it activates the operation of the secondary
cache, and "m" sectors are pre-read. If the second parameter is not specified,
the secondary cache is not activated.

If you specify to buffers values, extra buffers are then allocated during MS-DOS
initialization for the secondary cache. As a result, MS-DOS takes up more memory
since the secondary cache is present.

NOTE: Under MS-DOS 5.0 and later, the secondary cache is not loaded into the high
memory area (HMA) even if MS-DOS is loaded high; the secondary cache is always
allocated in conventional memory.

Additional query words: 6.22 4.00 4.00a 4.01 5.00 5.00a 6.00 6.20

======================================================================
Keywords          :  
Technology        : kbMSDOSSearch kbMSDOS400 kbMSDOS621 kbMSDOS622 kbMSDOS620 kbMSDOS600 kbMSDOS500 kbMSDOS401 kbMSDOS500a
Version           : MS-DOS:4.x,5.x,6.0,6.2,6.21,6.22

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.