The Second Parameter of the BUFFERS Command (78573)


The information in this article applies to:
    • Microsoft MS-DOS operating system 4.0
    • Microsoft MS-DOS operating system 4.01
    • Microsoft MS-DOS operating system 5.0
    • Microsoft MS-DOS operating system 5.0a
    • Microsoft MS-DOS operating system 6.0
    • Microsoft MS-DOS operating system 6.2
    • Microsoft MS-DOS operating system 6.21
    • Microsoft MS-DOS operating system 6.22
This article was previously published under Q78573

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.
Modification Type: Major Last Reviewed: 5/12/2003
Keywords: KB78573
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