Improve 16 bit DMA transfers by increasing DMA buffer size

Windows 9x is able to run 16 bit programs, and when they attempt to allocate DMA buffers to perform Direct Memory Access (DMA) transfers they are limited to the pre-allocated DMA buffer (with double buffering), unless they can provide a physically contiguous memory allocation themselves.

To configure the size of the pre-allocated DMA buffer, add this line in the file SYSTEM.INI in the section [386Enh]:

[386Enh]
DMABufferSize=64 (Default - 16 Range 1-256)

More Info MS KB82711
More Info MS KB82790
More Info MS KB124729

Note the above setting can also be configured by going to the "Control Panel" -> "System" -> "Device Manager", and expand the "System"-node, and select properties for "Direct Memory Access Controller", and select the tab "Settings" and set the "Reserve DMA buffer" to 64.

Updated: 2 July 2007

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