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.