from AMD manual:

=AD Enhanced DMA controller includes double buffer
chaining, extended address and transfer counts,
and flexible channel routing
=AD Two 16550-compatible UARTs operate at baud
rates up to 1.15 Mbit/s with optional DMA interface
            ^^^^^^^^^^^


it's bad soekris does not include drivers that make use of it.


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Instead of asking why a piece of software is using "1970s technology,"
start asking why software is ignoring 30 years of accumulated wisdom.