Lee Jones wrote:

> Check Intel for 82586 and 82596;

  The *original* chipset is (NatSemi) 8390 (controller), 8391
(serialiser) and 8392 (line interface).  There are many "improved"
versions such as the above, some are 16-bit and some include the buffer
RAM.

  I managed to find datasheets for the "839x" variants which, with some
work, should permit you to write a protocol.
--
  Cheers,
        Paul B.