Then plug in an 8-bit ISA Ethernet card.

    I'd choose one which has on-board buffer memory.

The most popular 8bit (and 16 bit too, I think) ethernet design for PCs
(NE1000 style) is based on a national Semiconductor "reference circuit" for
their low-end ethernet controller.  These ALL have some on board buffer
memory (usually 8k.)  They're under $20 now (new), I think.  You can
probably still get copies of the reference design, even though the whole
thing has since become a single chip.

I *believe* that bus-mastering on ISA bus was sufficiently difficult and
incompatible with the buffering schemes of higher performance ethernet
controllers that there was NEVER an ISA ethernet card that didn't have
on-board buffers...

BillW
cisco