Gary:

You said you already have the DP8390 Network Interface controller chips.

In the obsolete data sheet for this part National Semiconductor shows the use of the companion DP8392 Serial Network Interface chip. Do you also have these parts in hand?

The data sheet also shows the use of a DP8392 Coax Transceiver Interface to gate the local network onto and off a coaxial implementation of Ethernet. Is the topology of the network you intend to use? If so do you already have the DP8392 chips? If not what is your planned method of gating your local serial drop (AUI level interface) onto and off the Ethernet transmission medium?

Answers to these questions may help shed some light on the further integration of the DP8390 core into an 8051 system.

Michael Karas