AKA: I fell down an Internet rabbit hole and don't have the time to chase it further myself, documentation dump follows ;-)
I recently found out about the Lantronix UDS-10, which is basically an Ethernet to serial adaptor for terminal server and similar uses. It's now 10+ years old so companies are mass dumping them on eBay at US$20-$40. As a result, it's become a big thing with TI-99 users
to be able to do telnet and FTP, and it's started to catch on with C64 and other 8-bit microcomputer users as well.
It's based on a customized 80186 with a DMA controller, timers, Ethernet, and UART on-board. The programming manual for the custom SoC is available here:http://gridconnect.com/media/documentation/grid_connect/DSTni-LX_DataBook_F.pdf
There's a nice, bare power-of-2 64k flash firmware image here: http://www.lantronix.com/products/uds-10/#docs-downloads
Note that the chip *does* contain a small bootloader ROM, but it's more than well-documented enough to simulate. In the usual case it just does a quick POST, copies the flash ROM to RAM at 800h, and jumps to it.
The Ethernet controller is derived from the well-known AMD Am7990 LANCE chip and its ISA cousin the Am79C960, which are chips we'll eventually want to emulate. Every workstation ever in the late 80s/early 90s used a LANCE chip for Ethernet
ETA: there's a TI99 web browser
that uses this thing. Amazing.
Last edited by R. Belmont; 12/13/15 02:55 PM. Reason: Added TI browser link