I'm going to bring this up from the dead with some tech info. Just about every Localtalk to Ethernet bridge made uses a Zilog SCC or compatible to interface with the Localtalk side of things. Here are the hardware specs for the "high end" Fastpath boxes. I'd imagine the Gatorbox CS uses similar hardware. Both are capable of routing Appletalk, DECNet, and TCP/IP. They can also tunnel Appletalk over TCP/IP.

Fastpath 4

CPU: 8Mhz 68000

RAM: 256k, upgradable to 512k

Localtalk Interface: Zilog SCC

Ethernet Interface: Intel i82586 10Mbit NIC

Onboard ROM has Appletalk routing software

Fastpath 5

CPU: 10Mhz 68000

RAM: 512k, PCB has solderpads to take 1MB

Localtalk Interface: Zilog Z181

Ethernet Interface: Fujitsu Etherstar 86950 10Mbit NIC

Minimal onboard boot ROM. Appletalk routing software is RAM based and has to be uploaded.

The "K-STAR" TCP/IP routing software is RAM based on both units and is an optional install. It is based on the now open source KIP routing software (later dubbed MacIP by Apple) from Stanford University.