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Uthernet II

Uthernet II is an Ethernet card for the Apple IIe and Apple IIgs. In GSSquared it gives emulated software a working TCP/IP path to the internet without installing drivers or virtual adapters on your host computer.

What it does

  • Emulates a W5100-based Uthernet II in an expansion slot.
  • Uses user-space networking (slirp): HTTP, DHCP, and many TCP apps work out of the box on macOS, Windows, and Linux.
  • No root/admin privileges, TAP device, or WinPcap/Npcap install required for normal use.

Limits: The guest is behind NAT. Local LAN broadcast / SMB discovery of machines on your real network generally will not work. Passive browsing and many TCP clients are fine; active-mode FTP is unreliable under double NAT.

How to enable it

In the config editor

  1. At System Select, open + or Edit….
  2. Choose a platform: Enhanced //e or Apple IIgs (ROM 01 or ROM 03).
  3. Click an empty slot (1–7) and pick Uthernet II.
  4. Save the .gs2 config, then launch it.

In a .gs2 file

[[cards]]
slot = 3
card = "uthernet2"

You can install more than one Uthernet II in different slots if needed.

Using it from Apple II software

Configure the guest stack for Uthernet II (W5100), not the older Uthernet (CS8900). The I/O base is $C0x4 where x = 8 + slot (slot 3 → $C0B4).

Contiki (Enhanced IIe)

Contiki does not auto-detect the card. On each Contiki disk:

  1. Run ETHCONFI.SYSTEM, choose Uthernet II, and set the same slot as in your config.
  2. Run IPCONFIG.SYSTEM (DHCP or manual).

A slot mismatch usually shows as w5100.eth: No hardware.

GS/OS / Marinetti

File → Mount Drivers mounts /GS2.DRIVERS. Run the installer on that volume and choose Marinetti and Uthernet II (and Host FST if you want :Host as well). Then configure Marinetti for Uthernet II in the slot you chose. With DHCP, the guest typically receives an address on slirp’s private /24 (gateway often .2, DNS .3).