ZZ9000Net.device Ethernet emulation

Amiberry’s ZZ9000 board exposes the Ethernet register and frame windows used by the installed SANA-II ZZ9000Net.device. Select a ZZ9000 board in the Expansions panel, then choose its Ethernet backend. The default is SLIRP user mode NAT. The backend is separate from bsdsocket.library emulation and from other emulated network cards. The settings are saved in .uae files:

zz9000_net=slirp
zz9000_int2=false

For a test of the installed SANA-II stack, set bsdsocket_emu=false in the Amiberry configuration. Otherwise a guest application can use Amiberry’s host bsdsocket.library emulation without sending frames through the ZZ9000.

zz9000_net=none disconnects the card. TAP and pcap adapters appear in the selector when those backends are built and available. An unavailable backend leaves the card visible to the guest but causes transmit to return an error; Amiberry logs the failed host connection. SLIRP does not provide a bridge to other devices on the host’s physical LAN.

SLIRP supports one emulated network card at a time. If another card already uses it, the ZZ9000 host backend stays disconnected. Choose TAP or pcap for one card, or disable the other card, to use ZZ9000Net through SLIRP.

The interface uses board offsets 0x2000 for the current RX frame and 0x8000 for TX staging. Writing a frame length to register 0x80 transmits the staged frame and reading it returns the send status. The RX window starts with a big-endian size and serial header. Writing that serial to 0x82 accepts the frame; the previous driver’s constant 1 acknowledgement also works. An empty window reads as zero. Frames are bounded to 1518 bytes and the receive backlog holds up to 128 frames. The MAC address uses registers 0x84 through 0x88; status and drop counters use 0x8c and 0x8e.

The Ethernet interrupt is bit 0 of register 0x04. It shares Paula’s EXTER line (INT6) with ZZ9000AX by default. The guest’s ENV:ZZ9K_INT2 or ZZ9000.CFG INT2 setting requires zz9000_int2=true in Amiberry, selecting the PORTS line (INT2) for both functions. Change the setting before booting.

The A4000 test boot used writable copies of both real-machine hardfiles, zz9000_net=slirp, and bsdsocket_emu=false. The installed guest network stack carried traffic while ZZ9000AX audio played. The originals were not mounted by that test. The focused frame protocol test and Windows debug build passed. Longer bidirectional transfers, reset during traffic, TAP/pcap, Zorro II, and INT2 remain to be qualified.