The Hydra board is a Zorro II compatible full length Ethernet network adapter for all Zorro bus compatible machines. It is widely acknowledged as a superior board to the A2065, having faster throughput.
Physically, it has an AUI port for transceiver and a pair of BNCs for RG58 ThinNet Coax. This strange configuration has a plus: it means you won't need an extra T connector for each board! Just daisychain the ThinNet cables in and out of each Hydra. This means you won't need an extra T connector for each board; just daisy-chain the ThinNet cables in and out of each Hydra. There is no difference between the two BNCs, just make sure that there is either another station attached to the other BNC, or a terminator if you're on the end of the chain.
Onboard, there is only one set of jumpers, block F1, which has six pairs of pins. When all are in the down pair jumpered position, it is set to ThinNet 10Base2 (CheaperNet). When all are jumpered on the up pair, the Hydra is set to use the AUI port for 10Base5. (Meaning you can attach a Thick transceiver, a FOIRL optic box, or a 10BaseT twisted pair adapter.) This shouldn't really be needed-it's already printed on the board and VERY clearly marked. It uses a NatSemi 32490CN Ethernet chip.
Software-wise, a SANA2 driver, hydra.device, is provided with the board.
| :::::: F1 |
| |# 10Base5
| |# /AUI
| |# Port
| |# (DB15)
| |_| BNC
| |_| BNC