A2065 Reference

The A2065 is a full-length Zorro-II network card that supports the Ethernet standard. Both BNC (coax) and DB15 (AUI) connectors are provided. While the A2065 hasn't been produced for some time, it's still the most common Ethernet board found in Zorro-bus Amigas.

Ethernet Configurations

10Base-2 (coax cable, or "thin net") and 10Base-T (twisted pair) are now the most common variations of Ethernet.

Thin Net (10Base-2, or coax)

The coaxial cable variant of Ethernet uses a bus arrangement, where a "t-connector" is attached to the BNC connector of the Ethernet board, and RG58 coaxial cable is connected to the two BNC connectors on it. (Note that "stub" extension cables between the t-connector and the card are *not* allowed.) At the ends of the bus, 50-ohm terminating resistors are installed on the unused BNC connectors of the t-connector.

Twisted Pair (10Base-T)

Twisted-pair Ethernet uses two pairs of Category 3 (or higher) twisted- pair wire, although the wire usually used actually contains four pairs. Eight-conductor RJ45 phone-type connectors are used (the actual pins connected are 1,2,3 and 6). Topologically, 10Base-T uses a star arrangement, where wire is run between each workstation and a "concentrator," or hub. Two cards can be directly connected with a "null- modem" version of the standard cable, in which the pairs are swapped (1-2 connect to 3-6, and 3-6 connect to 1-2).

While the A2065 does not directly support 10Base-T, inexpensive transceivers are available to plug into the AUI port.

Board Address

The firmware Ethernet address of the A2065 can be determined by taking the registered CBM block number (00-80-10) and appending the hex value shown on the sticker on chip U4.

Board Layout

 |                                                                 |___
 |                                                                 |
 |                                                                 |
 |                                                                 |_
 |                                                                 |_| BNC
 |                                                                 |
 |                                             JP7       ABC       |_
 |                                             :         ABC       | |
 |                                                       ABC       | | AUI
 |           JP1-JP6                                               | |
 |           ::::::                                                |_|
 |                                                                 |
     |||||||||||||||||||||||||||                                   |


  JP1-JP6: Interrupt (default is JP2).

  JP7: Ethernet Type
    Off: Type 1.
     On: Type 2 (default).

  ABC Jumpers: Select Thick/Thin Ethernet.
    AB: Select BNC connector (thin Ethernet).
    BC: Select AUI connector (thick Ethernet).