Ethernet transceiver
From Computer History Wiki
Contents
Ethernet Transceiver Functions
From "EK-H4000-TM-PRE H4000 Ethernet Transceiver Technical Manual", chapter 1.2.2 "Transceiver Functional Description":
The transceiver performs the following functions:
- Transmit: Responds to the signals input from the transceiver cable and transmits the signals on the coaxial cable.
- Receive: Responds to signals transmitted on the coaxial cable and couples the received signals to the transceiver cable.
- Collision Detect: Monitors the signals transmitted on the coaxial cable and, if a collision occurs, signals appropriately on the transceiver cable.
Additionally, the transceiver does the following:
- Maintains electrical isolation between the coaxial cable and the transceiver cable,
- Maintains low loading/high impedance on the coaxial cable,
- Provides continuous data loopback (i.e., the receiver portion of the transceiver is always active; thus, the message being transmitted is coupled back on the transceiver cable),
- Provides self test of the collision detection circuitry at the end of each transmission,
- Contains protective circuitry which ensures that network integrity will be maintained in the event of a faulty transceiver, controller, or repeater.
DEC Ethernet Transceiver Models
H4000 Ethernet Transceiver (Thickwire)
1982
H4000 with Inclusive Tap
H4000 with Removable Tap
H4005 Ethernet Transceiver (Thickwire)
????
DESTA Thinwire Ethernet Station Adapter
1986
Early DESTA
The early DESTA (REV A) is a H4005 with a modified top assembly carrying a female BNC socket.
You can replace the BNC top assembly with that of an H4005 and thus use the early DESTA with Thickwire Ethernet.
On the other hand you can use the top assembly of an early DESTA to use an H4005 for Thinwire Ethernet.
Late DESTA
The late DESTA (REV B) is housed in a slightly smaller box and the BNC socket is fixed.
H3350 Twisted Pair Transceiver
????
DECXM Thinwire Transceiver
????
DETPM 10BaseT Transceiver
????
