am79c940 Advanced Micro Devices, am79c940 Datasheet - Page 83

• Manufacturer Part Number: am79c940
• Description: Media Access Controller For Ethernet Mace
• Manufacturer: Advanced Micro Devices

Attachment Unit Interface (AUI)
The AUI can drive up to 50 m of standard drop cable to
allow the transceiver to be remotely located, as is typi-
cally the case in IEEE 803.3 10BASE5 or thick Ether-
net
such as 802.3 10BASE2 or Cheapernet interface, the
isolation transformer requirements between the trans-
ceiver and the MACE device can be reduced.
10BASE5/Ethernet
installations. For a locally mounted transceiver,
10BASE2/Cheapernet
CPU
System
Engine
DMA
CPU
Local Bus
Memory
Memory
Local
DTE
AUI-10BASE2/Cheapernet Example
AUI-10BASE5/Ethernet Example
I/O Bus
Am79C940
Am79C940
Am79C940
When used with the Am79C98 TPEX
Ethernet Transceiver), the isolation requirements of the
AUI are completely removed providing that the trans-
ceiver is mounted locally. For remote location of the
TPEX via an AUI drop cable, the isolation requirement is
necessary to meet IEEE 802.3 specifications for fault
tolerance and recovery.
Cable
AUI
Transceiver
Am7996
Supply
Power
MAU
Transceiver
Am7996
Supply
Power
Ethernet
Cheapernet
Coax
16235C-14
16235C-15
RG58
BNC “T”
Coax
(Twisted Pair
AMD
Tap
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