AM79C983A Advanced Micro Devices, AM79C983A Datasheet - Page 45

• Manufacturer Part Number: AM79C983A
• Description: Integrated Multiport Repeater 2 (IMR2)
• Manufacturer: Advanced Micro Devices

SYSTEM APPLICATIONS
IMR2 to QuIET Connection
The IMR2 device provides a system solution to design-
ing repeaters. It can be used with the QuIET
transceivers to design 10BASE-T hubs or with other
types of MAUs for 10BASE2 or 10BASE-FL hubs. The
MAU types can be mixed to design a hub that supports
multiple media types. The IMR2 device connects di-
rectly to the QuIET device transceivers. 7 shows the
simplified connection. Three QuIET devices may be
connected to a single IMR2 device for 12 ports. Only
one connection is shown for simplicity.
Other Media
The IMR2 device, with some supporting circuitry, can be
connected to the AUI port of any MAU device. Thus, it
can support 10BASE2 and 10BASE-FL. The example in
8 shows a PAUI port connected to a 10BASE-FL trans-
ceiver (ml4663). For the ml4663, signals TX, RX, and
COL are equivalent to the AUI signals DO, DI, and CI.
The 360
MAC Interface
The IMR2 device can be connected to a MAC using either
the RAUI port or the PR port. The RAUI port supports a
direct connection. The PR port requires some glue logic.
resistors are required by the ml4663 drivers.
P R E L I M I N A R Y
Am79C983A
RAUI Port
When the RAUI port is to be connected to a MAC, it
should be configured in reverse mode and connected
as shown in 9 (a). Notice that RDI is connected to DO
of the MAC and RDO is connected to DI. This is be-
cause the reverse configuration only affects RCI. 9 (b)
shows the normal AUI configuration for reference.
PR Port Configuration
The PR port may be connected to the GPSI port of a
MAC. Communication with the MAC involves both the
PR port and the Expansion Bus. The PR port connects
to the receive side of the MAC and the expansion bus
connects to the transmit side.
An example of the MAC connection is shown in 10.
Here the IMR2 device is connected to the SIA interface
of the Am79C90 (C-LANCE). MACEN, DAT, and ECLK
are bus signals. Therefore, the AND gates and buffers
to these signals must be open-collector or open-drain.
The OR gate for RENA satisfies the loopback require-
ments for the C-LANCE.
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