AM79C983A datasheet(45/60 Pages) AMD

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Am79C983A

PRELIMINARY

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

−Ω resistors are required by the ml4663 drivers.

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.

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.

AM79C983A Datasheet(PDF) 45 Page - Advanced Micro Devices

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