AM79C983A Advanced Micro Devices, AM79C983A Datasheet - Page 13

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

PIN DESCRIPTION
Pseudo AUI Pins
PDO
Pseudo AUI Data Output
Output/High Impedance
PDO is a single-ended output driver. PDO can be
placed into a high impedance state, allowing multiple
IMR2 devices to connect to a single QuIET device (port
switching). The output data is Manchester encoded.
PDI
Pseudo AUI Receive Data Input
Input
The input data is Manchester encoded.
PCI
Pseudo AUI Collision Input
Input
PAUI port collision data receiver. A 10-MHz square wave
indicates a collision has been detected on that port.
RAUI Port Pins
RDO+, RDO-
Reversible AUI Data Output
Output
RDO is a differential, Manchester output driver.
RDI+, RDI-
Reversible AUI Data Input
Input
RDI is a differential, Manchester receiver.
RCI+, RCI-
Reversible AUI Collision Input
Input/Output
RCI is a differential I/O. As an input, RCI receives a col-
lision indication. As an output, RCI generates a 10-MHz
square wave when a collision is sensed.
PS
Output
This pin is reserved for factory use.
AUI Pins
DO+, DO-
AUI Data Output
Output
AUI port differential driver. Manchester encoded data.
DI+, DI-
AUI Data Input
Input
AUI port differential receiver. Manchester encoded data.
0-11
0-11
0-11
P R E L I M I N A R Y
Am79C983A
CI+, CI-
AUI Collision Input
Input
AUI port collision differential receiver.
Expansion Bus Pins
DAT
Data
Input/Output/High Impedance
The IMR2 device drives the DAT line with NRZ data
when both REQ and ACK pins are asserted. DAT is an
input if only the ACK signal is asserted. If REQ and ACK
are not asserted, DAT enters a high impedance state.
During collision when JAM is HIGH, DAT is used to sig-
nal a multiport (DAT=0) or single port (DAT=1) condition.
JAM
Jam
Input/Output/High Impedance
This pin is an output if the device is the only active
IMR2 device. An IMR2 device is defined as active when
it has one or more ports receiving or colliding, is in the
state where it is still transmitting data from the internal
FIFO, or is extending a packet to the minimum 96-bit
times. If active, the IMR2 device drives the JAM pin
HIGH to indicate that it is in a Collision state when both
REQ and ACK pins are asserted. JAM is an input if only
the ACK signal is asserted. If REQ and ACK are not as-
serted, JAM enters a high impedance state.
REQ
Request
Output, Active LOW
This pin is driven LOW when the IMR2 device senses
activity. An IMR2 device is defined as ACTIVE when it
has one or more ports receiving or colliding, is in the
state where it is still transmitting data from the internal
FIFO, or is extending a packet to the minimum 96-bit
times. The assertion of this signal signifies that the
IMR2 device requires the DAT and JAM lines to transfer
repeated data and collision status information to other
IMR2 devices.
ACK
Acknowledge
Input, Active LOW
When this signal is asserted by an external arbiter, it
signals to the requesting IMR2 device that it may drive
the DAT and JAM pins. It signals to other IMR2 devices
the presence of valid collision status on the JAM line
and valid data on the DAT line.
13