am79c981 Advanced Micro Devices, am79c981 Datasheet - Page 12

• Manufacturer Part Number: am79c981
• Description: Integrated Multiport Repeater Plus? Imr+? ??9
• Manufacturer: Advanced Micro Devices

Modular Repeater Design
The expansion port of the IMR+ chip also allows for
modular expansion. By sharing the arbitration duties be-
tween a backplane bus architecture and several sepa-
rate repeater modules one can build an expandable
repeater based on modular ‘plug-in’ cards. Each
1–82
ASYNC
RESET
Note 1:
Direction
B
A
AMD
A
B
D
1/2 ’74
D FF
XTAL
OSC.
CK
LOW
HIGH
Q
DIR
Figure 1. Multiple IMR+ Devices
PRELIMINARY
Am79C981
ACK
COL
RST
X1
ACK
COL
RST
X1
ACK
COL
RST
X1
REQ2 REQ3 REQ1
COL
ACK
Am79C981
Am79C981
Am79C981
ARBITER
IMR+ Chip
IMR+ Chip
IMR+ Chip
repeater module performs the local arbitration function
for the IMR+ devices on that module, and provides sig-
nals to the backplane for use by a global arbiter.
For more detailed information, see AMD’s IEEE 802.3
Repeater Technical Manual, PID# 17314A.
REQ
REQ
1
2
3
REQ
DAT
DAT
DAT
REQ
ACK
JAM
JAM
JAM
Bus transceivers needed
if DAT and JAM buses
exceed 100 pF loading.
A
DIR
B
Note 1
17306B-5