PM3350-SW datasheet(115/224 Pages) PMC

115 / 224 page

ELAN 8X10

PM3350 ELAN 8 X10

DATA SHEET

PMC-970109

ISSUE 3

8 PORT ETHERNET SWITCH

PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND PMC-SIERRA, INC. CUSTOMERS ONLY

113

Note that the use of counters rather than flags or registers permits multiple requests or

acknowledges to be outstanding at any device without problems. Each destination

device must thus maintain a request counter that the source device can increment, and

each source device must maintain a counter that the destination can increment in

acknowledgement. If the "destination" device wishes to send frames back to the

"source" device, then a mirror set of request and acknowledge counters must be

implemented in the devices, and the same protocol works but in mirrored fashion.

To extend the protocol to support multiple devices in the system, a bank of request

counters and a bank of acknowledge counters are built into each device: each device in

the system contains eight request counters and eight acknowledge counters, thereby

permitting systems to be built with up to eight inter-communicating devices. The

counters are mapped into the PCI memory address space starting at offset 0xffff00 hex

from the base address assigned to the device, as follows:

PM3350-SW Datasheet(PDF) 115 Page - PMC-Sierra, Inc