Subsystem id, Register: 0x2e–0x2f – Avago Technologies LSI53C1020 User Manual
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PCI Host Register Description
Version 2.4
Copyright © 2001–2004 by LSI Logic Corporation. All rights reserved.
Register: 0x2E–0x2F
Subsystem ID
Read Only
Subsystem ID
[15:0]
This 16-bit register uniquely identifies the add-in board or
subsystem where this PCI device resides. This register
provides a mechanism for an add-in card vendor to dis-
tinguish their cards from one another even if the cards
use the same PCI controller (and have the same
Vendor ID and Device ID). The board designer can store
a vendor-specific, 16-bit value in an external serial
EEPROM.
The ID Control Power-On Sense pin (MAD[10]) and the
serial EEPROM enable Power-On Sense pin (MAD[7])
control the value of this register. These pins have internal
pull-downs. Allowing MAD[7] to remain internally pulled
down enables the serial EEPROM interface and permits
the LSI53C1020 to load this register from the serial
EEPROM at power up. Pulling MAD[7] HIGH disables the
serial EEPROM interface. Allowing the ID Control pin to
remain internally pulled LOW has no effect on this regis-
ter. Pulling the ID Control pin HIGH sets bit [15] of this
register. Pulling the ID Control pin HIGH takes prece-
dence over all other settings for bit [15].
lists the configuration options for the Power-On
Sense pins and settings for this register. If the serial
EEPROM interface is disabled and the ID Control pin is
internally pulled LOW, this register contains 0x1000. If the
serial EEPROM interface is disabled and the ID Control
pin is pulled HIGH, this register contains 0x8000. If a
download from the serial EEPROM fails and the
ID Control pin is internally pulled LOW, this register con-
tains 0x0000. If a download from the serial EEPROM fails
and the ID Control pin is pulled HIGH, this register con-
tains 0x8000. Refer to
, for additional information.
15
0
Subsystem ID
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x