Avago Technologies LSI53C1020 - Manual (Page 109)

PCI Configuration Space Register Descriptions 4-31
Version 2.4 Copyright © 2001–2004 by LSI Logic Corporation. All rights reserved.
Device Number [7:3]
These read-only bits indicate the device number of the
LSI53C1020. This PCI function uses this number as part
of its Requester ID and Completer ID. This field is read
for diagnostic purposes only.
Function Number [2:0]
These read-only bits indicate the number in the Function
Number field (AD[10:8]) of a Type 0 PCI configuration
transaction. The PCI function uses this number as part of
its Requester ID and Completer ID. This field always
returns 0b000 to indicate the single PCI function on the
LSI53C1020. This field is read for diagnostic purposes
only.