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154 21555 Non-Transparent PCI-to-PCI Bridge User Manual
List of Registers
Pr
Table 69. Subsystem Vendor ID Register
• Primary byte offset: 2D:2Ch and 6D:6Ch
• Secondary byte offset: 6D:6Ch and 2D:2Ch
Bit Name R/W Description
15:0
Subsystem
Vendor ID
R/(WS)
Identifies the vendor of the add
-in card or subsystem. This register is
initialized by either the local processor or by serial ROM preload.
Table 70. Subsystem ID Register
• Primary byte offset: 2F:2Eh and 6F:6Eh
• Secondary byte offset: 6F:6Eh and 2F:2Eh
Bit Name R/W Description
15:0
Subsystem
ID
R/(WS)
Identifies the vendor
-specific device ID for subsystem. This register is
initialized by either the local processor or by serial ROM preload.
Table 71. Enhanced Capabilities Pointer Register
Bit Name R/W Description
7:0 ECP R
Pointer to the first set of ECP registers. Returns DCh to indicate that the first
set of ECP registers begins at configuration offset DCh. For the 21555, this
points to the Power Management registers.
Reset value is DCh
Table 72. Primary and Secondary Interrupt Line Registers
Bit Name R/W Description
7:0 Interrupt Line R/W
This register is used to communicate interrupt line routing information for
the corresponding interface. This register must be initialized by
initialization code so a default state after reset assertion is not specified.
Initialization code writes this register with a value indicating to which input
of the system interrupt controller the 21555 bus interrupt signal pin INTA#
is connected.
Offsets ECP
Primary byte 34h and 74h
Secondary byte 34h and 74h
Offsets Primary Interrupt Line Secondary Interrupt Line
Primary byte 3Ch 7Ch
Secondary byte 7Ch 3Ch