Avago Technologies LSI53C895A - Manual (Page 121)

PCI Configuration Registers 4-13
The host system detects the size of the external memory
by first writing the
Expansion ROM Base Address register
with all ones and then reading back the register. The
LSI53C895A responds with zeros in all don’t care
locations. The ones in the remaining bits represent the
binary version of the external memory size. For example,
to indicate an external memory size of 32 Kbytes, this
register, when written with ones and read back, returns
ones in the upper 17 bits.
The size of the external memory is set through MAD[3:1].
Please see the section on
MAD Bus Programming for the
possible size encodings available.
Register: 0x34
Capabilities Pointer
Read Only
CP Capabilities Pointer [7:0]
This register indicates that the first extended capability
register is located at offset 0x40 in the PCI Configuration.
Registers: 0x35–0x3B
Reserved
Register: 0x3C
Interrupt Line
Read/Write
IL Interrupt Line [7:0]
This register is used to communicate interrupt line routing
information. POST software writes the routing information
into this register as it configures the system. The value in
this register tells which input of the system interrupt
7 0
CP
0 1 0 0 0 0 0 0
7 0
IL
0 0 0 0 0 0 0 0