User`s guide

A.2 PCI Sparse I/O Space
A.2.1 PCI Sparse I/O Space—Region A
PCI sparse I/O space—region A—occupies physical addresses 85.8000.0000
through 85.BFFF.FFFF. The ISA devices are included in this space. Sections
A.2.1.1 through A.2.1.4 list the ISA device address maps.
A.2.1.1 PC87312 Combination Controller Register Address Space
Table A–1 lists the base address values for the PC87312 combination
integrated drive electronics (IDE), diskette, serial port, and parallel port
controller.
The general registers are located at addresses 398 (index address) and 399
(data address). For example, writing an index value of 1 to address 398 selects
the function address register. If a read operation from address 399 follows,
the data associated with the function address register is returned. If a write
operation to address 399 follows, the function address register will be updated.
Table A–1 PC87312 Combination Controller Register Address Space Map
Address Offset
Read/Write
Physical
Address Register
General Registers
398 85.8000.7300 Index address
399 85.8000.7320 Data address
Index Register
0 Function enable
1 Function address
2 Power and test
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A–2 I/O Space Address Maps