Technical information

7-2
AIC-6915 Ethernet LAN Controller Programmer’s Manual
AIC-6915 Address Space
A device on a PCI bus can be accessed using different PCI command types. The AIC-6915
can be accessed using Memory, I/O and Configuration commands. The 512-KByte
address space is mapped to a base address defined by the operating system at boot time.
The first 256-KBytes are also mapped to the expansion ROM space. In addition, the first
256-bytes of the second 256-KBytes are mapped to Configuration and I/O space and are
directly accessed using one of the three PCI command types: Memory, I/O, and
Configuration. Indirect I/O commands can be used for accessing the rest of the space. The
AIC-6915 address space is divided to a number of major subspaces with different
characteristics. Table 7-2 describes these subspaces.
AIC-6915 PCI Address Map
Figure 7-1 illustrates the AIC-6915 PCI address map.
Table 7-2. AIC-6915 PCI Address Space
Name
Byte Address
Range
Size
(bytes) Description
Reserved 0x70084 -
0x7FFFF
64K Reserved for future use
Status Registers 0x70000 -
0x70083
Contains status registers.
Ethernet Fifo 0x60000 -
0x6FFFF
64K Used for accessing the internal
receive/transmit data FIFO
General_Registers 0x50100 -
0x5FFFF
Used for accessing physical chip registers,
Serial EPROM, MAC registers and
additional status/debug registers.
Internal_Functional_
Registers
0x50000 -
0x500FF
64K Used for accessing the PCI configuration
header and AIC-6915 internal functional
registers that are mostly accessed by the
software driver during normal chip
operation.
Ext_General_Purpose_
Registers
0x40000 -
0x4FFFF
64K Used for connecting an external device to
the AIC-6915.
[[E]EP]ROM 0x00000 -
0x3FFFF
256K Read/Write external [E]EPROM. This
sub-space is mapped also to the PCI
Expansion ROM space.