PCI9060ES datasheet(34/192 Pages) ETC

34 / 192 page

SECTION 3

PCI 9080

FUNCTIONAL DESCRIPTION

©PLX Technology, Inc., 1997

Page 25

Version 1.02

3.6.2.2.2 Local Bus Initialization Software

Range—Specifies which PCI address bits to use for

decoding a PCI access to local bus space. Each of the

bits

corresponds

PCI

address

bit.

Bit

corresponds to Address bit 31. Write a value of 1 to all

bits that must be included in decode and a 0 to all

others.

Remap PCI to Local Addresses into a Local Address

Space—Bits in this register remap (replace) the PCI

address bits used in decode as the Local Address bits.

Local Bus Region Descriptor—Specifies the local bus

characteristics.

3.6.2.2.3 PCI Initialization Software

PCI reset software determines how much address space

is required by writing a value of all ones (1) to a PCI

Base Address register and then reading back the value.

PCI 9080 return zeroes in “don’t care” address bits,

effectively specifying the address space required. The

PCI software then maps the Local Address space into

the PCI Address space by programming the PCI Base

Address register. (Refer to Figure 3-13.)

&& ' %

( '

)*'

( && && ' %

( '

( && )*'

Figure 3-13. Direct Slave Access of Local Bus

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