PCI6621 datasheet(128/204 Pages) TI

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5−16

5.14 ExCA Memory Windows 0−4 Start-Address High-Byte Registers

These registers contain the high nibble of the 16-bit memory window start address for memory windows 0, 1, 2, 3,

and 4. The lower 4 bits of these registers correspond to bits A23−A20 of the start address. In addition, the memory

window data width and wait states are set in this register. See Table 5−11 for a complete description of the register

contents.

Bit

Name

ExCA memory windows 0−4 start-address high-byte

Type

Default

ExCA memory window 0 start-address high-byte

Offset:

CardBus Socket Address + 811h:

Card A ExCA Offset 11h

Card B ExCA Offset 51h

ExCA memory window 1 start-address high-byte

Offset:

CardBus Socket Address + 819h:

Card A ExCA Offset 19h

Card B ExCA Offset 59h

ExCA memory window 2 start-address high-byte

Offset:

CardBus Socket Address + 821h:

Card A ExCA Offset 21h

Card B ExCA Offset 61h

ExCA memory window 3 start-address high-byte

Offset:

CardBus Socket Address + 829h:

Card A ExCA Offset 29h

Card B ExCA Offset 69h

ExCA memory window 4 start-address high-byte

Offset:

CardBus Socket Address + 831h:

Card A ExCA Offset 31h

Card B ExCA Offset 71h

Type:

Read/Write

Default:

00h

Table 5−11. ExCA Memory Windows 0−4 Start-Address High-Byte Registers Description

BIT

SIGNAL

TYPE

FUNCTION

DATASIZE

This bit controls the memory window data width. This bit is encoded as:

0 = Window data width is 8 bits (default)

1 = Window data width is 16 bits

ZEROWAIT

Zero wait-state. This bit controls the memory window wait state for 8- and 16-bit accesses. This wait-state

timing emulates the ISA wait state used by the 82365SL-DF. This bit is encoded as:

0 = 8- and 16-bit cycles have standard length (default).

1 = 8-bit cycles reduced to equivalent of three ISA cycles

16-bit cycles reduced to the equivalent of two ISA cycles

5−4

SCRATCH

Scratch pad bits. These bits have no effect on memory window operation.

3−0

STAHN

Start address high-nibble. These bits represent the upper address bits A23−A20 of the memory window

start address.

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