OX12PCI840 Datasheet, PDF (25/33 Pages) List of Unclassifed Manufacturers – Integrated Parallel Port and PCI interface

OXFORD SEMICONDUCTOR LTD.
OX12PCI840
6.2.5 Zone4: Function Access
Zone 4 allows the parallel port to be configured, prior to PCI access. This can be useful for patching designs to work with generic
drivers, enabling interrupts, etc. Each 8-bit (function) access is equivalent to accessing the function through I/O bars 0 and 1,
with the exception that a function read access does not return any data (discarded). Each entry in zone 4 comprises 2 16 bit
words. The format is as shown in Table 14.
1^st WORD of FUNCTION ACCESS PAIR
Word
Bits
15
14:12
11
10:8
7:0
Description
‘1’ - another WORD to follow
BAR number to access
000 for BAR 0
001 for BAR 1
others reserved
‘0’ : Read access (data discarded)
‘1’ : Write access
Reserved – write 0’s
I/O address to access
This is the location (I/O offset from
the relevant Base Address) that
needs to be written/read.
2^nd WORD of FUNCTION ACCESS PAIR
Word
Bits Description
15 ‘1’ – another function access
WORD pair to follow.
‘0’ – no more function access
pairs. End EEPROM program.
14:8 Reserved – write 0’s
7:0 Data to be written to location.
Field unused for function access
READS.
DS-0021 Jun 05
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