I have some questions about 82815 and ICH2 bridges. I wonder if anybody in this community can help me. I raise the first question as follows:
In ICH2 I/O cycles targeted USB, IDE and AC'97 will be sent to Device 31 directly according to the data sheet of ICH2. I want to know how it is possible? While Device 31 has a subtractive decoder while Device 30 has a positive decoder. I want to say that ICH2 is getting far from PCI specification in this scenario, It is just my guess i wonder if anybody can clarify the issue more. It seems that in this implentation of the logic of PCI bus something has been added to that logic nad has extended the PCI logic. Is that true?
or I am missing some thing or my information is wrong? Maybe there is another feature of PCI bus that I have not yet understood....
