Intel ECB-865 Computer Hardware User Manual


 
ECB-865
ECB-865 User’s Manual 49
3.11.38.6 Interrupts
PIRQ#
Interrupts on PCI are optional and defined as "level sensitive," asserted low (negative
true), using open drain output drivers. The assertion and deassertion of INTx# is
asynchronous to CLK. A device asserts its INTx# line when requesting attention from
its device driver. Once the INTx# signal is asserted, it remains asserted until the
device driver clears the pending request. When the request is cleared, the device
deasserts its INTx# signal. PCI defines one interrupt line for a single function device
and up to four interrupt lines for a multi-function
7 device or connector. For a single
function device, only INTA# may be used while the other three interrupt lines have no
meaning. PIRQ# is connected to INTB#