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32 CPCI-7806/CPCI-7806RC Pentium/Celeron M Universal CompactPCI Single Board Computer
Publication No. 500-657806-000 Rev. G
2.4.2 PCI Interrupts
Interrupts on Peripheral Component Interconnect (PCI) Local Bus are optional
and defined as “level sensitive,” asserted low (negative true), using open drain
output drivers. The assertion and de-assertion of an interrupt line, 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 de-asserts its INTx# signal.
PCI defines one interrupt line for a single function device and up to four interrupt
lines for a multifunction device or connector. For a single function device, only
INTA# may be used while the other three interrupt lines have no meaning.
depicts the CPCI-7806/CPCI-7806RC interrupt logic
pertaining to CompactPCI operations and the PMC site.
Any function on a multifunction device can be connected to any of the INTx#
lines. The Interrupt Pin register defines which INTx# line the function uses to
request an interrupt. If a device implements a single INTx# line, it is called INTA#;
if it implements two lines, they are called INTA# and INTB#; and so forth. For a
multifunction device, all functions may use the same INTx# line, or each may
have its own (up to a maximum of four functions), or any combination thereof. A
single function can never generate an interrupt request on more than one INTx#
line.
28
40
DOS Keyboard Idle Loop
Same as Real Mode
29
41
DOS CON Dev. Raw Output Same as Real Mode
2A
42
DOS 3.x+ Network Comm
Same as Real Mode
2B
43
DOS Internal Use
Same as Real Mode
2C
44
DOS Internal Use
Same as Real Mode
2D
45
DOS Internal Use
Same as Real Mode
2E
46
DOS Internal Use
Same as Real Mode
2F
47
DOS Print Spooler Driver
Same as Real Mode
30-60
48-96
Reserved by DOS
Same as Real Mode
61-66
97-102
User Available
Same as Real Mode
67-6F
103-111
Reserved by DOS
Same as Real Mode
70
112
IRQ8
Real Time Clock
71
113
IRQ9
Redirect to IRQ2
72
114
IRQ10
Not Assigned
73
115
IRQ11
Not Assigned
74
116
IRQ12
Mouse
75
117
IRQ13
Math Coprocessor
76
118
IRQ14
AT Hard Drive
77
119
IRQ15
CompactFlash Drive
78-7F
120-127
Reserved by DOS
Same as Real Mode
80-F0
128-240
Reserved for BASIC
Same as Real Mode
F1-FF
241-255
Reserved by DOS
Same as Real Mode
Table 2-3 PC Interrupt Vector Table (Continued)
INTERRUPT NO.
IRQ
LINE
REAL MODE
PROTECTED MODE
HEX
DEC