© National Instruments Corporation
B- 1
VXIpc-850 Series User Manual
VXIpc-850 System
Resources
B
Appendix
This appendix describes what systems resources are available on the
VXIpc-850 and where they are allocated. Because PCI is a relatively
new addition to PCs, this chapter describes how PCI interrupts fit into a
PC architecture before listing the devices that use them.
PCI Interrupts
PCI interrupts can be shared by multiple devices and are therefore more
flexible than ISA interrupts . They do not actually connect to the
processor directly; they are instead mapped through ISA interrupts in
the system I/O module . The interrupt handler for a particular ISA
interrupt must know if it will be acknowledging a PCI device.
Resource Tables
This section provides tables describing where system resources are
assigned. Table B-1 lists how the ISA interrupts are allocated on the
VXIpc-850 and whether they are driven by a PCI interrupt. Table B-2
lists DMA channel allocation, and Table B-3 gives the I/O address
map.
Table B-1. ISA Interrupt Resource Allocations
ISA
Interrupt
PCI
Interrupt
Device
NMI
None
Parity
0
None
Timer
1
None
Keyboard
(continues)