vMultiple messages occur when the first error causes additional errors. Follow the suggested action of the first error displayed.
System resource conflicts
System failures occur when there are system resource conflicts with the following:
vInterrupt Request Queue (IRQ)
vDirect Memory Access (DMA)
vI/O Address
vROM and RAM Addresses.
IRQ
vAssigns a unique interrupt request line to every I/O device (line numbers range from 0 to 15).
vInterrupts the processor to force it to service the request.
vHandles interrupts on a priority basis (low numbers have the highest priority).
vQueues interrupt request.
IRQ conflicts occur when there are multiple assignments to the same interrupt level. If there is an IRQ conflict, the system will hang. Use the systems diagnostics to check for multiple assignments to the same interrupt level before replacing any hardware component.
DMA
vAccesses the memory by bypassing the processor. This allows the processor more time for applications and programs.
vAccesses memory directly from the serial and parallel ports on some systems.
vAccesses memory directly from some adapters using a DMA channel. This allows the adapter to operate faster.
vProvides from 4 to 15 DMA channels. The number varies depending on the system.
If multiple assignments of the same DMA channel occur, the system will hang. Use the system diagnostics to check for multiple assignments to the same DMA channel before replacing any hardware components.
I/O address
A unique I/O address is assigned to each system component.
If multiple assignments of the same I/O address occur, the system will hang. Use the DOS MEM command to check for multiple assignments to the same I/O address before replacing any hardware component.
ROM and RAM Addresses
Adapter cards with processors can contain RAM and ROM. If the adapter cards have onboard memory, then the following are true.
vROM contains operating instructions for the adapter I/O.
vRAM is used for buffering.
Two adapters using the same memory area will cause a failure. This failure might appear as a hardware failure.
Chapter 8. Related service information 109
