IRQ conflict

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In computing, an IRQ conflict is a once common hardware error, received when two devices were trying to use the same interrupt request (or IRQ) to signal an interrupt to the Programmable Interrupt Controller (PIC).

The PIC expects interrupt requests from only one device per line, thus more than one device sending IRQ signals along the same line will generally cause an IRQ conflict that can freeze a computer.

In some rare conditions, two devices can share the same IRQ as long as they are not used simultaneously.

[edit] Example

If one adds a modem expansion card to a system, and assign it to IRQ4, which is traditionally assigned to the COM1 serial port, it will likely cause an IRQ conflict.

[edit] References

• IRQ interrupt request
• Expansion Bus Configuration