IRQ conflict
Encyclopedia
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.
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.
Interrupt request
The computing phrase "interrupt request" is used to refer to either the act of interrupting the bus lines used to signal an interrupt, or the interrupt input lines on a Programmable Interrupt Controller...
(or IRQ) to signal an interrupt to the Programmable Interrupt Controller
Programmable Interrupt Controller
In computing, a programmable interrupt controller is a device that is used to combine several sources of interrupt onto one or more CPU lines, while allowing priority levels to be assigned to its interrupt outputs. When the device has multiple interrupt outputs to assert, it will assert them in...
(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
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...
.
In some rare conditions, two devices can share the same IRQ as long as they are not used simultaneously.
Example
If one adds a modemModem
A modem is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data...
expansion card
Expansion card
The expansion card in computing is a printed circuit board that can be inserted into an expansion slot of a computer motherboard or backplane to add functionality to a computer system via the expansion bus.One edge of the expansion card holds the contacts that fit exactly into the slot...
to a system, and assign it to IRQ4, which is traditionally assigned to the COM1 serial port
Serial port
In computing, a serial port is a serial communication physical interface through which information transfers in or out one bit at a time...
, it will likely cause an IRQ conflict.