What is an IRQ or Interrupt request?
A. An IRQ is is really an Interrupt Request line. In the case of expansion boards, it is an actual contact (finger) on the board, and it is a corresponding pin in the sockets on the bus connected by a trace on the motherboard. A device sends a interrupt to the motherboard’s interrupt circuitry by changing the voltage level on the interrupt request line. This voltage change acts via interrupt controller circuitry to interrupt the processor to service the device needing the CPU’s attention. Simply put, if, for example, a serial port is receiving data from a MODEM, it can’t wait until it’s buffer overflows for the CPU, etc. to come to its assistance. The CPU will then temporally store the program and data it is working on in an area of memory know as the stack and load a routine (program) to service the interrupting device, service the device (move that data out of its buffer, etc.), and then restore the program and data it was previously working on and resume what it was doing. A CPU can
Related Questions
- When an interrupt request having the same priority level as the interrupt being processed is generated during a certain type of interrupt processing, does a multiple interrupt occur?
- If a higher interrupt request occurs immediately after an interrupt request, when is the higher request started?
- What is an IRQ or Interrupt request?
