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In computer systems programming, an interrupt handler, also known as an interrupt service routine or ISR, is a special block of code associated with a specific interrupt condition. Interrupt handlers are initiated by hardware interrupts, software interrupt instructions, or software exceptions , and are used for implementing device drivers or ...
In a computer, an interrupt request (or IRQ) is a hardware signal sent to the processor that temporarily stops a running program and allows a special program, an interrupt handler, to run instead. Hardware interrupts are used to handle events such as receiving data from a modem or network card, key presses, or mouse movements.
A hardware interrupt is a condition related to the state of the hardware that may be signaled by an external hardware device, e.g., an interrupt request (IRQ) line on a PC, or detected by devices embedded in processor logic (e.g., the CPU timer in IBM System/370), to communicate that the device needs attention from the operating system (OS) [7] or, if there is no OS, from the bare metal ...
The IRR specifies which interrupts are pending acknowledgement, and is typically a symbolic register which can not be directly accessed. The ISR register specifies which interrupts have been acknowledged, but are still waiting for an end of interrupt (EOI). The IMR specifies which interrupts are to be ignored and not acknowledged.
INT is an x86 instruction that triggers a software interrupt, and 13 hex is the interrupt number (as a hexadecimal value) being called. Modern computers come with both BIOS INT 13h and UEFI functionality that provides the same services and more, with the exception of UEFI Class 3 that completely removes CSM thus lacks INT 13h and other interrupts.
On uni-processor systems, the simplest solution to achieve mutual exclusion is to disable interrupts during a process's critical section. This will prevent any interrupt service routines from running (effectively preventing a process from being preempted). Although this solution is effective, it leads to many problems.
An interrupt vector table (IVT) is a data structure that associates a list of interrupt handlers with a list of interrupt requests in a table of interrupt vectors. Each entry of the interrupt vector table, called an interrupt vector, is the address of an interrupt handler (also known as ISR). While the concept is common across processor ...
Fast interrupt request (FIQ) is a specialized type of interrupt request, which is a standard technique used in computer CPUs to deal with events that need to be processed as they occur, such as receiving data from a network card, or keyboard or mouse actions.