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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 ...
This definition originates from multiprogramming environments, where multiple processes may be active concurrently and where the flow of control could be interrupted by an interrupt and transferred to an interrupt service routine (ISR) or "handler" subroutine. Any subroutine used by the handler that could potentially have been executing when ...
A software interrupt is a specific variety of the general concept of an interrupt. An interrupt is a mechanism by which the CPU can be directed to stop executing the main-line program and immediately execute a special program, called an Interrupt Service Routine (ISR), instead. Once the ISR finishes, the CPU continues with the main program.
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 ...
A well-designed and succinct interrupt handler or interrupt service routine (ISR) will not only expeditiously service any event that causes an interrupt, it will do so without interfering in any way with the interrupted foreground task—the ISR must be "transparent" to the interrupted task (although exceptions may apply in specialized cases ...
The typical method of using an interrupt vector involves reading its present value (the address), storing it within the memory space of the TSR, and replacing it with an address in its own code. The stored address is called from the TSR, in effect forming a singly linked list of interrupt handlers, also called interrupt service routines, or
When an I/O device interrupts a program, it places the address of its vector on the bus to indicate which service routine should take control. The lowest vectors are service routines to handle various types of trap. Traps occur on some program errors, such as an attempt to execute an undefined instruction; and also when the program executes an ...
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 ...