Software Interrupt

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What Does Software Interrupt Mean?

A software interrupt is a type of interrupt that is caused either by a special instruction in the instruction set or by an exceptional condition in the processor itself. A software interrupt is invoked by software, unlike a hardware interrupt, and is considered one of the ways to communicate with the kernel or to invoke system calls, especially during error or exception handling.

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Techopedia Explains Software Interrupt

A software interrupt often occurs when an application software terminates or when it requests the operating system for some service. This is quite unlike a hardware interrupt, which occurs at the hardware level. A software interrupt only communicates with the kernel and indirectly interrupts the central processing unit. All software interrupts are associated with an interrupt handler, which is actually just a routine that is activated when an interrupt happens. Only one bit of information is communicated during a software interrupt. Often, a software interrupt is used to perform an input/output request. This request, in turn, calls kernel routines that actually perform the service.

A software interrupt often emulates most of the features of a hardware interrupt. Like a hardware interrupt, it calls only a specific interrupt vector and saves the accumulators and registers. A software interrupt can also make use of some of the hardware interrupt routines.

Similar in functionality to a subroutine call, a software interrupt is used for different purposes in a device. One notable example is when communicating with the disk controller for reading and writing data to and from a disk.

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Margaret Rouse
Technology Expert
Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.