What is an interrupt, how is it generated and how is it processed?

• What is an interrupt

In communications and computer science, an interrupt is a signal which is able to transmit data intermittently rather than in a steady stream, known as a synchronous signal.

Operating on an interrupt request line, they can be used in both software and hardware. For example a hardware interrupt will allow a computer processor to stop and save a current task, while beginning a new execution.

In software an interrupt will usually be used as an instruction in the programming architecture of the computer. The process of interrupting is called an interrupt request (IRQ), and they are used to allow a computer to multitask. This in essence means that different programs can share processes in order to complete tasks.

Different types of interrupt signal include:

• Level triggered

An unserviced interrupt used to reduce wasteful signals, indicated by being on either a high or low level interrupt request line.

• An edge triggered interrupt

Found at a level transition on an interrupt request line, it is actioned by a falling edge or a rising edge. More than one device can share an edge-triggered line at one time.

• Hybrid

A mix of both level triggered and edge triggered interrupt signals.

• Message signaled

Similar to edge triggered interrupts, however they do not operate on a physical interrupt line, but instead the signal is sent over another communication medium.

For further information on Interrupt signals and processes, it is recommended you consult a textbook or periodical. These can be purchased from all good bookshops or online at amazon.com