The Rise of the Personal Non-Maskable Interrupt (NMI)


In computer technology a processor interrupt is a signal to the processor indicating an event that needs attention. The processor responds by suspending its current activities, saving its state and executing a routine to deal with the event. This interruption is temporary and after the interrupt handler finishes, the processor resumes normal activities.

As an interrupt is expensive for processors, most interrupts are maskable. Basically, they can be ignored or delayed. A good example is your mouse. As you slide it across the desk it generates signals on its motions. In fact, it generates way more signals than are actually required to position your cursor on the screen, therefore most of them are ignored.

The counter example is holding the ctrl-alt-delete key combination down on your Windows device. This is a non-maskable interrupt. It says, stop whatever you are doing and ask me if it’s time to reboot the computer or kill a process.


One of the biggest challenges we face as connected humans these days is the pernicious rise of the non-maskable personal interrupt. In the 1970’s if you called someone’s telephone and they were not at their desk, you simply tried again later or someone answered and took a message for you to call them back. There was no expectation on the part of the caller of an immediate response.

In 1979, voicemail systems started to arrive on the scene, where a verbal message could be left for the person, they could dial in and pick up messages and return your call. The expectation was now that the time to return the call was shorter.

In 1983 the first analog cell phones were launched. When the recipient of a call was in range of a cell tower, the caller could get through. If the person was in a meeting, very likely the brick sized cell phone was not with them. It would simply ring. Whether a call was received or returned quickly was random.

It was 1992 when the first SMS message was sent. Here was a great answer to send someone a short message asynchronously and they could call back or text a response when it was convenient. Again, there was no expectation of the caller of immediate response.

In 2002 the first high speed cellular digital networks went into global use. With this, internet tools and instant messaging were now mobile. Unlike SMS, it was now expected that you were always connected and always available to response. Then in 2006 Facebook launched globally and mobile with global social networking added to the capabilities and higher subsequent expectation of responsiveness.

Today, I carry an advanced Windows smartphone with me almost 100% of the time. I am rarely in an area where there is no high speed data service and there is a deluge of information that pours into this device daily.

Each day, on average, I receive a few hundred corporate emails, dozens of Yammer notifications, Facebook notifications, Linkedin notifications and a few dozen personal emails across a few accounts. Oh… and not to forget text messages and proxied text messages (sent from another IM source such as Facebook to my SMS device channel)

So when you receive a text, what happens if you don’t respond quickly?


As it is with processors, human interrupts are expensive, distracting and for the most part unnecessary where a delayed response may be perfectly fine. The expectation that any text sent will be treated as a non-maskable interrupt is an expectation we need to reset with people who communicate with us. Simply by letting everyone know that your SLA for returning a message is 3-4 hours will fix this problem.

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