The iIimpact of unobservable events has long been a subject over which humans have pondered. Some questions are either well known or commonly shared.
- If a tree falls in the forest and no one hears it then does it make a sound?
- When I close the door on the fridge does the light go out?
- Is Schrodinger's cat dead or alive?
- When I press the power button on my Windows Mobile phone do the programs stop running?
These are all questions will all be answered by the end of this blog post. Thanks to the availability of inexpensive electronics such as digital video and audio recorders we can show that falling tress make noises and that the lights in the fridge do go out. Figuring out what happens when the power button is pressed on Windows Mobile was a little more difficult.
My first attempt at answering this question was based on programs that changed what they were displaying over their execute cycles. If the Windows Mobile device suspends when I press the power button then after pressing the button, waiting a few seconds, and pressing it again the program's display should show the same thing that it did before I pressed the button. If the device continues to run when I press the power button then after the test I should see something that is noticably different. I ran my test and concluded that the processor continued to run after the power button was pressed. As it turned out my initial conclusion was wrong.
After performing much more research on the matter I found that my conclusion contradicticted other material I found such as the "Power to the Programmers" post on the Windows Mobile Team Blog. I performed my tests again and increased the amount of time that I left the device in its alleged suspended state. After successive test I achieved enlightenment. Pressing the power button on a Windows Mobile Professional device powers down the display and some other hardware, but the processor continues to run. After a certain amount of time has passed unless a program has indicated a desire to do otherwise the device's processor will halt until something wakes it up. When the device is in this state it's not off; the programs are still in memory. Windows Mobile Standard devices are always on, there's no questioning that.
In a forthcoming post I'll cover the details of power control on Windows Mobile devices.
So the only question that leaves open is whether or not Schrodinger's cat is alive. I will leave that question unanswerd and hope for the best for his cat.