But computers, particularly those running Windows, have always been more complicated. On is on, of course. For off, though, Windows XP machines offer several options--including hibernate, stand by and shut down.
"Users don't always understand the difference," said Pat Stemen, a program manager in Microsoft's core operating-system division.
With Vista, Microsoft is changing shut-down options so that pressing the power button feels more like turning the machine off.
The OS will typically send the computer to sleep rather than shutting down when the button is pressed to off--a power-saving move.
What's worse is that even when people do know enough to choose hibernate or stand by, which turn off most parts of the system but don't clear files away, the computer often ends up staying on. That's because today's Windows lets an application or hardware device veto a PC user's decision.
That won't be the case in Windows Vista, which is due for general release next year. (A beta version of the operating system, formerly known by the code name Longhorn, was released in late July.) Applications will be warned that a computer is entering sleep and have a second or two to save whatever they need to, but the programs won't get a say in whether the machine slumbers.
And with Vista, Microsoft plans to make it so that a PC seems more like all the other consumer electronics out there. Pressing the power button will give users the feeling they are either turning the machine on or turning it off.
In reality, pressing the button to off will more likely send the machine into some form of sleep mode than turn it off. PC manufacturers will be able to map a shut down or a sleep option to the button's off position--including several sleep modes being developed by Microsoft.
Microsoft says that the operating system change is needed because today's options aren't working. Despite the multitude of choices, Windows users either leave their machine on all the time or choose to shut it down, the company has discovered from customer feedback. People don't tend to opt for hibernate or stand by. As a result, they either waste power or have to suffer through the delay while Windows starts up again.
Stemen pointed to an all-too-typical scenario in which a mobile worker shuts his or her laptop, assuming it will go into stand by. But if any of the applications or some other system process vetoes the stand by request, the laptop could remain on, heating up and draining the battery--the whole situation could end in data loss.
When it's sleepytime
For Vista notebooks, the plan is for the machines to go into a stand by mode when the power button is turned off. In stand by, all the work the user has done is saved in the memory, and the machine receives enough power to keep that data there. If battery levels reach a critically low level, the laptop will power up enough to save the needed information onto the hard drive, and then it will power down completely.
Desktop machines will enter a mode Microsoft is calling "hybrid sleep." In this case, Vista will save the system state and other information to disk, just in case power is lost, but will then enter a sleep mode from which the computer can quickly be roused.
People will likely still be able to go to the start menu if they want to shut down the computer. But being able to send it into a particular kind of sleep at the push of a button will be a boon, said Greg Graceffo, a product manager in Microsoft's Windows client unit.
"For the end user, there is simplicity," Graceffo said. "All you really need to know about is sleep."
"The issue is the user experience," he said, noting that in the past computers have taken too long to turn on and off, meaning most people leave their machines on as much of the time as possible. "The cost for turning it off and on should be so low (that) people feel comfortable doing it."
In changing the settings, Microsoft is making some trade-offs. With Windows XP, if you try to put your machine to sleep while burning a CD, for example, the program can veto the attempt.
With Vista, applications won't have that option. That means PCs should go to sleep more reliably. But if people are burning Coldplay's latest album when they flip the switch, they're not likely to get a good copy.
"If you push the button, I think you are going to have a coaster," Graceffo said.
In part to address this issue, Microsoft is also developing a third mode, known as "away" mode, for media-centered PCs. In that setting, the user will push a button and the machine will look off and sound off. However, it will actually still be quietly operating and ready to record a TV show or serve up content to a TV in another room, if needed.
However, Kay said the "away mode" notion for media center desktops seemed less than elegant. "You really do want it to go into a low-power sleep," Kay said, as opposed to just appearing to be off.
In addition to making it easier to turn a PC off, Microsoft is also trying to make it simpler to make choices about power use when the machine is on. With Windows XP, there are at least six different options. Some, such as "always on" and "max battery" are relatively straightforward, while others, such as "presentation mode" and "home/office desk," are less fathomable.
In Vista, there will be just three standard options: maximize performance, maximize battery power, or let Windows automatically make the best choice.
Another way Microsoft is trying to shift power use is by changing the default settings that ship with a PC. With Vista, the monitor will shut itself off by default after a period of inactivity. Some time later, the system will put itself to sleep if nothing has happened.
People will still be able to adjust these settings, and--in a shift from Microsoft's past practice--won't have to have administrator privileges to do it. That's part of a broader effort Microsoft is undertaking with Vista to enable people to run a machine without constantly having to switch to administrator mode. Moving to more operating as general user should make it easier for people to manage their system but harder for spyware and other malicious code to take control of it.
The challenge, Kay said, is that most people want the kind of instant on-and-off experience they get from televisions and other consumer electronics. He said that notion is something Intel and Microsoft have been touting for years but have yet to deliver on.
"If between the two of them they get it together, they've got a feature people want," Kay said.
Vista will also allow businesses to enforce power management settings across their whole fleet of computers, if they choose to do so. Using Microsoft's group policy tools, IT administrators will be able to decide that all machines will go to sleep after an hour of inactivity, for example. Graceffo said that data from the Environmental Protection Agency indicates that in many large companies, there are tons of computers that are left on all the time.
"Implementing this sleep state is really giving companies the means to shut down machines when they are idle," he said.
With Vista, Microsoft gives the choice of turning a PC on, off or sending it to sleep. With current Windows, there are several other choices.
The open applications and other information are saved to memory. System continues to draw enough power to make sure that contents are preserved.
Applications and other information are saved to disk. Data is retained even if power is removed, though resume time is slower than standby as the needed data is retrieved from the hard drive.
System is completely powered off. No applications are left open either in memory or disk.
The savings from this and the other power changes Microsoft is making could be dramatic, top executives at the software maker said.
"We've done some calculations of power savings that we expect," Windows chief Jim Allchin said in a July interview. "I saw a number that showed, basically, when 100 million machines are running Vista, the power savings around the world. It is unbelievable."
In an effort to get members of the Windows team more excited about the progress they were making, Allchin shared some estimates internally. However, Graceffo said Microsoft is not releasing them publicly, because it wants to make sure its numbers are solid before touting them.
To fully realize its goals, though, Microsoft will need support from software makers. Customers will only adhere to the energy-saving default options if the software they use behaves properly. Since programs will no longer be able to block a Windows computer from going to sleep, some applications may need to be rewritten in order to gracefully handle such transitions.
For software makers that want to be proactive, Microsoft plans to smooth the way for programs to be notified of changes to the PC's power state. A program could be set to shift to simpler graphics when it is notified that a computer has been unplugged and has moved to battery power, for example. Or, say, a program might decide not to send display images at all once if it learns that a monitor has been turned off.
The power management changes also tie into broader work Microsoft is doing to improve the experience of using a Windows laptop.
In Vista, Microsoft is planning a central place for changing all manner of laptop-related settings such as power options, display settings, system volume, synchronization options and other features. Known as the "mobility center," it is similar in concept to the security center Microsoft added to Windows with XP Service Pack 2.
Graceffo said that the work his team is doing may not be sexy, but it is part of an effort to make sure that Vista "just works" in a way that past versions of Windows have not.
"Some people treat it as ho-hum and yawn," he said. But "It's a significant area for us."