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This actually reminded me of the old "It is now safe to turn off your computer" orange text that would come up on older versions of Windows.

Eventually computers began being able to turn themselves off.

Does anyone know what prevented older computers from doing this? And if it was possible, why the design decision was made to make the users turn the computers off themselves? Was it some sort of "feel in control of this new thing in your house" thing?




With AT motherboards the power button on the computer was linked directly to the power supply. There was simply no option of turning the computer off through software. See http://en.wikipedia.org/wiki/ATX#Power_switch


Software power-off is a feature of ACPI, which didn't even exist when Win95 came out: http://en.wikipedia.org/wiki/Advanced_Configuration_and_Powe...


Auto shutdown (and wake-up) was an improvement of the ATX form factor standard introduced in 1995, replacing the previously AT form factor:

http://en.wikipedia.org/wiki/ATX


>Does anyone know what prevented older computers from doing this?

Your master power switch was actually just that, a master power switch within the power supply. Your computer was shocked to life by having this switch turned on, and your computer was turned off by literally having this turned off.

It was just easier to design around this. Also bios functionality was incredibly limited at the time, normally being configured via DIP switches on board and hardware control via OS was a long way off, typically the only hardware control was to assign interrupts and handle them.


Older computers had a mechanical on/off switch, rather than the soft power buttons we have these days


I suspect it wasn't so much a decision as a lack of one. Every appliance up until then had a simple power switch: an actual switch, that physically disconnected the power feed to/from the device. Why would a computer be any different?


Fun fact about that "It is now safe to turn off your computer" orange text: you were actually dumped to a DOS prompt even though the display was set to a graphics mode. You could type commands and switch the display to text mode.


You mean in Win95? What would you type in?

In WinNT 4 the same text is displayed in a window. Though, afaik it is displayed by kernel mode and not from Win32 subsystem.


Yeah, Win95 (and subsequent versions to ME). It was a DOS prompt, so you could type anything. I believe typing CLS<enter> would clear the screen and show you the prompt.




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