ON/OFF Switch for a Computer?

The documentation for the Windows API seems to indicate that you could do most of this by writing a driver which provides power button facilities. Have you checked it out?

Cheers, Nicholas Sherlock

No, 'holding down' the power button for 4 secs on most setups just forces the system off. A quick press and release does an 'orderly shutdown'

The delay is set by a capacitor value. If you need it adjustable at run time, you could switch in different capacitors - a bit messy, but may do the trick.

back when......

the x86 processors had a reset pin which wasn't hooked up in the PC architecture; i would install a momentary contact pushbutton to it (from ground? B+? I forget) so i could reboot without making the hard drive grind to a halt. unfortuately, DOS would wipe the memory on reload, unlike CP/M where you could reset a stuck processor and have all the stuff in memory still intact.

so... why don't we have a reboot button in 2008?

On a sunny day (Tue, 1 Apr 2008 08:36:56 -0700 (PDT)) it happened z wrote in :

You could, at least in Linux there is a button module IIRC. Pressing power for a short movement starts kernel shutdown, followed by power down, if enabled. Pressing power for a longer time (adjustable in BIOS), does a true power off. As everything is cached in DRAM buffers need to be written back to disk before power is removed, there fore do not use 'reset'.

Anyways my Reiser FS and ext2 do not seem to suffer from a true power down. I did have problems with the reset button though.

What I do these days is type 'reboot now' and then wait for the BIOS beep, then use the real power switch.

As far as MS software goes, no idea what it does or does not do. YMMV. Best just to upgrade to Linux.

Windows allows something like this using a Kernel debugger, and using one is quite common for those writing device drivers. The idea isn't so much that you're going to reboot the PC, but rather that you can always break into the PC to try to figure out what it's doing or, if it blue screens, start poking around to try to figure out the cause of the crash.

These days it requires some effort to actually enable Kernel debugging on Windows; some of this is due to security concerns: *Not* wiping memory when a computer reboots is a well-known technique for stealing information. (On YouTube or somewhere there's even a video where they demonstrate taking a laptop that has an encrypted file system, forcing a reboot from a memory stick, and then sniffing through what's left of memory to dig out the encryption keys...)

"so... why don't we have a reboot button in 2008?"

Many desktop machines still do. For laptops you just remove the battery? :-)

---Joel

Why, you asked for a schemo for the on off switch of a pc - which is what you got.

The circuitry behind the switch is proprietary to the board vendor, who will not release schemo / gerber files to any Jo Bloggs.

Interestingly, when I run my Slackware (dual-boot w/W2K), apmd says that the BIOS doesn't support it. This is interesting; apparently W2K does some secret magkical schtuff, because it shuts down just fine.

Thanks, Rich

On a sunny day (Tue, 01 Apr 2008 19:22:44 GMT) it happened Rich Grise wrote in :

No idea why, really, I run grml these days. Tyan mobo, good stuff, been up 7 years in this server. Dual boot? Win 98 is a choice here, last MS OS I bought. :-)

Uhh....Thanks, Einstein!

ll

No shit?

Do the world a favor: Stick with motorcycles.....

...

ed yet!

IC chips.

if the

m the 3-5 second

Ok, that takes care of the power down delay.

But i need a delay for turn-on as well.

This is why i'm leaning towards the PIC.....

FYATHYRIHO.

EYOSMF!

Huh?

My reply did not say anything about holding the button for 4 seconds. I think I just said that I hit the on/off button

Is the bottom paragraph not your reply to the one above it?

Nope, it generally gives an orderly shut down. Since you have never tried it you don't have a clue as to what you are talking about

If it isn't, I apologise, if it is, well..

If the OS is really not responsive then it is not going to respond and perform an orderly shut down is it? Sometimes a 120 reset is the only option even with the potential for data loss.

I know, done it loads of times over the years.