The National Weather Service has issued a High Wind Warning for Southern Worcester County. (Note: link is for current weather info, so if you click it tomorrow, the same info likely won’t be there.)
Power outages are expected to increase late today from the Hartford Springfield region to near Worcester and Providence as well as the high terrain near the blue hills southwest of Boston.
So here’s a friendly reminder: Save Early, and Save Often.
This is why God invented Auxiliary Power Systems.
Yes… And I may get one of those at some point. But until I do, and for those who don’t have them yet, I thought that people might appreciate the reminder.
Bruce Tognazzini, in his 10 Most Persistent Design Bugs column, says that all computers ought to have capacitors or small batteries so that on a power failure it can dump memory to disk and hibernate. It should not be that hard to implement, and there’s no excuse for home computers being around for so long without this feature.
Thanks for the reminder! I’d hate to lose my CV work.
Storing enough power to write a 1GB chunk of memory to disk is probably a bit more expensive than you might think. Hard disks use motors, which drink electricity like cheap wine — there’s a reason that half this nation’s power consumption goes into motors. Flash memory might be more reasonable, but that would add a noticeable expense to the unit. To conserve energy, you’d probably want to shut down everything you could, including the processor, in which case you’d have to modify the architecture to hijack the memory bus. Mmm, mm good.
Well, I think that a 9V battery would power the motors enough, and I as a user would appreciate having one in my computer for saving my memory state to disk during a power outage (and as Tognazzini says, only for a power outage lasting more than a few seconds). I do it as a battery backup for smoke detectors and alarm clocks, so why not computers as well? I think I’d much rather have a little cost onto each computer with a slot for a 9V than need to buy a UPS system that can handle them all (although this might change depending on the number of computers I have and how many I expect to be active at a time).
I don’t think a 9V battery would do the trick, but I could be wrong.
Well, lets do the math. The average computer probably has around a 250W power supply. This is the maximum, and we wouldn’t need that much since don’t need to be powering the CD drives and such. So lets see which components we’d need to use.. Probably just CPU, RAM and HDD. For now lets assume that it just dumpd the memory onto the hard drive, and we don’t have any solid state storage devices that would use less power. A rough estimate of the power would be 50W, but thats more of a guess. A Typical 9V rechargable battery is rates at 150mAH. So 50W / (9V * 150mAH) = 50 / (9 * .150 * 3600) = 0.0103 seconds. With lets say 200MB in RAM, at 400MHz FSB, this would be 0.50 seconds. And the hard drive operates slower than that. Plus there’s the fact that a battery cannot discharge all of its energy in a fraction of a second. Capacitors would probably be more suited for this situation, since they can discharge quite rapidly and quite rechargable. However they are also expensive.
BTW, I’m half asleep writing this so there’s probably some mistakes :)
My reasoning was “If I attach a 9V to a motor, it lasts for much longer than a Hibernate does.”. I figured that CPU and memory weren’t all that much in relation to the high-drain motor. So, I estimated that that would be enough. But then again, I Am Not A EE.
*blink blink*
A 0.01F 100V capacitor stores 50 Joules, and is available from Digikey for $12. I would guess that this feature implemented using capacitors and hibernation would add about $20 to the retail price of a power supply.
The problem with the 9V battery is not the energy storage, but power: batteries do not like being discharged in seconds. Ben actually calculated the inverse of the correct time of about 100 seconds.
A webpage claiming a particular hard drive uses an average of about 10 Watts with peak of about 25 Watts: http://www.pcguide.com/ref/hdd/perf/perf/spec/otherPower-c.html
I can’t find a data sheet for 9V batteries that gives performance for such a high-power usage. If someome has a 9V battery to donate and some 9V 50W device (hard to find a 50W resistor!), the experiment shouldn’t be hard. Guessing based on what I could find, I think a lantern battery (~$4) would work, but a 9V is iffy.