document updated 18 years ago, on Apr 5, 2006
Again, the laptop presents itself as an interesting solution:
- Power outages of 2 hours or less in duration won't affect it
- It meets all my alarm clock requirements with no extra hardware (eg. namely has a big display, and a stereo jack for sound output)
But has these issues:
- It seems that laptops aren't meant to be left on 24/7. At the very least, laptop PSU capacitors seem to get very hot, and I'm fairly sure that this is the primary thing that cuts down on their lifespan. Laptop motherboards and other internals also seem very hot.
- Laptop software (Windows OS + drivers + application software) is vastly more complex than standard alarm software, which makes it much more likely to have stability issues.
But those can be addressed to at least a small extent:
- The APM/ACPI specs allow the laptop to be brought out of standby by external hardware. I'll have to look into it, but hopefully the laptop can also be brought out of stasndby via a software timer.
- ACPI spec here
- Window's suspend-to-RAM is the same as what ACPI calls the S3 state
- section 5.6.2 lists types of ACPI events
- RS232 "ring indicator" can be a wake event
- acpi.sourceforge.net suggests that the real time clock can be configured to generate a hardware wake event (woohoo!) (and even provides examples about how to do this in linux)
- on the other hand, windows don't mention shit about RTC alarm wake events
- some BIOSes will have an explicit setting to allow wakeup per the RTC alarm (on mine, it's called "alarm resume")
- sounds like Windows uses the soonest task scheduler to determine what to set the RTC clock to
- WinXP has the command-line util schtasks. Though it may take the full API along with SystemRequired flag to make it wake up
- Windows XP is much more stable than previous OS's, and is very likely to not have an issue. Alternatively, we could boot into a dedicated minimal linux distro if we wanted more stability.