Windows XP has several options for boot-up and shutdown of your computer using the [WIKI]ACPI [/WIKI]power states.
They include shutdown, hibernation & standby
Shutdown (Cold Boot)
A typical computer boot-up. Everything starts from a non-powered state and is initialised by the computer during the boot-up sequence. This is the slowest option.
All information in the RAM when the computer enters hibernation is stored to a file on the hard drive. The computer then switches off and enters a completely cold state. Nothing is running and it is using effectively no electricity. When the pc is tunred back on, Windows reads the file from the hard drive and relaods it back into the RAM. The computer is now running in the exact same state as it was when you shut it down. Any programs that where open when the computer was put into hibernation will still be open exactly how they were. This method still takes some time to load, but is generally quicker than a normal cold boot. If the main power supply is cut and reconnected while the computer is in hibernation, the computer will still come out of hibernation like nothing happened.
When a computer is in standby is isn’t actually ‘off’. Although the monitor and hard drives are switched off, the CPU, motherboard, RAM and some other devices (Eg. USB devices depending on your system settings) are still powered and working. Although the computer is in a low power state, it is still using electricity. Why would you want to do this then? The almost instantaneous ‘shutdown’ and ‘bootup’ times.
As the important components are still running when the computer is in standby, the computer doesn’t need to initialise everything. The BIOS doesn’t even need to be loaded. when the power button is pushed, within a few seconds you are back to where you where when you put the pc into standby. Like hibernation, your programs will be running just how you left them. If the power supply is cut to the computer while in standby mode however, any unsaved information will be lost and the computer will be in a completely cold state, just like a normal computer shutdown. This means that once the power is re-connected the pc needs to do a full cold-boot.
Standby is fine when you are using a desktop pc or a laptop plugged into a wall socket (and you don’t get any blackouts, or you’ll be in trouble as mentioned above) because you have an unlimited supply of electricity. With a car, of course all you have to run everything is your battery. Leaving your computer in standby while you’re not using the car will eventually drain your battery in the same way a stand-alone laptop in standby will eventually drain it’s battery and require a complete cold-boot.