When does the palmtop detect a low main battery condition?
According to the SDK: The main or system battery consists of two 1.5 volt batteries in series. These batteries may be either NiCad or Alkaline, and feed the HP palmtop power supply in normal operation. The low main battery warning condition is nominally 2.2 (2.3 for NiCad) Volts. When the level reaches about 1.8 volts, the power supply can no longer reliably operate off of the main batteries, and an NMI Low Power In terrupt triggers a transition to Backup mode. Because it is desirable to avoid warmstart, there is an intermediate state betwe en the first low battery warnings and the time of the Low Power NMI that MAY be entered. This state, called Software Shutdown, will be entered when the battery voltage reaches 2.0 Volts (NiCad or Alkaline). In this state the unit will be shut down, and attempts to wake it up will result in a pair of hi pitched beeps. Recovery from this state will not result in a warmstart provided that System Memory still appears to have integrity. It should be note
