Newsgroup: comp.sys.palmtops

In article <azilker.716656489@unixg.ubc.ca> azilker@unixg.ubc.ca (Andreas Zilker) writes:
>The situation:
>HP95LX (512 k model) operated on 2 NEW Duracell Alkaline AAs.
>A little bit of file transfer (2-8 kByte) with Kermit, battery
>indicator in setup shows one tick less than full, all applications are
>shutdown (topcard visible), calc turned off.
[...]
>later calc shuts down again and appears to be dead until...
>You put in new batteries !!!
[...]
The low power detection on the HP 95 LX works using a double
threshold.  When voltage falls under a specific level, a low power
condition is signalled.  This also sets a flag indicating that such a
condition has been detected, so that erroneous small battery voltage
fluctuations will not reset the low voltage warning.  Whenever the HP
turns on the low power message will appear.  In order to turn that flag
off the voltage must increase to a value substantially higher than that
of the low voltage detection, as show in the following diagram.


      V |    /
	|   /
	|  /
	| /
	|/
	+---------
	  ^   ^
	  |   +-----Reset low voltage flag.
	  +---------Set low voltage flag.

It is conceivable that in your case the use of the serial port
temporarilly lowered the battery voltage bellow the low voltage
detection level and that the batteries were already bellow the voltage
reset level.  From that point the only way to reset the low voltage
condition, is to install new batteries.  If you KNOW that the old
batteries still had some juice in them you could THEN re-install them
(having cleared the low voltage flag).  You could also ensure that you
do not leave the HP on the DOS prompt overnight.  The machine wakes up
every midnight to plan the next day.  If it finds itsself in DOS it can
not go back to sleep again...

Diomidis
-- 
Diomidis Spinellis    Internet: <dds@doc.ic.ac.uk>  UUCP: ...!uknet!icdoc!dds
Department of Computing, Imperial College, London SW7     #include "/dev/tty"

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