Path: utzoo!attcan!uunet!zaphod.mps.ohio-state.edu!sdd.hp.com!hp-pcd!hpcvra!rnews!hpcvbbs!akcs.michaelv
From: akcs.michaelv@hpcvbbs.UUCP (Michael VanLoon)
Newsgroups: comp.sys.handhelds
Subject: Re: Battery problem in 48SX?
Keywords: 48SX,batteries,I/O,alarms
Message-ID: <2723d496-39d.3comp.sys.handhelds-1@hpcvbbs.UUCP>
Date: 23 Oct 90 05:40:04 GMT
References: <1990Oct18.013921.28895@santra.uucp> <16465@shlump.nac.dec.com>
Lines: 16

Although I have no way of knowing this for sure, my assumption for the
alarms is this: the 48sx has a countdown timer that operates off a small
oscillator when the 48sx is off (and on, as well).  Whenever an alarm is
set, the calculator looks to see which one is the next one to be
activated.  It then sets the countdown timer to do in interrupt in so
many clock ticks, which will set off the alarm (and wake up the machine,
if needed).  Note that it only sets one timer no matter how many alarms
you have set.  Once the most recent alarm goes off, it resets that timer
for the number of ticks until the next alarm.  Consequently, the
calculator would use the same amount of power no matter how many alarms
you have set.

This is just my theory, but it seems like the most logical way for the
alarm mechanism to be implemented.

Michael V
ISU