Re: A86: batt checker

To: <assembly-86@lists.ticalc.org>
Subject: Re: A86: batt checker
From: "Dux Gregis" <assets@eden.rutgers.edu>
Date: Tue, 1 Dec 1998 16:12:15 -0500
Delivered-To: assembly-86-outgoing@towerguard.unix.edu.sollentuna.se
Reply-To: assembly-86@lists.ticalc.org

I'm talking about Kirk Meyer's routine.  I was never really following the
thread and thought that this is what you were trying to determine.
But anyhow, here's what the ROM does: it puts a value out port one that sets
up a mask for a keypress, then it checks a little later to see if the mask
is still effective; if the mask runs out of time, it means that the cpu is
running at good speed, if not, then the cpu is operating much slower than
the hardware on port 1.  That explains why certain keypresses will diplay
the battery message when the calc is turned on.  This is only the routine
used to check batteries when the calc is turned on, it looks like there are
other times when the calc might do other things to check battery level.

>
>interesting.  so kirk meyer's routine was actually sort of like the rom's.
>that's kinda weird.  btw, where is the routine that gets the battery power
>located?  that's a lot more relevant than what i found, which only gets
called
>after the fact.
>
>
>
>In a message dated 12/1/98 13:32:21 Eastern Standard Time,
>assets@eden.rutgers.edu writes:
>
>>
>>  I decided to look at the routine, so here is what it does:  it counts
the
>>  number of times bc is incremented in a loop in the time that it takes
for
>19
>>  interrupts to occur.  Interestingly, in order for this to work, the
clock
>>  controlling the interrupt must be independent of the clock controlling
the
>>  rest of the cpu and not as adversly affected by battery power as the
rest
>of
>>  the overall performance is ... maybe an accurate clock is possible after
>>  all.
>>
>>
>>  >
>>  >> i have actually found the routine which displays the "Your batteries
>>  >are
>>  >> low..." message, but unfortunately that doesn't do much good because
>>  >that's
>>  >> only called after the calc knows the batteries are low.
>>  >
>>  >Where is that? If we could find a call or something elsewhere in the
>>  >rom, then that would be what actually checks the battery power... BTW,
>>  >might it be port 4?
>>  >_________________________