Re: A83: Time on TI-83


[Prev][Next][Index][Thread]

Re: A83: Time on TI-83





-----Original Message-----
From: Justin Karneges <jgkarneges@ucdavis.edu>
To: assembly-83@lists.ticalc.org <assembly-83@lists.ticalc.org>
Date: Tuesday, November 10, 1998 3:31 PM
Subject: Re: A83: Time on TI-83


>
>I have messed around with such an idea, and you can probably do it with
>minimal power.  Basically, when you press [2nd]+[ON] to turn off the calc,
>it does this:
>
>ld a, 1
>out (3), a
>ei
>halt
>ld a, 11
>out (3), a


Please pardon my ignorance of the TI-83 system design, but does this mean
that TI didn't include any _alt_on or _alt_off routines?  On the 86, they
included special ares in memory for your own custom routines that are called
when the calc is turned off, turned on, when the timer interrupt is called,
when silent linking occurs, and I think another one.  Seems strange that TI
wouldn't include these in the 83 (though they documented almost everything
about the 83, practically wrote a tutorial about it on their website, on the
86 they only threw up a few nclude files).

>
>turned it on.  This means that the Z80 and RAM use very very little battery
>power.


Note that it uses very little power when it is HALT mode.  When working, it
uses up much more.  (he did imply this, I'm just clarifying)

>Anyways, a good way to implement a clock would be to shut off the LCD, then
>just sit in a loop counting.  When the user presses [ON], turn the LCD back
>on.  I don't know how to detect the ON key, but I know it can be done.


Wouldn't a counting loop like that consume ALOT of power?  Remember, the Z80
only uses little power when executing a HALT.  If you could figure out a way
to let the timer interrupt get called while the calc was off, you could
update the clock in that like you would when it was on, just don't print the
time if it's off.



Follow-Ups: