Re: TIB: Stopwatch


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Re: TIB: Stopwatch




Okay you did bring up some very good points about the lack of acurate time
measurement.  However, these are not a major factor when using interupts.  I
am not sure how much you know about the calcs rom so ask me anything you
don't get.... First you might want to know what the interupts can do for you
on your calc.  Well lets start with the run indicator, this is a interupt
routine, after a certain amount of clock cycles the indicator will be drawn
or erased.  Also, you can say the same thing for the blinking curser, it too
follows the same idea of interupts.  Now here is the one you might be most
interested in, the auto power down.  Of course you know that if you leave
the calc on for more than x amount on minutes the calc shuts off.
Taken from ACZ's 86 Central
The interrupt handles the APD, or Auto Power Down, which is basically a
timer that counts down per interrupt cycle. After about 5 minutes, the
calculator shuts off (sleeps). Every time you press a key, it appears to
reset the counter back to 5 minutes. Since the interrupts are activated 200
times per second, it would take a countdown value of 200 to wait one second.
200 hz * 30 seconds = 6000 (count down value).

Thus with this knowlege you can more acuratly than not calculate the amount
of time it takes.  Now with this you can simulate a clock by changing a few
key things.  *i hope you did see that the clock stops when you turn off the
calc and restarts where it left off*
Dave
******************************
ACZ
assembly coders zenith
e-mail: scheltem@aaps.k12.mi.us
ICQ #16817590

>How does that work?  The z80 is not run by a crystal.  It is run off a
>resister/capacitator oscillator, which varies dependant on voltage and
>temperature...
>
>You could take care of voltage variations with a regulator, but even then,
>temperature would affect it greatly.