Re: A86: Questions on Port 3, calc on, off, APD, etc
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Re: A86: Questions on Port 3, calc on, off, APD, etc
> I believe that a processor uses the same amount of power at
> all times when it is on.
No, actually it varies greatly. When a HALT command or a
NOP is run, you save more than 3/4 CPU power (I don't remem-
ber the numbers, they used to be on ticalc.org somewhere). If
maskable interrupts are disabled, you get some (but not a lot)
of power off that. If the interrupts are disabled and the processor
is halted, it uses like 7 microwatts of power (the lithium battery
can provide this for years). All the CPU has to do is refresh the
RAM to keep it from being lost. This is the condition it's in when
off (and/or lacking AAA power).
> By leaving an interrupt running in the background, you consume
> as much power when "off" than while "on", except while "off" the
> display is not consuming any power, since it is off.
Actually, leaving interrupts enabled when off does use some
power. More than the lithium battery can output anyway. The
AAA batteries still could run the calculator like that for months
though.
> Does the display consume more power than the CPU?
As I can remember, the display uses about 75% of your
power, depending upon contrast level and what is displayed.
> If you disable interrupts before turning it off, you'd lock it
> since it can't turn it back on with on, since the [on] interrupt
> would be disabled, along with the timer interrupt. I think
> you'd have to pull all five batteries. I'll test after I finish my
> AP Stat final tomorrow...
No, the [ON] interrupt is an NMI (non-maskable interrupt). It
cannot be shut off. It is written on the circuit board. In fact,
because of this, you will never have to pull all 5 batteries
unless sqrtON (or whatever the user [ON] interrupt handler is)
is corrupted.