Re: A86: Re: LCD stuff

To: assembly-86@lists.ticalc.org
Subject: Re: A86: Re: LCD stuff
From: Joshua J Seagoe <rabidcow@juno.com>
Date: Thu, 18 Nov 1999 22:22:37 -0800
Reply-To: assembly-86@lists.ticalc.org

under normal circumstances, the calc is never truly off, no.  the lcd is
shut down, and the halt instruction lowers power consumption (i think),
but it's still alive, waiting for any interrupt that happens by.

the calc might use static ram, which wouldn't require refreshing, but it
seems like that would be a waste of money if the z80 has built in dram
refresh curcuitry.  you'd have to look up the part number on the ram chip
to be sure.  i think it's a seperate chip.

perhaps the processor recieves power from the backup battery unless the
on key is pressed?

some versions of the z80 can be effectively halted by stopping their
clock.  this would let you run at low power anywhere in the code and
resume without any problems.  they might do that

-josh

On Thu, 18 Nov 1999 20:19:50 -0800 Cassady Roop <croop@oregontrail.net>
writes:
>
>By the way, how much power does the processor consume when the calc 
>is
>'off'?  I looked up the halt instruction in the z80 data book to try 
>and
>resolve an old dispute with a friend of mine over whether it is ever
>truly off or not (off as in no power usage).  I found that the halt
>instruction waits for an interrupt, during which time it runs a
>continual cycle of NOP instructions internally, to maintain memory
>refresh logic for dynamic memory chips.  I don't think the 86 uses
>dynamic memory (or maybe it does?), but the z80 still runs during a
>halt, so therefore it must consume power, so therefore the calculator 
>is
>never truly turned off except when the batteries have been removed.  
>How
>much power does it take?  If you left it off for a long time, would 
>your
>batts run down?
>
>Can the processor run off the backup battery, or is the backup 
>battery
>isolated to the memory power circuit?
>
>Cassady Roop
>
>> Is it relying on the back-up or regular batteries when
>> the LCD is off using this method?
>> 
>>         -Barcode (Andy D.)
>

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