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 22:38:08 -0800
Reply-To: assembly-86@lists.ticalc.org

On Thu, 18 Nov 1999 21:38:06 -0700 "David Phillips" <david@acz.org>
writes:
>
>I am not positive how the memory backup works when it is missing 
>AAA's, but
>99% sure it is a simple circuit that mantains the memory state.  
>Otherwise,
>things like Game Boy carts wouldn't work, since everything is 
>maintained
>inside the cart itself (hence no CPU).

don't be so hasty to assume the calc is designed the same way as the game
boy

>set of batteries if it was always off.  The 86 uses dynamic memory: 
>the ram

if there was only a simple circuit to maintain the memory, it's more
likely that they would use static ram than dynamic ram.  dynamic ram is
not a simple thing to keep going.  you have to have a timer and a counter
to periodically scan every row of memory.  static ram is very simple, you
have to keep power to it.
static ram also takes much more power and is much more expensive (but
faster), so i rather think they would use dynamic ram, hence keep power
to more than just the simplest of circuitry.  (blah, blah, blah...)

does anyone actually understand what it does from $0000?
aside from some port stuff, it scans sp from $fe9f-$ffff with long
delays, and prints something from (hl), which is never loaded.  then it
returns to whatever address is at $fbce.  why does it do all this??

-josh

>My manuals for the Z80 are at my house, but I do remember that the 
>power
>usage was very small when in HALT mode.  ZiLOG doesn't seem to have 
>the data
>sheets on their website anymore :-(
>

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Re: A86: Re: LCD stuff

From: "David Phillips" <david@acz.org>