A86: RAM Page $80 ??

To: Assembly-86 <assembly-86@lists.ticalc.org>
Subject: A86: RAM Page $80 ??
From: Dan Eble <eble@cis.ohio-state.edu>
Date: Mon, 11 Aug 1997 23:49:34 -0400 (EDT)
Reply-To: assembly-86@lists.ticalc.org


I was snooping around in the ROM, as I am wont to do, and stumbled across
a piece of code that does something like this: (this is not exact)

     ld a,$80
     out (6),a
     ld a,(somewhere)
     ld ($8000),a

Then it restores the previous RAM page.  When I send $80 to port 6, every
byte in $8000-BFFF reads as $1A.  My first thought was that this might be 
some kind of memory-mapped I/O, but when I write various values to
($8000), nothing happens.  Anyone have any ideas?

--------
Dan Eble (mailto:eble@cis.ohio-state.edu)
         (http://www.cis.ohio-state.edu/~eble)

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