1541 $01xx area

1541 $01xx area

From: Ruud_at_baltissen.org
Date: Mon, 20 Apr 2009 19:32:17 +0200
Message-ID: <49ECCDC1.8048.3DE352@Ruud.Baltissen.org>
Hallo allemaal,

I'm playing with an idea. Both my 1541IDE projects are going fine; the D64-
image version and the 16 MB with subdirectories. The ide is to extend the 
D64 version by maintaining the floppy drive. 

My D64 version doesn't need any GCR en/decoding and therefore doesn't need 
the area $01BB-$01FF. This enabled me for using this area for my own 
purposes. It also enabled my to make a bigger stack. Originally the stack 
starts at $0145. Why here and why not $01B0 for example? Is the area $0146-
$01BA used by other things I don't know of?

My idea was to move this GCR area to $0800, in the RAM I piggybacked on top 
of the  original one. As there are only two variables used to address this 
area, A_0100 and A_01BB, I thought this was a quick win by letting them 
point to $0800 and $08BB. But I was wrong: 23,READ ERROR,18,00 speaks for 
it self. I must have missed something but where?

Info is very welcome !!!

   / __|__
  / /  |_/     Groetjes, Ruud Baltissen
  \ \__|_\
   \___|       http://Ruud.C64.org

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