Re: A82: CrASH v1.5 released!

To: assembly-82@lists.ticalc.org
Subject: Re: A82: CrASH v1.5 released!
From: "Evil Sam" <evil_sam@hotmail.com>
Date: Tue, 13 Oct 1998 13:58:43 PDT
Delivered-To: assembly-82-outgoing@towerguard.unix.edu.sollentuna.se
Reply-To: assembly-82@lists.ticalc.org


>The readme doesn't give any details about the "Evil Sam" bug. What
>exactly was wrong Sam? I am just curious.

   I believe I said this in the list string about "CrASH bug solved", 
but here is an explanation again.
   CrASH was missing 2 important set/res commands. Before CrASH/ASH 
starts a program and returns from a program, the shell sets a few 
set/res commands to make sure no system data is overwritten. The CrASH 
team forgot to put in the set/res commands dealing with TEXT_MEM. 
Specifically, CrASH needed these commands:
   res 1,(iy+13) ;Do not affect TEXT_MEM
   call runprog
   set 1,(iy+13) ;Affect text_mem
   set 2,(iy+13) ;Enable text scrolling

    The set/res 1,(iy+13) is very important. Without it, most games that 
use TEXT_MEM as a storage space will be negatively affected in some way. 
Although I'm sure other games were affected, this is why Ark v1.1, 
Ztetris(ASH), and PlainJump(the first release) did not work with CrASH.
    The set 2,(iy+13) is rather trivial, but in order for games to write 
to the bottom line in CURSOR_ROW font, they must disable scrolling text. 
This disabling caused the CrASH bug found in Galaxian, Orzunoid, 
Pac-Man, BoulderDash, Picross, Zkart, Zkart 3-D, and others. 
   Sam

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