Re: A86: How did they find the ROM calls???

To: assembly-86@lists.ticalc.org
Subject: Re: A86: How did they find the ROM calls???
From: JayEll64@aol.com
Date: Sun, 5 Mar 2000 21:56:21 EST
Reply-To: assembly-86@lists.ticalc.org

In a message dated 3/5/00 7:33:35 PM Mountain Standard Time, Pbf16@aol.com 
writes:

> Does anybody know how the authors of Zshell or Ash found out the ROM calls 
> for thier specific calcs?

Yeah, it's called fun-fun ROM searching ;)

I'm *guessing* that they simply started with how the calculator started up 
from $0000, and followed the ROM code up until the calc was ready for 
home-screen input.  I do know that with VTI, it's fairly easy to get a 
"starting address" where you can look at the dissassembled code and kinda 
decipher whats happening there.  However, VTI wasn't around back then...

If you just look through the ROM, too, you'll find "signiture" places in the 
ROM where ROM functions obviously start and end, and by looking at the code 
within the function, you can sometimes get a pretty good idea of what it does.

JayEll

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