Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!unmvax!pprg.unm.edu!hc!lll-winken!uunet!portal!cup.portal.com!Chris_F_Chiesa
From: Chris_F_Chiesa@cup.portal.com
Newsgroups: comp.sys.atari.8bit
Subject: Re: 850 Interface Handler Code - attn Jean Goulet
Message-ID: <16552@cup.portal.com>
Date: 1 Apr 89 18:04:20 GMT
References: <8903310230.AA08623@maxwell>
Organization: The Portal System (TM)
Lines: 32


 In an article whose header Portal doesn't pull into the reply, Jean Goulet
writes:

> I'm looking for 6502 source code for the handler for the Atari 850
> interface module.  [...]

If you haven't had any other responses to your query, write me e-mail at

   Chris_F_Chiesa@cup.portal.com

and we can discuss this; I may be able to help.

The actual 6502 code that handles the 850 Interface Module is downloaded from
the 850 itself at boot time, through a sequence of SIO commands that I've never
seen documented but which I have investigated on my own.  This approach seems
capable of allowing a person to "fool" the 850 into sending the handler to 
the computer under the control of a debugger (DDT, nee Bug/65) whence it may
be saved to disk, investigated in memory, single-stepped, etc.  I haven't 
taken it this far myself, but it seems it ought to be fairly straightforward.

One concern is that this will NOT produce "source code."  At the immediate
level, of course, all one would have would be executable code -- but with 
proper tools that could at least be disassembled.  If this is adequate to your
needs, Jean, write me and we'll see if we can work something out.  If not,
best of luck finding the information you seek.  (And, while you're at it,
tell me more about this "other" handler you've obtained?  I've never heard
of it.)

Cordially,

   Chris Chiesa