Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!iuvax!cica!tut.cis.ohio-state.edu!attctc!chasm
From: chasm@attctc.DALLAS.TX.US (Charles Marslett)
Newsgroups: comp.sys.atari.8bit
Subject: Re: Densities and their Interactions
Summary: Any version of Atari DOS that stays below the starting address of
	 BUILD ($3800??) should work.
Keywords: 1050 US Doubler Enhanced Density Double Density
Message-ID: <8575@attctc.DALLAS.TX.US>
Date: 8 Jul 89 02:47:45 GMT
References: <8057@bsu-cs.bsu.edu> <5531@stiatl.UUCP> <8125@bsu-cs.bsu.edu>
Organization: The Unix(R) Connection, Dallas, Texas
Lines: 27

In article <8125@bsu-cs.bsu.edu>, cfchiesa@bsu-cs.bsu.edu (Christopher Chiesa) writes:
> Second, and this is a general question: I'm concerned about the "BUILD" program
> that was supplied with the MyDOS sources.  I notice that it runs "under your
> current version of MyDOS," and just REPLACES the existing DOS "in memory" and
> poof, you're in the new version.  My question is, will this work under all prior
> versions of MyDOS, or am I going to be in trouble if I don't have a "relatively
> recent" version?  I think I have (gulp) something like 1.0 !  I know things can
> change pretty drastically between major revisions, so I would like to have the
> answer to this question BEFORE I try to install 4.51.  Thanks in advance.

See the summary above, the current DOS (whatever it is) is used to load the
new version of MYDOS into a temporary buffer above the BUILD code in memory,
then (after it is no longer needed) the new MYDOS code is copied down to
memory location $0700 on top of the old DOS -- it is then initialized and
started up.  The only problem you should have is if the old DOS has some
permanently active interrupt vectors (an embedded display list, or real time
clock support routine, for example) -- Sparta may, I doubt anyone else does.

> Chris 
> -- 
> UUCP: <backbones>!{iuvax,pur-ee,uunet}!bsu-cs!cfchiesa 
> cfchiesa@bsu-cs.UUCP                                           
===========================================================================
Charles Marslett
STB Systems, Inc.  <== Apply all standard disclaimers
Wordmark Systems   <== No disclaimers required -- that's just me
chasm@attctc.dallas.tx.us