Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!cs.utexas.edu!uunet!mcvax!ukc!reading!bru-cc!ralph
From: ralph@cc.brunel.ac.uk (Ralph Mitchell)
Newsgroups: comp.sys.atari.st
Subject: Re: ZOO bombs
Message-ID: <764@Terra.cc.brunel.ac.uk>
Date: 20 Jul 89 11:55:46 GMT
References: <8907131551.AA27783@ucbvax.Berkeley.EDU> <2514@water.waterloo.edu>
Reply-To: ralph@ccs.brunel.ac.uk (Ralph Mitchell)
Organization: Brunel University, Uxbridge, UK
Lines: 23

In article <2514@water.waterloo.edu> ljdickey@water.waterloo.edu (Lee Dickey) writes:
>I suspect the ramdisk.  I used ZOO with ETRNL2 by Moshe Braner. 
>and had nothing like the problem you mention.  This ram disk,
>like many ram disks today, survives warm boot.  You can control
>the size and name of the disk.   The program is very small, 
>presumably because it is written in assembler.


ETERNAL2 doesn't actually work in a Mega 4...  Using HiSoft's resident
monitor I have tracked it down to the bit where it checks to see if the
ram disk is already resident.  It picks up the system variable that gives
the physical top of memory and then fetches the word (or byte ?) from that
location.  The location specified is one past the end of real memory, but
the MMU is quite happy to return 0xFF for non-existent locations.  In the
Mega 4, however, the non-existent location is beyond the maximum address
that the MMU can handle, so it gets a real bus error.  Moshe ??

Ralph Mitchell
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