Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!swrinde!cs.utexas.edu!sun-barr!ccut!wnoc-tyo-news!toumon!wucc!ytsuji
From: ytsuji@wucc.waseda.ac.jp (Y.Tsuji)
Newsgroups: comp.sys.atari.st.tech
Subject: Re: *** HELP!  Annoying Verticle line screen garbage! ***
Summary: check the memory contents.
Keywords: atari-st monitor
Message-ID: <5552@wucc.waseda.ac.jp>
Date: 29 Apr 91 23:02:55 GMT
References: <1970@ahds.UUCP> <47867@ut-emx.uucp> <1991Apr29.163055.7126@rhrk.uni-kl.de>
Organization: The Centre for Informatics, WASEDA Univ.
Lines: 20

Andreas Schuch says his screen goes funny when
>  - starting or finishing TEMPUS,
>  - ViewGIF displays a picture,
>  - SysMon is invoked,
>  - tracing over certain TRAPs with MonST debugger (couldn't find out
> which in special).
(deleted)
Aha! The monitor seems OK. It looks like a problem of poorly written
software that don't look after other interrupt handlers well. To test
whether the problem comes from the screen memory or the monitor, read
the address of the funny picture while it is shown on the screen.
You may need a pocket calculator to work out where because TOS tells us
only of the base of the screen memory. One thing I do often is to use
the 'pokew' command of GULAAM. Your debugger should be more versatile.
If the source of the trouble is suspected to bugs of the software,
you can ask the bug fix from the vendor.
Hope this might fix the problem.

P.S. The easiest way to detect the problem is to do the same thing on
someone else's monitor or machine.