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From: rnews@qut.edu.au
Newsgroups: comp.sys.atari.st,comp.sys.atari.st.tech
Subject: Re: Troubles!
Message-ID: <14939.26ed15b6@qut.edu.au>
Date: 11 Sep 90 16:49:58 GMT
References: <1990Sep10.005330.28401@agate.berkeley.edu>
Organization: Queensland University of Technology
Lines: 24

In article <1990Sep10.005330.28401@agate.berkeley.edu>, kawakami@ocf.berkeley.edu (John Kawakami) writes:
> Lately, my 520ST has been havng problems.  The screen begins to show garbage.
> It seems like the memory is being corrupted because the mouse will be going
> and the garbage is still on the screen.  What happens is the pixels in the
> even columns (of a mono screen) get garbled.  The end result is a screen
> of clean columns and dirty columns.  The dirty columns also show 
> bands of white and black.  I suspect this is a memory problem because the
> garbage shows up on byte boundaries.  Could it be that one bank of SIMMs
> is not being refreshed properly?
> 

This is a pretty common problem with upgrades and has to do with ringing on
the CAS lines to the extended ram board, a couple of 33pf capacitors on the
end of the two CAS lines on the expansion board will probably work wonders.

                          BOB





> John Kawakami                  kawakami@ocf.berkeley.edu
>                                ucbvax!ocf.berkeley.edu!kawakami
> Amateur crank!                 My Atari Macks!