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From: halkoD@batman.moravian.EDU (David Halko)
Newsgroups: comp.sys.m6809
Subject: Re: Speaking of 512K upgrades...
Summary: video problem
Message-ID: <3176@batman.moravian.EDU>
Date: 15 Mar 91 16:09:02 GMT
References: <1991Mar4.151832.1@wharton.upenn.edu>
Organization: Moravian College, Bethlehem, PA
Lines: 44

In article <1991Mar4.151832.1@wharton.upenn.edu>, sirolly10@wharton.upenn.edu (Michael Sirolly) writes:
> 
> Speaking of 512K upgrades, I've had a wierd video problem ever
> since I performed mine.  For background, it was a board with
> 120 ns chips that I put in by the "remove the 128K and clip the
> two capacitors" operation.
> 
> The memory seems to work fine, but since it was installed my
> CoCo has been fidgety about switching video modes. If the 
> computer has been on for a while, a BASIC command switching
> HSCREEN's or PMODE's, or running any program that does the
> same, is risky and may send the computer off into la-la land.
> 
> Sometimes it doesn't lock up right away, but the graphics 
> screen comes up with scattered pixels that weren't cleared or
> were cleared wrong. Similar shrapnel of the operation is 
> distributed througout memory, vandalizing BASIC progams and
> corrupting BASIC or the application itself.
> 
> Even if the computer is just turned on and still completely
> "cooled off," a direct statement like:
> 
> FOR X=1 TO 1000:WIDTH 80:WIDTH 32:NEXT X
> 
> ..will kill the thing in a matter of seconds.
> 
> However, under OS-9, it is usually possible to set up as many
> windows under different screen modes as desired and hold down
> the [CLEAR] key to rapidly flip between them - without 
> incident.  Add in Multiview and do the same thing, and disaster
> will come rather quickly.  
> 
> Any ideas where my CoCo's problem might be?
> 
> Michael Sirolly     "SIROLLY10@wilma.wharton.upenn.edu"

Well,

I have had a similar problem at one time... mine was due to excessive
heat and a bad power supply... immidately after moving my system to a
PC case, it disappeared... you may just try a big muffen fan from
Radio Shack to solve that problem...

	Dave Halko