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From: sirolly10@wharton.upenn.edu (Michael Sirolly)
Newsgroups: comp.sys.m6809
Subject: Speaking of 512K upgrades...
Message-ID: <1991Mar4.151832.1@wharton.upenn.edu>
Date: 4 Mar 91 20:18:31 GMT
Sender: news@netnews.upenn.edu
Organization: University of Pennsylvania
Lines: 34


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"