🚀 go-pugleaf

> foo!
> Well I did it. I attempted the fatal up grade. The good news is that I
> did not fry my ST. She boots-up all right along with the 5 or six
> accessories on the desk top [fonts,ramdisk,etc...]. The ramdisk says
> ~690+K byte available! Looks  good right!?
> 
> However a little after after boot-up,vertical lines appear up and down
> across the whole screen!!! Sometimes the lines shift color as I move the
> mouse. I can still run programs, copy files to and from the RAM disk,
> but invariably, after a short time it crashes, lines and all. My
> thinking is that one of the RAM chips is flakey. WHy?
> 
> 	A. the vertical lines appear on every 8th pixel
> 					      ---------
> 	B. When pressing memory to its limit by coping whole disks into
> 	   the RAM disk, I can see the patterns of these vertical lines
> 	   change in exact sequence with the "clicks" of the floppy disk.
> 
> Questions: 1. Any suggestions on what else it might be? 
> 	   2. How does one test for a bad RAM chip?
> 
> 		All comments will be MOST welcome. Thanks - Geoff
> 				     ****

When I had this problem it was simply shorted address lines. With the upgrade
the screen memory ends up in high memory, thus the wierd display. I located
the address lines in question by using SID to write to a large zero filled
array one byte at a time and observing which locations caused more than one
location to change.

If you are unlucky the shorted lines will have to be located visually because
you won't be able to keep the system up long enough.

-- 
Dave Burris
..!ihnp4!ihopa!riccb!djb
Rockwell Switching Systems, Downers Grove, Il.