🚀 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
> 				     ****

*** REPLACE THIS LINE WITH YOUR MESSAGE ***
It looks like that you certainly have a bad bit. Since the screen
memory is placed in the uppermost 32k of memory, you can see it on the
screen. I would suggest using sed to deposity end retrive bytes from
addresses in the upper 512k range to determine which bit is bad, and
then replace the chip coresponding to that bit.

-- 
					Jwahar R. Bammi
			       Usenet:  .....!decvax!cwruecmp!bammi
			        CSnet:  bammi@case
				 Arpa:  bammi%case@csnet-relay
			   CompuServe:  71515,155

> 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.

> When I had this problem it was simply shorted address lines. With the upgrade
> ........
> 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

Don't hunt for it visually at first -- that takes forever and may never
find the short.  Instead, use a modern digital VOM (Volt-Ohm-Meter),
preferably one with a "beeper" continuity check feature,
to measure between each address line and all the others.
Takes only a few minutes.  
	Once you've found the guilty pair, then go visual, or
even rip those two out and re-do them.
Don't use an old non-electronic VOM, as they may feed
high enough currents thru your chips to damage them.
Also make sure your instrument won't indicate continuity (short)
thru forward-biased solid state junctions (as in chips), thus
giving false short indications.  Test it on a diode, both directions,
to be sure.
	If you can't borrow such a VOM, Radio Shack sells them
for $40 (sale price, tho).  Worth every cent if you hack hardware.
	Best of luck, mike k