🚀 go-pugleaf

> 
> For your information, I've gotten responses back from people you have NOT
> been able to update their 520ST to 1meg.  So far no one has been able to
> verify if the mmu has changed or not, in the other peoples machine the
> drams had a metal cover (unremovable) on them so you couldn't piggy back
> the chips.  I would guess that you might be able to replace all the chips
> but I don't know.
> 
> 
>    Ray Roux
> 	{ucbvax|decvax}!trwrb!trwspp!spp3!rroux 

I would like to add my experience to these rumors. Having an early 520ST
(rev A) I was able to upgrade to 1Meg. Now the bad news: The now avai-
lable ROM version of TOS will ignore this upgrade. It will still work if
the additional DRAMs are in but without using them. Furthermore if you
change the appropriate system variables to update top of memory and 'MMU"
configuration byte the system will NOT work after a reset. One has to turn
it off and on again. I haven't found the routines yet who make it appearently
impossible to utilize a selfupgraded 520ST (any hints?)

Some remarks about the ROM version:
The ROM version seems to be more stable when recovering from a system crash.
It boots up in ~less than 10 seconds (still reads the *.INF and *.ACC files
from disk). The 'MUSHROOMS' were replaced be the pictore of little bombs (they
DON'T explode).

Stephan W. Wendl