exxos's Atari, Amiga & retro forum

I received the message at boot "Internal memory low, use folder100.PRG, system halted."
I have never seen that before and can find no reference to it. What happened? I caused it myself by doing a 1mb piggyback RAM upgrade on this 520ST.
All the chips that I used except one were new from the Exxos shop. The single old chip I put at the end of the row because I didn't know if it would work to make access to it easier.
First of all the extra 512K wasn't recognised. I guessed it might be the odd one out chip and replaced it with another old chip from the same donor board. Then it was recognised but the GEM desktop didn't display correctly. Having no idea but just using a process of elimination I swapped the two CAS1H and CAS1L wires and then it displayed correctly.
It passed the memory test but when playing 1mb games I kept getting random crashes and the "system halted" message on boot sometimes. So I decided to replace that chip again. So far it looks like that solved the problem.
A piggyback RAM upgrade is fiddly but as long as you know that the chips are working it is relatively straight forward and when one or more is faulty it isn't.

Useful to have a post explaining what you found to cure the problem, it's helpful for other folks.

Personally I'd always advocate against piggy back RAM expansions, they can be a bind to troubleshoot, at least the one in my own 520ST was, and there are better options these days.

Good job on getting one done though, they are a fiddle :)

I would agree with that and I did think to myself "maybe that wasn't a good idea?" but I had the chips available and now I can use that machine for regular use instead of just packing it away because of too little RAM for practical use.

russellnash wrote: 03 Jun 2024 10:03 I would agree with that and I did think to myself "maybe that wasn't a good idea?" but I had the chips available and now I can use that machine for regular use instead of just packing it away because of too little RAM for practical use.

I know what you mean, I've done the same sort of thing 'because I have the parts' even if it isn't the most sensible move :)