I left it running last night, got to around loop 50 and died.
Rebooted it ran until about loop 10.
Rebooted it ran until about loop 8.
Rebooted it ran until about loop 5.
This seems more like the CPU is overheating and crapping out. I left it overnight, turned it on this morning, ran up until about loop 9 (half hour run). This was running with 2 WS on ROM and 38MHZ.
I put my previous board in, thats running at 40MHz to see how long that runs for...
So I think I am leaning towards not all CPU's can run at 40MHz.. or so far, not even 38MHz. I will have to order a 32MHz OSC to try that.. I might get a 20MHz one.. its possible new CPU's may not even to be able to run at higher speeds. Which will be a pain if all 200 of them can't run faster than 20MHz!
So the overall plan would be I would have to build the boosters all at 40MHz.. leave them running all day, if they crash, swap it to a 32MHz OSC and try again and sell them as 32MHz ones. The ones which run at 40MHz will be sold as such. Problem being that's a hell of a lot of testing.. Also it would beg the question if it even be worth producing this booster if the CPU's can't run faster than 20MHz. Time will sell.
I think what's compounding the problem is the V1 booster ran at 8/32MHz, so the CPU wasn't being overclocked at all when accessing the bus. Obviously this overall runs a bit slower than running the CPU at constant speeds (40MHz etc). So the CPU heats up more. 8/32MHz switching might be equivalent "heat" to 20MHz constant speed for example. I'm not sure which one would ultimately be faster yet.. Though 20MHz constant run might be close to speeds of 8/32Mhz switching anyway.. That will be fun explaining to people why this 20Mhz booster is faster than the previous 32Mhz one!
Right so while typing this this other 40MHz one crashed at starting loop 8.... So time to start looking at slower OSC's...
Hacked on a 25MHz one.. see what happens...

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EDIT:
OK it crashed after 15mins

Really don't understand it when the first one I made ran for like 100hours.. I need to re-try the 8/32 switching but I have a feeling that had some odd issues aswell, put that down to iffy soldering but maybe something else going on
I think this project will just have to go on hold for now until I got time and patience to keep messing about with it. Getting a backlog of machines to repair and upgrade so need to get cracking on those.