LarryL wrote: 14 Apr 2023 12:24
maybe of interest re stability of Mega STs...
I recently added a "TF536 ST edition" into my Mega ST
It is a C103277 Rev2.2 - no IMP, all Atari chips, Blitter removed
I did all the "mandatory fixes" upfront
runs rock-stable, incl. IDE from the TF, Floppy and external UltraSatan via ACSI
so, seems there are stable Mega ST setups with boosters - but maybe I am just lucky :-)
Thanks for the information. Though yes, if you have done all the fixes then it fixes all the currently known problems with most machines. So you will of course stand the best chance of fitting accelerators and such without them malfunctioning.
I think somewhere in Atari's own documents it said generally machines can tolerate one IMP chip. but this is just how unstable and problematic machines can be when they are in "stock" form.
Even adding something like a DIP to PLCC CPU adapter is enough to cause problems even at stock speeds. So then when you add an accelerator like mine which speeds up ROM access to 16MHz or above. Is just not going to work reliably without doing all the fixes.
Even running the accelerator on stock speeds malfunction. Though I presume a lot of accelerators only use the bus that stock speeds are maybe it is not always as noticeable in some cases. But in any case I've always found repeatedly similar problems on various machines where the solutions were also common. That is where the mandatory fixes of basically born from.
IIRC the ST536 isolates the ST bus during fast-rom access. So it is possible it may be inherently more tolerant to bus stability issues as it is not accessing anything on the ST bus any faster than stock speeds. But again, it is very hit and miss depending on multiple factors.
