JimDrew wrote:I have tinkered with the Atari ST stuff since they were released.
I guess over the years you’ve forgotten a few things... TOS 1.00 was the original version, while later STFMs shipped with 1.02 and then 1.04. TOS 1.6 / 1.62 were the STE versions, TOS 2.05 / 2.06 were Mega STE versions. 2.06 was also made available as after market upgrades for the earlier models since it made things nicer in the desktop so was good for productivity users, or those with other hardware upgrades - but as you have seen, added compatibility issues, so people wanted to retain their 1.x version as well.
Differences between 1.00 and 1.04 (last STFM version) are minimal and usually don’t cause any issues (truly ancient software might not run on 1.04 but would work on 1.00 if they did naughty things before 1.04 was released).
Basically, by putting in 1.00, the most compatible version is already there.
(For completeness, TOS 3.xx was the same as 2.xx but built for the TT and TOS 4.xx was for the Falcon).
All of the above versions were available in the US (and UK, DE etc) versions.
NTSC vs PAL refresh rate is an entirely separate issue.