I didn't see that: exxos created an alt motherboard for Atari STF. You need to put all original chipsets from an Atari STF and it's 100% compatible, but with many extensions.
The picture shows the H4 revision with an alternative HDMI shifter on it.
Like the later STF revisions, you can also populate a blitter on it (yes, a lot of STF motherboards had socket connections for the blitter's IC).
For more information: https://www.exxoshost.co.uk/forum/viewforum.php?f=78
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