What is located in I/O User Space?

[elmer]

I can see from the docs that the memory range $EC0000-$ECFFFF is allocated for user-created  expansion boards.

So my question is ... if I wanted to design a new expansion board, how much of that can I use?

Is there a list anywhere of what address regions are currently being used by stuff like the Neptune/Nereid/and-whatever-else-exists?

I'm curious if I can get away with a whole 8KB block within that region and so maybe fit the interface logic for a simple circuit into a 44-pin CPLD.

Otherwise, I think that the next step up is a 100-pin TQFP CPLD.

[neko68k]

This should help.

[elmer]

Thank you!

So it looks like there are 2 "known" things in the $ECxxxx user region ...

$C000-$DFFF mercury
$E000-$FFFF nereid

I'm sure that there must have been a few more devices than that ... and I'd love to know if the Neptune cards are located in the same space as the Nereid card.

But it's really good to know that an 8KB allocation is the "norm".