I would add that the 6100 riser for the DOS card effectively converts the PPC PDS into an 040 PDS (meaning the DOS card is actually an 040 PDS card, not a PPC PDS card). I have successfully used a DOS card from a 6100, removed from its riser, directly plugged into the PDS of a Quadra 800. No issues, no workarounds, everything Just Worked.

From that, I would expect that with the correct riser in the 610 it would also work.

Some Google-sleuthing produced this helpful page: http://www.renewingmind.com/quadrados/q610dos.html

...From the page:

I own one of the original Houdini Mac 610s. I removed the 4/25SX board from the 610 PDS adapter and installed a 4/66 board (with sound blaster) from a 6100 DOS kit. The screw holes and connecter are the same on both PDS adapters.

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