What's this PDS/LC PDS/PDS Compatible stuff about?
Yes, a Quadra 605 doesn't have a real PDS. :)
To clarify, PDS stands for Processor Direct Slot, and essentially that explains it's intended abilities - the pins in a PDS are directly connected to a CPU's address, control, data and clock lines - with some extra connections depending on specific models.
In the original 68020 LCs this was a 96-pin Euro-DIN connector, in the LCII and III it was expanded to also include an extra 18-pin segment for a total of 114 pins, to carry the extra signals needed to address the 68030. A normal full 68040 PDS as found in models such as Quadra 650s, 700s, 900s etc is a 140 pin connector, with signals specifically connected directly to a 68040.
In a Q605 however, due to the model being a continuation of the LC pizzabox line which had succesfully used 020/030 PDS's and their cards, the same slot was used, but not in the capability of a true PDS as it doesn't directly access the 68030 processor bus - there is no 68030!. However, for most useful purposes it IS compatible. Cards which required specific direct access to a 68030 will not work - most of these are either expansion boards designed to add features to a 68030 which the 68040 can do by itself (such as cache or FPU cards).
Cards that do not require direct CPU access will still work fine. the original Apple II compatible card will work (provided 32 bit addressing is turned off in the OS), Ethernet, video and sound cards should also all work fine.
have two Knowledge Archive articles specifically on this subject: