". . . supports many PDS cards designed to operate with the MC68030 bus.."
It says with the MC68030 bus, not in the LC Card Slot.
It's sort of splitting hairs. The original LC card slot *is* a 68020/030 PDS slot, or *almost* one, anyway, it's missing a few address lines and signals. The LC III added an extension (from 96 to 114 pins) that made it a "True" PDS slot, or at least a complete one. It's the LC III one that the bus converter in the PrimeTime IC emulates.
Again, the PDS slot in the 610 (and 650/800) is a *TRUE* "PDS" slot because it's basically the raw 68040 bus brought to a connector. The bus converter in the LC 475/Quadra 605 may be less complex than a NuBus bridge but it's still a *bridge*, and it's a bridge the 610 doesn't have.
To use an imperfect analogy, the Quadra 605 is sort of like an ISA-bus equipped 486 machine; ISA is essentially a 286 PDS, and requires more and more complex glue to use on later Intel CPUs, just like running a card designed to talk to a 68030 needs a little glue to talk to a 68040. The 650/800 is like a dual EISA/VL-Bus 486 (EISA being roughly equivalent to NuBus if you forget about its backwards ISA compatibility, and VL-Bus is basically a 486 PDS), and the 610 is like a 486 with *just* a VL-Bus slot that can be converted to an EISA slot by plugging a bridge in. The BIOS (IE, slot manager), mostly papers over the difference for DOS, but these differences are going to matter a lot if you try loading Linux on any of them.
... and, again, by the analogy above, the 630 is a 486 that has both an ISA slot and some *other* kind of slot. What's a Comm slot most like, S-100? [ ]