: >>My friend recently purchased a LC III and he wants to know if there is
: >>such a demon called NuBus adapter for his PDS slot? 

: > The LC family of Macs can only
: > use PDS cards. They are not able to use NuBus.

: Ah, but why?  Can some technically-hip Macslinger tell us what the
: difference is between PDS and Nubus?  

: Is it impossible to make a gadget that plugs into PDS and ends in a
: Nubus card cage?  At least, Marvin's friend has not been able to
: locate one and neither have I.  What is the fundamental reason for
: this?

I think that there do exist NuBus expansion cages (I'm sure I've seen
them advertised occassionally), but I think that the main problem is that
they cost much more than the difference in price between say a LC and IIvx
so unless you need lots of NuBus slots its not worth the bother.

(Of course, it may be that these extra boxes are so expensive because
no one buys them because they are so expensive...)

NuBus technology isn't a special Apple Proprietry thing (I have this
sneaky feeling that it is licensed from Texas Instruments???) so there
is no problem building an expansion box.

The difference between NuBus and PDS is that NuBus is a clever interface
with lots of neat toys built in to make sure that lots of cards can work
together on the same computer. PDS (processor direct slot) is just that:
here are all the connections to the processor. You can do anything with
this and it is as quick as it can be, but there's no cooperation. You
may be able to get double PDS slot adaptors but you try plugging 2
video cards in, and just watch them conflict! Of course, the extra 
electronics in a NuBus slot makes it appreciably more expensive, so
guess why Apple doesn't put it in it's cheaper machines?

So, yah pays yer money and yah takes yah choice.