At 7:05 Uhr +0100 25.3.2000, Bob Nestor wrote:
>Chris Brown  (cblist@cityb.net) wrote:

>>The IIci has only nubus slots; it is virtually guaranteed that your PDS
>>Ethernet card won't work in it.

The IIci has one PDS slot additionally to its three Nubus slots, dedicated
to an optional 2nd level cache card. This may or may not help you with the
LCIII PDS card, because there are quite a few PDS designs out there,
differing in electrical and mechanical layout. Makes sense when you keep in
mind that unlike the Nubus the PDS is closely tied to tke machine and
processor capabilities. A PDS is basically the processor's
data/address/control bus lines wired to a connector.

Apple's tech documents library, available on the web, should be able to
provide details.

>I think the PDS and nubus are basically the same but physically oriented
>differently.

Nope. The Nubus was designed to be processor architecture independant - it
even uses little endian byte order, contrary to the m68k family.

>They act the same as far a programming

That is related to software architecture (declaration ROM) and MMU address
mapping.

>and I could swear
>I've seen nubus to PDS converters available.  I was under the impression
>that all they did was re-orient the nubus slot and add a PDS header for
>the PDS card to mate with.

You have it the other way 'round - there are PDS-to-Nubus bridges (IIsi,
Q605). As the Nubus is substantially slower than even the '030 PDS (which
is why the PDS was introduced, think of VESA Local Bus vs. EISA or AGP vs.
PCI) anything else would not make much sense.

	hau "proud owner of 'Designing Cards and Drivers'" ke

;)




--
"It's never straight up and down"     (DEVO)