Subject: Re: FPU for the IIsi -- Which one?
To: Scott Lipcon <>
From: John P. Wittkoski <>
List: macbsd-general
Date: 06/22/1995 09:57:01
> 	Hmm... I thought that the IIsi had a PDS slot, and you can buy an 
> apple Nubus adapter for it, which changes the PDS slot to a NuBus, and 
> adds a FPU.  I thought it was pretty cheap (around $50).
> Maybe I'm wrong (I dont even have a IIsi!)

Actually, Apple doesn't call the connection on the IIsi motherboard a "PDS" 
slot.  They call it something else, like an expansion slot or similar (I don't
have my "Designing Cards & Drivers" here at work). The idea is that you
buy a little adaptor which plugs into this connector on the motherboard and
gives you EITHER a PDS slot (a SE/30 style PDS slot, that is) or a NuBus 
slot. Apple puts the FPU on this little adaptor card. Some other companies
put a cache here instead of or in addition to the FPU. One company (Extreme)
even had (has?) a card with a 50MHz 68030/68882 and cache on there and 
even has room for the PDS connector. If I remember correctly, the only real 
difference between the motherboard connector and the PDS connection is that 
the PDS connector lacks 3 or 4 signals from the motherboard (I think it's 
the FPU CS signal and several cache related signals). Other than that, they 
are the same.

And don't confuse these types of "adaptors" with the kind of "adaptors" that
are used by Daystar/DiiMO. I'm pretty sure the Daystar/DiiMO type gives you
a IIci-cache-card type of connector, which you can then plug one of their
accelerators into. 


 John Wittkoski				InSoft, Inc.
 Senior Systems Engineer                Phone: (717) 730-9501
 Email:                  Fax  : (717) 730-9504