On Sat, Mar 29, 2003 at 11:45:33AM +1000, Ray Phillips wrote:
> > > Could someone explain about the two long (64-bit?) PCI slots in the
> > > PWS, please?  I mean what's special about them...
> >
> >The Pyxis bug.  PCI DMA transfers that cross page boundaries are broken in 
> >the
> >earlier Pyxis hardware, found on Miatas.
> 
> I suppose the faulty IC is on the the main logic board (the one the 
> 21164 CPU is on) rather than the lower one containing the ISA and PCI 
> slots?
> 
> The boot probing messages at boot say
> 
> cia0 at mainbus0: DECchip 2117x Core Logic Chipset (Pyxis), pass 1
> cia0: extended capabilities: 1<BWEN>
> cia0: using BWX for PCI config access
> cia0: WARNING: Pyxis pass 1 DMA bug; no bets...
> 
> However, I couldn't find an IC labelled something like 2117 or which 
> had Pyxis on it.

It is a smallish chip the size of a poststamp but it probably
(for the newer production units) a heatsink on it. Which obscures
the part# markings.

See http://people.freebsd.org/~wilko/Alpha-gallery/MiataMX5/dcp_0281.jpg
The Pyxis is just below the DIMM sockets

The GL board:

http://people.freebsd.org/~wilko/Alpha-gallery/MiataGL/dcp_0259.jpg

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