Re: Teknor System

["Dave New" <den@aisinc.com>]

Dan wrote:
> 
> 
> Has anyone tried their PCI add-on card in a Teknor TEK933 PCI-ISA single 
> board computer with passive backplane?
> I tried 3 of my pci cards (frame grabbers) all caused system to not boot
(no 
> VGA display).  I also dis-abled the on-board VGA and tried several PCI
VGA 
> cards with the same result.  My DEC PPB extender card also caused no VGA.

>  Any good/bad experiences with this system?
> 
> Dan Rafuse
> Imaging Tech. Inc.
> danr@imaging.com
> 
> 
Right off the bat I'd say you've gotten one of those passive backplanes
that
are *so* passive they don't have bus arbitration signals on the extra
PCI connectors.  This means that you can't put anything that attempts to
master the PCI bus in those connecters and get anything to work. 
Framegrabbers
almost always master the bus.  As for the VGA board, that may be an issue
with supporting the 'legacy' I/O-mapped VGA controller addresses.  The
combo board may not allow (or the BIOS may not know what to do with) such
a device on the PCI side.  You might be able to plug in an ISA VGA and get
it to work, but why bother? 8-)

I've seen some of these types of combo cards at shows, that have a PCI-ISA
board that "bridges" the two busses.  There are at least a couple of
vendors
that claim to support bus mastering PCI boards in the expansion connectors,
by virtue of using some of the 'reserved' PCI pins at the combo board
site to run the REQ# and GNT# lines off the combo card and get them to
the other sites (remember, these lines are not bussed, they must be
individually connected to each of the other sites).  This scheme, however,
introduces a nasty clock skew in the REQ# and GNT# lines, and some PCI-
compliant boards won't play to this skew, which is generally out-of-spec.

There is a PCI passive backplane spec (no connection with the PCI sig), but
I don't have a copy of it.  I suppose that it's possible to design a board
that can play in a system with these kinds of hurdles, but I imagine that
there will be a lot of off-the-shelf 2.1-compliant products that simply
won't.

DaveN
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