Re: JTAG Signals on PCI Backplanes.

[Alan Deikman <Alan.Deikman@znyx.com>]

>From: Richard Rooney <richard.rooney@mentec.ie>

>Does anyone know if the JTAG signals on PCI backplanes are actually
>normally connected to anything ?
>Are they even bussed from one slot to another ?

I haven't ever seen a mother-board that 
actually used the JTAG signals for their 
nominal/intended purpose, but we did have 
a situation where on one mother-board 
enough noise was present on those lines 
to start triggering the JTAG functions 
on the plug in card.  We ended up having
to cut the JTAG traces to accommodate the
mother-board.

Anyway, I haven't seen any mother-board
chipsets that provide software access to
the JTAG signals, which would allow the
POST to perform deeper diagnostics.  I
would have guessed that mother-board
manufacturers would have wanted to use
JTAG headers to reduce the need for ICT 
fixtures, (it sure would be a lot cheaper)
but it seems it just never has caught on.

Regards,
-----------------------
  Alan.Deikman@znyx.com