Right... As I said, I've only been inside the 9000/340 (I
 have a number of those that I was given, all with high-res
 video boards, and IIRC, 16M RAM.). Somewhere I have an
 interface board for an external video box, the different back
 panel that goes with that, and a little cardcage you can fit
 to that backpanel that has a DIO slot).  
 Is it for the Graphic coprocessor ? 
 
The interface board (that fits in place of the graphics board) may well
be. Somwehre I have an HP box, the same size as a 9000/340, which appears
to be some kind of grapghics processor (there's an i860 on one of the
boards and lots of ASICs IIRC). That came with an HP9000/400 series
machine, but it may well (a) not have gone with that one and (b) might
work on the 9000/340 too.
The DIO slot seems normal. There was a 98625 (high speed HPIB using the
Medusa chip) with it. I assume that went in said DIO slot.
    The interface board contains 1 big pga i/o chip
 (propriarity hp) but
  the rest is TTL and some LSI-chips. 
 Custom LSI, or things I might have heard of? It's not the PGA
 package I oject to per se, rather it's the fact I can't get
 data or replacements for some of the ICs. 
 
 One custom LSI I think it's the I/O controller.
 The others are Lance Ethernet Ti HP-IB controller HIL-chip, serial
 controller 1820-3623 and some other standaard interface chips. The only one 
 
Oh that doesn't sound too bad. I don't recognise that serial chip off the
top of my head, but it might be something standard.
For some inexplicable reason, HP used the 8250 in the 9000/200 series. A
very odd choice given that it's a 68000 machine...
  that would bother you would be the HP 1TQ4-0401.
 I'll make some pictures this week and put them on flickr so you can look at
 them. 
Thanks...
  Hardware problems are always 'fun' ;-) 
Indeed. Well, as everyone knows by now, my primary interest is hardware...
-tony