When I started using Auto-routing to do boards, I was introduced to it
through Applicon 870, a DEC PDP 11-35 based system back in the early 1980's.
It was painful and required many passes of different algorithms to get the
results and you could not observe its progress in real time, it was batch
processed. It used a MAZE routine, and a Stitch routine which propagated
zillions of vias. Then once it was choked, you had to run a via minimization
pass to open channels... all of this was based upon a grid system with
obstructions being the pins of the components.. (pre-surface mount
 Later I used the CADNETIX auto-router and had good success with it. It has
since become the basis for the Veribest product and is now the property of
Mentor Graphics and is in their Expedition product. It automated these
routines with a rip up and retry algorithm that helped reduce the labor of
clean up afterwards... 
 I heard stories of 'grid-less routers' and much of the cooper-chian
development was similar to what was developed before but improvements were
in the ability to automate and control the passes that the router did to
complete the connections. 

Have you seen anyone make a significant breakthrough in the approach to
routing a board that would change the way we even think about routing? 

I have always envisioned a router that would virtually route the board real
time and allow the designer to pick up a part and move it and have the
routing done a few milliseconds later flowing in around the part
dynamically, rerouting as you go... dragging a part would change the routing
in a fluid manner to optimized trace paths that followed the electrical and
physical rule sets. 
 Ah... but I am a dreamer.

Bill Brooks 
PCB Design Engineer , C.I.D., C.I.I.
Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510

-----Original Message-----
From: Indrek Rebane [mailto:[EMAIL PROTECTED] 
Sent: Thursday, July 15, 2004 11:54 AM
To: Protel Developers Forum
Subject: Re: [PDEV] Situs Router questions

Brooks,Bill wrote:
> I'm very interested in finding out more about the algorithms used in 
> the Situs router...

Same here, not much info on Altiums implementation thou, bit S.O.B. here:

> where did they come from and who developed them? Could someone post 
> some detailed info on the subject?

There is quite a lot of info about rubber-band/topological routing in
general, hanging around the net. For example:

Use CiteSeer (Google of Scientific material, for more. I'm quite interested in theory
of autorouting and it's algorithms myself. Have quite a pile of stuff
collected to 'Will take a look at one day when I have loads of free
time' folder ;)


  Indrek Rebane           |      Borthwick-Pignon
  Electronics Engineer    |    Tartu Science Park
  Phone: (+372) 7 302 641 | Riia 185, 51014 Tartu
  Fax:   (+372) 7 383 041 |               Estonia
  [EMAIL PROTECTED]        |

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