At 06:35 AM 10/23/01 -0400, [EMAIL PROTECTED] wrote:
>By placing vias with P-V, you're actually placing double vias. The manual
>routing will automatically place vias as you change layers. If you press the
>End key right after it removes those vias, to force a redraw, I think you'll
>find that there are still vias there.

I was writing about vias removed -- or apparently removed -- when routing 
over a trace that includes a via. I *think* I've seen such vias disappear. 
But it is certainly worth checking it out by redrawing the screen. Loop 
removal often leaves screen artifacts, and disappearing vias could be part 
of that.

Loop removal is, I think, slightly buggy in a reasonably harmless way. 
Sometimes it leaves extra track, sometimes it rips it up; it may have to do 
with track endpoints not being coincident, I haven't figured it all out. I 
just know that, even with the minor bugs, loop removal is one of the 
greatest tools to come along in years. I would seriously miss it if it were 

As a note for Protel newcomers and the occasional old-timer who has 
overlooked loop removal, it's easy to misunderstand what loop removal is 
and why one should normally leave it on. Its purpose is not to eliminate 
ground loops and the like. Rather it simply allows rerouting a track 
without deleting any of it. When a new track duplicates an existing 
connection, loop removal will rip up the previous routing of that 
connection. It saves a *lot* of time. And if you really need to route a 
loop, you just turn it off while you are routing the loop and then turn it 
back on when you are done. It does not remove all loops on the board, just 
one newly created!

(Loop removal is an option on the Tools/Preferences page. Together with 
"avoid obstacle" and the snap indicators (those circles that appear when 
snap is active) it makes Protel manual routing shine, I can route fine 
pitch traces when I can barely see them, saving a lot of zooming in and out.

Avoid obstacle only helps in routing traces at minimum separation when one 
can bang the new trace up against the virtual obstacle created by the 
clearance rule. In the other direction, when one wants to pull back a trace 
to minimum clearance, I resort to moving the trace back and forth, watching 
for its extension to appear when the rules are satisfied by the current 
proposed track, or disappear when the trace (that would be placed if avoid 
obstacle were turned off) violates the clearance rule. This takes much more 
time and is more difficult to do at low zoom levels than routing in the 
other direction.

Having a command, perhaps a key to press, to pull a pending track back to 
minimum clearance, would be great, as would the "complete connection" 
command that has elsewhere been selected. This command simply reduces a 
connection (rat's nest) line to track. Tango DOS PCB had it, it saved a lot 
of time when the completion of a connection requires moving off-screen, 
plus a little time on the last segment of every track, since one could 
routinely hit the slash key (Tango's implementation of this) while routing 
when one wanted the remaining track to go from the currently placed end to 
the other end of the rat's nest. That is much faster than requiring that 
the cursor actually be placed at the other end and clicked, *plus* one 
could easily make the last segment be off-angle, which itself saves, at 
least, track segments and work, plus if one *wants* the last segment to be 
off-angle, the only way to do it now requires several steps.
Abdulrahman Lomax
Easthampton, Massachusetts USA

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