5.0 Analysis Tutorial - TERMINATORS & WAVEFORMS:
The tutorial is now calculating data for 4 ECL nets.
The driver and
receiver waveforms are displayed as processed. (Triggered by
the param setup check under "Use waveform files".)
You are done the bulk analyzing when the tutorial message "Ready to scroll
through the help instructions" appears.  This will only happen
when the message "connection 1 of 4 is displayed in the SNA execution window. 
(After the messages "Analyzing xxxxx ... SHIFTIN12".
If you hit the L1 key during analysis it will
halt analysis prematurely AFTER it has complete the current
net being analyzed.)

 ****************************************************
 Use Next and Prev to step through these 4 nets
 ****************************************************

Note that the first net INDATA shows an unusual Noise immunity of nearly 3500mV
and shows the driver model as VALID_DEFAULT while the Receiver Model
is an appropriate ECL technology , i.e MOTOROLA_10K.  VALID_DEFAULT
always indicates a problem where a more appropriate model was not
matched up. In this case the J3 connector was not recognized as any
particular technology.  VALID_DEFAULT defines a 0 t0 5volt driver
feeding a Motorolla_10K receiver device which expects a completely
different -2 to 0 volt swing  You can optionally edit to the elecmodel.dat 
file to fix this mismatch by forcing elecmodel.dat 
to use all MOTOROLLA_10K models.
 

 ***** OPTIONAL ******************************************
 Type the command "shell" to bring up a new window and edit 
 the file elecmodel.dat  Change the 3rd line from:
     DEVMATCH=10H*
 to
    DEVMATCH=*
 Save this revised elecmodel.dat, then analyze_again INDATA.
 ***** OPTIONAL ******************************************


(For more selective control of model usage, VOLT_TEMP_MODEL properties
can be added to the device library or to individual pin instances but this is beyond
the scope of this tutorial.)

ECL nets must be properly terminated to avoid unacceptable noise from 
reflections.  The value of the termination
resistor should roughly match the nets cline impedance.  If the wrong
value resistor is connected or if no termination resistor connection
has been made an excessive reflection will occur.  Reflections are the
cause of large overshoot, and undershoot, and can also cause timing
violations such as excessive "Final Settle Delays".

SNA relies on correct modeling of termination resistors in their device library
definitions.  They must have "VALUE" and "TERMINATOR_PACK" properties
on their library device definitions.  Value properties on GED resistor
instances are NOT recognized by ALLEGRO.  (Value on instances is too
vague a property, Allegro requires the unambiguous library entries).

F1 has been setup to run a script to show what happens to an ecl net
if the termination is missing.  What it does is delete the cline segments
attaching the terminator to the net.

 *************************************************
 Press <F1> to disconnect the SHIFTIN10 terminator 
 *************************************************

Note that without the proper termination the overshoot, undershoot and 
settle times are all now huge.

                    Before  After(Deleting termination)
                    ------  ------
 Overshoot          ~80mV   ~725mV
 Undershoot         ~12mV   ~500mV
 Settle Delay         0.5ns   3.5ns

The script just run, also saves the waveforms before
disconnection of the terminator under the name oldU3-4.sim

You can superimpose the old waves with the etchwave display of the
current waveforms.  

 *************************************************************
 Place the cursor in the etchwave window then type:
   use oldU3-4.sim
   display U3-4
   display U16-12
 *************************************************************

Note that a "-" is used where you might normally have a "."
in a refdes.pin style of name passed to etchwave. This etchwave window
is actually a separate window tool which you can bring up independent
of the Allegro_editor to view .sim waveform files.  It may be moved and
resized using standard window tools.  Unlike the Allegro subwindows it may
be positioned anywhere on your screen and is not
tied up when allegro is processing some command.

 ** OPTIONAL *****************************************************
 You might use the Edit->Vertex command to reattach the terminator
 and restore the cleaner waveform.  (Window in, 
 and be prepared to use the middle botton pulldown "reject" if you
 pick the wrong cline vertex
 ** Optional ******************************************************

 ***********************************************************
 Hold down the right button over the top edge of the etchwave
 window to "CLOSE" it to an icon. Use a left button pick to
 open the icon. Instead of "CLOSE" try a "RESIZE->FULLSCREEN"
 Select the etchwave [EXIT] menu option to end its display
 ***********************************************************

 *******************************************
 Press <F1> to continue to next frame ...
 *******************************************

