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Signals & Noise: April 25, 1996


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Timing-diagram editors offer asynchronous solutions

"To be or not to be asynchronous; that is the question" by #Clive "Max" Maxfield (EDN, Dec 7, 1995, pg 157) mentions digital simulators and dynamic timing-analysis tools as being appropriate only for asynchronous design. However, an important class of tools, called "timing-diagram editors," offers a cost-effective alternative for asynchronous design. Timing-diagram editors let the user draw waveforms and set up delays with uncertainty regions between the signal transitions, thus allowing the designer to simultaneously verify minimum/maximum timing.

With a timing diagram, you can easily see the critical paths in an asynchronous design, because the delays show the causal relationships between the signal transistors. This feature explains why designers, even those with access to powerful digital simulators, still hand-draw timing diagrams. Designers can use the WaveFormer from SynaptiCad and dV/dt from Engineerium as timing-diagram editors to design asynchronous circuits. These tools sell for less than $1000 and offer capabilities lacking in more expensive digital simulators.

Dan Notestein
SynaptiCad
Blacksburg, VA


Kickbacks in theEDA industry? The NT cheerleading article, "Windows-based EDA tools: shifting into high gear" (EDN, Feb 1, 1996, pg 42), makes me wonder if you have the Microsoft ministry of propaganda working behind the scenes. A quick scan of the Advertisers Index does not show any paid advertising from Microsoft. Could it be that the money passes under the table, or do EDA industry pundits get two paychecks for their articles?
Tim Miller
e-mail: tim@glenatl.glenayre.com

(Technical Editor Jim Lipman responds: The article reflects an EDA-industry trend toward Windows-based tools for certain tasks. The article does not endorse any particular tool or operating system but provides timely information for the readers. MicrosoftÕs release of and promotion for Windows 95 did not influence my decision to do the story; the number of chip and pc-board designers looking into Windows-based design tools did.

Remembering John Gallant

In 1978, I met John Gallant when he and I worked at ESL in Sunnyvale, CA. At that time, my interest in jazz was beginning, and John recommended my first jazz album, "Oscar Peterson in Russia" (Pablo records). A group of us, with John as the leader, would go to the "Bach Dancing and Dynamite Society" in Half Moon Bay to listen to live jazz.

On his desk, John had a picture of himself surrounded by snowdrifts in Massachusetts. He said with a smile that the picture was there to remind him why he was in California. There were other reasons that he was in California, of course. A graphic presentation on the effects on humans that the weapons his employer designed and manufactured led John to realize that he could not, in good conscience, participate any longer.

Your editorial delighted and saddened me. I am delighted that John contributed so much to others, and I am sad that he is gone. The photo you ran wonderfully captured his spirit: a gentle, happy man.

Au revoir, John; be at peace.

Brian Gross
via e-mail: briang@sdingo.sr.hp.com

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