Path: utzoo!attcan!uunet!wuarchive!udel!princeton!siemens!demon.siemens.com
From: pjd@demon.siemens.com (dr. funk)
Newsgroups: comp.lsi.cad
Subject: IRSIM and T-gates
Message-ID: <44007@siemens.siemens.com>
Date: 5 Nov 90 15:42:26 GMT
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Organization: siemens corporate research inc
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Greetings! We are just getting started with the latest release
of irsim -- the one currently being distributed with Magic. We
noticed that occasionally irsim will produce an X value in
combinational logic that checks-out OK at the subsystem level.
(That is, A, B and C are functionally correct, but A+B+C will
produce some X's.) Yes, we have checked our connections --
several times :-)

The problem appears to be related to the treatment of transmission
gates in a multiplexer circuit. When we insert the functional
equivalent of the MUX using the classic AND-OR gate form, our
undefines go away. Two questions for the audience:

  1. Does irsim have known problems with T-gates?
  2. Are there rules (work-arounds) for irsim T-gates?

Thanks, as they say, in advance.

paul drongowski
pjd@demon.siemens.com

--
paul j. drongowski
siemens corporate research inc
pjd@demon.siemens.com