MICROELECTRONIC SYSTEMS NEWS
FILENUMBER: 9802
BEGIN_KEYWORDS
LOGIC SIMULATOR
END_KEYWORDS
DATE: January 1998
TITLE: Free Logic Simulator
Announcing Yalsim: Yet Another Logic Simulator
I would like to announce the availability (currently for free) of
a switch/gate/circuit timing logic simulator that is now available. I have
used Yalsim very effectively for simulating mixed-mode systems at a
difference-equation level (for the analog stuff) and at a timing/gate
level for the digital stuff.
Yalsim is a hierarchical timing logic simulator that has been in
development (on and off) for over fifteen years, and the first pre-beta version
is now being sampled. Yalsim can now be obtained (with source code) by
individuals from:
ftp:/ftp.eecg.toronto.edu/pub/software/martin/linux_logsim.tar.gz
or
ftp:/ftp.eecg.toronto.edu/pub/software/martin/sun_logsim.tar.gz
The only difference between the two is the Linux version useds flex and
-lfl as opposed to lex and -ll.
It can also be ftp'd by
>ftp ftp.eecg.toronto.edu
Login as anonymous, and give your id and then
ftp>bin
ftp>cd pub/software/martin
ftp>mget linux_logsim.tar.gz
After getting the file, do the usual
zcat linux_logsim.tar.gz | tar xf -
It will unwarp into a single directory. Do a
>cd linux_logsim
>MAKE
and you should be on your way.
The MAKE file is juvenile (I haven't had time and the interest to figure
out how to do proper distribution files), but Yalsim has been compiled on
many different machines, using many different compilers, so that most
moderately-capable hackers should have minimal difficulties fixing problems.
Yalsim was originally started on a PDP-44 running Unix Version 7 (that the
author was maintaining at that time).
The current cost for Yalsim is $1 CDN, when you have time to send it.
Sending four U.S. quarters is also acceptable. This may change in the future.
However, seriously, please do read the LICENSE file. Yalsim is not public domain
or being released under a GNU-like license, although individuals, at non-profit
institutions, will always be able to obtain at least binary versions of Yalsim
at no cost.
Now some of the details regarding Yalsim:
To try and pick up interest:
Yalsim comes, with what I believe, is the only free simulation of a
direct digital frequency synthesizer, as an example. It also has an example
of a bit-level simulation of a second-order digital filter. Both simulations
include timing. In addtion, Yalsim has an example of modelling a phase-locked-
loop with the phase/frequency comparator being modelled at the gate-level
including timing. As far a I know, this ups the ante on what is available for
free wrt logic/timing simulators.
Yalsim is a fast, hierarchical, logic timing simulator. It is easily
extended using the user-supplied circuit feature. It has its own
hardware-description-language which is non standard. This may be one of its
best and worst features. The parser for the language is very robust (I haven't
had to touch it in years) and could possibly be modified to support other
standard languages.
The user interface is felt to be useable, but a major limitation. It
does allow Yalsim to be run on fast computers over slow modems, a feature that
modern window-based interfaces do not have. This is not a justification, just a
consolation. This is the major area where future work is needed. If interest
warrants, I am contemplating putting a Tcl.Tk wrapper on Yalsim with perhaps
Expectk, but in order to do this, I need some positive feedback, as it's getting
harder to justify hobbies with other pressing issues (a new son - Jeremy
Llewellyn Cosson-Martin).
Documentation for Yalsim is in the ./doc file in postscript form. You need
at least Chapters 1 & 2 to even try out Yalsim. There is no man file yet.
The startup source code is near the beginning of read.c in ~yalsim/anal.
This code needs cleaning as well, but does work.
Since source code is being made available, serious hackers, with the manual,
should be able to figure out how to use Yalsim. The 70-page manual is just
finished, far from perfect, but useable as a start.
What happens in the future with Yalsim is uncertain, but I haven't given
up on it yet for 15 years, and it is only now I can make it available, so who
knows. Cheers.
-Ken Martin
(Primarily an analog IC designer who enjoys some hacking).
Ken Martin: 416 978-0503, Fax: 416 535-5515,
Dept. of ECE, Univ. of Toronto, 10 King's College Rd., Toronto, ON M5S 3G4
=================================================================
dbouldin@utk.edu
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