ACS 0.29 release notes  (06/30/2001)

The primary effort has been to implement IBIS, which is still not
done.  The changes here are mostly infrastructure changes needed to
support IBIS.


New features:

1. "Fit" function has choice of fit order and extrapolation.  You can
have order 0, 1, 2, or 3.

2. "Posy" has even and odd options, to determine what happens in the
negative region.

3. Modelgen improvements.  It now is useful for the whole device,
sometimes.  It now handles probes and the device side of the model.
The diode uses it completely.  There are still a few missing features
needed for the MOSFET and BJT.

4. Spice-3 compatible semiconductor resistor and capacitor.

5. "Table" model statement.


Improvements, bug fixes, etc.

1. Option "numdgt" really works.

2. Better error messages from modelgen.

3. Code changes for optimization of commons.  This should reduce
memory use, sometimes, by sharing commons.  Common sharing is still
not fully implemented.

4. Fix two bugs that sometimes caused problems after a "modify" or on
a "fault".

5. Better handling of "vmin" and "vmax".  It should be much less
likely that limiting causes convergence to a nonsense result.


Some things that are still partially implemented:

1. Internal element: non-quasi-static poly-capacitor.

2. BSIM models, charge effects, "alpha0" parameter.  (computed then ignored)


Bugs (nothing new, but needs repeating):

1. The transmission line initial conditions are not propagated until
the transient analysis runs.

2. The makefile does not set up the proper link for the model
compiler.  You need to do it manually.

3. On some systems, you will get a warning from the linker that "the
use of 'tmpnam' is dangerous".  You can ignore this warning.


Hot items for a future release (no promises, but highly probable):

1. Charge effects and substrate current (alpha0) in BSIM models.  They
are computed, but not loaded to the matrix.

2. Completion of model compiler, and its documentation.

3. Completion of multi-rate.

4. Homotopy methods to improve convergence.

5. Transmission line accuracy and speed improvements, using a step
control mechanism similar to that used for capacitors.

6. Parameterized subcircuits and defined parameters.

7. A "trigger" element, so time dependent values can be triggered by
the circuit, as an alternate to simple time.

8. IBIS support.

9. Spice-3 compatible "B" device.


To reach me, try this email address:
	aldavis@ieee.org

ACS ftp sites:
	ftp://ftp.geda.seul.org/pub/geda/dist/acs-0.29.tar.gz
	http://www.geda.seul.org/dist/acs-0.29.tar.gz
	ftp://sunsite.unc.edu/pub/Linux/apps/circuits/acs-0.29.tar.gz