Software
I have written some programs to help me in my work, including programs for schematic capture, event-driven simulation, waveform plotting, and interactive 3D rendering. Some screen-shots and descriptions are given below.
Schematic Capture
This schematic capture program (NewDraw) was a clone of the program ViewDraw
by ViewLogic. We were using ViewDraw at Synaptics and at Arithmos
in the early 1990's, and I wanted to have a program I could use at
home that would be customizable and compatible with ViewDraw,
without requiring a
dongle. Plus, I wanted to understand how to write a big interactive
object-oriented Windows program with memory allocation for arbitrary
databases. Once I got it far enough, I began to think about
new features that would improve upon ViewDraw (parameterized busses and
arrays, parameter passing through hierarchy), and actually wrote
a business plan to carry the work further. Fortunately, the business
planning process indicated that it was a stinky little business
with a shrinking customer base, not worth going into, and I turned to more profitable and interesting
projects.
Waveform Plotting
Also at Arithmos, we were using HSpice to simulate our analog circuits.
I was unsatisfied with the waveform viewers available at the time, and
again decided to write my own, a little program called Plot.
I actually used this program on the job for about a year.
These screen-shots look simple but the program was capable of
displaying real industrial-strength simulation outputs.
Event-Driven Simulation of Spiking Neurons
At Caltech, I developed a fast event-driven simulator,
called
Spike,
for simulating large networks of simple spiking neurons.
I have been supporting this software via the Internet since 1992.
You can enter your neural circuit graphically or textually, and
view the simulation output logic-analyzer-style, as shown below.
The above circuit is an Adapting Tonic Burster. That is, it has
bursting response based on a tonic input current, and it has an
inhibitory feedback path that causes its firing rate during a burst
to decrease, or adapt. The circuit demonstrates the use of the
summating synapse feature of Spike, which in this case is used to
model a calcium-dependent potassium channel, to create the adapting
behavior.
The above circuit is a locust walking circuit developed by Sylvie Ryckebusch in 1991. This was the first use of Spike to model a real biological circuit.