2 - Forth Interest Group

A Forth Story
Allen Cekorich
Walnut Creek, California
In 1975, I was fresh out of college with a bachelors
degree in physics and a need to find a job that paid enough
to support myself. After a six-month search, I landed an
entry-level position at MDH Industries in Monrovia, Cali-
fornia, where they promised to increase my minimum
wage starting salary once I proved myself useful. I was to
work with the president and owner, Dr. Howard Marshall,
Ph.D., on a project to develop an instrument to measure
the real-time sulfur content of a coal stream by detecting
and analyzing the prompt gamma ray spectrum resulting
from the absorption of thermal neutrons from a Cali-
fornium 252 radioactive source. The opportunity sounded
exciting to my naive ears, as it was my first professional
job. I was finally in the real work world of adults and ready
to go on to do great things. Remember, this was twenty
years ago and I was only twenty-two years old. I had no
previous experience to guide me in the situation I was in,
no mentor to teach me, no helping hand and no idea of
where to begin or what to do. Like most good engineers,
I decided to fake it until I understood my value.
- progress toward a controller began.
-
I was preoccupied with designing the sulfur meter
I I him the device / based on my Fortran simulation. but the natural need to
I not - be - - ~roarammed in Forth
I-
I
--
Why would I say such a thing?
It came to pass by the natural events of the develop-
ment process that construction of a sulfur meter prototype
was to take place. Howard Marshall had earned his
doctorate in physics from the California Institute of Tech-
nology, which is very much in bed with the Jet Propulsion
Laboratory in Pasadena. His contacts encouraged a com-
puter-based instrument and recommended a strange lan-
guage called Forth that was floating around the lab. They
convinced him it was possible to build a small, Z80-based
controller that could acquire the spectrum from the
sodium iodide detector and maintain real-time signal-
processing rates to compute the actual sulfur content.
Somehow, outside my area of responsibility, an S100-bus
system showed up from the Empirical Research Group. My
electrical engineer office mate had been assigned the task
of fooling around with it for development purposes, but
no progress seemed to ever be at hand. After some time
had passed, a fellow named Martin Smith showed up from
the Cal Tech network. He brought with him a Forth
running on a Monolithic 280-based multibus system, and
verify the model from real data taken from the prototype
was growing important. With the help of Marty, I started
playing with the Forth computer. This was the first time in
my life that I had actual, physical contact with a computer.
I spent the first Year or So understanding the design
parameters of a Sulfur meter, which involved creating a
computer model on a T~mshare IBM 370 System accessed
with a teletype terminal at the fantastic rate of 30 characters
Per second. This was a revolution from the punch
cards I had used in college on a CDC 3150 that could be
viewed through a glass window in the foyer of the
computer department. MY degree in physics mandated
that the modeling language would be Fortran, and I
naturally enjoyed programming, which was probably
related to my ability and love for mathematics. I had
completed the coursework for a degree in mathematics
with a 4.0 average in college. I was proud of the growing
complexity and depth of my simulation, which was now
consuming hours of computer time during the night hours
when the cost was lowest.
Those big, eight-inch Shugart floppy drives that held a
whopping 120K bytes, and the awesome 6 4 of ~ fast RAM,
along with the character-based video display terminal,
intoxicated me. ~~t what was more puzzling was this
strange way of talking to the computer, called Forth. I had
taken a computer language survey class in college which
included Fortran, Algol, PWM, Cobol, Trac, Lisp, and APL,
but had never heard of anything called Forth. It was
strange and unnatural without programstatements. I could
not find the compiler, linker, or listing output. I could not
figure out how it worked, but I realized that I now had direct
contact with the CPU without the need to learn complex
system manuals. I finally had a computer under my control
and I went to town. Over the next few years, I had a good
time writing programs on that small Forth system to do data
Forth Dimensions 11 July 1995 August