Computers in Chemistry

Computers have brought about a greater change in our society than any other force
since the industrial revolution. The first electronic digital computer ENIAC
(Electronic Numerical Integrator and Computer) was built in 1946 using
electromechanical relay technology. Although in the 1950s these relays were
superceeded by vacuum tubes, computers still remained massive in size and so
expensive that only large institutions could afford them. They had to be operated
by specially trained personnel and were employed exclusively on arithmetical
calculations and it was from such usage that the term number crunching arose. An
important stage in the evolution of the computer was the invention of the transistor
in 1948 by the Americans Bardeen, Brattain and Shockley at the Bell Telephone
Laboratories in the USA for which they were awarded the Nobel Prize in physics.
The first transistors were made from germanium but were subject to thermal runaway
(current flow generates heat which increases current flow thus generating more heat
...) and so were quickly replaced by ones made from silicon. It was also at the
Bell laboratories where the first transistorised digital computer TRADIC was built
in 1954. This new technology resulted in more reliable and faster machines but it
did not reduce their cost. It was not until around 1964 and the advent of the
integrated circuit that the cost of computers came into a range affordable by
industry, commerce and universities. Although the integrated circuit which
contained several transistors and a few other components etched onto a single piece
of silicon was relatively cheap, the memory devices were still expensive. The late
sixties witnessed the birth of medium scale integration and later large scale
integration. The former are devices that have a few hundred circuits etched onto
a single piece of silicon whilst the latter have a few thousand. It was this
high-density packaging which resulted in cheap memory devices...