COMPUTERS IN THE CHEMICAL WORLD
- PAST, PRESENT, AND FUTURE
Seven years have elapsed since the American of computers has been, it has lagged far behind the Chemical Society has given full attention [IND.ENGL use in other technological areas. One factor recomputers sponsible is the more d s c u l t mathematical formuCHEM.43, 2441-86 (1952)] to the role ginaering. lation of some fundamental processes, coupled with are playing in chemistry and chemic The purpose of the symposium publi n the fol- considerable uncertainty regarding fundamental lowing pages is to summarize the gains of the inter- data. Another factor is the lack of familiarity which vening years, to take a good look at where we stand still remains concerning the extraordinary ability of today and, most important, to extrap e recent these machines to solve the most complex problems omputer encountered in practice. growth in an effort to grasp the scope domination in the chemical world of tomorrow. The papers that follow cover four main topics: a In 1951, the only computers (by current definition) historical review, a descripton of modern installations, were installed in a handful of government and univer- a series typifying the best work being done on large sity laboratories. Today, there are over 250 large- machines today, and some prognostications of future scale computers, as well as nearly 2000 small and in- developments. termediate machines. Many of the major colleges ASCHER OPLERl and universities are making good use of computers. The Dow Chemical Co. Most of the larger chemical companies have at least New York, N. Y. one computer. Rapid as the development of chemical applications 1 Present address, Computer Usage CO.,Inc., New York, N. Y.
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JACK SHERMAN The Texas Co., Beacon, N. Y.
Development of Digital Computer Applications
PRIOR
to the introduction of the calculating punch in connection with punched card accounting, the only digital computing machines generally available to industry were desk calculators. These machines have virtually no capacity to store intermediate answers needed for subsequent computations within the same problem. The operator wrote down each result and later manually introduced it into the machine as required. The time needed to do the arithmetic was invariably the limiting factor in determining the practicability of any given data-processing problem. Consequently, results of computation were frequently much less reliable than the state of chemical knowledge requiredsimplifying assumptions had to be made in the theory to limit the amount of computation. For example, in the design of a distillation column, it was common practice to assume that the vapor-liquid equilibrium for each component is given by y, = &xi, in which K, the equilibrium constant, depends
upon the temperature, the particular component, and the particular mixture involved. In using desk calculators, every possible aid is employed in reducing the amount of arithmetic to be done-for example, charts, graphs, and tables, in which the entries occur at sufficiently small intervals to permit linear interpolation. However, this additional burden on the machine operator increases the probability of error in the final results, so that it is common practice to repeat part or all of the manual steps to check the final results, thus furcreasing the time required. ny chemical computations are of the trial and error type, such that a number of possible alternatives should be evaluated. When the computation time for each situation is long, the number of alternatives must be restricted. Thus, the advantages of utilizing a large capacity, high speed digital computing machine were realized before such machines were generally available.
Development of Digital Machines Reprints of this group of articles may be purchased at $1.00 for single copies or for $0.75, in lots of ten or more. Address Special Issue Sales Department, American Chemical Society, 1155 16th St., N.W., Washington 6, D. C.
During the late 1940’s, the first uses of punched card accounting machines for scientific computations required panel board wiring to define the sequence of computational steps. Because each application has its own set of arithmetic steps, it was necessary to wire a large
number of boards to perform a variety of computations. Thus, although these early punched card methods eliminated the necessity of writing intermediate results on paper, the time required to wire panel boards and the card handling necessary for most problems was still too great to permit high computation speeds. Nevertheless, punched card accounting machines were of real help in technical computations. Applications in the chemical field during this period included infrared and mass spectrometer analyses, distillation column design, chemical equilibria calculations of manycomponent systems, and crystal structure calculations. The electromechanical punched card machines used for such standardized accounting tasks as payroll are relatively efficient because many parallel operations can be carried out. I t is not necessary to process each employee’s payroll operations from beginning to end before the next employee is considered. However, in technical problems, sequential operation is usually necessary, and the sequence ofcomputational steps cannot be specified at the outset, as the course of the computation depends upon intermediate results. Consequently, it was realized quite early that if computation speed for technical problems was to be increased significantly intermediate card handling must be minimized, and the computer must
