Symposium Number Four on Technical Library Techniques PUNCHED-CARD TECHNIQUES AND THEIR APPLICATIONS TO SCIENTIFIC PROBLEMS' W. J. ECKERT International Business Machines Corporation, New York City
D ~ WtheGpast decade or so the punched card has come into general use for the handling of all k i d s of scientific data. In a score of laboratories throughout the country great masses of data are being handled automatically; included are those of astronomy, ballistics, chemistry, engineering, meteorology, navigation, and physics. The purpose of this paper is to describe the punched card machmes which are most useful in science and to outline in nontechnical terms some of the principal scientific projects which have been executed in various fields of science. From this broad general picture it is hoped the chemist will see the possibilities for his own specialty. The great effectiveness of the electric punched card method is that once the initial data have been recorded as holes in the cards, the machines will automatically read these holes and perform a wide variety of operations, such as rearranging the cards in any required sequence, transferring data from one card to another, printing the information on the cards or on a sheet of .paper, consulting tables of tabular data, and perforning the arithmetical operations of addition, subtraction, multiplication, and division. Electrical impulses through the holes in the cards are used not only to read the data on the cards but to control the operations of the machines. Pluggable connections permit the operator to direct these impulses almost a t will. The standard tabulating card is 3 114 X 7 3/8 inches and stacks 150 cards to the inch. It has 80 vertical
columns with 12 punching positions in each column. Of these, tenare indicated by the printed digits 0 to 9 which correspond to the digits of the numerical data to be punched. The 11th and 12th punching positions a t the top of the card are commonly referred to as the "x" and "y" positions. The "xu punch is usually used to control the operation of the various machines; for example, negative numbers are differentiated from positive ones by means of the "x" punch. A digit is indicated by a single hole in a column and a letter of the alphabet by two holes in one column, the "x," "y," or "0" being combined with one of the digits. While the above method of punching information on the cards is the conventional one and the one which the machmes handle automatically, various codes may be used for special problem^.^ The selection of a code depends not only on what information is to be recorded on the card but upon how it is to be taken out. As far as recording alone is concerned, it is obviously possible to record in a single column as many as 4096 combinations of the 12 available holes. The practical use, however, of all these combinations is quite another matter, even for sorting. One corner of the card is clipped to facilitate orient,ation and the face of the card is printed to assist in occasional reading by eye of the data punched on the card. Special printing may be used for individual projects if manual handling of the cards plays an important part in the problem. While special calulating equipment has been built for ' Presented before the Division of Chemicd Education a t the some purposes, the great bulk of the work now being 110th meeting of the American Chemical Soclety m Chlcago, September 9-13, 1946. done throughout the country is performed on standard , course, have the adcommercialmachmes. ~ h e s e of vantages of ready availability, systematic service, and "Y"-' 0 1 2 3 4 5 6 7 8 8 ,... A m , , , , ,, , , , ! ! 1, , s S T " emerienced oaerators. The followine machines are in thiscategory: The Key Punch is used to record the initial data on the cards, The punching is done manually in one cold r2
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Figure 1. Tabulating card showing 12 punching positions and combinations of punches to indicate letters
1 "The Preparation and Use of Codes, IBM Machine Methods of Accounting."
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FEBRUARY, 1947
have 14 keys, twelve for the punching and one each for column space and card eject; the alphabetical punches have, in addition, a typewriter keyboard. There are several types of key punches and the proper selection depends upon the particular type of work. The Verifier may be used to check the work of the key punch, although other methods involving proofreading and automatic comparing are frequentlyemployed. The Sorter is used to rearrange the cards in any desired order according to the data punched on the cards. It feeds cards from a hopper and sorts each card into one of 13 pockets, according to the hole read in a selected column of the card. The 13 pockets-correspond to the 12 punchmg positions and one for blank columns. By successive sortings the cards may be arranged in any desired order. The machine senses the first hole encountered in the passage of the card; if two or more holes are punched in a column, provision is made for the selection of the hole to be read. The Collator is a more elaborat,e sorting device. It sorts cards from two hoppers into four pockets according to data punched in several columns. The machine is very flexible and permits the handling of the cards according to a complicated pattern involving the comparison of two sets of data for high-low-equal. For example, two packs of cards, each in numerical order, can he merged into a single pack, in numerical order, with one run through the machine. It will test a pack of cards to determine whether they are in numerical se-
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quence according to the data in a selected group of columns (as many as 32 columns at a time). The Accounting Machine is a large-scale printing and adding machime which reads data from cards, adds and subtracts them, and prints on a sheet of paper data from individual cards or from the accumulated totals in the counters. The machine will add or subtract as many as 80 digits at a time and print as many as 88. Alphabetic as well as numerical data may be listed. The Interpreter reads the holes in a card and prints the information in type on the same card. Interpreted cards may be used in the conventional manner as file cards as well asin the machines. The Reprodun'ng Punch reads data from cards and punches them on other cards. This device is useful in preparing duplicate decks of cards, in rearranging data on the cards, and in copying data from "table" cards on to the work cards. It has a comparing unit which will compare two sets of data and detect any disagreement. The reproducing punch may be adapted for use as a Summary Punch to record on a new card data accumulated in the counters of the accounting machine. The Calculating Punch reads numbers from one or more cards, multiplies, divides, adds,, and subtracts them, and records the result on the card. It has provision for performing elaborate sequences of operations. The Multiplying Punch performs many of the functions of the calculating punch. It does not divide and has less sequencing facilities.
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JOURNAL OF CHEMICAL EIWCATION
The Electronic Multiplier is a high-speed multiplying machine which operates by means of electronic circuits. It forms and records 100 products per minute (the multiplication itself is actually performed in 17-thousandths of a second between the reading and punching of the card). These individual machines have specialized functions but, since they read and write by means of punched holes, they may be used in combmation to handle almost any kmd of data. The unit construction permits the elimination of machines not required for a given type of work and the duplication of critical machines to furnish a balanced installation. A simple example of the use of these machines is that of consulting tables of tabular functions. Suppose, for example, during the course of a calculation 20,000 cards are derived, each of which contains the value of an angle between 0" and 90°, and it is required to find the value of the sine of the angle. The first step would be to prepare a punched-card sine table (unless such a table were already available). The first card of the table would contain the argument 0°, the sine of 0°, and if interpolation is necessary, the difference between sin OD and sin lo. The second card would contain the corresponding data for lo,and so on through the 90 cards. The first step in consulting the table is to put the two sets of cards in numerical order according to the angle and to merge the two setsso the final order will be, 1. 2. 3. 4. 5.
Table card for argument 0" Work cards with angles between 0' and lo Table card 1" Work cards with angles between loand 2" Etc.
The sorting and merging can be done entirely by the sorter or, if the collator is available, the merging of decks already in order can he done with one operation. The next step is to transfer the data from each table card to the work cards following it, This is performed automatically by the reproducing punch; an "x" punch on the table card instructs the machine to transfer data from table card to the following work cards but not from work cards to the following table card. Separation of the two sets now gives a set of work cards each of which has on it the required value of the sine together with data for interpolation if that is necessary. The entire process of "looking up" 20,000 sines has required three or four hours. The interpolation, if required, is performed with one run on the calculating punch (or the multiplying punch). This operation of consulting mathematical tables on punched cards is so efficient that methods of handling scientific data must be considered with this in mind. It must be remembered that as many as 80 columns of data for a single argument can be carried on a card and the cards rearranged a t the rate of 20,000 per hour and data transferred from one card to another a t the rate of 6000 cards per hour. Thus millions of figures can be "looked up" in a day with an accuraoyxever before
attainable. Card files of tabular data may be easily reproduced for use in another l a b o r a t ~ r y . ~ The accounting machine permits addition and subtraction a t an equally impressive rate. These operations are performed simultaneously in from one to 16 independent counter groups a t the rate of 9000 cards per hour. Here again millions of figures are added per day under elaborate automatic control of the cards and the pluggable control panel. This efficient means of addition is particularly useful in statistical operations, of correlation coefficients on a such as the ~omput~ation large scale. Data from the cards are listed on a sheet of paper a t the rate of 80 lines per minute. Thus when data have been punched on cards they may he printed in several different arrangements with great efficiency. These lists may be reproduced by means of mimeograph or photo-offset and, except where the style of printing is very important, they offer a very economical method of disseminating data. The following is a brief description ~f a number of laboratories now using these methods and the general type of problems handled. The Columbia University Statistical Bureau, organized in 1928, uses standard and special punchedcard equipment for statistical calculations, such as the computation of correlations, interpolation, table making, and problems of scoring objective type tests. About the same time in England, Comrie used punched
