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Sep 1 1962

Current status of IPL-V for the Philco 2000 computer (June 1962)

The initial version of IPL-V for the Philco 2000 has been completed and is now operating on the computer. This model, IPLT-1, contains the loader, interpreter, output, housekeeping functions, and some of the primitives of the 7090 version. This system was written mainly in JOVIAL, a procedure-oriented language, and was compiled to produce a Philco TAC binary operating deck. Certain portions were written in Philco TAC language to speed up the operation of the system during execution and to facilitate handling of primitives which in JOVIAL would have been uneconomical. These assembly-language coded sections constitute less than 3 percent of the system. The present model assembles IPL program cards at the rate of 500 per minute in the listing mode. This compares favorably with the 7090 model, since System Development Corporation's configuration of the Philco computer operates at approximately one-fifth the speed of the 7090. Interpretation time also compares favorably with the 7090 model taking into account the difference in speeds of the two computers. The package of J primitives produced by H. A. Simon is being used and assembled with the IPL program. With listing suppressed, assembly time of these routines is only a few seconds. Input to the Philco 2000 is by card, and the system operates as a program executed in phase three of the SL Philco operating system. The J165, J166 dump and reload features are working, and this technique can be used to save an assembled IPL program on tape for later use. Unused region assignments are not returned to available space; therefore additional routines may be added with new data for reload and run from a dump tape. However, card input is extremely fast (2000 cards per minute) and normal operating procedure at SDC is card input.
Aug 1 1962

Analysis of a file addressing method

This paper presents a new file addressing method based on the calculation of an address from the identification of a record. For large recirculating type files, it seems to be more advantageous than customary ones. The probability distribution of the displacement of records from their calculated address, which is one less than the number of probes required to address a record, is computed on the basis of a Markov chain model. For the reader not interested in the mathematics, the introduction and the summary should be sufficient.
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Aug 1 1962

Further remarks on line segment curve-fitting using dynamic programming

In a recent paper, Bellman showed how dynamic programming could be used to determine the solution to a problem previously considered by Stone. The problem comprises the determination, given N, of the N points of subdivision of a given interval (&agr;, &bgr; and the corresponding line segments, that give the best least squares fit to a function g(x) in the interval. Bellman confined himself primarily to the analytical derivation, suggesting briefly, however, how the solution of the equation derived for each particular point of subdivision ui could be reduced to a discrete search. In this paper, the computational procedure is considered more fully, and the similarities to some of Stone's equations are indicated. It is further shown that an equation for u2 involving no minimization may be found. In addition, it is shown how Bellman's method may be applied to the curve-fitting problem when the additional constraints are added that the ends of the line segments must be on the curve.
Aug 1 1962

The description list of concepts

A concept is defined as a class of objects whose members can be distinguished by processing its properties. Property is defined to mean a partition of the set of all objects into disjoint classes. The formal definition of a concept is recursive in nature. A concept is described by a list structure. A one-to-one correspondence is established between the recursive definition of a concept and its description list structure. Like the definition, the description list structure of a concept is also built up from elementary list structures by a recursive process. The list structures obtained this way are compared with the description list structure discussed by the author in a previous publication.

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