Theory
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A comparison of disks and tapes
The principal characteristics of current magnetic disks and tape units are summarized and compared. Some of the characteristics of disk files are illustrated in a sorting example and compared to a tapesort. The conclusion is presented that disk files are competitive to tapes in some important applications.
DATA-DIAL: two-way communication with computers from ordinary dial telphones
An operating system is described which allows users to call up a remotely located computer from ordinary dial telephones. No special hardware or connections are required at the users' telephones. Input to the computer is through the telephone dial; output from the computer is in spoken form. Results of a test with telephones in the Boston area are reported.
An experiment in automatic verification of programs
How effective is a compiler at replacing explicit verification, and what is the cost of this technique?
Character addressable, variable field computers permit ready establishment and manipulation of variable width stacks. Single machine commands may push variable field items down into such stacks or pop them up. The availability of a variety of field delimiters allows the machine to push down or pop up more than one variable width item with one command. Since these stacking operations can be made the basis of compiler decoding algorithms, the proper use of machines of this class for compilation has advantages over machines with fixed-length words.
A contour-map program for x-ray crystallography
A FORTRAN program is described for use with the IBM 7090 system and an x, y-plotter to produce a contour map. A matrix of points evenly spaced in each dimension is contoured. Scale factors along the axes may be different and the axes need not be perpendicular.
Machine calculation of moments of a probability distribution
A method is presented for the calculation on a machine of the moments of a probability distribution, necessitating little more than n additions and n references to memory for each moment, instead of the minimum of n multiplication, 2n additions, and 2n references to memory required by the most straightforward method (where n is the number of entries in the probability distribution). The method is directly applicable when a tabulated distribution exists, as when it has been computed by repeated convolution; but in this case it conserves both time and accuracy.
n-dimensional codes for detecting and correcting multiple errors0
The paper introduces a new family of codes for detecting and correcting multiple errors in a binary-coded message. The message itself is arranged (conceptually) into a multidimensional rectangular array. The processes of encoding and error detection are based upon parity evaluations along prescribed dimensions of the array. Effectiveness of the codes is increased by introducing a “system check bit”, which is essentially a parity check on the other parity bits. Only three-dimensional codes are discussed in this paper, with parity evaluations along the horizontal, the vertical, and one main diagonal. However, the family of codes is not restricted to three dimensions, as evidenced by the discussion by Minnick and Ashenhurst on a similar multidimensional single-bit selection plan used for another purpose [6]. A four-dimensional code, correcting three and detecting four errors, has been developed; the extension to higher-dimensional codes with greater correction power is straightforward.
Inefficiency of the use of Boolean functions for information retrieval systems
In this note we attempt to point out why boolean functions are, in general, not applicable in information retrieval systems.
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