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The principal approaches to random-access file organization and addressing are reviewed in this paper. The review is general, in the sense that it is relatively independent of specific equipment. I n the case of a number of unsettled questions, the author's evaluations of alternatives are included. The relation between sorting and random-access file addressing is clarified by viewing both as belonging to a common class of ordering operations. Basic considerations of both sequential and randomaccess approaches, arithmetical key-to-address transformation methods with their overflow problems, and table lookup methods are discussed. Results of an experimental analysis of key transformation techniques are presented.

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The binary num/)er system offers many advantages over a decimal representation for a higb-perfornmnee, generalpurpose computer. The greater simplicity of a binary arithmetic unit and the greater compactness of binary numbers both contrit)ute directly to arithmetic speed. Less obvious and perhaps more important is the way binary addressing and instruction formats can increase the overall performance.:Binltry addresses are also essential to certain powerful operations which ark not practical with decimal instruction formats.On the other haltd, decimal numt)ers are essential for com-..... muni~a~ing between man and the computer. In applications re-{ quiring the processing of a large volume of inherently decimal input and outi)ut data, the time for decimal-binary conversion nee(ted by a purely t)inary computer may be signifieant. A slower decimal adder may take less time than a fast binary adder doing an a(ldition and two eonversions. A careful review ef the significance of decimal and binary number systems led to the adoption in the IBM ST~:'rc~ computer of bimu'y addressing and l)oih i)inary and decimal data arithmetic, supl)lementcd by eftieient conversion instructions.