Cost, Performance, and Size Tradeoffs for Different Levels in a Memory Hierarchy*

Abstract

Until recently, electronically addressable devices such as ferrite core, plated wire, semiconductor memories, and electromechanically addressable devices such as magnetic tapes, disks, and drums were the few technologies from which a computer system designer could build a memory system. A number of different new technologies and devices have been developed that close the "access gap" <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">14</sup> between the two dissimilar technologies mentioned above. These include charge-coupled devices (CCD's), <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> bubble memories, <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> electron beam addressed memories (EBAM), <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">17</sup> and domain tip propagation (DOT). <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">16</sup> Other technologies like CMOS <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> and integrated injection logic (I <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> L), <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">9</sup> compete directly with the existing technologies. Table 1 (see p. 46) shows the possibility of a six-level hierarchy and some cost and performance projections for these technologies.