Comparison of IBM and Digital Storage Architectures

This document, dated March 29, 1990, provides a technical comparison of I/O storage architectures between IBM and Digital Equipment Corporation. It outlines the evolution of IBM's System/360 to 370/ESA architectures and introduces Digital's Storage Architecture (DSA). The report analyzes the architectural differences, including how each handles storage performance, queuing, and caching. It also provides performance quantifications, such as RPS (Rotational Position Sensing) miss calculations and cumulative delay assessments for various storage controllers, including Digital's HSC and KDM70 models, and the Vail storage element. The document serves as an internal reference for Digital engineering and marketing personnel.