Microtape: Its Features and Applications

This document, reprinted from a 1963 DECUS meeting, provides a detailed technical overview of the Digital Equipment Corporation Microtape system. It describes the physical components of the Type 555 Dual Microtape Transport and the Type 550 Control, explaining the Manchester-type polarity sensing recording technique that ensures high reliability through redundant track recording. The paper details the tape format, including the crucial pre-recorded timing and mark tracks that facilitate bi-directional reading and writing, random access, and precise block/word addressing. It also outlines the programmed modes of operation—Search, Read, and Write—and discusses the available software subroutines for the PDP-1 and PDP-4, along with future development trends for the system.