Drum System for the PDP-1

This document, dated July 14, 1961, outlines the technical specifications and programming requirements for the Magnetic Drum storage system used with the PDP-1 computer. It describes the physical hardware characteristics—including dimensions, rotational speed, and storage capacity—and details the addressing scheme. The document also provides a guide for programmers, explaining the specific I/O Transfer (IOT) commands used to manage data movement between the drum and core memory, as well as procedures for handling parity errors and sequence break actions.