Serial Drum

This document provides comprehensive technical information for the Digital Equipment Corporation (DEC) Type 24 Serial Drum, a data storage peripheral used with the PDP-1, PDP-4, and PDP-7 computer systems. The manual covers functional and physical descriptions, operating principles, interface specifications, installation and maintenance procedures, programming instructions, and includes a set of engineering drawings. It details how the serial drum stores data in 256-word sectors and describes the NRZ phase modulation recording technique, along with error checking mechanisms and mechanical actuator operation.